While the title of this publication is the Renewable Energy Review, today we are going to talk about natural gas – a distinctly non-renewable energy resource. Why are we doing this? The reason is simple: It has become increasingly clear to us that natural gas is going to play a major role in global energy systems for several decades to come.

Today, the transition away from fossil fuels towards renewable energy resources is already underway. However, all of the best authorities on the subject agree that this process will not be completed overnight. A wholly renewable energy grid, even in just the developed nations, will take at least a few decades to build.

Here we will discuss the particular properties of natural gas that make it the fuel of choice to interim generation during these key periods of transition towards renewable sources. We will attempt to give our readers an understanding of the broad issues surrounding the accelerating use of natural gas in our world.

What is natural gas?

Natural gas is a gaseous fossil fuel, extracted from deposits in the earth using techniques somewhat similar to those used to recover oil. Natural gas primarily consists of methane, one of the simplest hydrocarbons.

Since the natural gas wells are often remote, there can be vast distances between the point of extraction and where the gas will be stored or used. Continent-spanning networks of pipelines carry the gaseous fuel on these journeys.

Undesired constituents of raw natural gas such as sulphur, water vapour, and carbon dioxide must be removed prior to usage to produce a high quality combustible fuel.

Non-renewable extraction

Natural gas can often be found along side other fossil fuels. Thus many natural gas wells exist near oil shale and coal beds. As with all resource exploration, new techniques have been developed over the years to find and develop deeper, smaller, and more remote reservoirs.

The story of the history of natural gas exploitation is much the same as that of other fossil fuels and resources. It was initially found along with other desirable products such as coal. It proved to be a cheap and plentiful source of energy in its own right. Development sped up over the years as many uses were found for natural gas in areas such as fertilizers, electricity, and home heating.

Just like all other nonrenewable natural resources that humanity has tapped into, natural gas has become harder to find and harder to access over time. We have depleted many of the easiest to access reservoirs and are now searching farther afield to meet our growing demand.

Natural gas extraction is a major discussion point today. The advent of hydro fracturing or ‘fracking’ has led to rapid growth in both the extraction industry and its environmental effects. Debates are currently raging around the world as to the safety of this technique. We will look at the fracking debate in more detail later in this piece.

Renewable sources of natural gas?

Curious what we literally mean by ‘renewable’? Check out our piece about what renewable really means.

Renewable sources of combustible gases exist. These gases are not identical to natural gas, but they share many of the same primary properties. As an example, biogas is composed of methane, hydrogen, and carbon monoxide. Biogas can be produced from a variety of sources, refined, then used in a manner almost identical to natural gas.

How can we make biogas? Almost any system that decomposes (in the absence of oxygen) produces a form of biogas. Thus, there are a variety of potential renewable sources we might tap into. Systems have been set up to harness biogas from animal waste, landfills, and waste water treatment plants to name a few. Cleaning these biogases up to natural gas purity can be a challenging and costly technological effort.

Natural gas prices have historically been quite low. This has hampered the development of renewable gas sources in the past. Today we live in an age of somewhat uncertain natural gas prices and a cultural shift towards green technologies. Biogas is currently seeing accelerated development in many areas of the world as the price of natural gas climbs higher. Additionally, biogas utilization has the advantageous side effect of converting a potent greenhouse gas (methane) into much less potent ones (water and carbon dioxide), and generating usable power in the process.

It would be wise for our society to economically encourage the maturing of various biogas technologies so that a cost effective alternative exists in the near future when natural gas supplies will be falling further behind demand. As demand continues to grow, and extraction becomes more difficult, prices are definitely going to climb. A major question facing our society will be whether we will choose to be ready to make a smooth transition to a renewable fuel gas or a suitable substitute such as electricity produced from renewable sources.

Why is it so important?

Natural gas is used to heat millions of buildings in North America alone. About half of US households get their heating energy from natural gas. ((NaturalGas.org: Residential Uses. Accessed June 17th, 2011.)) In Canada the number is around 56% of all households. ((The ways we heat our homes. Statistics Canada. Accessed June 23rd, 2011.))

The world’s supply of ammonia fertilizer is heavily reliant on natural gas for its low cost production. This fertilizer is primarily produced through the Haber-Bosch process which process utilizes about 3-5% of world natural gas production and is responsible for feeding approximately 40% of the human population. ((“We can thus conclude that the Haber-Bosch synthesis now provides the very means of survival for about 40% of humanity.” Nitrogen and Food Production: Proteins for Human Diets. Vaclav Smil. University of Manitoba. Accessed June 18th, 2011. )) Therefore, a cheap and abundant natural gas supply is a cornerstone of humanity’s food production system.

In short, it is clear that natural gas is currently responsible for keeping large portions of humanity fed and warm.

Natural gas is also seeing increasing use in the area of electricity production. We will now discuss in some detail why natural gas has been so popular recently for new power plants.

Interim power source

While transitioning to a larger share of renewable, clean power sources, we will likely be using natural gas more heavily than ever before. Why is this so?

For those so inclined, a previous issue of the Renewable Energy Review was written about all of the important properties of power system technologies. This is a highly recommended read for anyone interested in attaining a solid understanding of electric power systems in general.

A proven technology

Natural gas turbines are an existing and proven power production technology. They have been adapted to a variety of scales, from small district heat and power systems to multi-megawatt turbines capable of providing a large portion of the grid power.

Low Cost

When compared to other sources of power, natural gas turbines tend to have the lowest setup cost. A turbine can also be purchased and installed in a matter of months, making natural gas one of the fastest power systems to set up.

The majority of the cost of natural gas power comes from the cost of the gas itself. This makes the cost of power highly dependent on the daily, monthly, or yearly price of natural gas. Many power companies will own and operate natural gas storage facilities so that they can avoid some of this price uncertainty.

Cost-effectiveness is not true everywhere. The costs of transporting natural gas long-distances can be very substantial. Natural gas is quite expensive in California for instance. We discuss the particular situation in California in much more detail later in this piece.

The cost effectiveness of natural gas power has another major limitation. The turbines that can respond quickly to demand (which we discuss in the next section) are inefficient compared to their slower-responding brethren. This means that their cost of operation can be very high for a given amount of power. This typically means that natural gas peaking power generation cannot compete very well in terms of cost against established hydroelectric power if it exists locally.

Dispatchable power

Natural gas power can be implemented in such a manner that it can be ‘turned on’ in a relatively short amount of time. Thus natural gas power is regarded as being ‘dispatchable’. In another piece we go into a lot of detail about why dispatchable power sources are so important and the many niches that need to be filled in a functioning grid.

In short, natural gas power is there when you need it.

However, as we mentioned earlier, the natural gas turbines that can turn on and off the fastest are the ones that are the least efficient. That is, they produce less electricity from burning the same amount of natural gas as their slower-responding cousins. Turbine designs thus face an inevitable trade-off between responsiveness and the price per unit of energy produced.

Natural gas power plants are designed to fill particular roles in the power grid. There is a lot of flexibility with regards to what those roles can be at the design stage. However, once a plant is built and operating, it is essentially locked into its role. This is why natural gas power plants need to be designed carefully, keeping in mind the nature of power that they are expected to provide.

Less C02 emission than coal

Power production using natural gas produces 45% lower carbon emissions than coal per unit energy. This is because coal is almost pure carbon while natural gas contains a lot of hydrogen in addition to carbon. Both of these elements combine with the oxygen in the air to produce energy as they burn.

These lower C02 emissions are an important reason why natural gas has been an attractive choice in the developed nations as the evidence of climate change continues to mount. Readers interested in the climate change debate may be interested in the climate change section of our deliberate societal change publication.

Cogeneration / waste heat

Since natural gas power is thermal in nature, it produces a lot of waste heat. This waste heat cannot be effectively used for more electricity production, but it can be economically used for heating buildings and running industrial processes. This use of ‘waste heat’ for productive purposes is known as cogeneration, and it is possible with all thermal power plants including coal, nuclear, solar thermal, biomass, biogas, and geothermal.

Storage

It is very hard to store electricity. This is such a difficult and important problem that we devoted an entire issue of the renewable energy review to looking at why energy storage is useful.

Natural gas can be stored rather easily in certain geological formations (including those from which natural gas was first extracted). It can then be piped out and used when it is needed. This is a form of energy storage.

Natural gas can be extracted throughout the year and stockpiled for use during times of great energy need. This is currently the case during the winter in North America for example. During this time, natural gas is burned much faster than it is extracted.

Synergy with renewable power sources

One of the key weaknesses of renewable energy is the highly variable nature of wind and solar energy production. For more information, see our renewable energy review issue on the variability and dispatchability of renewable energy sources.

Some of this variability is relatively predictable such as daily tides, daily / weekly wind forecasts,  monthly river flow estimates, or annual direct sunlight. Each resource has its own level of predictability.

Similarly, different forms of electricity demand (such as heating, lighting, or industrial usage) can be somewhat unpredictable on different time scales. Uncertainty both in supply and demand of power is currently met primarily using dispatchable power sources, such as natural gas turbines.

The flexibility of some natural gas power plant designs allows them to fill in when renewable energy sources are producing low amounts of power. A popular version of this is the idea of leveraging dammed hydro to use wind power.

Additionally, natural gas can be used in conjunction with heat-based green power systems like biogas, biomass, or solar thermal. Solar thermal can provide the heat to run a power plant during times of steady sunshine. When the sun is hidden by clouds, or at night, natural gas heating can kick in to keep the power production smooth and steady. These ‘solar-gas’ power plants may soon be widespread in the sunniest regions of the globe.

The fuel supplies for biomass/biogas can be somewhat uncertain. If natural gas can affordably fill in the gaps in their supply, then biomass/biogas power plants will be possible in many more locations than they are currently. This increased reliability would certainly also help with the acquisition of venture capital for these renewable projects.

We are fortunate that natural gas power has a healthy mix of the advantages of coal power and strong synergy with renewable power sources.

Better than coal, but…

Better than coal isn’t saying much. Of all major electricity production systems in existence, coal is the most damaging to humans and ecosystems. For a more complete picture of this subject, see our piece about just how bad coal really is.

We will now begin to look at some of the major downsides of our societal shift towards natural gas.

In the next section we will attempt to spell out a number of adverse effects that we think should be considered when a natural gas power plant is being proposed. It is important to note that many of these are systemic rather than local concerns. A single natural gas power plant in one place might not pose that much of a problem either locally or regionally. However, a national or international shift towards natural gas as a fuel for electric power generation will create a number of major problems and exacerbate others.

Volatile prices

Before dealing with some of the other effects of our increased natural gas usage, we will first discuss the volatility of natural gas prices. A variety of factors contribute to the instability of natural gas prices. One of the more obvious ones is weather. A cold snap across North America could increase demand immensely in only a few days.

Pipelines are another important concern. If a region begins to demand more than the capacity of the pipelines into that region, then the price can skyrocket. A rather telling example is that of California in the last dozen years or so. In 1999, California produced about 50% of its electricity using natural gas. In 2009, it produced 60%! ((US Energy Information Administration. California State Electricity Profile 2009. Accessed June 19th, 2011.))  Now, take a glance at these natural gas prices in California over the last couple decades. You can see the cost of a standard unit of natural gas (1000 cubic feet) go from between $2 and $3 in the late 1990’s to $6 to $8 in 2004-2008.

This is a rather spectacular change in price for a major commodity. Demand was going up and the pipelines did not have the capacity to match. It is important to note that the California example is not a small incident. California has a population of about 37 million people and is the 8th largest economy in the world. ((MSNBC. Sorry Arnold, California isn’t sixth any more. Accessed June 19th, 2011.)) What happened to California can also certainly happen to other regions with limited local resources and a constrained ability to import.

The high volatility of natural gas prices in Canada is also startling. Canada produces far more natural gas than it consumes. In Canada, the most major issue is its extensive connections to other markets. Much of this natural gas is exported to the United States for their heating and electricity needs. A relatively small change in demand in the United States is likely to mean a relatively large change in the amount of natural gas that Canada can export. Thus demand volatility is driven to a great extent by the price volatility in the much larger market of the United States.

Staying warm

We mentioned earlier that natural gas is already used very heavily for heating buildings. Extensive infrastructure already exists to deliver it directly to most of these buildings. If natural gas prices are pushed high(er) by electricity production, then it may hasten the end of the usefulness of this infrastructure. We must be aware that this is a definite effect of greater use. Greater demand of a resource with a constrained supply leads to an increase in price of the resource.

North America is currently importing some liquefied natural gas from overseas to serve current demand on this continent. ((The natural gas in North America : USA, Canada, Mexico.  Thomas Chaize. Accessed June 19th, 2011.)) The price is likely to go up quite a bit if demand continues to increase quickly. Home heating will become more expensive. The brunt of this cost increase will be felt by the people who live in the coldest climatic zones of North America. Similar problems exist in some other regions of the world such as Europe.

As natural gas becomes more and more expensive, using it to heat buildings becomes less and less economical. This can create an additional burden on those regions that are heavily reliant on it for heating. Transitioning to a different form of heating is expected to be quite costly. This transition will likely be extremely expensive as well as disruptive to the economy. Unless another cheap gaseous fuel can be produced in spectacular quantities, there will have to be substantial new infrastructure to handle the form(s) of heating energy intended to replace natural gas.

Even if there is simply a transition towards electric heating, there will be very substantial costs. Most cold regions of North America utilize a lot of natural gas heating currently, so their electric grid connections are not currently designed to handle the tremendous additional electrical load needed to heat homes in addition to powering them. Upgrading power transmission infrastructure tends to be very expensive. Also, this transition would increase demand for electricity immensely. This is a non-trivial problem in its own right, and an extremely expensive one at that.

We are consuming the natural gas that is easily recoverable. Burning even more of it to produce electricity will hasten the end of cheap natural gas. We as a society may want to think long and hard about what we plan to do about heating our homes a few decades from now.

Compound effects

Because natural gas is a such a popular form/source of energy, increases in its price will cause compounding effects on the prices of other vital goods and services. For example, the prices of natural gas and electricity are correlated. When natural gas prices spike, people consider using electricity for heating instead. However, since much electricity is derived from natural gas (more in some regions than in others), then the cost of this heating substitute goes up as well.

We see similar effects in the world economy when one of the world’s other major energy sources increases substantially in price, oil. Because the world transportation infrastructure is  so highly dependant on oil, increases in the price of oil drive up the cost of everything that relies on our cheap globalized economy. Not only does the price of shipping plastic goods from Southeast Asia increase, but the cost of raw materials used to produce those goods increases as well. Therefore, an increase in the price of one important form of energy can have an alarmingly inflationary effect on prices in general.

In Canada, very large amounts of natural gas are used to heat bitumen in the Alberta oil sands project. A rise in natural gas price would cause an increase in the cost of oil produced through this method. This could lead to a rise in oil prices in North America that will lead to a corresponding rise in fuel prices.

If the price of natural gas were to rise sharply the price of your electricity, your home heating, your car fuel, and your food would increase as well. These are likely outcomes if our society continues to rely more and more heavily on natural gas in the coming decades.

Geopolitical concerns

Many areas of the world do not have substantial domestic natural gas resources. Some of these, such as the United States and Europe, do not extract nearly enough natural gas to meet their domestic needs. These places need to import substantial amounts to meet their demand. Due to this effect, a number of nations and regions are gaining increased geopolitical influence through their control of natural gas exports.

North America

The United States currently imports natural gas from a number of places including Canada, South America, and the Middle East. North American supply is increasing (thanks mainly to fracking, discussed below), but it is not expected to meet the rapidly growing domestic demand. It is expected that overseas imports will increase to around 11% of all natural gas consumed in North America by the year 2020. ((Natural Resources Canada. Canadian Natural Gas: Review of 2007-2008 & Outlook to 2020. Accessed June 21st, 2011.))

Europe

Another important geopolitical situation is that of Europe. About one quarter of Europe’s natural gas comes from Russia. ((The Oil Drum. The European Gas Market. Accessed June 21st, 2011.)) On Jan 1st, 2009, Russia cut off shipments to Europe. Note that this date is during the European winter, so temperatures were quite cold across the region. Thus gas demand was quite high and inflexible – people don’t like being cold! This move set off a series of intense negotiations and technological scrambles as Europe desperately tried to make ends meet. This situation highlighted the tremendous bargaining power that Russia now wields over the EU in particular. ((USA Today. Cutoff highlights Europe’s reliance on Russian natural gas. David Lynch. Jan 8th, 2009. Accessed June 21st, 2011.)) ((MSNBC: Europeans shiver as Russia cuts gas shipments. Jan 7th, 2009. Accessed June 21st, 2011.))

Interestingly, many predictions state that European reliance on Russian natural gas will continue for at least a decade. European domestic production is expected to fall while demand continues to rise. It is also worth noting that Europe draws a tremendous amount of natural gas out of Northern African countries like Algeria. The future of natural gas in Europe appears to one of high prices driven by demand that far outstrips domestic production. It is expected that their supply will rely heavily upon overseas trading as well as Northern Africa, the Middle East, and Russia.

Hard to replace

If we are going to invest spectacular amounts of money in heating, industrial, and electric power infrastructure, we definitely want to use it as long as we can. It seems reasonable to assume that some of the natural gas infrastructure that exists today will outlive the era of affordable natural gas. In a few decades time, natural gas will no longer be a cost-effective solution for all of the things we currently use it for.

What will we replace it with? Ideally we would have a fuel that is very similar so that we could use much of the existing infrastructure. Biogas is certainly a candidate for this job, but it is very unclear how much biogas we are capable of producing, and how cost-effectively it can be done. On a planetary scale, if we are limited to current technologies then it does not seem possible for biogas to literally pick up where natural gas leaves off. We consume too much natural gas to feasibly replace it with any similar gaseous fuels that we can make today.

Monopoly corporations

The middle steps of the natural gas system (refinement and distribution for example) are controlled by a few corporations. In most locations, natural gas pipelines are a natural monopoly. That is, it is infeasible for there to be multiple players on the market. The costs of building and maintaining a pipeline network are simply too high for redundant infrastructure to be feasible in most places. Only in densely populated or highly industrialized areas is there genuine competition among pipeline networks.

This centralization of power can be problematic. The energy industry is often very carefully regulated to ensure that natural monopolies cannot overly misuse their power. However, the push for deregulation has in some cases been successful. Deregulated energy markets are the prime cause of some major problems such as the California energy crises of 2000-2001. In these situations, corporations exploited the weak regulation to make enormous amounts of extra money off the society that they were supposedly serving. In a practical sense, it is very clear that the California crisis cause enormous damage to the Californian economy and inconvenienced tens of millions of people.

Dangers of Production

Natural gas kills more people per unit energy than wind, solar, and nuclear, but far fewer than coal and oil. ((Lifetime deaths per TWH from energy sources. NextBigFuture. Accessed June 23rd, 2011.)) These statistics include workers and civilians who die in accidents as well as members of the general public who die from pollution. While the claim ‘better than coal’ can still be made, it can be sobering to think that our energy system choices have a fairly predictable effect on the number of deaths that our energy system as a whole will cause.

Fracking

Much of the recent increase in natural gas production can be attributed to the exploitation of new drilling and extraction techniques. Primary amongst this new set of technologies is hydro-fracturing, or ‘fracking’.

Natural gas in the ground is often found to be bound up in disconnected, non-porous rock formations. Some of these pockets are quite large but most are small. Natural gas drilling has traditionally targeted and extracted from these large, economically attractive reserves. Hydro-fracturing is used to connect these small pockets and increase the amount of natural gas that can be extracted from a single site.

Hydro-fracturing is the pumping of water, sand, and a variety of chemical agents at high pressure into a natural gas site. The rock formations shatter and pockets connect, allowing for the natural gas to flow more easily. The natural gas can then be extracted more economically and for a longer time. Sometimes this is done at new sites, and sometimes at natural gas extraction points that were previously abandoned as uneconomic due to the geological properties of the remaining reserves. With hydro-fracturing, new and old reserves alike can produce large quantities of natural gas in addition to the gas that could be extracted conventionally.

So, hydro-fracturing sounds awesome!

Not quite, there are a number of major concerns about its use.

Concerns

A number of communities and citizens in areas near hydro-fracturing sites have complained that the process is contaminating their land, streams, rivers, and aquifers. It is claimed that this contamination consists both of hydro-fracturing chemicals, as well as natural gas itself.

Legally, it has been claimed that whether or not contamination is occurring is a moot point in the United States. The Safe Drinking Water Act of 2005 contains a loophole, sometimes called the “Halliburton Loophole” which stripped the EPA of its authority to regulate hydraulic fracturing. The regulatory battle over fracking bears many similarities to the current regulatory battle over coal fly ash in the United States. These regulatory wars could be summarized as follows: Relatively weak regulation of the byproducts of fossil fuel extraction, refinement, and usage is creating a situation in which long-term harm is being done to both human and ecosystem health. Some of the more obvious problems are contaminated water and air as well as giant quantities of fly ash. On the economic end of things, this lack of strong regulation acts as an effective subsidy for these industries since they do not have to pay for the full ‘costs’ of their activities. These costs will continue to be paid in human lives, health bills, and ecosystem destruction now and into the future.

Here we will try to focus on the relevant physical concerns and not the broader governmental and regulatory issues that have prevented effective regulation of fracking. We plan to discuss this subject in much more detail in a future publication.

The process of contamination

Natural gas and the chemicals used in fracking are contaminants for drinking water. However, this has been particularly difficult to prove (in the case of the fracking chemicals) because drilling companies claim that their mix of chemicals is proprietary knowledge, therefore they refuse to divulge the list and proportions of chemicals used. Despite this, studies have been conducted on contaminated water, looking for distinctly man-made pollutants. This process has been aided by some court cases which have forced drilling companies to reveal some information about what chemicals they use in their formulas.

Drilling companies also claim that it is impossible for these chemicals to migrate from the deep reservoirs where they tap natural gas into the near-surface aquifers used for drinking water. Despite there being some practical merit to these claims, there are some good reasons to believe that contamination is possible. Conventional drilling does not generally shatter large quantities of rock and rupture the barriers between sealed underground formations. Hydrofracturing however does both, so it is reasonable to expect that the dangers of groundwater contamination are much higher than with conventional techniques.

Natural gas reserves are generally far below the fresh water aquifers used for drinking water supplies. Hydro-fracturing can affect these aquifers in at least two ways.

1. The fracturing process can create routes by which natural gas can migrate upward through other rock formations into the aquifer.
2. As with all natural gas wells, poor cement work can sometimes allow natural gas to migrate back up the original well shaft. Even if the drillers produce the first and only connection between these deeper gas-bearing formations and near-surface aquifers, this connection can form a migration path for natural gas to enter the aquifers.

Conclusion

A perceptive reader will have noticed that one of the underlying themes of this piece has been cautioning against over-investment in natural gas infrastructure. Shifting a large proportion of our energy demands onto natural gas is not a long-term solution and it is likely to cause a number of major problems. Instead, we should make wise use of our natural gas resource in transitioning towards long-term energy solutions. With intelligent use of the natural gas that remains, we should be able to transition relatively painlessly into a renewable energy future.

Natural gas can be a useful platform that will help us build the next generation of energy infrastructure. A wholly renewable energy grid is the only true long-term solution, and that is where we must aim with our policy decisions.

If we fail to take note of these burgeoning problems with regards to our increasing reliance on natural gas, we will be driving our society towards a painful and costly period of rapid and intense adjustment that will destabilize almost every aspect of our lives. It is our firm belief that these concerns should lead our societies to begin actively planning for the end of the age of natural gas and how to gracefully incorporate it into our transition towards renewable energy sources.

The first section of this piece will be a look into the major areas of knowledge that our writings in the year 2010 dealt with. Listed with brief summaries are:

1. all the issues of the Renewable Energy Review
2. the major energy technologies we chose to investigate deeply (including solar PV, solar thermal, nuclear fusion and nuclear fission)
3. the ideas in social innovation for a better energy system that we advocated for the year 2010 and beyond.

The second section will look at some of the new work that we have been exposed to in the last month regarding developments in both renewable energy technologies and deployment. For the first time, this publication will resemble a Blog Carnival. A number of these articles are submission to this carnival, but several have simply been found by us during our readings. We hope you enjoy them.

A look back at 2010

Renewable Energy Review

Progress and potential of renewable energy

The first issue of the Renewable Energy Review was intended to be a broad introduction to the field of renewable energy development. First we look at what ‘renewable’ means in some detail. We draw a clear distinction between energy developments that are labelled as ‘green’ and those that are distinctly renewable. Then we go on to dig into the different forms of renewable energy that are available to us on the earth (Hydroelectricity, Wind, Solar, Geothermal, Biomass, and Tidal Power). In each case we attempt to outline the potential, problems, and feasibility of each energy resource.

Why electrical energy storage is useful

There are a number of important reasons why energy storage systems are desirable for power grids. Thanks to their generally very fast ramp-up times, energy storage systems can be utilized in order to stabilize the grid, a very valuable role. We detail a number of the distinct roles in which energy storage systems can be deployed in the power grid. Lastly, we look at a few exciting developments in the area of energy storage: compressed air storage and gravel-argon heat batteries.

Types of hydroelectric power: How do the dam things work?

Hydroelectricity, or ‘hydro’, is generated from the energy in the water cycle of the earth. In this piece we look in detail at the numerous forms of hydro power. We focus on dam-reservoir systems, pumped hydroelectric energy storage, and run-of-river hydro. We also look briefly at the idea of hydro dam uprating, an idea that will help maximize the ability of hydro to fill the role of a dispatchable peaking power source. The dispatchability of hydro makes it very special among the renewable energy technologies currently available.

Land use of coal vs wind: Still room for debate

Land usage for power systems is a common comparison metric, touted most prominently by energy expert Vaclav Smil. In this piece, we examine the land use arguments for two energy systems: coal and wind. While land usage is a useful metric for examining power systems, great care must be applied when conducting such analyses. We go into detail about how comparing coal and wind on the basis of this metric alone will lead to a very distorted perspective on the land usage and feasibility of these two power systems.

How can renewables deliver dispatchable power on demand?

A crucial discussion with regards to the viability of a renewable power grid is the fact that power must be there when you need it. Dispatchable power plants are those that can be turned on and off essentially at will, and on relatively short time frames. Power systems of this sort play a crucial role in our power grid. In this piece we look in detail at how this is done currently, and which forms of renewable energy can fulfill this role. In closing, we look at a number of other technological solutions to this problem.

Feed-in tariffs: A fitting policy for renewable energy

A feed-in tariff is a policy mechanism for stimulating development of specific power systems. While these policies have a common overall structure, it is possibly to tailor them to the specific needs and resources of a geographic region. In this piece we look at the various facets of a feed-in tariff law, and also conduct an overview of how effective feed in tariffs have been at stimulating the renewable energy industry around the world.

Power system performance metrics

Everything has its price. Every form of power production has costs in dollars, time, land, materials, pollutants, greenhouse gas emissions, and human deaths. We look at the most important factors for analyzing the feasibility of a proposed power project. Considering only some of these factors will inevitably lead to an incomplete picture of power system costs and abilities. We believe that every proposed power system should be scrutinized according to all of these criteria, as all of them can be crucially important to our society.

Demand side management to help build a renewable power grid

Demand side management helps make our power grid more cost-effective and aids in the transition towards renewable energy. It can also be considered as a very green policy on its own, as it reduces the amount of power we need to produce, and thus our impact on the environment.

Major Technologies

Solar Thermal Power

Solar thermal power generation presents a unique opportunity among renewable technologies today. Prototypes and commercial power plants of this sort exist. It has capabilities for both baseload and peak-matching power generation. Lastly, it is very affordable in locations with lots of sunlight. Costs are in the range 10-15¢/kWh currently, with great potential for the near future.

Solar power from photovoltaic panels

Photovoltaic (PV) solar power is the technical term for solar panels that convert sunlight directly into electricity. In this piece we look into the various advantages and disadvantages of this power system. While PV installations can be put almost anywhere and scale almost perfectly in size, it is important to notice that their efficiency is heavily influenced by location. PV is still rather expensive, and some types of installations suffer from notable disadvantages in terms of land usage and aesthetics.

How can we create power from nuclear fusion?

Achieving sustained nuclear fusion for power production is incredibly challenging. Scientists have been working on this problem for decades. This piece is an overview of the basic concepts and technologies needed for nuclear fusion power. One could also view this as a tutorial, or a crash-course, in fusion power. Following the publication of this piece, we wrote a series of articles (all linked from within this introductory piece) detailing in much more detail the exciting developments in fusion power.

Social Innovation

Publicly Administered Green Energy Futures

Our goal is to keep our physical power infrastructure publicly owned, but gain some of the advantages of the private sector. The key to our recommendation is voluntary public investment from the people of Saskatchewan. In order to stimulate new renewable energy construction, we recommend that SaskPower open up renewable energy projects for direct public investment.

Personal and social change for a green energy future

The question is: what can we do to be more in harmony with the environment? The answers we present here are intended to be practical pieces of an answer to that question. We look at a few distinct categories of development towards a green energy future: personal energy conservation, green buildings, buying ‘green power’, personal power generation, investment, political pressure, education, and activism. This article should give you a deep look into what we believe it means to live green.

Specific Issues

Is nuclear fission power renewable?

The long term supply for nuclear fission fuels on the planet earth is estimated to last several thousand years at current consumption levels. This assumes that we adopt reprocessing as well as develop and implement breeder reactors. This discussion is inextricably caught somewhere between the factual and the possible. We regard status-quo nuclear fission as non-renewable, but that does not mean that fission should play no role in our present and future. Most importantly, we know that the potential for fission power goes far beyond what our current plants can do. With careful development and steady support, nuclear fission can be an incredibly valuable long-term energy resource for humanity.

Misconceptions spreading about the price of solar power

A recent Clean Technica article said that solar power would be cheaper than coal if it received the same subsidies. This is incorrect, and we show just how incorrect it is in this piece.

A look forward

Here is a collection of some of the things that have leaped at us off the news pages in the last couple months.

Framing the question of sustainable development

Building on the analogies of ‘push’ and ‘pull’ resolutions, which represent forced legislation and voluntary action respectively, this author brings up what we think is an important point about sustainable development.We have written in the past about voluntary and communal efforts towards sustainability because we consider these efforts to be the most effective at creating genuine change in our society. Coercive measures such as law might be inevitably necessary in order to preserve a semblance of balance with nature, but these measures can be less than ideal.

Fuel-cell bus research seeing some support

Public transit systems are often at the forefront of transportation technology. We hope to see continued innovation of mass transit systems in cities. In North America the roads are still of prime importance, and that is where most of our public transit takes place. A fleet of buses is often the mainstay of a public transit system. In other areas of the world there are extensive systems in place that are arguably much more efficient such as streetcars, light rail, and subways.

Whether fuel-cells will prove to be economical in the short term is another question entirely. There are reasons to be critical of hydrogen fuel cells, including their relatively low energy conversion efficiency. Despite these problems however, ongoing research into energy storage techniques such as this will continue to intensify well into the next decades.

Hydrofracturing

Hydrofracturing (colloquially known as frac’ing or fracking) is a technique for extracting large amounts of natural gas from the ground quickly and cheaply. It has garnered a great deal of attention over the past few years because of the vast effects it is projected to have on our health, our environment, and our energy future. While our society might expand our reserves of recoverable natural gas, we will have to deal with consequences as extreme as having tap water that can be ignited (due to contamination of ground water). We expect many new developments regarding this controversial technology in the upcoming year.

Recently, the EPA has begun a review of this technology as activists and excellent documentarians, such as those behind Gasland, have let their voices be heard. It has been shown to cause damage aquifers, releasing hydrofracturing chemicals and natural gas into water supplies. This technology will either become greatly more widespread and its destruction more evident, or become strictly regulated to maximize the value it can deliver while minimizing risks.

Already there is rising resistance to this technology as major municipalities in the United States ban fracking. We feel that over the next year which path has been taken will become apparent. For a good read on fracking in North America, with particular attention being paid to British Colombia, check out this excellent piece at straight.com called Hydro-fracturing has a lucrative dirty secret.

CCS

Carbon Capture and Sequestration (CCS), refers to a variety of technologies for capturing carbon and storing it permanently. Typically these systems are intended for use at point sources of C02 such as coal power plants and will be coupled with deep geological storage techniques including enhanced oil recovery to make it more economically feasible.

CCS is already a hot topic in energy discussions. Many people feel that it is an absolutely crucial technology to develop and deploy. Without it, they argue, we are doomed to push the C02 parts per million (ppm) in the atmosphere substantially higher than we would if we successfully capture and store most of our fossil fuel C02 emissions from power plants.

There have been some crucial questions however about the viability, costs, and efficiencies of CCS systems. Many of these questions are still very much unanswered. It remains to be seen in the next few years whether cost-effective CCS can be implemented on a large scale. Additionally, there remain a number of crucial questions about the effectiveness of deep C02 storage. The next section briefly discusses some effects which are believed to be due in part to a C02 sequestration test site.

Carbon Dioxide leaking out of ground in Southern Saskatchewan

Near the carbon capture and sequestration pilot project in Saskatchewan, a couple has noticed bubbling ponds, algae blooms, and dead farm animals. A consultant was brought in to ascertain the causes, and discovered that C02 seems to be bubbling up from underground.

This may be a very problematic finding since there have been high hopes of storing very large amounts of C02 in the Williston Basin area. CCS would be an extremely useful technology for speeding our society’s transition towards a carbon neutral society. If C02 is found to be leaking upwards from this test site however, it may cause a paralyzing effect on the continued experiments and research. It is important to note that significant quantities of C02 leaking into low-lying areas can be a health hazard for humans, even causing deaths in the past through events like the Lake Nyos disaster. A deeper investigation of these events is underway, and is something we will be watching out for with great anticipation in the coming year.

Carbon Taxes

Anyone who takes an interest in renewable energy, climate change, or global warming will be familiar with the idea of a carbon tax. Make the carbon polluters pay for the amount they are contributing towards climate change. The financial burden on polluters would thus raise the economic competitiveness of low-carbon forms of power such as wind and solar.

Carbon taxes have been deployed in many jurisdictions around the world. This debate is likely to reach a fever pitch in the next few years in places such as the United States. The Republican party has made it clear that they do not believe climate change is happening, so they will likely resist any proposed carbon tax.

Climate Change Debate

The scientific consensus on climate change continues to be strong, but the media continues to cover the subject as if it is a debate with two equally valid sides. Climate change scientists have made continual efforts to improve their methods of discussing these issues with the public.

It has increasingly become clear that the climate change ‘debate’ in the media is non-accidental. This stance of equality and uncertainty is being deliberately created by organizations that have a vested interest in the status-quo of carbon emissions.

These companies control a very substantial portion of the world’s money and industry. Corporations are entities that will try to protect themselves from things that will affect their profits. In this case there is a negative externality in the form of climate change that they do not want to take responsibility for. This has led to the anti-climate change think tanks and lobby groups to be very well funded. For more information on this subject, you might be interested in our piece on how to change your society, in which we wrote a section about the climate change meme war. Another excellent resource is the DeSmogBlog and its highly-regarded book, the Climate Cover-Up.

This debate seems likely to intensify in the coming years. As the battle becomes entrenched, the minds of the citizenry of the world become the battleground. We encourage anyone taking an active interest in this issue (from either camp) to read more on this issue. A person cannot become a climate expert overnight, but any of us can garner a lot of broad understanding by reading what the experts have to say on the matter.

Greenland ice sheet melting at increased rate in 2010

The summer of 2010 was unusually warm in Greenland. It also started exceptionally early and ended exceptionally late. This paper outlines some of the observed mechanisms of the increased melting, including a decrease in the ice/snow albedo effect – which is essentially the reflectivity of the surface. A lower reflectivity means that more energy is absorbed, leading to an increased rate of melt.

Renewable Energy Review in 2011

In the year 2011, we expect to be publishing new issues of the Renewable Energy Review on a monthly or bi-monthly basis. The uncertainty in this claim is due to our extensive time commitments in other areas such as work and school.

In the context of electricity, demand side management is the deliberate modification of consumer demand for power through various methods such as fiscal incentives or education. ((Wikipedia: Energy Demand Management. Accessed December 7th, 2010.)) These efforts are traditionally undertaken by governments, utilities, and interested non-governmental organizations.

Today, demand side management generally means an effort to reduce overall demand, or to move demand to different times. In the past however, demand management was often undertaken to encourage increased consumption.

In this piece, we examine why the focus of demand management has changed in the last several decades. We will also look at some specific tools that are currently being used to reduce demand or shift it to different times. In closing, we will discuss why this topic is of such importance with regards to renewable energy.

Why now, but not 50 years ago?

Demand side management is being avidly pursued today for many reasons. These reasons range from economics to pollution to climatology. We will begin first with a look at the reasons why policies intended to do exactly the opposite thing were advocated in the past.

The history of electrical power production has been marked by reductions in real price (inflation adjusted) as the technology and economies of scale improved. So as time passed, a given amount of electricity cost progressively less to produce.

As new power generation was added, more consumption was encouraged for at least two major reasons:

1. Investors who had created power plants wanted to see their commodity (electricity) valued highly, so they encouraged greater power usage.
2. Energy usage is usually strongly correlated with economic growth. In planned (or mixed) economies there were often significant subsidies on energy resources because of the powerful stimulating effect that low energy prices can have on an economy. ((Wikipedia: Energy demand management. Accessed December 6th, 2010.))

To put it in another way, in the past there were clear reasons for governments and many corporations to encourage greater power usage. We live in a different world today. The future of electricity is looking to be quite different from the past in this regard.

While real costs of electricity production historically fell for many decades, they are expected to rise in the coming decades. Also, the normally strong connection between increasing energy usage and increasing wealth is becoming very disputable, especially in the richest nations in the world.

Energy usage and wealth diverging?

As a simple illustration of why this may be so, see this Gapminder graph of Energy Usage per person in tons of oil equivalent (toe) vs wealth per capita. The trend of the points near the left (poor) side of the graph rise steeply, indicating that increasing energy usage and increasing wealth are correlated. However, at around 4 boe per person you can see that the trend seems to flatten out substantially and becomes much more random. This is an indication that increasing energy usage stimulates developing economies more than developed ones.

Let us be clear that this is not proof that increasing energy consumption in rich nations is unrelated to economic growth. Recent studies have demonstrated that increasing energy consumption in OECD nations does cause some economic growth. It certainly appears though that there are diminishing returns as humans use more and more energy. Wealth and well-being are becoming increasingly de-coupled from energy usage as nations become more advanced.

This makes sense when looking at the aggregate perspective: The poorest countries of the world cannot easily afford heating, roads, and industrialized food production. The developing nations of the world are still building the infrastructure to meet their basic needs. Conversely, the industrialization of the richest countries in the world has slowed or even reversed.

The rich world has met its primary infrastructure needs for now, and can be regarded as being in what we might call ‘maintenance mode’. This is not to say that we are merely maintaining existing infrastructure. We are also not claiming that the industry in rich nations is stagnant in any way. We are merely saying that in order to continue to meet and even exceed our basic needs in rich nations we do not need to industrialize our society more than we already have.

Policy changing to reflect the new facts

What does all of this mean from a policy perspective? It no longer makes sense for governments of the developed world to encourage their people to consume more power. When it is clear that using our energy more efficiently contributes more to our economic well-being than producing more energy, policy recommendations are clear.

Around the world there has been a movement towards policies that encourage energy efficiency. Here are some general categories that these policies fall into:

1. Subsidies, rebates, or tax-deductions for appliances, homes, and vehicles that meet energy-efficiency standards.
2. Power rates that escalate with increasing consumption. That is, someone who uses twice as much power as you do per month will pay a bit of a premium per kilowatt hour.
3. Time of day pricing of electricity or a ‘smart grid’. Since peak electricity costs so much more to produce, charge people more for their consumption during peak times. The implementation of time-of-day pricing tends to encourage the shifting of power usage away from peak times as well as a general reduction in demand.
4. Dispatchable demand management, or dispatchable loads, are programs through which people or companies can allow some of their appliances or machinery to be shut off by a signal from the grid operator. If you don’t know what the term ‘dispatchable’ means in the context of power generation, you may be interested in reading another issue of the Renewable Energy Review which deals with dispatchable power from renewable sources. We go into more detail about dispatchable demand management later in this article.

The cost-effectiveness of energy efficiency

It has been found that one dollar used to increase the energy-efficiency of our society can save about two dollars that would have needed to be spent on new power production equipment or fuel. ((Renewable Energy and Energy Efficiency: The Solutions to Climate Change. Beyond Nuclear.org. Accessed December 7th, 2010. )) This is particularly noticeable for demand management techniques that reduce the peak power usage, since peak power tends to be vastly more expensive than baseload.

How big of an overall effect can these policies have on our power grids? The EPA in the United States estimates that over 50% of projected load growth before the year 2025 can be avoided with energy efficiency policies. ((Understanding Cost-Effectiveness of Energy Eficiency Programs. United States Environmental Protection Agency. December 7th, 2010.))

Time-shifting vs demand reduction

Important to note that peak demand management generally does not reduce the amount of energy used, it merely moves it to another time. We can think of this as shifting the consumption away from the expensive sources used at peak times toward the lower-cost sources that provide power at off-peak times.

Demand side management in general however can reduce the energy used. For instance if the government or utility created small rebates for CFL light bulbs and energy efficient home construction or retrofits, these efforts would lead to a reduction in the total energy demanded.

Time of day pricing: Low hanging fruit

Exposing consumers to some degree of price fluctuation to reflect generation costs has the effect of flattening the demand curve. The introduction of time-of-day pricing tends to reduce the demand for electricity during peak times, and distribute some of the displaced demand to other times of day.

Normally power users are relatively inflexible with their power use. However, today we are empowered by technologies that can manage consumption based on energy market prices. It is even possible to inexpensively hook up almost every appliance in a home to a central system that can turn them off at high-cost times.

Energy intensive industries

For example, many energy-intensive industries try to consume all of their power during low demand periods when electricity is produced at a very low cost. Energy intensive industries were early adopters of this practice for several reasons.

1. They can have a major effect on the grid, so power utilities would often create contracts with them regarding cooperation for a more stable and cost-effective power grid. Big energy users generally have to negotiate unique contracts with their electricity providers. Often these contracts include fiscal encouragement for off-peak power usage and dispatchable load. If you don’t know what dispatchable load is, we go into it in more detail later in this document.
2. Energy intensive industries tend to be very conscious of where their electricity is going, and when it is being demanded. This is due primarily to the fact that their energy costs can be tremendous. If there is net fiscal gain to be made by consuming off-peak, they will very likely implement such a policy.
3. These industries have had the technological capability for a long time to automatically monitor and adjust their consumption. These technologies however are only now seeing widespread adoption to the public for use in homes and small businesses.

Dispatchable demand management

What does dispatchable demand mean? In a very simple sense, it means that grid operators have the ability to turn off some electric devices that are consuming power. In this way the grid operator can reduce demand at certain times when it would be overly expensive or dangerous to try to meet the demand merely through increased supply.

The owner of the electric device usually has some say in the matter. Dispatchable demand management programs are usually voluntary. The grid operator offers some financial incentives for people and companies to sign up for the program. Generally the payment is some fraction of the money ‘saved’ by not having to turn on expensive peak-matching power generation at peak demand times. The more peak power you can save, the more money you can get back from your power utility.

In Ontario there is a program called Dispatchable Loads that does exactly this.

Heavy usage industries

Another fact of life in the power industry is that the grid operators do reserve the right to cut off access to power on short or no notice in order to preserve the integrity of the grid. This means that major power users, such as industries, will work out contracts with the grid management system about whether they can be shut down, and on how short of notice. Through this system a heavy power user can negotiate for lower power rates or other preferential treatment because they are being a good ‘energy citizen’.

What this means is that the heaviest power users may not have much choice in the matter. In order to acquire power they may need to sign binding contracts with the grid management company.

Why implement this policy?

Offering this choice to all companies and individuals can create a very powerful grid management tool.

1. Being able to turn off several hundred megawatts of demand is generally vastly preferable to having to fire up a gas turbine on short notice in terms of both cost and emissions.
2. Dispatchable demand is fast, perhaps even on the order of seconds. This makes it incredibly useful in the same ways that energy storage is useful. For a deep look at why we need fast-responding power systems, see the previous issue of the Renewable Energy Review on the topic of why electrical energy storage is useful.
3. Technology exists today and is quite affordable. This was not true in previous decades, but is definitely true today. Smart meters are not very different from standard meters in cost. Other useful electronics, such as the computerized systems that can manage power usage for an entire home, have also become quite affordable. While it may be true that these costs are likely to continue to go down slowly over time, this does not change the fact that there is great opportunity today for tremendous efficiency gains if we invest in this technology today.
4. Citizen and business participation in a power market. In a sense this is allowing the individual to partake in some aspect of the power grid. People often convince themselves that nothing they personally do matters to society at large. This is clearly not the case when many people contribute to a central planning authority. For example, in the city of Toronto, the grid management company Toronto Hydro can use dispatchable demand management to reduce the load by 50 megawatts in a short time. ((Volatile energy prices demand new form of management. Business Green. Accessed December 8th, 2010.))

Demand management plus renewable energy

You may have been asking yourself, why are we talking about demand management in a publication named the Renewable Energy Review. The connection may not be clear, so we will spend a bit of time looking at why we believe demand management is incredibly important for a deep discussion of the possibilities for renewable energy in our world.

Playing catch-up

With the implementation of demand management policies, the growth of demand will be slowed. Renewable energy technologies are in a stage of rapid innovation as several of them have recently become economically viable as grid power sources. It is difficult enough to build a renewable power grid without the demand growing rapidly. The slowed growth of demand will help us replace a larger percentage of our conventional generation in a given amount of time than we otherwise could have.

Reduced demand is better than green power

Every unit of energy we harness and consume causes some amount of environmental damage. Reducing our total usage reduces our total impact. This applies even to the renewable power systems of today. There is no power system that we yet have that has zero environmental effects. Our understanding of physics, engineering, and ecology leads us to claim that such a technology, if possible, is spectacularly far in the future.

In case that last point is misunderstood, we would like to restate it: We should definitely be investing in renewable power infrastructure and innovation. Our point is that we should also be investing in demand management because of its myriad of benefits to our society. Demand management won’t make the difficulty of ‘greening our grid’ go away, but it can help to reduce the difficulty of reinventing the way we power our society.

Renewables are not very dispatchable

Dispatchable means power that you can turn on when you need it. Only a few implementations of renewable power can deliver power of this sort. We have looked in detail at some of these sources in previous issues. If you are interested in which renewable energy sources can do this, read about hydro, solar thermal, and biomass.

The creation of dispatchable loads is an excellent way to improve our grid management ability without necessarily adding more dispatchable power generation to the grid. This would allow us to more extensively utilize variable output technologies such as wind, solar, tidal, and run-of-river hydro.

These forms of renewable energy can be very cost-effective for the delivery of energy, but cannot always be counted on to be producing power when you need it. The combination of these cost-effective energy technologies with dispatchable loads is a powerful concept indeed. We will still need dispatchable power on the grid, at least for the foreseeable future, but the implementation of dispatchable loads will allow us to use greater quantities of variable or intermittent power sources.

Call for submissions

This concludes the eighth installment of the Renewable Energy Review Blog Carnival. For a complete list of all publications in this series, see our post regarding the launch of the carnival. If you are interested in submitting an blog post or article to this publication, see our submission page on the Blog Carnival website. This carnival is currently published weekly or bi-weekly, and we are always interested in seeing new material.

The intent of this publication is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority.

Everything has its price. Every form of power production brings with it costs in terms of dollars, time, land, materials, pollutants, greenhouse gas emissions, and human deaths.

Here we look at what we have found to be the most important factors for analyzing the feasibility of a proposed power project.

The purpose of this publication is to illustrate the fact that there are a number of important criteria for evaluating the relative advantages and disadvantages of different power sources. Any analysis that proceeds based on only one or a few of these criteria will be incomplete.

Harmful emissions

Radiation

The two forms of power associated with the largest radioactive emissions are coal and nuclear power. Some people may be surprised to know that more radioactivity is delivered to the environment (and the public) by coal power than from an equivalent amount of nuclear power. We have dealt with this issue in much more detail in our post about the radiation emissions of nuclear and coal power, which is part of our nuclear myth and fact project.

Air pollutants

A number of power sources create a lot of air pollution. Coal power is the most well known of these. We went into great detail about the air pollution of coal in our article coal power: pollution, politics, and profits.

While coal power is the most notorious in terms of air pollutants, other power sources produce some of them too. Nuclear power plants, natural gas turbines, biomass plants, and fuel oil plants all produce some air pollutants. By comparison, renewable forms such as wind, solar, hydro, and tidal produce minuscule amounts of air pollutants.

It is also worth noting that hydroelectric reservoirs, when flooding vegetated land, can trigger the long term release of relatively large amounts of methane as the submerged biomass biodegrades. Methane is a potent greenhouse gas and certainly an air pollutant.

C02 per unit energy

CO₂ is an air pollutant that deserves its own section due to its importance. C0₂ is the greenhouse gas that is the primary force behind human-made climate change. We won’t get into the climate change debate in this article. For a very nice image of what ‘the debate’ is, check out this excellent summary at Information is Beautiful.

C0₂ emissions per unit energy are now an important factor.

Wastewater and effluents

Effluent is a term referring to water that is returned to lakes and rivers after being contaminated in an industrial process. With regards to power production, the major problems are mostly with coal power effluents, although some of the other power sources such as nuclear may contaminate water to some extent.

Noise pollution

Even turbines on their own make noise. Every power system has a different noise profile. The biggest power plants in the world are generally quite far from residential areas because they can create intense noise pollution. This can apply to thermal plants such as coal, natural gas, and nuclear, but it can also apply to hydroelectricity since the release of water through the dam can be thunderous.

Run of river hydro systems may make some noise, and wind power make some noise. The noise levels of wind power are the subject of some public debate currently, but that is primarily because they pose so little danger in all other ways that people are interested in placing them in or near residential areas.

Comparisons are often made between a wind turbine that is several hundred meters away and a refrigerator heard from another room. In a quantitative sense, the decibel readings of wind turbines that are more than 1 kilometer away are quite small compared with many everyday sounds.

As of yet there are no confirmed health issues from wind turbine sound, but there is certainly a lot of public backlash on the issue. Entire wind projects are being stopped in places such as the UK and US. One of the common topics is the health effects of low-level noise from wind turbines, despite the fact that no such effect has been scientifically confirmed. A 2009 review of the noise pollution from wind turbines found so miniscule of effects that governments around the world are uninterested in researching the matter further because there is no significant threat to their people. ((Wikipedia: Environmental effects of wind power: 2009 Review. Accessed November 24th, 2010.)) On the other hand, it seems that the Japanese Environment Ministry will be conducting a review of the sound emission from all of the country’s wind turbines.

The only noise that comes from solar photovoltaic systems would be the rotation motors (if the PV system has systems that angle the panels towards the sun), and the transformers to convert the power to alternating current.

Human lives

All of the above emissions can degrade the longevity and quality-of-life of humans. These are certainly factors that have to be included in any serious consideration of power sources.

However, there are also more acute dangers associated with power sources. Many of these are occupational effects, meaning that they primarily affect workers in the power plants, mines, and supporting industries. Heavy industry can be dangerous, and estimates of the human lives lost in various industries can be very sobering.

There are also acute dangers to members of the public. Hydroelectric dams can fail, flooding land, destroying property, and causing human deaths. Nuclear power plants are famous for the accident at Chernobyl. Natural gas lines leak and explode, often killing civilians, even to this day. ((2010 San Bruno Pipeline Explosion. Wikipedia. Accessed November 25th, 2010.)) Coal power air emissions, effluents, and fly-ash spills poison large areas and are considered responsible for large numbers of public deaths. ((China is the chief bad example for coal deaths in the world today, as evidenced by this section of the Wikipedia article on coal power in china. Accessed November 25th, 2010.)) See another article of ours that takes a deeper look at the broad issues that contribute to the death toll of coal.

A brief literature review on the Internet found a few studies available online regarding the relative cost in human lives of various electricity generation techniques.

The first article we will mention was published by the World Nuclear Association. While they do seem to have a vested interest in making nuclear look good compared to other sources, they do have some estimates that closely agree with other studies. The full piece is available online as Environment, Health and Safety in Electricity Generation.

Next we will look at a study prepared in 2005 for the Canadian province of Ontario with regards to the economic feasibility of replacing their coal-fired electricity production. The piece makes a strong case against business-as-usual coal power use, since it seems to be the power source that causes the most human deaths per unit energy. It is interesting to note that since the creation of this report, Ontario has directed its efforts heavily towards renewable energy through feed in tariffs.

Lastly, we found this report on various options for electricity production in various European Union countries. Some very interesting conclusions are drawn from this analysis that are worth noting. There are some very clear answers to questions regarding the societal health effects of some forms of electrical power generation. For example, hydro and nuclear power are two orders of magnitude less of a risk than coal and oil. For those that are new to the term, and order of magnitude is a power of ten, so two orders of magnitude less risk means approximately 100 times less risk.

An interesting extension of this reasoning can be added in the case of oil and other contested resources. It is well understood that oil has been a valuable enough energy resource that wars have been fought, and continue to be fought, over its acquisition. Adding in the deaths, stresses, expenses, and damage to infrastructure from oil wars would raise its already notoriously high detrimental human health effects.

Land

Areal power density

We looked into the issue of areal power density in some detail in a previous issue of the Renewable Energy Review titled: Land use of coal vs wind: Still room for debate. In that publication we show how to perform simple calculations of areal power density, and show some detailed examples.
People familiar with the work of Vaclav Smil will know this criteria as ‘power density’. One of the only criticisms that we level at Smil’s work is that he tends to overstate the significance of power density when considering possible future plans for our society’s energy future. We acknowledge that power density is a very important factor to consider, but disagree about the extent to which it is weighted against all of the other criteria listed in this article. Additionally, we did comment on what we identified as some notable methodology gaps in his analysis of coal and wind power in our look at the land use of coal vs wind. We will now discuss those issues briefly here.

Coal power

Coal power has a growing areal footprint. It damages incrementally more land with mining and fly ash storage. It also damages arable land with airborne toxins and water effluents. Also, new coal development is taking place with lower quality coal seams and less-than-ideal locations that may be further from mining locations, cooling water, and population centers. Finally, if we add in the dangers of land damage and flooding due to climate change and sea level rise caused by the C02 emissions from coal, there will also be some substantial changes to the relatively high power density of coal.

Wind power

As for wind power, we feel that great care must be taken in assigning an areal power density number. Firstly, the land used for wind power can also be used for other things such as herding and farming. It is not an exclusive use of land like a coal plant or mining location is. Secondly, existing wind power installations, which Smil uses for his analysis, are not optimized to maximize power density. They are optimized for cost-effectiveness.

Today, turbines are typically much more expensive than the land that they will be placed on. This means that in order to optimize costs, the turbines are placed rather far from each other to minimize their interference with one another. By looking at the areal power density of existing wind farms, we are not looking at how high the power density can be. We are merely getting a snapshot of what the power density of wind is when it is optimized for costs in the current turbine and land markets. As the best locations for wind are filled with turbines, and if land becomes more expensive, we are likely to see some notable increases in the areal power density of wind.

Lastly, wind power lacks the incrementally growing land use of coal. The land formerly occupied by wind power turbines is unharmed and able to be used after the wind power systems have been taken down.

Solar synergies

There are some other land use synergies for solar photovoltaics. They can be placed on building roofs. Even considering only the south-facing roofs without obstructions in the northern hemisphere, this is a very substantial area that is already in use. Also, it is possible to use a short herding animal such as sheep to keep the grass short in fields of photovoltaics. There has been an unfortunate tendency in some places to sterilize the ground under photovoltaic installations so that nothing grows there. We believe that grazing animals would be a better solution.

Siting requirements

Certain types of power plants can only be built in certain places. For example, hydroelectricity needs a lake, river or stream. Some other power plants are more effective in certain places, but can be built almost anywhere. For example, solar power works best with maximal direct sunlight, so building in an area permanently shadowed by a mountain for instance would be a really bad idea, but it can be done. Solar panels can produce some energy even from diffuse light.

Thermal power plants such as coal, natural gas, and nuclear produce about 80% of the world’s electricity. These systems require both a heat source such as coal, natural gas, or nuclear energy, but they also require a way to cool themselves. This is because heat engines operate based on differences in temperatures. Generally the cooling is accomplished using a large body of water, a river, or cooling towers. The most cost-effective thermal plants are generally near large sources of water that they can use for cooling.

Money

The issue of capital costs tends to dominate our discussion of many issues, including power production. What are the facts that we consider then regarding the relative costs of power generation equipment?

Construction time

It is important to keep in mind that an important factor in the cost-effectiveness of a power plant is the length of time it takes to design, certify, and build. Nuclear power plants have become notorious for coming in substantially over budget. Much of these cost increases are actually due to interest accruing on the several billion dollar loan that is taken out to fund the construction of a new nuclear plant. Delays of months can be expensive. Delays of years can be debilitating.

Changes in governmental regulation have sometimes been the culprits for delays in nuclear plant construction. There has also been a failure to utilize modular designs with quick construction times. To some extent this may be excusable because of the public safety role of regulation, but we believe that a lot of improvement is possible.

Realistic costs for all long term projects should include provisions for unexpected delays. However, we have only run into a few power cost estimates that take into account these delays. Most cost estimations for future development are thus typically a bit low. We feel that this is misleading with regards to power plants that take a long time to build, such as nuclear power, because even slight delays (which are common) will introduce very notable additional expense.

Cost per installed kilowatt

Here we are talking about how much money it costs to create a power plant per kilowatt of generating power. If you are unfamiliar with the term kilowatt or kilowatt-hour, see our piece on energy definitions.

For example, in March 2009 I was quoted a price of $13,000 for a grid-tie photovoltaic system that had a max power of 1.9 kilowatts. What would our cost per installed kilowatt be for this system? We take $13,000 and divide it by 1.9 to get $6842 per installed kilowatt. People familiar with power systems may see that this is a relatively high cost. This is partially due to the fact that power systems have large economies of scale. It is also due to the fact that solar photovoltaics are reasonably expensive for personal use.

The local utility estimated their costs for creating various forms of power production in their publication: SaskPower: Powering the future. They cite for instance the cost per installed kilowatt for large-scale wind power to be $2000-$3000, for solar photovoltaics between $7,000 to $13,000, and for large-scale ‘compliant’ coal about $4,300 to $5,700. They also cite prices for natural gas, hydro, and biomass which we will not repeat here. These prices are ‘overnight’ costs, where the plant is theoretically built instantly. These costs do not include interest charges on debts, inflation, or escalating labour costs. All of these factors would be expected to increase these prices by some amount.

Cost per kilowatt-hour

While a kilowatt is a unit of power, a kilowatt-hour is a unit of energy. For those of you who are not as familiar with these units, it may be helpful to look at this brief explanation of power vs energy at Wikipedia.

Here we are discussing the cost of energy produced by a power system, rather than its maximal power rating. In order to understand this concept deeply, it must be understood that all power systems have a capacity factor. The capacity factor is the fraction of the amount of energy actually produced over the amount of energy that could possibly have been produced if the power system had been producing maximally.

For example, a home wind turbine might have a power rating of 1 kilowatt. However, over the course of 10 hours it might only have produced 2 kilowatt-hours because the wind was not going fast enough for it to produce at the peak rate. The turbine had a theoretical maximum energy potential during those 10 hours of 10 kilowatt-hours (power of 1 kilowatt multiplied by the number of hours it was running). If we calculate 2 kwh / 10 kwh we get 0.20 or 20%. We would say that for this 10 hour segment this wind turbine had a capacity factor of 20%.

Cost per kilowatt-hour refers to the monetary cost of a kilowatt-hour of energy from a particular power source. This is definitely one of the most important economic factors for a power system. Why? Because power plants are generally paid primarily based on how much total energy they produce. At least two distinct caveats must be immediately applied to this statement. There are at least two major factors that will change the price being paid for a unit of electric energy: 1) Whether the power is dispatchable, or there-when-you-ask-for-it, which we look at later on in this article. 2) Whether the power is available near peak-demand times such as mid-afternoon on a hot summer day in California. During these times electricity is being demanded much more than at other times.

With the above caveats in mind, we can still state with confidence that cost per kilowatt-hour of electricity is the major driving force for the economic viability of power systems. A good example of this would be wind power. Wind power has seen incredible growth in the world in the last decade despite the fact that it is neither dispatchable or predictably available at times of peak demand. Its economic viability is based almost entirely on its relatively low cost per kilowatt-hour of electricity. That is, wind might not produce the power when you need it, but it can produce cost-effective power during its lifetime.

Since this is the most important economic metric for power systems, there has been a lot of research about the comparative costs of various forms of power. We will not recite these studies here, but we can point out the best ones that we are aware of.

A nice review article on the subject is the Wikipedia article on Cost of electricity by source. In it, they go through the general methodologies for such an analysis, and then summarize the findings of several major studies of costs. The broadest study seems to be that one completed by the U.S. Department of Energy, which is summarized below:

When reading the summary tables, the costs are often given in dollars per megawatt-hour (MWh). A megawatt-hour is one thousand kilowatt-hours. The price of electricity that is paid by a consumer for their home in North America is usually around $0.10 per kilowatt-hour, which works out to $100 per MWh. Somewhat similar rates can be found around the world.

We feel that it is important to point out that tables of costs per installed watt are very location specific. Different geographic regions have different labour costs, specialized industries, land costs, and natural resources. Natural resources in this case refers to everything from domestic natural gas to rivers, wind and sunlight. An obvious example would be that Nevada and Spain get a lot more sun than Alaska.

All of the major studies in the Wikipedia article include some degree of geographic specificity. This is necessary in order for these studies to be meaningful. There is no unified cost estimate for everywhere in the world. Building things in different places costs different amounts of worker time as well as physical resources. As pointed out above, the energy resources of different locations can also be quite different.

Energy characteristics

There are a number of important factors to consider when examining the abilities of power generation equipment.

Energy return on investment

Energy return on energy invested (EROEI) is the ratio of the amount of electricity produced by a piece of equipment over the amount of energy required to create that piece of equipment. For example, if during its entire lifetime a hydroelectric turbine created 100 MWh of energy and it took 2 MWh to build the turbine, then the EROEI of this turbine would be 50.

EROEI is important because it puts some fundamental limits on how quickly we can add power generation to our grid. For example, our above example of the hydro turbine should be able to, during its lifetime, pay back the energy debt for its own construction and then a surplus of 98MWh. This could in theory provide enough energy for the creation of 49 more turbines like it. This number is rather high. Most fossil fuel and nuclear power systems that we are aware of have smaller EROEIs in the range of 4 to 20.

Fossil fuel EROEI tends to fall

EROEI tends to fall over time for non-renewable resources such as oil, coal, and natural gas. This is because the most easily accessible resources are generally exploited first. Accessibility is comprised of a combination of location, difficulty in extraction, and difficulty in refinement. For instance, oil in Saudi Arabia is often cited as having an EROEI of approximately ten. This can be compared to oil is North America which we have seen cited as having an EROEI of approximately five! ((Wikipedia: Energy Returned on Energy Invested. Accessed November 24th, 2010.)) It is clear that technological improvements in the extraction, transport, and refining of fossil fuels have not outpaced the increased difficulty of more remote and lower-quality resources. These decreasing EROEIs for fossil fuels have definite consequences for the energy fate of our civilization.

Farmland

Farmland has also seen decreasing EROEIs in recent decades. This may sound strange since our food yields have been increasing. The fact is however, that we are using much larger amounts of energy to work our land and to create and distribute the growing amounts of pesticides, herbicides, and fertilizers. Many of the chemical bases of these products are drawn from non-renewable resources. For instance, potash (a non-renewable resource) is being heavily mined to produce fertilizer through the very energy-intensive Haber-Bosch process. Our farming practices today are relying heavily on huge energy and resource inputs from elsewhere. It is clear that farming practices will need to be refined in the coming decades or face skyrocketing EROEIs. The alternative is to use even more energy to create these additive chemicals. This additional energy might be used to mine increasingly remote and low-quality deposits of raw materials, or perhaps to create fertilizer through energy-expensive techniques.

Solar is rising

On the other hand, EROEIs for renewable energy sources are on the rise. Thin film photovoltaics have recently been cited at 30, and some even above that high value. ((Real Energy: EROEI. Accessed November 24th, 2010.)) Concentrated solar thermal power has been cited as having EROEIs between 30 and 70. ((JGZ: Implications of EROEI ratios. Accessed November 24th, 2010.))

Wind and hydro very high

The Encyclopedia of Earth’s article on the Energy Return on Energy Invested for a number of existing wind turbine installations demonstrates an average result of 19.8 for the EROEI of wind power. This is a number they claim is quite high when compared to conventional power sources (other than hydro). Some individual turbines were in the single digits, while some others were as high as 30 to 70. It is also worth noting that all but one of the turbines studied were analysed through publications from before the year 2002. Wind power has made great progress since then, and we would expect that its EROEIs have improved by some amount in the years since.

Drawing upon the links and references given above, it is clear that the EROEI of hydro power also tends to be very impressive, in the range of 20 to 200. There is a reason why hydro is still the king of renewable energy in terms of power produced. Hydro is an incredible resource, but care must be taken with further development because we have used many of the ideal locations already.

Energy payback time

Energy payback time is closely related to the EROEIs that we just looked at. Energy payback time refers to how long a piece of power generation equipment needs to be in operation before it creates the same amount of usable electricity as the amount of energy that went into constructing it.

We can calculate energy payback time from the EROEI if we know the average lifetime of the power plants used to create the EROEI estimate. We would take the lifetime and divide it by the EROEI to get an estimate of the energy payback time.

For example, an article at JGZ estimates of the energy payback time of concentrated solar thermal power is around 8 months, a very impressive number! Energy pay back times for photovoltaics are estimated by the National Renewable Energy Laboratory in the United States to be between 1 and 3.8 years, depending on the technology and implementation. ((National Renewable Energy Laboratory. What is the Energy Payback for PV? Accessed November 24th, 2010.)) Again, these are very impressive numbers.

An earlier citation from Real Energy gives some useful numbers for the calculation of energy payback times from EROEIs. It is clear that most of the conventional fossil fuel sources have relatively high energy payback times while the currently developing renewables are quite impressive.

It is important to note that EROEI and energy payback time numbers are not the same for every installation for a given type of power. Techniques vary, as do the quality of resources such as wind and hydro. There is room for innovation and improvement for all energy types. Our understanding of physics leads us to the belief that the conventional fossil fuels are not going to substantially improve their EROEIs or energy payback times with new innovations. We are rapidly reaching the limits of what those energy resources can do for us.

On the other hand, there are still very impressive gains expected for the renewable energy forms. Most of them are young industries that are currently driving innovation at a spectacular rate. Another notable exception may be the development of advanced nuclear reactors. Reactors such as the Liquid Fluoride Thorium Reactor (LFTR) may be incredible power sources, if they are researched and developed. There is currently an ongoing project at Energy from Thorium to encourage investment in the development of LFTR. To that end, Energy from Thorium has collected all the relevant science and scholarship that they can get their hands on. They make an impressive case for LFTR, convincing us that it certainly deserves to be researched.

Lifetime

The lifetime of a proposed power plant is important for a number of reasons. Long-term planning by power authorities will examine the entire lifecycle of the power resource. The lifetime of a power system will also affect planning by local communities and investors.

Dispatchability

We looked in great detail at the concept of dispatchable power in a previous publication of the Renewable Energy Review. Essentially if a power system is ‘dispatchable’, it means that we can turn it on and off at will in seconds, minutes, or hours. If a power system takes most of a day to turn on, it is likely to be considered a baseload source rather than a dispatchable one.

Intermittency

Power sources that are intermittent are power sources that are not baseload or dispatchable. These are sources such as wind power and solar photovoltaics that only produce power when there is wind or sunshine respectively.

In the case of wind power, it is worth mentioning another facet of its limitations. Some areas of the world experience temperatures below -20ºC. In these places, wind turbines often have an automatic shutdown temperature at around -30ºC. This is not always the case however, since there are functioning wind turbines on Antarctica where it gets much colder.

However, the fact remains that many wind power installations will not produce power when it is extremely cold. This is problematic for my home province of Saskatchewan since the maximum demand is usually during the coldest times of the year.

Predictability

The predictability of an intermittent power source is very important for grid control operations. In order to ensure grid stability, we need to be able to match the drops in intermittent power production with dispatchable sources.

Energy resources can vary a lot in terms of how predictable they are. For example, in our home province of Saskatchewan, the wind is often predictable on a scale of hours to even days. Run-of-river hydroelectricity in our neighboring province of Manitoba is very predictable on the scale of weeks to seasons.

The key point here is that not all intermittent sources have the same character of intermittency.  Depending on the resource type (wind, solar, hydro, etc) and the specific location, predictability can vary greatly.

With the exception of hydroelectricity, most of the fastest-responding dispatchable sources such as natural gas and energy storage are quite expensive. In general it is true that the grid management costs will decrease with increasing predictability.

Today’s energy market currently favours wind power despite its unpredictable nature. This is because the grid management costs thus far have been relatively small. The low price of wind energy makes it an attractive investment in many places even though it is usually relatively unpredictable.

Load-following

Intermittent power sources can sometimes follow the patterns of usage to some extent. For example, solar photovoltaics produce the most power near the middle of the day, which often coincides with high power use due to things such as air conditioning during hot days. Thus to some extent solar photovoltaics produce power when it is needed most in these areas.

However, many places in the world have a midwinter peak power usage. This is true for our home province of Saskatchewan. The maximum power usage in a Saskatchewan year is usually on or near the coldest days of the year. In this setting solar photovoltaics would be extremely poor at matching the load at all.

Wind power in Saskatchewan has been found to produce more energy during winter. This helps a bit with meeting the energy requirements during these times. However, as we looked at above, most wind power turbines can only function above temperatures of -30ºC.

The feed-in tariff is a policy mechanism that applies to the electricity generation industry. It has been applied in many countries with the intent of encouraging the development of renewable power generation. Such a policy typically involves guarantees to certain renewable energy industries specific long-term prices for electricity they produce and guaranteed grid access. This means that renewable power producers are paid higher prices for electricity that they produce and they are guaranteed to be able to sell their power to the grid.

Prices

Why would we want to offer higher prices for certain types of power generation? Because we want more of that sort of energy in our system. This is a market solution because there is still competition among companies and individuals to create power infrastructure that can tap into these power prices. That is, we are tapping into the self-organizing power of the market.

This is also a public solution because it must be centrally led. The public, either through government or through a crown corporation, makes a set of priorities clear through the clearly defined prices. The intent of the public is reflected in a feed-in tariff designed to distort the market in ways that make investment in the renewable energy industry more desirable.

The intent is to harness the natural competition and resource distribution of the market, while keeping some control of the direction of development in public hands. In this way the people can ensure that development happens in the directions that they desire, and the powers of the market lead to increased efficiency of the provided solutions.

In some feed-in tariff systems, the resource intensity is taken into account. So if a wind farm is being placed in an area that has only moderate wind, it may be paid more for its power than a wind farm that is built in a place with very high winds. Generally however, there is still a strong incentive to build in the best locations, since renewable energy is highly dependent on placement. This adjustment according to resource intensity can be justified in a number of ways. One way that we think it is reasonable is if the highest quality renewable energy resources are already in the process of being developed, and additional incentives are necessary to cause development in other less ideal geographical locations. We don’t have an infinite amount of perfect locations, so tailoring the incentives to help grow the industry to less-than-perfect locations makes sense in this regard.

We do not believe however that adjusting rates according to resource intensity should be a way for poor planning and implementation to acquire higher profits than high quality installlations. FITs are intended to nudge the market in the right direction, not destroy the market’s ability to distinguish between economically effective and ineffective businesses. FITs that reward lower resource intensity may be treading on dangerous ground unless they are carefully managed. The most cost-effective implementations of a power system deserve the best profits compared to their less effective counterparts. If someone puts up low-quality wind turbines in a valley with slow wind, the system should not be under an obligation to deliver them a profit, especially a profit above that garnered by high-quality installations in high wind speed zones. If this rule is broken, the market aspect of the FIT is being undermined.

Grid access

The reason that grid access needs to be guaranteed is because quite often grid access can be a very large hurdle for the development of renewable energy. For instance, if you want to build a hydroelectric dam in an area that is currently undeveloped, you would normally have to pay for the transmission infrastructure to carry the power you produce some distance so that you can connect with the power grid. Remote renewable energy resources can have great long term value, despite being located far from existing transmission infrastructure. An excellent example of this is the James Bay Project in Quebec, Canada, which is located several hundred kilometers from any major cities. The transmission infrastructure was expensive, but has been well worth the investment.

Similar transmission issues exist for other renewable energy resources such as wind, solar photovoltaics, geothermal, tidal power, and solar thermal power. Cost-effective development of these resources is currently constrained to suitable locations, many of which are located far from transmission infrastructure.

However, providing universal grid access could be very problematic for the power authority in charge. In nations like Canada for instance, transmission costs can be very high due to the nation’s enormous geographic size and generally sparse population. A very aggressive feed-in tariff law in Ontario, Canada kept some discretionary powers in the hands of their power authority regarding which renewable energy projects could be granted grid access, and on what schedule. This allowed them to balance the needs of their residents against the possible decreasing cost-effectiveness of transmission infrastructure construction.

Tapering

Feed-in tariffs (FITs) are generally guaranteed for a few decades. I have seen FIT laws that range from 20 to 60 years in their applicability, often depending on generation type. For instance, hydroelectricity generally has a much longer lifetime than other forms, so it makes sense that the power prices be guaranteed for longer to encourage development.

Many FIT programs are designed so that the highest power prices are delivered at the beginning, and slowly wane over the decades of the agreement. There are several reasons that we have identified for this. Firstly, the most important revenue for investors is often the first few years of their return on investment. This has a lot to do with the realities of financing large power projects, where the money needs to be delivered up front, but the project often does not create revenue until it is completed.  Another goal of slowly reducing the prices is to stimulate the market towards innovation.

Slowly reducing the power prices will be an incentive for companies to improve their methods for producing, installing, and managing power systems. This means that over time, the renewable energy installations will have to improve in order to be able to make money even with a FIT in place. The goal of course is to help renewables through their tumultuous adolescence towards grid parity, where they are equally as cost-effective as the traditional forms. It is important to note that different renewable energy technologies are at different levels of cost effectiveness. For more information, you can check out our review of renewable energy forms.

Utilization and effectiveness

A report published in 2008 by the European Commission stated that “well-adapted Feed-in tariff regimes are generally the most efficient and effective support schemes for promoting renewable electricity”. ((European Commission (COM), 2008. Commission Staff Working Document, Brussels, 57, 23 January 2008. Retrieved Sept 12th, 2010.)) A large number of jurisdictions in the world have implemented feed-in tariffs for this reason.

Development of renewable energy can actually lead to a reduction in total costs for the consumer. This can happen for instance when the demand for natural gas goes down because less of it is required for peaking power plants. This reduced demand lowers the price, which will lower the cost of heating a home in those areas that use natural gas for heating. The total effect of feed-in tariffs is usually very small, hardly noticeable on a monthly power bill. Some studies, such as this one for instance, show that electricity prices actually end up falling as a result of feed-in tariffs. ((de Miera, G. S.; González P. del Río, Vizcaíno, I. (2008) “Analysing the impact of renewable electricity support schemes on power prices: The case of wind electricity in Spain.” Energy Policy (36, 9) pp. 3345-3359))

Some of the most notable examples of successful feed-in tariffs are Germany and Spain, where residents have seen very stable electricity prices coupled with tremendous growth of the renewable energy sector of their economies.

Germany

Germany instituted a law in 1990 which guaranteed that wind and solar power producers would be paid electricity rates that were 90% of the residential retail price of electricity. This is substantially higher than standard, which is often less than 50% from what we have seen. Similarly, other renewables were guaranteed rates between 65% and 80%. This law remained in effect until 1999, but subsequent legislation took its place. ((Germany, Stromeinspeisungsgesetz (StrEG) (1990). “Germany’s Act on Feeding Renewable Energies into the Grid of 7 December 1990,” Federal Law Gazette I p.2663, unofficial translation from Wind-Works. Retrieved Sept 12th, 2010.)) This law was very effective at stimulating private investment in renewable energy sources. By 1999, Germany had approximately one third of the world’s wind generation capacity. ((Germany, Renewable Energy Sources Act (RES Act) (2000). “Act on Granting Priority to Renewable Energy Sources,”Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). Retrieved Sept 12th, 2010. ))

In 2000, Germany adopted the Erneuerbare Energien Gesetz (EEG) which expanded the mandate and goals of the original legislation. Under the EEG, solar photovoltaic (PV) power production in Germany increased 9 fold between 2000 and 2005. ((Solar Choice: Solar Energy Update from Germany. Accessed November 16th, 2010.)) Since 2005, solar PV production has continued to explode in Germany, making them the world’s largest provider of solar PV power in the world, with 47% of global solar PV installations (9.8 GW) at the end of 2009. ((Renewables 2010 Global Status Report. Ren21. Accessed November 16th, 2010.))

Ontario

Ontario introduced the Renewable Energy Standard Offer Program on November 22, 2006 with the intent of stimulating growth in the development of renewable energy in the province. The program exceeded expectations with 1400MW of contracted projects since its inception. ((RESOP Program Update. Ontario Power Authority. March 12, 2009. Retrieved Sept 12th, 2010.))

On May 14th, 2009 Ontario passed into law the Green Energy and Green Economy Act, 2009. The act is intended to help phase out the last coal generation in Ontario and boost the economy. The act is also intended to stimulate research into renewable technologies and create environmentally friendly industry and jobs. ((What is the Feed In Tariff Program? Ontario Power Authority, 2009.  Retrieved Sept 12th, 2010.)) It is important to note that the Ontario FIT provided a small but notable additional incentive for Native groups to propose projects. It also included a requirement of certain percentages of renewable energy equipment had to be purchased from Ontario companies. The goal was to create a strong Ontario renewable energy industry.

When Ontario’s Feed-in tariff program was one year old, there was some journalistic coverage of how successful it had been. It seems to have been incredibly successful, with many projects waiting in the queue for transmission line space to be built. Tens of thousands of proposals are for rooftop solar, but this represents only a small portion of the proposed power production. It is expected that this aggressive policy is bringing many jobs to Ontario. People have been complaining, often comparing the electricity rates for green power to the rates they have paid in the past. As this reporter correctly points out: that is the wrong question to ask. The right question to ask is how they compare to the rates that Ontario is paying for its current power, and what it will be paying for power in the near future.

Further Reading

In early 2010 Vision of Earth took part in the public consultations on Saskatchewan’s Energy Future, in which we tabled a proposal for a Saskatchewan feed-in tariff. We also wrote a piece about why we proposed a feed-in tariff for Saskatchewan.

An alternative or complementary policy to the feed-in tariff is proposed in our piece publicly administered green energy futures. Essentially what we propose is the ability of citizens to invest directly in guaranteeing their energy future by choosing publicly vetted projects that they want to support. On this topic we also wrote a piece regarding the debate of public ownership or feed-in tariffs for Saskatchewan’s power development.

Paul Gipe, a prolific author, renewable energy advocate, energy industry analyst, and the creator of Wind Works, recently completed an interview with us. See our interview with wind power guru Paul Gipe.

Wind Works has an excellent table of renewable tariffs in the world. As of the time of this writing, it was last updated February 1st, 2010.

An aggressive Swiss Feed-In-Tariff was launched in 2008.

Feed In Tarriffs for Grid Connected Systems. This is an overview of the feed-in tariff as a mechanism. It looks in detail at Germany’s progress and policy. Written with the intent of making it clear how Australia has tremendous potential in the renewable energy scene if they adopt a feed-in tariff.

Call for submissions

This concludes the sixth issue of the Renewable Energy Review. See the launch of the renewable energy review for a listing of all our publications.

If you are interested in submitting a blog post or article to this carnival, see our submission page on the Blog Carnival website. This carnival is currently being published weekly, and we are always interested in seeing new material.

The intent of this blog carnival is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority.

This is the fifth installment of the renewable energy review.

What does dispatchable mean?

Dispatchable energy sources are those sources that can be ramped up or shut down in a relatively short amount of time. This could refer to time intervals of a few seconds up to a couple of hours.

Depending on the response speed of a form of dispatchable power, it may fulfill one of many distinct roles in the power grid. For instance, hydroelectricity generally has very quick response times while coal and nuclear are relatively slow. While hydroelectricity might be used to match peaks in demand on a second to minute scale, the flexibility of some coal stations might be used to help follow the general trend of power usage during the day.

Dispatchable power sources are what we turn to when we need guaranteed power. There are many different distinct uses for this guaranteed power, which we go into later in this article.

This is intended to be an overview of the concept of dispatchable power (which includes peak-matching and load-following power). We will also be focusing on the problem of dispatchable power that is renewable in nature. Lastly, we will consider some related technologies such as energy storage and dispatchable loads.

Why do we need dispatchable sources?

Load match

Load matching refers to the fact that power usage changes during the day. Typically far less electricity is demanded at night than during the day. Load-matching power plants use their flexibility to adapt their power output over the course of hours to match the general shape of the demand.

Load-matching power plants however do not meet the little ups and downs in power usage. That role goes to the peak-matching power plants that we look at next.

Peak matching

Peak matching power plants (aka peaking power plants) are employed to match the highest demand during the day. Demand typically peaks for power grids at a relatively predictable time, depending on culture, weather and geographic location.

For instance, in many affluent places that have hot weather, 4-5pm is typically very hot, and it is also the time that people tend to go home from work and start using their electric devices there. This hour between 4-5pm is a typical peak demand hour, where electricity demand hits its maximum for the entire day.

Some power systems that are not strictly dispatchable can help to meet peak demand to some extent. For instance, solar photovoltaics hit their maximal power output when the day is clear and sunny, with the sun still high in the sky. This can coincide rather closely with the power demand due to air conditioning due to the heat. It should be noted however that AC demand continues to be high even into the late afternoon, when solar photovoltaic power has begun to wane.

Cover lead-in times

First of all, a lead-in time for a power plant is the amount of time it needs to ramp up to producing power. For example, a coal power plant might take several hours to reach maximum power output, but it can produce intermediate amounts of power in less time, such as a few hundred megawatts in half an hour perhaps.

Dispatchable power generation that can deploy quickly, on a scale of seconds to minutes, is extensively used to cover the lead-in times for power systems that react more slowly. This is extremely useful for ensuring that there are no gaps in supply due to quickly increasing demand.

Frequency regulation

When a power grid raises or lowers the amount of electricity that they are delivering in total, there tends to be disturbances created in the power signal. These disturbances are generally due to a slight change in frequency because of either a slight oversupply or undersupply of electricity. Large frequency disturbances lead to a reduction in power quality.

These disturbances in frequency must be dealt with rather quickly. Responding to these events even in as short of a time as several seconds can mean that the disturbance is already gone when the corrective action arrives. This can lead to a tendency to overshoot or undershoot substantially in terms of frequency regulation.

Natural gas units are often used for this task, but often respond rather sluggishly compared with what we would prefer. Studies have been done on using fast responding energy storage techniques such as flywheels to fulfill this role. The results seem promising and compelling. We may see energy storage technologies, including flywheels, implemented more widely in this regard.

Why do we care so much about frequency regulation? Any noticeable deviation from the standard frequency is termed ‘dirty power’. People may have personal experience with dirty power, and how it can damage electronics, or drastically reduce electronic lifetimes. Dirty power causes problems for electricity grid equipment and for consumer uses. Extreme cases can include incidents known as ‘brownouts‘. The cleanliness of power is very valuable.

Cover intermittent sources

Some forms of energy production are intermittent or variable. They do not produce consistent electricity, and are not dispatchable. Essentially we have little to no control over the power production from these units.

Depending on the relative capacity of the intermittent sources on a power grid, there can be some problems. Intermittent sources can provide valuable electricity, but they cannot provide guaranteed electricity. In order to ensure that demand is met, dispatchable sources are often needed to help when the intermittent sources have a period of low production.

For example, on the 23rd of January, 2009, Spain encountered unexpectedly high winds that caused much of their wind production to go into automatic shutdown mode. This is because most wind power systems have a maximum wind speed that they can safely operate at. During the January 23rd incident, Spain had to turn on a lot of dispatchable pumped hydro power as well as coal and gas turbines. They had enough flexibility in their grid to handle even this exceptionally bad circumstance. They had been expecting a lot of wind power that day because of high wind speeds. What they did not expect was winds so fast that many of their wind turbines turned off.

Different deployment speeds

Here are some different forms of power production, with their associated deployment speeds.

Fast (seconds)

Capacitor systems can respond to a discharge signal in milliseconds if they need to. They are the fastest form of dispatchable power than we know of. This is because a capacitor is one of the very few ways to store electricity directly. Most energy storage forms utilize other energy forms such as mechanical, chemical, or thermal. They then convert these energy forms to electricity, typically losing some fraction of the energy in the process. Capacitors on the other hand have almost zero losses since the power stays electrical the whole time.

Flywheel energy storage can be dispatched in seconds. It is one of the fastest-responding sources of power that exist. Similarly, batteries can usually be dispatched in a few seconds.

Some hydroelectric systems can be dispatched in seconds. For instance, Dinorwig power station, a pumped-hydro system in the United Kingdom, is capable of dispatching from a ready state to its full power of 11.8 GW in about 16 seconds.

Medium (minutes)

Slower reservoir hydro systems can respond in a few minutes. ((Wind and Pumped-Hydro Power Storage: Determining Optimal Commitment Policies with Knowledge Gradient Non-Parametric Estimation. Christine Schoppe, Advisor: Professor Warren B. Powell. Accessed November 9th, 2010.))

Natural gas turbines are a very common dispatchable source, and they can generally be ramped up in minutes. We learned that SaskPower uses some gas turbines that stay spinning at relatively high speed but not producing power ((Gary Wilkinson, SaskPower: Powering a Sustainable Energy Future, Saskatchewan’s Energy Future Public Consultation, Saskatchewan Legislature, available in the Standing Committee on Crown and Central Agencies Archives)). In this way they burn very minimal fuel but are ready for almost instant deployment in energy production. Techniques such as these can make it so that gas turbines can be dispatchable in under a minute.

Solar thermal power, or concentrated solar power, can utilize systems of efficient thermal energy storage. It is possible to design these systems to be dispatchable on roughly equivalent timeframes to natural gas turbines. Solar thermal power has been getting a lot of interest lately due to this property, as well as the fact that it can be run as baseload generation. For more information, see our article on solar thermal power.

Slow (hours)

On the slower end we have things like most biomass, nuclear, or coal plants, which can take hours to change their energy output significantly. While these systems are typically regarded as baseload generation, they often have some flexibility. Also, many coal and biomass plants can be fired up from cold within a few hours.

Dispatchable renewable energy

Hydro

Here we are discussing reservoir-based hydroelectric facilities. To learn about all of the different sorts of hydro power, see our article: Types of hydroelectric power: How do the dam things work?

Reservoir-hydroelectric capacity can depend on seasonal variations in precipitation and spring run-off, as well as the size of the reservoir. Larger reservoirs essentially mean that there is more flexibility of power generation. In effect, the ‘fuel supply’ of hydro power is the water in the reservoir.

These properties do not make hydro strictly dispatchable, in that its capacity for producing dispatchable power is constrained to some extent by the natural water supply. The ability to store energy gives it some dispatchable and peak matching abilities. A dammed hydro system may be used more for peak-matching during the dry season, while fulfilling baseload and dispatchable roles at other times of the year.

There is often a minimal amount of water that has to released from a hydro facility to maintain the downstream habitats of the river biota. This means that some small percentage of a hydroelectric plant’s power will be baseload, because it is providing water to keep the river in existence.

In general however, reservoir based hydroelectric systems are among the most flexible and affordable power systems in the world. As a result, they have been extensively deployed throughout the world. Most of the easily accessible locations for dammed hydro stations have already been constructed. There is still a lot of potential for development, but newer development is generally in one of three directions:

1. More remote. Having used up the most easily accessible locations, we are going further afield.
2. Bigger. There is a trend towards larger and larger hydro facilities. The Three Gorges Dam, Itaipu Dam, Guri Dam, and Tucurui Dam are the four largest electric power facilities in the world according to wikipedia. As the world becomes more industrialized, and our technological reach increases, larger facilities become possible.
3. Smaller. There is also a separate trend towards ‘small’, ‘micro’, and ‘pico’ hydro plants. These systems have a variety of uses. They have garnered particular interest because of their extremely small environmental impact, and their possibility for off-grid use as well as grid-connected use. I recommend starting here at the wikipedia entry for these power types if you desire more information on this subject.

Biomass and biofuel

A form of power that humans are very familiar with, biomass power relies on the combustion of plant and tree matter to create energy. Biomass plants can fulfill either dispatchable or baseload roles depending on their fuel sources and design.

One key issue is whether biomass is really renewable or not. This is in question because humans are depleting the biomass of the planet, as well as degrading the soils in which biomass grows. We rely increasingly on chemical inputs such as fertilizers. When these fertilizers are drawn from non-renewable sources such as potash mines, we cannot regard the biomass grown as being strictly renewable.

Despite misleading diagrams such as this one by Potash One, our fertilizer use today is unsustainable. Just like with oil, we are depleting our potash resources far faster than the geological processes can replace them.

It is important to keep in mind that biomass power can be fully renewable, but it would require management of land and soil that we do not do today. It is important also to keep in mind that the capability of biomass to meet our future power requirements may be very limited.
Why? Because biomass power relies on the same energy resource that our food does. Our arable land and water systems are already tremendously leveraged for food production. Increasing meat consumption is also significantly increasing the strain on our arable land today. Lastly, in recent years we have seen the rise of the biofuels movement.

In short, biomass production is competing for resources that are already tremendously leveraged. Biomass plants tend to be small, and there are no large-scale implementation plans that we are aware of for biomass in the world.

Biogas or landfill gas

These power sources depend on decomposition of biomass. The breakdown of organic matter creates several flammable gases. These can be captured and used to produce power.

Biogas and landfill gas have similar problems to biomass. The source of their energy is not entirely renewable, since there are non-renewable inputs into the arable land used to grow the organic matter that decays to create biogas and landfill gas.

There are also some definite constraints on the amount of landfill gas that can be created and captured. Waste is not infinite. Landfill gas may allow us to more effectively use our garbage heaps, but they are not a renewable energy solution.

Concentrated solar thermal

As mentioned above, concentrated solar thermal power can be used in conjunction with a heat storage system. This means that, unlike most forms of solar energy, concentrated solar thermal power can provide baseload or dispatchable energy.

This may be a very important innovation for renewable energy in general. Until this development, there have been essentially no renewable dispatchable sources except hydro and biomass.

Biomass has the constraints given above, which limit its power production ability severely. Hydro stations are very site-specific, and much of our hydro capacity has been developed already. Solar thermal has a different set of location-specific constraints. This means that many areas, such as deserts, which have had little power-production capability in the past, as well as low power demand, will start to see increasing development with solar thermal.

Concentrated solar thermal is drawing tremendous interest in the world currently partly because of its ability to be baseload or dispatchable. The other part of the equation is that concentrated solar thermal power is quite cost-competitive. It is expected to very soon reach $0.10 per kilowatt-hour, a price that will begin to seriously compete with currently popular forms of power.

For more information, see our article on the subject of concentrated solar thermal power.

Energy storage

It may seem strange to call an energy storage system ‘renewable’. The key point here is that energy storage can be very effective when used in conjunction with renewable energy sources. A number of energy storage systems have properties that make the labels ‘clean’ or ‘green’ apply well to them.

Why is energy storage so useful? If you are interested in the details, we wrote a previous issue of the renewable energy review on the subject of why electrical energy storage is useful.

Depending on the implementation, a number of the various energy storage technologies can be regarded as clean or green. We would like to mention pumped-hydro, chemical, and mechanical storage as methods that can be implemented in a green fashion. The machinery and chemicals used for these methods can be designed with eventual recycling in mind.

Batteries are currently only partly recyclable. Until we design batteries that are more fully recyclable, we cannot regard them as a very green solution.

Capacitors have amazing speed, very long lifetimes, and essentially infinite numbers of discharges. However, they are still quite expensive, and like batteries are not easily recyclable.

Compressed-air energy storage (CAES) has been receiving a lot of attention lately as an energy storage technique. In a previous issue of the renewable energy review, we looked at compressed air energy storage in detail. Current implementations seem to require a notable source of on-demand heat, such as natural gas. It is possible to use renewable energy sources for this heat, but it is likely to be constrained to thermal sources like biomass/biogas/landfill gas. Despite this problem, and a number of other specific constraints, CAES shows great potential and merits further investigation.

In short, energy storage can play a key role in a renewable power grid. It can also be constructed in a green fashion, where materials used can be recovered and recycled easily after their useful lifetimes.

Dispatchable load

In a future publication we plan to discuss in more detail the idea of dispatchable loads. A dispatchable load is basically a power user that you can tell to use less power.

Example: a grid operator realizes that the peak usage for a day is going to be substantially higher than expected. They use automated systems to contact heavy power users, telling them to reduce their power usage in a timely manner.

Why would the companies choose to go along with this? Well for one thing, the power utility can make them agree to a dispatchable load contract when they negotiate the initial hookup. Grid management operators often reserve this right in the interests of the grid’s stability.

Also, if a company can agree to being a quickly dispatchable load, they can negotiate lower electricity prices. That is, if they can safely power down their equipment in a short time, and allow the grid control operators to use them as a dispatchable load, they are often rewarded with lower power prices.

Advocates of renewable energy grids often mention this as a powerful tool of demand-side management. The additional flexibility that dispatchable loads would give to grid operators means that less dispatchable power production needs to be available.

For some information on the Ontario implementation of this concept, you can see their dispatchable loads program.

What do you have to say?

This concludes our fifth issue of the Renewable Energy Review Blog Carnival. See our post about the launch of the carnival for a listing of all our publications in this series.

If you are interested in submitting a blog post or article to this carnival, see our submission page on the Blog Carnival website. This carnival is currently being published weekly, and we are always interested in seeing new material.

The intent of this blog carnival is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority.

For this week’s Renewable Energy Review we will be discussing the spatial footprint of wind power as compared to coal power. We will also discuss the advantages and disadvantages of looking at these power systems in terms of their land requirements.

The idea of comparing power sources on the basis of their spatial footprint was popularized by University of Manitoba professor Vaclav Smil. We found his book Energy at the Crossroads to be an enlightening read. It presents a fresh perspective and a few new ways tools for looking at power sources. Smil extensively uses the metric (in SI units no less) of how much power can be generated from a square meter of land (W/m^2).

While this metric allows the scientist to bring their depth of experience using these units in different contexts to bear, it has some distinct disadvantages. Power densities leave out large portions of an energy story, such as the reliability of the energy bring produced or the externalities that will go on to effect other areas, such as when pollution spreads.

Robin Whitlock recently wrote a renewable energy article

in which he looks at wind power through the lens of Smil’s land use figures. Reading his article led us at Vision of Earth to an intense discussion of the pros and cons of simplifying our descriptions of power systems down to even as useful of a metric as areal power density. In this piece we demonstrate some problems with using this concept as the sole metric of comparison for power systems.

What is areal power density?

While Smil uses the term ‘power density’, we find this may be confusing because it has other technical definitions already. ((Wikipedia: Power Density. Accessed November 1st, 2010.)) Instead we will be using the term areal power density to distinguish it from the other definitions. Areal power density refers to the power produced per unit area of land. In SI units this quantity is watts per meter squared (W/m2). Higher power densities are more desirable, because it means that more power can be produced from less land area.

What does this mean? Let us consider some examples for clarification.

Solar example

If solar panels (along with their requisite maintenance roads and appropriate spacing) cover an area of 100m² of land, and produce 1000 watts of power on average (over a year), we would say that this solar installation has a areal power density of 1000 watts per 100m² or equivalently: 10 W/m².

In practice, the sun shines with varying intensity every day, and over the day; depending on factors such as the weather, latitude, and season. In considering intermittent power sources, Smil and VOE will be considering the yearly averaged power output. When the full potential power output (or nameplate capacity) is discussed, it differs from the actual average power output by a factor known as the capacity factor.

Things get a bit more complicated when we begin to consider other infrastructure and other land required for power generation. In the case of solar power, this is relatively straightforward since we only need to consider maintenance systems and power distribution equipment. These systems take up some area, and would contribute to the total area required to use solar power.

Looking a bit deeper, we could also add the land use for acquiring the materials that go into solar panels.

An additional consideration for solar power is transmission infrastructure. The areas with the most yearly sunlight (such as deserts) may be very far from the places where power is needed most, such as cities. High-voltage transmission lines can carry the power over great distances, but this does require additional land use.

Coal example

However, for power sources such as coal, we are faced with a more complicated calculation. We need to consider not only the area required for the power plant and transmission lines. We must also consider systems like the cooling water loop, mining facilities, transportation systems, fly ash settling ponds, and fly ash storage.

Coal mining, fly ash, and coal pollution all contribute to a incrementally growing areal footprint. That is, as more coal is mined, more ground is damaged through the effects of mining. Remediated coal mine areas are generally not as productive or healthy as they were prior to the coal mining commenced. Substantial remediation requires a large (additional) investment of time and money.

Fly ash, one of the products of coal combustion, also requires extensive storage. The more coal that is burnt, the more fly ash storage is required unless the fly ash is used for other purposes or is buried in a previously mined coal seem. Currently only about 40% of fly ash is used in other products, meaning that 60% of it is stored. ((Wikipedia: Fly ash. Accessed November 1st, 2010.)) This creates a large, and growing, waste disposal issue. For more detail on the broader effects of coal, see our article on coal power’s products and impact.

In short, the power density of coal power shrinks over time, because it impacts a larger area the longer it is used.

Why is this metric useful?

Areal power density is very useful for evaluating the relative merits of various power sources. Land use is a very crucial factor in determining the feasibility of large-scale power systems.

In this perspective, power production can be regarded as analogous to food production from agricultural land. This is an apt analogy since agriculture is also a form of power production. Humans get their energy from food, which is ‘produced’ using tracts of land.

If producing our electricity requires exclusive use of too much area, it will crowd out other land uses such as food production, human habitat, and wild ecosystems. Since all of these land uses are of prime importance for the continued existence of our civilization, areal power density becomes a factor of some importance.

Some issues with Smil’s technique

The area required to generate electricity does not tell the whole story; and we’re not suggesting that Smil meant it as such. However, we wish to clarify the fact that something as complicated as power production cannot be captured in a single quantity.

Coal power

Efficiency

For his scenarios, Smil assumes a coal-fired power plant has an efficiency of 38% for his high-efficiency scenario, and 33% for a low-efficiency scenario. According to the World Coal Institute, average coal power plant efficiencies are actually 28%. This is a deviation from Smil’s usual technique of using real-world numbers for his analyses. For coal, he chose relatively high efficiencies that have been attained by some power plants, but do not reflect the real world averages.

Long term land damage

Land will still be damaged even after the coal plant stops producing power. Coal power plant sites are not remediated back to their former quality. This is partially due to soil contaminants and heavy metal buildup. Also, the burning of coal produces particulate and gaseous emissions that can severely affect health of ecosystems, cropland, and humans on a broader scale. These effects are also not limited to the time frame of the plant operation.

Land that has been used for coal mining is generally seriously degraded, even after the mining is completed. Mining coal creates liquid and solid wastes that are then spread into the surrounding environment. This degradation is long-term, since the biology, chemistry, topology, and ecology of the area has often been irrevocably changed. Wildlife in the area will be slow to recover, and may suffer from chronic setbacks due to contaminants left over from the coal mining process.

Pollution from these sources diffuses, impacting an area massively larger than that used to generate the power. The true tally of the land impact of coal power should attempt to include these factors. If areal power density is to be used to compare power sources, this must somehow fairly be accounted for.

In Smil’s estimation of coal, he takes a whole coal mine, power plant, and waste disposal area into account so that he doesn’t have a growing land use figure. We think he fails to mention an important fact when he does not account for land being only marginally useful even after the coal resource is exhausted.

When we consider coal power in the long term, we see that it will continue to use more land over time. More mining and more fly ash ponds will contribute directly to this fact. However, the additional degrading factor of the spreading pollutants from the mining and burning of coal will also be applied to vast areas of land. This degradation has been scaled back by the western nations to some extent, but lobbying battles continue as coal producers look to keep their waste management costs low. Smil does not mention the fact that generations of coal plants will continue to do incremental long-term damage to land, and will also continue to require new sites.

No land use synergies

No land uses that we are aware of can be conducted in harmony with an open pit or ‘mountaintop removal’ coal mine. An underground mine may also cause land subsistence or an underground coal seam fire, causing long-term problems. This is an important fact when we compare with other forms of power production (such as wind and solar), which can be conducted on land in synergy with other land uses.

Ideal spots used already

Smil also glosses over the fact that generally only old coal power plants have the ideal spots that he talks about in his optimistic estimate. We have used the ideal spots, and are quickly moving on to less ideal ones.

Wind power

When considered for only one turbine, wind power appears to have the potential to be one of the most energetically dense forms of renewable power. However it does require sufficient spacing of turbines, so its areal power density drops substantially in real-world application.

Land use synergy

Here are some questions that we will use to examine the important ways in which the land use of wind turbines is dramatically different than it is for coal power:

1. How was that land used before wind was built on it?
2. What other land uses are possible synchronously with wind power?
3. How might that land be used after the turbines exhaust their usefulness?

Wind turbines are often build on hilltops, ridges, and shallow ocean. These are generally areas that are not intensively used by humans except for farming, herding, fishing, and recreation. On land, the area around the bases of the turbines is still largely useful for cultivation and herding. ((It has been observed that livestock and even wild animals don’t mind being near wind power at all. Capturing the wind by Erin Buller, Herald Editor. Accessed November 1st, 2010.))

There are some limits of course on the land uses that synergize with wind. Some people prefer not to live near wind turbines for various reasons, so this currently precludes intensive human dwelling development near large-scale wind installations.

Healthy land afterwards

Turbines may be removed after their useful lifetime, leaving behind few traces of their previous residency. This allows the land to return to its former land use at full productivity.

Land is cheaper than turbines!

Smil analyzes current wind farms for his analysis. While this makes sense, we would like to point out an unwritten implication from his analysis which has dubious basis. Smil’s estimates assume that power production is conducted on minimal land use. This agrees with common sense because power companies won’t bother to pay for more land than they need.

However, a very important facet of wind power is that there is a bit of a trade off between cost-effectiveness and land area. That is, if we pack in the turbines into too small of an area, we see reduced cost effectiveness. That is why turbines are spaced 5-10 blade lengths away from each other, depending on the situation. Sometimes they are placed in lines when the prevailing wind is from a very predictable direction.

Analyzing our current wind power installations gives us a snapshot of the turbine density per unit area that maximizes the cost-effectiveness of the wind installation. For most installations currently, the turbines themselves cost a lot more than the land that they are on. This means that in order to be cost-effective, they are spread out very substantially. Using more land currently doesn’t change the cost of wind power very much, but having inefficiently spaced turbines matters a lot.

Since wind synergizes with other land uses such as agriculture, there are vast tracts of land available for wind power development. To maximize cost-effectiveness, these turbines are placed quite far from one another. With very sparse wind farms, transmission infrastructure tends to be become a notable cost that will limit their geographic spread in a definitive manner.

We argue that Smil’s numbers are not measuring the potential of wind as an energy resource at all. They are measuring the areal energy density of the currently cost-effective wind power solutions. The areal energy density of wind may change dramatically in the near future with innovations like larger, slower spinning turbines, or greater market penetration of wind. It may soon make economic sense to place more turbines in closer proximity in areas that have very strong winds and high capacity factors. This may be more cost-effective than spread-out wind turbines that are built in less favourable locations.

Intermittency

On a last note, wind power and solar photovoltaics are intermittent power sources. This means that they will have to be matched with either energy storage or dispatchable generation in order to be baseload like coal or solar thermal power. We must keep this fact in mind when comparing their areal energy density with a baseload sources, or a dispatchable sources.

For more information on dispatchable power, and how we can meet it using renewable energy, see our article: How can renewables deliver dispatchable power on demand?

Call for submissions

This concludes the fourth installment of the Renewable Energy Review Blog Carnival. For a complete list of all publications in this series, see our post regarding the launch of the carnival. If you are interested in submitting an blog post or article to this carnival, see our submission page on the Blog Carnival website. This carnival is published weekly, and we are always interested in seeing new material.

The intent of this publication is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority.

Energy from water cycle

Hydroelectricity, or ‘hydro’, is generated from the energy in the water cycle of the earth. The sun evaporates water on the surface of the earth, causing it to rise up to form clouds. Clouds eventually form droplets, which then rain, snow, or hail down to the surface. Water on the surface flows downhill until it evaporates again. During this time it may become trapped in glaciers, lakes, ponds, puddles, or the ocean. Driven by the sun, the water cycle is a truly renewable resource.

Here we are not considering tidal power because it is not powered by the water cycle. Tides are driven by the gravitational interaction of the earth and moon.

How much electricity is from hydro?

Hydro is the most well-established form of renewable electricity production. In 2010, hydro comprised about 80% of all of the renewable electricity capacity in the world, and accounted for about 20% of global electricity production capacity. In the same year, about 15% of the electricity consumed in the world came from hydro. ((Ren21. Global Status Report. Accessed October 25th, 2010.)) For more information on how electrical capacity and delivery are different, we suggest you read more about capacity factor.

Installed hydro capacity is only growing at about 3% per year currently compared to solar (53%), wind (32%), and geothermal (4%). However, hydro accounted for 39% of all renewable energy capacity growth in 2009. This difference is due to hydro’s large historical share of the renewable market; so a few percent increase in capacity translates into large increases in gigawatts.

Cost

Hydroelectricity is generally competitive with other forms of power in terms of cost. Sites under current or planned development are generally more remote or difficult to build on than the sites of historical hydro development. This has contributed to a rise in prices for large scale hydro electric projects.

Trends towards both big and small

There are two distinct trends in hydro development today. One trend is towards larger dammed projects. New and planned large-scale hydro projects are designed to produce progressively more electricity. That is, the scale of projects has been increasing throughout the 20th century. This trend is evidenced by recent development of hydroelectric mega-projects such as the Three Gorges Dam in China. This hydro station can produce up to 22.5 GW of power, several times the size of a large coal fired plant of 1 GW, and is in fact the largest electricity producing facility in the world. ((The Top 100 – The World’s Largest Power Plants. Power plants around the world. Accessed October 25th, 2010.))

The second trend in hydro development is towards small hydro. These systems may have no reservoir, such as with run-of-river hydro. Run-of-river systems generally have a reduced environmental impact as compared to large reservoir techniques. The trade-off is that they are generally not dispatchable, limiting their usefulness. However, if a river flows year-round, then some fraction of a run-of-river hydro system’s power capacity can be considered baseload. Small hydro is being pursued heavily in North America because of its reduced environmental impact. ((Environmental Impacts of Renewable Energy Technologies. Union of Concerned Scientists. Accessed October 25th, 2010.)) China has led the world in small hydro development recently as part of their efforts to provide renewable electricity in rural areas. ((Wikipedia: China Village Electrification Program. Accessed October 25th, 2010.))

Reservoirs

Most large scale installations use reservoirs to stabilize power production by controlling water levels. The reservoir is a form of energy storage. Energy storage can be very useful for grid management. Reservoirs allow hydro power to be dispatchable, meaning that power is available on demand.

If you are interested in a more in-depth discussion of renewable energy forms that can fulfill the dispatchable role, see our article: How can renewables deliver dispatchable power on demand?

Environmental issues

The construction and use of a water reservoir can have both positive and negative effects. Reservoirs have many uses, such as irrigation, recreation, and flood control, but they also tend to force the migration of people, flood valuable cropland, and damage local ecosystems. Flooded land also contributes to greenhouse gas emissions, since decaying biomass underwater tends to produce a lot of methane, particularly in tropical zones, and particularly when lumber isn’t recovered before flooding.

Somewhat inflexible

There are some limitations on the flexibility of hydro power even with a reservoir. For instance, since rivers are homes to many sensitive species, efforts are generally undertaken to protect species affected by the hydro development. Also, people who own waterfront property on the reservoir, or river users downstream, may lobby for some controls on how the water is used. Seasonal variations in water availability also introduce constraints on the plant’s operations.

Ideal locations built already

In the developed nations, the majority of the ideal reservoir hydroelectric locations have been developed. Newer development is often forced to use locations that are not as ideal as those used for earlier installations. ((This is mentioned in the article Environmental Impacts of Renewable Energy Technologies by the Union of Concerned Scientists as one of the major reasons why reservoir-based hydro potential in the United States may be nearing its maximum. New developments undergo far more environmental and cultural scrutiny than past developments saw. This may limit the economic viability of newly considered projects.)) However, advancing technology and societal wealth have also unlocked opportunities that were infeasible in the past. Additional development of hydro will eventually be restricted as a result of us having developed all of the economically viable locations.

Pumped hydroelectric storage

Pumped-hydro storage requires two reservoirs at different elevations. When power demand is high, water is run out of the higher reservoir to generate electricity. When demand is low, water is pumped upwards from the lower reservoir to the higher one, effectively storing it for later use.

Two reservoirs close by

An ideal location would be where you can create two reservoirs of vastly different height, but very close to each other. This greatly limits the possible locations that pumped hydro storage can be employed. Due to the sometimes sudden cycles of these power plants, they can have substantial environmental effects that would need to be studied.

Sometimes the turbines themselves are designed to spin backwards to pump water back up into the upper reservoir. The total efficiency of a pumped hydro system is generally around 65-75%. ((Wikipedia: Grid energy storage: Pumped water. Accessed October 25th, 2010.)) A pumped-hydro system is generally relatively expensive per installed GW compared to its normal reservoir or run-of-river brethren.

Existing plants

Pumped-hydro can come in a wide range of sizes, depending on factors such as economics, need for storage, ecological and cultural considerations. Some nations have invested substantially in pumped hydro storage because of the tremendous value of dispatchable sources in creating reliable power. Here are two case studies among the many existing pumped hydro plants in the world.

The UK has Dinorwig Power Station, which has a max power output of 1.8 GW and a storage capacity of about 9.1 GWh. ((Energy Storage & Renewables: Is it an uphill struggle? Edison Mission Energy. Accessed on October 25th, 2010.))  Dinorwig can dispatch from zero output to max power in 16 seconds, making it one of the fastest-responding power plants in the world. ((Dinorwig power station. International Power. First hydro.)) Dispatchability of this much power can be extremely advantageous for peak-matching during the high demand times of the day when demand is also often quite volatile. See our article on energy storage for more information.

In 1993 China commissioned the Tianhuangping Pumped-Storage Hydro Plant. Completed in 2001, it can generate a max power of 1.83 GW, making it comparable to Dinorwig. Its storage capacity is a bit higher however, at 13 GWh. ((Wikipedia: Grid Energy Storage: Pumped Water. Accessed October 25th, 2010.)) The difference between the heights of the two reservoirs is an impressive 600 meters. The overall cycle efficiency is around 70%.

Dam uprating

This is a term that we only ran into recently. However, we have been studying the concept for some time. Dam uprating is the process of upgrading the power output of a reservoir-based hydroelectric system. This can be accomplished by adding turbines, or installing higher capacity ones. ((Wikipedia: Grid energy storage: Hydroelectric dam uprating. Accessed October 25th, 2010.)) This concept can be applied to both traditional dams and pumped-hydro storage systems.

We are very interested in the possible synergy of wind and hydro. To this end we have been researching what is possible on the Canadian prairies in this direction. This led us to examine the quantity of dispatchable hydro on the prairies, as well as whether this hydro power was already allocated to other tasks. For instance, since reservoir hydro is such a fast-responding power source, it is often used to cover the lead-in times for slower forms of generation. This is necessary if demand rises sharply, and the slower forms of generation cannot keep up.

We have inquired about dispatchable hydro issues with one of the prairie power crown corporations, but not received any response. One of our core ideas for innovating the power grid of the prairies is that we can up-rate our existing reservoir-based hydroelectric capacity so that we can use it to leverage more wind power. ((This is primarily because the wind resource in south-western Saskatchewan is so impressive. With wind and dispatchable hydro working in synergy, we could be well on our way to a renewable power grid on the prairies.))

Run of river hydro

Run-of-river hydro power does not have a large reservoir, if any. If there is a dam across a river, it will create power from the power that collects behind the dam. In other forms, the run-of-river plant is one large part of the river flow, while another part flows on unobstructed. Using this second method it is possible to minimize the environmental effects of the power production.

Some even smaller run-of-river systems simply use a turbine placed in the middle of the flow of the river, or something similar to a classic water wheel. These systems are generally much smaller, perhaps only a few kilowatts in size.

Induction generators

Induction generators are a useful technology for run-of-river hydro when it will be connected to a power grid. Induction generators need connection to a central power source (or some electrical energy storage) because they require some energy to run. They produce more energy than they use as long as the turbine is being spun above a certain minimum speed. They are designed to be able to utilize turbines spinning at any speed. The have been used extensively in wind turbines because of the variable speed of the wind and thus the rotation speed of the blades. These turbines are generally simpler and longer-lived than other generator types.

Baseload to some extent

Run-of-river systems can be intermittent depending on many factors. Variation can exist day to day or even hour to hour in flowing water sources. Significant variation also exists on the scale of seasons in most places. During the rainy season a run-of-river plant is likely to be running near full capacity. Dry season power production can be drastically lower than capacity in some cases.

If a river flows all year, as most rivers in the world do, some amount of the power production from a run-of-river plant can be considered baseload. Run-of-river hydro is somewhat intermittent, but not as intermittent as wind power for instance. Wind power is very hard to predict more than a few minutes or hours in advance sometimes, but run-of-river hydro can be predicted rather well.

Less intermittent is better

Intermittent sources require dispatchable sources to compensate for them. We go into more detail on this subject in our post on leveraging dispatchable hydro to use wind. What is important to understand is that the predictability and size of your intermittent power sources is very closely related with how easy or difficult it is to manage your grid. Since run-of-river hydro is more predictable than wind power, it should introduce less grid management costs. Uncertainty about power generation can end up being expensive, because a larger spinning reserve is required.

Call for submissions

This concludes the third installment of the Renewable Energy Review Blog Carnival. For a complete list of all publications in this series, see our post regarding the launch of the carnival. If you are interested in submitting an blog post or article to this carnival, see our submission page on the Blog Carnival website. This carnival is published weekly, and we are always interested in seeing new material.

The intent of this publication is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority.

Readers who are new to the subject of energy may find it useful to look over our brief documents on important energy terms and electricity grid terms.

This week we are taking a look at electric energy storage. There are a number of important reasons why energy storage systems are desirable for power grids. ((Energy Storage – More Information. U.S. Department of Energy. Accessed October 18th, 2010.)) Here are some of the major uses for energy storage on an electric power grid:

Peak shaving

Different amount of power are demanded from second to second. Power grids controllers must respond to changes in power usage on rapid time scales. However, even the most rapidly controllable forms of generation, such as dispatchable hydro or natural gas turbines, can take many seconds or even minutes to ramp up. The amount of time that is needed to ramp up a given form of generation is called its lead-in time. Conversely, some energy storage methods allow for much faster lead-in times. Capacitors and flywheels for instance can have lead-in times numbered in milliseconds.

There is always some gap between what power is being produced and what is being demanded. Depending on the specifics of the power grid, this gap may vary in size. This depends primarily on two factors: 1) how quickly the peak-matching generating equipment can be ramped up, and 2) how quickly demand can be expected to rise. All else being equal, power grids that have slower-responding generating equipment will need a larger gap. Since their system would be unable to respond quickly to a fast change in demand, they would need to have extra power being produced in case more is suddenly needed. Similarly, if there have historically been sharp demand spikes (where demand increased very rapidly), the power grid will need to maintain a larger gap.

Peak shaving is the concept of using fast-responding power equipment to match relatively small increases in demand. This gives grid operators more flexibility when managing their power grid. Thanks to fast-responding power systems, they can make the gap smaller between production and demand. This means less fuel is wasted since we are maintaining a smaller gap between production and demand. Additionally, peak shaving means that natural gas units that are used for peak-matching can be run at specific power outputs. It can be relatively costly, inefficient, and polluting to run a natural gas power system at less than ideal levels. Most thermal power plants have specific levels at which they are most efficient and non-polluting.

Energy storage for power quality improvement

There is also another distinct use for energy storage. When a power grid increases or decreases the amount of power they produce, it often introduces power disturbances. These can be very short lived, generally not longer than tens of seconds. Most power generation systems cannot adjust their power production in this time. This may lead to ‘dirty power’ being delivered to customers, or an additional cost in cleaning up the power before delivery. The term ‘dirty power’ refers to power that differs significantly from the local standard. This is essentially instability of the power being delivered, and can have detrimental effects on devices that use this power.

Current solutions involve allowing frequency to change, and then injecting more real power into the grid using a fossil-fuel fired system or dispatchable hydro. ((Update 21/8/2011: Document has been removed from the web. Frequency Regulation using Fast Energy Storage. Imre Gyuk, Program Manager, Energy Storage Research, U.S. Dept. of Energy. Accessed October 18th, 2010.)) A lot of investigation has been done on flywheels for this sort of work. With the advent of magnetically-levitated flywheels, the number of discharges these systems can undergo has massively increased. Additionally, there are none of the associated problems that occur with some forms of batteries such as the memory effect or disposal concerns of toxic battery materials.

It seems that a fast-responding energy storage system can provide the same functional frequency regulation of a fossil-fuel facility that has twice the capacity. This is very interesting, since it illustrates the tremendous value to the power grid of a fast-responding energy source. Fast-responding energy storage is estimated to have a 67-89% smaller carbon footprint than an equivalently capable fossil-fuel system. ((ref:2))

Large-scale energy storage systems

Our electrical utilities are largely structured around the largely baseload power sources we currently derive most of our power from. The majority of emerging renewable energy is coming in intermittent forms, such as wind and solar photovoltaics. To leverage these immense renewable energy sources, we must develop ways to produce reliable power while including sources that are unreliable on their own. One way of doing this is to utilize our steadily improving systems of energy storage.

Energy storage for intermittent power source balancing

In order to produce reliable power, a grid must generally use dispatchable power sources or energy storage to cope with the unreliability of intermittent power sources. Intermittent power sources sometimes synergize to some extent, such as how wind tends to be stronger at night, and solar produces power during the day. In general however, we cannot rely on these natural synergies to deliver reliable power. We need dispatchable electricity sources to call upon for balancing the grid, or we require a method to storage energy produced in excess of demand to be called upon when demand outstrips supply. Alternatively, we can request that customers reduce their demand when supply is low, this is known as managing the demand response.

Here we will discuss two interesting examples of energy storage systems that we believe show tremendous promise today.

Compressed air energy storage (CAES)

The Basics

Energy is required to compress air into a storage system, and energy can be extracted when air is uncompressed. Using a variety of storage methods and compression techniques, as well as playing on the thermodynamic realities of compression and decompression of gases, energy can be stored for later release back into the grid.

Different types of reservoirs

A CAES storage reservoir requires a large confined volume in which to store compressed gases. The maximum pressure attainable depends on the reservoir characteristics. The greater the compression of the air, the greater the energy storage density. Reservoir types include salt caverns, old mines, underground aquifers, and sealed underwater vessels. The solid reservoirs perform similarly, while the water ones have distinct advantages.

In any reservoir, air can be compressed to within a safe margin of the reservoirs’s breaking point, which varies from reservoir to reservoir. As this is done, the pressure in the cavern will vary from the ambient (atmospheric) pressure upwards. In an aquifer or underwater vessel, the compressed air will displace a volume of water until the water pressure is in balance with the air pressure; providing bonuses to turbine operation due to the narrowed range of operating pressures, and a variable reservoir.

The difficulties

During compression some of the energy will go into heating the air, all other important variables remaining the same. During decompression, each unit of work extracted reduces the temperature of the remaining air, reducing its pressure and therefore the work that can be extracted from the same mass of air. Increased temperature due to compression will make the air more difficult to compress, and much of this heat energy will be lost as the air reservoir cools to the ambient surrounding temperature.

The thermodynamic efficiency of the compression and decompression stages is determined by the ratio of compression/decompression undergone per stage. For acceptable efficiencies to be achieved, the change in pressure per stage should be minimized, but each additional stage adds time and equipment cost, and there is a declining rate of return as we add more stages. When a proper balance is struck, roughly 75% of the energy stored can be retrieved, including loses due to equipment.

When compressing gas into the reservoir, this heat energy will be lost unless it is channelled to alternative uses, such as space heating or process heat. To make efficient use of the compressed air, it must be heated during the decompression stage. This heating can be achieved by allowing time and utilizing heat exchangers to assist the air in rising to the ambient temperature, but this is costly. In practice, natural gas turbines are often used to provide additional heat. This practice strikes the most effective balance between cost, speed, and efficiency. In a purely renewable compressed air energy storage system, sustainable sources of biogas may be used as the heat source and a different operational balance struck.

There are a few large scale commercial air storage systems in use, such as the Iowa Stored Energy Park with a peak output capacity of 270 MW at a cost of 200 to 225 million USD ($740 to $830 per kilowatt peak output) to and a few others we are aware of. Costs have also been estimated at around $600 to $700 per kilowatt of generation capacity for a wind-integrated system ((Wind Integrated Compressed Air Energy Storage in Colorado. Richard Moutoux. University of Colorado at Boulder, Colorado, Frank Barnes. University of Colorado at Boulder. Accessed October 18th, 2010.)).

Cambridge gravel-argon battery: Great potential

Researchers at Cambridge have experimented on a gravel-argon battery that can store energy in the temperature difference between two large gravel masses. Essentially the system acts like a refrigerator when it is storing the energy, so it causes one silo to heat up to about 500ºC, and the other to cool down to about -160ºC. This temperature difference leads to a theoretical thermal efficiency (initially) of about 85%. The researchers claim a practical conversion of up to 80% efficiency.

The cost of the system is quoted at about 10-55 dollars/kWh of storage. Also, the energy leaks away only very slowly. The designer is quoted as saying that a large insulated system (50m diameter, 50m tall) would lose half its energy to leakage in about three years. Additionally, this storage mechanism would occupy a very small area compared to pumped-hydro storage, our best energy storage mechanism today.

Dispatchable renewables

Update: A later issue of the renewable energy review covers the issue of how we can produce dispatchable power using renewable sources.

Call for submissions

This concludes the second installment of the Renewable Energy Review Blog Carnival. For a complete list of all publications in this series, see our post regarding the launch of the carnival. If you are interested in submitting an blog post or article to this carnival, see our submission page on the Blog Carnival website. This carnival is published regularly, and we are always interested in seeing new material.

The intent of this publication is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority.

Renewable Energy Review

The intent of this publication is an ongoing investigation of the progress and potential of renewable energy in our world. Our goal is to collect the best writing and news on the subject of renewable energy projects and policies. We have observed that humanity is innovating rapidly as the energy security of the future becomes a global priority. Current trends indicate that the age of coal will end before we run out of coal.

This is a Blog Carnival, where people can submit their blog posts and articles on this topic for inclusion in the next issue. For more information on article submission, see the launch post for the Renewable Energy Review.

What is renewable?

In order to be precise about what it means for an energy resource to be renewable, it is necessary to look at the original source of the energy in question. We have written a longer piece on the subject of what does ‘renewable’ mean for those interested in a deeper look. In short, renewable energy is a term to describe energy resources that are not depleted through use. All energy resources that we currently know of have limited lifetimes. Even renewable energy resources can be depleted on time scales of millions to billions of years. For all intents and purposes though, energy resources that can last that long are considered ‘renewable’.

Most forms of renewable energy that we are familiar with such as wind, hydro and solar depend on energy emitted by our sun. The sun uses nuclear fusion as its power source. The sun’s estimated lifetime is several billion more years. Similarly, if we had fusion power plants, we would have billions of years worth of energy available just using materials such as deuterium, which we can find in the earth’s oceans. For more information, see how we create power from nuclear fusion.

‘Green’ but not renewable

There are a number of energy sources that are regarded as ‘green’ to some extent, but are not strictly renewable. In some cases, such as biomass, an energy source could be renewable but the way in which we currently use it is not.

Landfill gas

Landfill gas plants require a source of waste. Currently there is a lot of such waste to be had, but the supply is not guaranteed for the long term, especially since we are likely to pollute our environment badly if we continue on this path. Landfill gas plants might be making more efficient use of our waste, but they are not an actual solution to the waste problem, nor are they technically renewable unless all of the waste they use is of renewable origin.

Geothermal

Geothermal is expected to be renewable on very long time scales. The source of the earth’s central heat is not well-understood, but there is a very large amount of it. It is very unlikely that our efforts will significantly change the temperature of the mantle and core. However, the practical difficulty of extracting heat from ever-deeper in the earth will eventually cause the price of deep geothermal to be too high for us to bother constructing it as long as alternatives exist. This is because in theory we would have to drill deeper and deeper to attain high temperatures. For the foreseeable future however, we can regard geothermal as renewable for the time scales that we humans normally plan for.

Biomass

Biomass energy relies on the sun’s light to power plant growth. As long as the plant growth can be sustained, biomass can be considered renewable. Non-renewable biomass consumption can happen in two ways:

1. If we consume our biomass resources more quickly than they grow, such as chopping down old growth forest. This is an ongoing problem in our world today.
2. Using external chemical inputs such as fertilizer, pesticides, or herbicides to help the growth of biomass. If these inputs depend on non-renewable resources such as potash and natural gas, as they often do, the biomass production is somewhat non-renewable. Similar arguments can be made if petroleum products are used since they are also non-renewable.

Material Cycles

On a related note, renewable industry, when considered in a general sense, has some additional overarching goals. Materials should be used in cycles driven by renewable energy. Materials should be used until they need replacement. Renewable energy should be used to make them useful again. There should be theoretically little to no ‘waste’.

As elaborated in the book Cradle To Cradle by McDonough and Braungart, we can distinguish between two general categories of cycles: biological and technical. Biological cycles are driven by life and the sun. Technical cycles are everything else we create. For instance, we might get aluminium from rocks, use it to make a drink can, and then use some renewable energy to reform it into a new can after it has been used. Renewable industry of this sort will require rethinking our designs from the ground up.

Types of Renewable Energy

Hydroelectricity

Hydroelectricity, or ‘hydro’, is energy drawn from the water cycle of the earth. The sun’s light powers the evaporation of water on the surface of the earth, causing it to rise up to form clouds. Clouds eventually form droplets, which then rain down to the surface. The cycle then starts again. Driven by the sun, the water cycle is a truly renewable resource. Hydro is the most well-established form of renewable electricity production. It accounts for about 20% of global electricity production ((Renewables Global Status Report 2006. Renewable Energy Policy Network for the 21st Century.)). Hydro in 2006 produced about 88% of all of the ‘renewable’ electricity in the world.

New and planned large-scale hydro projects are producing progressively more electricity. That is, the scale of projects has been increasing throughout the 20th century. This has led to the recent development of hydroelectric mega-projects such as the Three Gorges Dam in China, which can produce up to 22.5 GW of power. Most of these large scale installations utilize reservoirs to stabilize power production and water levels. The construction and use of a water reservoir can have both positive and negative effects. Reservoirs have many uses, such as irrigation and flood control, but they also tend to force the migration of people, flood valuable cropland, and damage local ecosystems. Flooded land also contributes to greenhouse gas emissions, since decaying biomass underwater tends to produce a lot of methane.

In the developed nations, the majority of the ideal reservoir hydroelectric locations have been developed. Newer development is often forced to use locations that are not as ideal as those used for earlier installations. However, advancing technology and societal wealth have also unlocked opportunities that were infeasible in the past. Additional development of hydro will eventually be restricted as a result of us having developed all of the really good locations.

On the other hand, there has also been a resurgence of interest in the smaller forms of hydropower ((Wikipedia: Hydroelectricity: Small Hydro. Accessed October 11th, 2010.)) and non-reservoir forms such as run-of-river hydro. Run-of-river systems generally have a reduced environmental impact as compared to reservoir-based techniques. The problem is however that they are generally not dispatchable, limiting their usefulness. If a river flows year-round, then some fraction of a run-of-river hydro system’s power capacity can be considered baseload.

Wind

Wind power has been seeing rapid development all over the world. The installed capacity of wind power has been increasing in recent years at nearly 30% per year. Growth is expected to continue into the next few years at the very least. The cost-effectiveness of wind turbines has improved as larger and taller turbines are built.

A recent trend in wind turbines is towards bigger turbines that reach their maximum power at a slower wind speed. For more information on the subject, see the CNet News: Green Tech article on The next big thing in wind: Slow wind, huge turbines.

Overall the wind power sector has seen tremendous growth and interest in the last few years. It has attracted interest as a cost-effective renewable energy resource. It is important to keep in mind that wind power is intermittent and cannot be dispatched. This means that while it can provide useful energy for our society, it cannot be relied upon by itself. We need dispatchable sources to use in harmony with wind.

Solar

Direct solar energy can be captured in many different ways, and for many different uses. Major implementations that we have looked at in our work are solar photovoltaics and solar thermal power. We give here a brief summary of each, along with a link to our more in-depth articles on each subject.

Solar photovoltaics (PV) are commonly called ‘solar panels’, and they are what most people think of when they think ‘solar electricity’. Solar PV capacity in the world has been growing at a tremendous rate in the last few years, around 60% per year! ((Renewables 2010 Global Status Report. Renewable Energy Policy Network for the 21st Century.)) This means that the installed capacity of solar PV is growing faster (by percentage) than any other power source.

Solar thermal power is created by focusing the sun’s light to create heat. The heat is then used to run a heat engine such as a steam turbine. Some variants of solar thermal power are cost-competitive today and show promise of being extremely cost-competitive in the near future. Solar thermal power has the potential to be both baseload and dispatchable due to its ability to utilize thermal energy storage effectively. These properties make it extremely desirable for use in conjunction with intermittent renewable sources such as wind, solar PV, and run-of-river hydro.

Geothermal

Electricity

The earth’s crust is a relatively thin shell covering a molten layer of material called the mantle. As we drill deeper into the earth’s crust, we find hotter and hotter ambient temperatures. Geothermal electric power uses these hot temperatures to turn water into steam to drive electric turbines. Additionally, the heat can be used for industrial purposes or for space heating.

The feasibility of geothermal power development is very strongly connected with the cost of drilling to a sufficient depth. Deep drilling is often required to obtain hot enough temperatures to make cost-effective electricity. Some areas of the world that are developing geothermal power are Iceland ((Wikipedia: Geothermal power in Iceland. Accessed October 11th, 2010)), the United States ((Wikipedia: Geothermal Power in the United States. Accessed October 11th, 2010.)), and the Philippines ((Wikipedia: Geothermal Power in the Philippines. Accessed October 11th, 2010.)). These countries have access to geothermal heat that is relatively close to the surface. This makes tapping the resource much more cost-effective, since the drilling does not have to go as deep. This has contributed to the development of geothermal energy in these nations.

Cost estimates regarding the future of geothermal energy vary greatly. It has been noted that the advancement of drilling techniques for oil field discovery and development has been contributing to a gradual reduction in cost for geothermal development.

Heat pumps

Another way to use geothermal energy is to use the earth as a thermal heat sink. For instance, in many areas of the world, the temperature around 4 meters underground is very stable, even season-to-season. Many homes in the world are now using geothermal heat pumps, or geoexchange systems, to help regulate the temperature of buildings ((Wikipedia: Geothermal heat pump. Accessed October 11th, 2010.)). The ground can provide both cooling in summertime and heating in wintertime. Leveraging this energy resource can lead to dramatically reduced energy use for air conditioning and heating.

Biomass

Biomass energy is essentially using living things like plants, fungi, and bacteria to change some of the sun’s energy into other forms that are useful for us. There are many different ways to accomplish this. However, we will not go into too much detail here. In general, biomass energy is used for electricity, heating, and as high-density fuel for transportation.

Humans have been generating heat by burning plants for thousands of years. In the last two centuries, we have used the heat from burning plants to produce electricity. In the last few decades we have begun to turn plants into high-density fuels such as ethanol and biodiesel on a large scale. This is new implementation but not new knowledge since it has been known since the  invention of the Diesel engine that plant-based oils could be used as vehicle fuel ((Wikipedia: Biodiesel: Historical Background. Accessed October 11th, 2010.)).

A lot of research is being conducted into possibilities for biofuels to replace petroleum fuels on a large scale. Some intriguing research is being conducted, but the challenges are very great. Not only is the goal to replace the largest human industry ever created, this task must be accomplished by leveraging one of the oldest and most well-established industries: farming.

Our arable land is already under great pressure to perform in order to feed our world’s population along with our gobally increasing meat consumption. In order to fuel this land productivity, we are drawing on enormous amounts of mineral wealth such as potash, and energy wealth from fossil fuels. The Haber-Bosch process for producing plant fertilizer is responsible for most of the gains in cereal crop production in the 20th century ((Wikipedia: Haber process. Accessed October 11th, 2010.)) ((Common Wealth: Economics for a Crowded Planet – by Jeffrey Sachs.)). This process requires a tremendous amount of energy, most of which we still draw from non-renewable sources. For this reason and others, the path we are currently taking with our agricultural production is unsustainable. Better methods of land management and crop choice need to be implemented such as biodynamic agriculture.

Tidal Power

The Earth-Moon system creates predictable movements of water, called tides. Tidal power production has seen relatively little development, but presents some intriguing potential for the future. There are a number of different techniques for capturing the energy of tides.

Some of these have already been implemented in power plants such as tidal stream generators, which can be likened to wind turbines that are underwater. Another type that has been implemented already is barrage tidal power, which involves creating a dam across the mouth of a river or bay area which has a large volume of water flow during tide changes. Electricity is produced from a barrage system in a similar fashion to reservoir-based hydroelectric stations. Dynamic tidal power is an ambitious and very interesting idea for large-scale tidal power. It requires very specific conditions and a very large dam, but it has the potential to harness a tremendous amount of energy.

Tidal power has not been implemented extensively, but it is being investigated more seriously in recent years. Tides are much more easily predicted than wind or cloud cover, making tidal power easier to forecast than wind or solar PV. Predictability is important with regards to intermittent resources. Knowing when you need more power from other sources means you can ramp up other generators exactly when you need them. Uncertainty about power production means that extra power needs to be available to cover any sudden blips. This extra power availability entails additional cost. Tidal power may be more intensely developed in the coming decades thanks to its predictability and possible cost-economy.

Dispatchable renewable energy

Update: A later publication of the renewable energy review includes a more in-depth discussion of how we can produce dispatchable power from renewables.

Call for submissions

This concludes the first installment of the Renewable Energy Review Blog Carnival. For a complete list of all publications in this series, see our post regarding the launch of the carnival. If you are interested in submitting an blog post or article to this carnival, see our submission page on the Blog Carnival website. This carnival is published regularly, and we are always interested in seeing new material.