Renewable Power Space

Dabancheng Wind Farm

2011-02-26T14:34:00.000-08:00

Capacity -

Dabancheng Wind Farm (达坂城风力发电站) is also known Three Gorges in the Western China, although its energy source is wind rather than water, because its capacity and scale is mimic to The Three Gorges in Central China. It’s the largest wind farm in China, and in Asia.

The total installed capacity of Dabancheng Wind Farm is 1,250MW. The potential capacity of Dabancheng Wind is 2,500MW.

Location -

Dabancheng Wind Farm is located in Xinjing Uygur Autonomous Region. It has over 300 howling wind turbines installed on 80 kilometers by 20 kilometers area of land.

The Three Gorges Hydro Project

2011-02-26T09:32:00.000-08:00

Capacity -

The Three Gorges Dam is the world’s largest capacity hydroelectric power station with a total generating capacity of 18,200MW. It has twenty-six 700MW turbines and eventually it will have 32 generators making a total capacity of 22,500MW. The first generator started on July 10, 2003. The 14 north side generators and 12 south side generators are in operation. Six underground generators are expected to be completed by 2012.

Distribution -

The power from The Three Gorges Dam is distributed to various cities and provinces in Central, South and East China at the price around $36/MWh. Nine provinces and two cities including Shanghai consume power from the dam.

Power distribution and transmission infrastructure cost about $5 billion. Power is distributed over multiple 500kV lines. 3 DC lines to the East China carry 7,200MW. 1 DC lines to the South China has capacity of 3,000MW. The DC lines have advantages of power transportation over long distance in the geography.

Environmental and economical -

The Three Gorges reduces coal consumption by 31 million tonnes per year, avoiding 100 million tonnes of greenhouse gas emissions, 370,000 tons of nitric oxide, 10,000 tons of carbon monoxide, and a significant amount of mercury, reducing carbon dioxide by 190 million tons, sulfur dioxide by 2.29 million tons and nitrogen oxides by 980,000 tons from 2003 to 2007 alone.

The Three Gorges Dam project costs $22.5 billion.

All about PV Panels

2011-01-06T22:09:00.000-08:00

Photovoltaic (PV) panels are critical for any solar roof system. Solar panels vary in many aspects. Major considerations for solar panel are technology, efficiency, wattage and amp output, size, price and brand. There are many brands available for solar panels too. Below is a quick overview of commercial available PV panels.

Technology: common types of solar panels are Monocrystalline, Polycrystalline, Amorphous, cadmium telluride, etc. When solar cells are cut from a chunk of silicon that has been grown from a single crystal, they are moncrystalline cells. In comparison, polycrystalline cells are cut from multifaceted silicon crystals. More surface area is related to inherent flaws and thus polycrystalline is less efficient and less expensive than monocrystalline cells. Amorphous silicons are non-crystalline form of silicon. Amorphous solar cells are relatively cheap to produce and widely available.

Efficiency: in general the efficiency of solar panels can range anywhere from 6% to 40%. Efficiency is measured as the electricity energy produced by solar cell compared to the sunlight energy it receives. Usually Monocrystalline cells have highest efficiency and can be as high as 20%. Polycrystalline cells are slightly less efficient than single crystal, but the actual difference in watts per square foot is not much. In comparison, the efficiency of amorphous solar cells is typically between 6-8%.

Wattage rating: solar modules can vary largely in rating. Commercial solar modules can range from 1 watt to about 300 watts. The size and weight of solar modules increase with the wattage rating. Roughly a solar module of 100 watts approximately needs an area of 10 square feet to install.

Size: A 100 watt solar model can weight around 20 lbs. Solar modules over 200 watts can weight 40 lbs. and above. For an average U.S. household need of 3,000 watts, roughly 300 square feet area to place solar panels. Larger area may be needed if considering other factors such as the number of rainy days (Solar Introduction) and the loss of the DC/AC inverter.

Price: Solar panels can vary widely in price. Typical price range is $3 to $6 per watt. Recently low price per watt (such as $1 per watt) solar panels are also available. In addition, tax credits and utility rebates also drive down the cost of solar roof system.

Brands/Solar Companies: There are many companies that make solar panels. Here is a non-exclusive list: ALPS, BP Solar, GE, Sharp, SolarTech, SolarWorld, SANYO, Photon Solar Panels, SolCharger, SunWize Solar, Suntech Solar, Trina Solar and Uni-Solar.

This article is not meant to be a guide for purchasing/installing a solar roof system, rather it provides basics of a solar system and list resources for those who may consider solar as alt. energy source.

Privacy Policy for futurepowersystem.blogspot.com

2011-01-06T22:07:00.001-08:00

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All about PV Panels

2010-12-19T21:10:00.000-08:00

Primary components of a solar roof system

2010-12-17T18:01:00.000-08:00

Basically a solar roof system is a system to convert solar energy to electricity for residential or industrial uses and usually it’s mounted on the roof of a house or building. The primary components that consist of a solar roof are the following:

1. Photovoltaic Panels (PV Array)

2. DC Disconnect

3. Inverter

4. AC Disconnect

5. Meter

6. Battery bank

Photovoltaic (PV) panels are a component to convert sunlight energy to direct current (DC) energy. PV panels are one of two main technologies (provide the link to the previous article) to achieve this conversion. PV panels can be rated in watts and the rating can help to determine how many panels one need to meet his or her electrical needs. Multiple modules (also called array) may be needed to provide sufficient energy.

DC Disconnect is a safety device to prevent electrical attack from the electricity output from PV panels. Normally the electricity generated by PV panels is fed to electrical appliance or grid through an inverter. When maintenance or troubleshooting is needed, the DC disconnect is required to interrupt the flow of electricity from the PV panel.

Inverter is a power electronics device to transfer the DC electricity produced by PV panels into the alternating current (AC) electricity. Most home appliance is compatible only with AC electricity and the power grid is also formed as AC electricity. If the electricity produced by PV panels is tied to the grid, then grid-tied inverters are required which not only convert DC to AC but also synchronize the PV electricity with the grid and allow the electricity from PV panels to flow back to the utility grid.

AC Disconnect or AC Breaker Panel can be found at most houses with and without solar roof system. The AC Breaker Panel is usually mounted on a wall such as in basement, garage or exterior of the house. The inverter will be wired to the AC breaker panel before the PV electricity flows to the grid or home appliance. Same as the DC disconnect, the AC disconnect (AC Breaker Panel) enables the electricity to be disconnected for servicing and protect the electricity equipment against overheating and electrical fires.

Meter is needed to measure the amount of energy from the grid being consumed by the household, measured in kilowatt hour (kWh). For households with solar roof system installed, a bidirectional meter may be desired, to measure not only the energy received from the utility grid, but also to measure unused energy produced by PV panels that is fed back to utility. Such bidirectional meter can be also used to provide information on power usage profile to help determine the need for additional PV panels.

Battery Bank is optional to a solar roof system. Battery bank can be used to store the electricity produced by solar panels when it’s not needed. Battery bank also serves a source to provide constant power for home appliance such as in cloudy days when the sun doesn’t shine. Battery bank may not be needed if the house is still tied to the utility grid.

What is typical capacity of new PV power plants?

2010-12-05T21:52:00.000-08:00

Recent years have seen rapid developments in solar power. From 2002 to Oct 2010, there are about 4.6 GW new additions of large-scale solar power plants in about 20 countries (large-scale meaning the capacity is over 1.5MW here). Among those new additions, Spain and Germany are the two countries where solar power development is fastest. For example, in Spain in 2008 alone, there is about 1.8GW addition of large-scale solar power plants. Not only the volume of new solar power grows very fast, but also many new solar power plants are large-scale power plants, and some are even comparable with conventional power plants in capacity. Below is a review of new solar power plants’ capacity from 2002 to 2010 for the following countries:

§ Spain

§ Germany

§ Czech Republic

§ USA

§ Italy

In those countries, although the number of larger size (over 20MW) PV solar plants are relatively small, but those plants account for a significant portion of total solar capacity.

The pie charts show the percentage of total capacity of PV power plants for each size category and the percentage of total number of PV power plants for each size category, for the countries mentioned above. Take Spain for an example, on one hand, the PV power plants with capacity of 2 to 5 MW account for 40% in capacity of all PV power plants installed with capacity of 2MW and above during the last 5 years, while they account for over 70% in the number. On the other hand, the PV power plants with capacity of 20MW and above account for23% in capacity and only 4% in number.

Spain:

Germany:

Czech Republic:

USA:

Italy:

Recent developments in solar power

2010-11-20T22:03:00.001-08:00

Recent years have seen rapid developments in solar power. According to the Renewables 2010 Global Status Report, the total existing capacity of solar PV exceeded 21GW worldwide and the solar capacity in 2009 is nearly six times that in 2004. Among all kinds of solar power, ground-mounted solar power plants and roof-mounted solar systems are two major categories. Due to implementation challenges and limited mounting roofs, roof-mounted solar systems are usually small scale solar power systems where the capacity is usually below 1MW. Therefore, large scale solar power systems are usually ground mounted solar power plants. In recent years, both ground-mounted solar power plants and roof-mounted solar systems grow fast; however, ground-mounted solar power plants grow more rapidly than ever in the last few years.

Ground-mounted solar power plants grow very fast, not only in volume but also in scale. For example, there are about 38 solar power plants with the capacity greater than 20MWp and most of them are completed after 2007. This indicates that the capacity of new and planned solar power plants will increase.

The development of solar power varies largely by country. So far, European countries are primary drivers of PV installation due to high feed-in tariffs subsidies and good solar resource. Those countries include Spain, Germany, Czech Republic, Italy, France, Portugal, Belgium, etc. North American countries also see large investments in solar power as well, such as in USA and Canada. Asia countries including China, Korea, Japan and Thailand also see substantial growth in solar power. The charts below show the added capacity of large-scale PV solar power plants between 2002 and 2010 in the above mentioned countries. In the chart, only solar power plants with the capacity greater than 2MWp are considered as large-scale and are counted (while a capacity above 200kW is generally considered as large scale in the solar industry).

As shown on the chart, about 2GW of Spain solar power plants installed between 2002 and 2010 have capacity larger than 2MW. For Germany, it’s about 1.3GW of installed solar during the period has capacity larger than 2MW. These two countries account for over 70% of all installed large-scale PV solar power in the time period. However, the picture might change, given the recent dynamics in solar policies and developments in other nations. For example, it is expected that a series of the renewable percentage standards will become mandate in USA and some developing countries such as China have ambitious plan in renewable energy investment and favorable national financial support. We will monitor the new developments in solar power closely. Please stay tuned.

Top 10 Largest PV Solar Plants on the Earth

2010-10-31T20:06:00.001-07:00

No. 1 Sarnia Ontario, Canada, 80MW, 2010

The 80 MW Sarnia Photovoltaic Power Plant in Canada is the world’s largest photovoltaic plant. It was built by First Solar, Inc. and Enbridge Inc., and was extended from 20MW to 80MW. The Sarnia Project consists of 1.3 million solar panels covering a surface of 950 acres and generates 120,000 MWh annually to power of 12,800 homes. The project also created 800 jobs. It is estimated that it saves 39,000 tonnes of CO2 annually.

The project was made possible by very favorable feed-in tariff established by the government of Ontario. The power output will be sold to the Ontario Power Authority pursuant to 20-year Power Purchase Agreements under the terms of the Ontario government’s Renewable Energy Standard Offer Program.

Although the Sarnia plant is the current world’s largest PV plant, the Blythe Solar Power Project will replace this plant to become the No. 1 in coming years. The 1 GW Blythe Solar Power Project is approved by the Secretary of The Interior and to be developed by Solar Millennium.

No. 2 Olmedilla solar plant, Spain, 60MW, 2008

The Olmedilla de Alarcon solar plant is located in Cuenca, Spain. It provides 60MW, uses 270,000 crystalline-Si modules from Siliken and was built by Nobesol. The electricity generated is used to power 40,000 homes.

No. 3 StraBkirchen, Germany, 54MW, 2009

This 54MW solar project was built by Q-Cells SE in Saxony-Anhalt and MEMC Electronic Materials Inc.

No. 4 Turnow-Preilack, Germany, 53MW, 2009

Built at Lieberose Photovoltaic Park in Lieberose, Brandenburg, Germany, this power station has 700,000 solar panels and capable to power 15,000 homes.

No.5 Puertollano, Spain, 50MW, 2008

No. 6 Moura, Portugal, 46MW, 2008

No. 7 Kothen, Germany, 45MW, 2010

No.8 Finsterwalde, Germany, 42MW, 2009

No. 9 Brandis, Germany, 40MW, 2007

No. 10 Reckhahn, Germany, 36MW, 2010

Solar power introduction

2010-10-20T21:51:00.000-07:00

How much solar energy available on the Earth?

It’s estimated that the energy from the sun to reach the ground of the earth is about 1kW/m² at the equator of the Earth. In addition, solar collectors have a lower efficiency because of the low sun angle during evenings and early mornings, and collect none solar energy at night. Considering the earth surface is a sophere, the average available energy reaching the ground at the equator is a little over 300W/m2 (1kW/m2 divided by pi (3.14159265)). Given that the typical efficiency in converting solar energy to useful power is from 15% to 30%, the average available energy reaching the ground at the equator is 50W to 100W/m2. This is the maximum useful solar energy reaching the Earth at the equator.

The maximum useful solar energy reaching the Earth at other places will be less than the value above (50 to 100W/m2), depending on the distance to the equator or, depending on the sun angle (the angle between the incoming sunlight and the Earth’s surface). For example, the maximum useful solar energy reaching the northern U.S. is about 90W/m2 for a 30% converting efficiency, and 45W/m2 for a 15% converting efficiency. Accounting for weather such as the number of cloudy and rainy days, the maximum useful solar energy is further reduced by another 35% on average, to approximately 30W/m2 with a 30% converting efficiency and 15W/m2 with a 15% converting efficiency. This compares to 3,000W, the power a typical U.S. household needs. In other words, a 100m2 solar collecting area is needed for a typical household if all the power the household consumes comes from the solar.

What are the technologies to convert the solar to electricity power?

Several technologies can be used to convert sunlight into electricity: photovoltaics (PV), concentrated solar power (CSP), sterling engine dishes and other technologies.

Image of Solar Panel

Photovoltaics (PV)

Solar cells are used to convert energy from the sun into electricity through Photovoltaic effect. Although solar power has grown rapidly only in recent years, the first practical application of PVs was to power satellites and spacecraft back in 50’s. Today due to environmental concerns and government feed-in Tariff in many countries, the major applications of PVs are to connect the power generated by solar cells to grid or grid-tied Building Integrated Photovoltaics (BIPV) like roof-top solar. Other applications include solar-powered batteries for the use in remote dwelling, boats, recreational vehicles, electric cars, emergency equipment, remote sensing and even some toys. The electricity produced by solar cells is direct current. If desired to be connected to power grid, an inverter is required to convert the DC to AC, since the bulk power system operates in AC (Alternative Current).

According to Renewables Global Status Report, Photovoltaic production is the world’s fastest-growing energy technology. It’s also reported that at the end of 2009, the cumulative global PV installations surpassed 21GW. Typical solar PV power stations range from 10-60 MW in the capacity and the capacity of many new solar PV power stations is expected to increase to 150MW or more. The average annual use of solar photovoltaic capacity, i.e. the capacity factor, is typically below 25%. The efficiency of typical practical solar PV panels, i.e. the efficiency of energy conversion, is roughly 12-18%. However, higher efficiency has been achieved by some companies like SunPower (24%) and some research institutions (40%). There is also an energy loss of 4-12% during the DC-AC conversion process due to the heat produced and electric power consumed by the inverter.

Regarding the material for PV panels, thin-film solar cells (CdTe CIGS, amorphous Si, microcrystalline Si) become popular and partially replace crystalline silicon modules.

Usually PVs are costly to install. Even some financial agents offer long term contract such as 25 year contract (or Power Purchase Agreement) to reduce up-from cost, much of the investment in a home-mounted system may be lost due to the change of the owner of the house.

Concentrated Solar Power (CSP)

Concentrated solar power systems are divided into three types: concentrated solar thermal (CST), concentrated photovoltaics (CPV), and concentrating photovoltaics and thermal (CPT).

Concentrated solar thermal (CST) system is basically similar to a conventional power plant but with the heat source being the concentrated light. Concentrating technologies include the parabolic trough, dish stirling, concentrating linear Fresnel reflector, solar chimney and solar power tower. For these concentrating technologies, high temperature is produced in the system, usually at 150-1000 ^oC.

Concentrated Photovoltaics (CPV) system is basically similar to a PV system but with concentrated sunlight instead of regular sunlight.

Concentrating Photovoltaics and Thermal (CPVT) system produces both electricity and thermal heat in the same module, much like a conventional thermal pant but with heat source being concentrated sunlight. Thermal heat produced can be used for hot tap water or heating purposes for houses and buildings.

Benefits and myths about renewables

2010-10-15T21:36:00.000-07:00

Renewables generally refer to natural resources that are renewable. Renewable energy has been a hot topic in recent years. There are many desired features about renewables that make adopting them an important national and industrial strategy. In 2008, over 19% of global final energy consumption came from renewables and the capacity of renewable resources (the total of generating capability of all installed renewable resources) is 25% [Renewable status report]. More importantly, renewables are growing very rapidly. For example, the wind power harnessed by the human being on the earth is 8 times big today as 10 years ago in the capacity [Renewable status report]. Recent years have seen rapid developments in solar power.

Figure 1: Wind Power, existing world capacity [Renewable status report]

So what exactly are the desired features of renewables that made such change and will continue make the change? Are there any undesirable features associated with large growth of renewables, or are we too enthusiastic about renewables especially given today’s economy? Let’s briefly talk about the desired features about renewables, and then reveal most common myths about renewables.

Key benefits about renewables:

Feature #1: environmental benefits

Conventional power plants including coal plants, gas-burning plants and nuclear plants can cause many environmental issues such as air pollution, water pollution, toxic wastes, etc. Those plants are widely blamed as threaten to some plants and animal life and as well as contributing to global warming. On the other hand, renewables such as solar and wind don’t have those issues, or to a lesser extent. In general renewable energy is considered as clean energy or green energy, with a much lower environmental impact than conventional energy technologies.

[http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/public-benefits-of-renewable.html] lists all environmental issues associated with conventional power plants

Feature #2: cost benefits

Hydro power is the most significant source of renewable energy, and also they are cheaper than coal or gas-fired power plants. Wind power may have some capital costs and maintenance costs, but the production cost (fuel cost) is near $0. So apparently some types of renewables bring significant cost benefits to the society.

Feature #3: sustainability

As the name implies, renewable energy never runs out. This is unlike conventional energy sources which are finite and will someday be depleted. Renewables don’t have fuel transportation and storage issues either.

Feature #4: jobs and economy

Although it’s true that some renewables are expensive, renewables can also bring a lot of jobs, and most importantly, they are green jobs. This is because renewables are usually localized energy sources, and explore such sources, local jobs will be created. Also, investments have been spent on materials and technology innovations related to renewables. Those investments bring a lot of high-tech jobs as well. Therefore, there is no wonder that a large portion of government economy stimulus package is targeted to the renewable industry.

Feature #5: energy independence

The skyrocket gas price from time to time emphasizes the importance of energy independence for the nation. If we continue to largely rely on conventional energy sources which are vulnerable to many serious issues including political instabilities, trade disputes and other disruptions, we will feel less secure as a nation.

Myths about renewables

Myth #1: Renewables don’t cost much because they are renewable

Although it may be true that once installed, a renewable facility will just produce energy with no cost or at a minimal cost, renewable projects usually require significant amount of capital investment which is 5-10 times high as conventional sources on a $/kW basis. Renewables can look much more expensive when considering that their capacity factor (the actual output divided by the capacity). For example, the capacity factor of solar energy is only about 20% - it’s understandable that a solar power plant can’t generate any power during nights. The typical capacity factor for wind is about 30%, which is also low.

Myth #2: Once installed, renewables will reduce the total cost of energy consumption for consumers.

It’s true that once installed, the cost to produce power is $0 or very low for renewables. It’s also generally true that once connected to the grid, renewables will lower down the total production cost for all power consumed by the grid users if the capital cost of those renewables is not considered. So it’s generally true that the renewables would reduce the electricity bills for the grid customers if the capacity cost of the renewables is paid off or not shared by the grid customers.

However, as more and more renewables are integrated into the grid, some specific issues related to renewables will become more and more salient. Compared to conventional energy sources such as gas-fired power plants which are easier to control their output and better follow the load, it’s very difficult or impractical to control the output of most renewables. For example, the wind may blow during nights and stop during day time, which is opposite to the load pattern (load is high during daytime and low during nights). The output of solar plants may be more aligned with load patterns, but they are not controllable – their output depends on the sun. Because of those reasons, as more renewables are integrated to the grid, the grid needs more capability to deal with uncertainties and inflexibilities associated with the renewable sources. Often the grid needs more conventional units sit around on the grid to fill the gap between the load pattern (which is usually dynamic) and the intermittent renewables generation. It follows then, as more renewables are integrated, the cost to operate the grid may increase. Thus the total cost for customers does not necessarily reduce as they consume more renewables.

Myth #3: Renewables can be integrated into today’s electric grid without significant changes on transmission systems.

One of the issues with the today’s power grid is that it is not designed for large renewables in the system. Most of today’s transmission systems are designed without consideration on potential large amount of renewables integrated into the system. The requirements on the transmission systems under renewables are different compared to those from conventional energy sources. Most renewable energy sources are localized resources, usually remote from the existing transmission system. Therefore, significant amount of transmission system usually needs to be built to support renewable integration, which is very often hard to achieve given today’s stringent limitations on issuing land/site permits. Also, to reliably operate the grid under renewables it requires many other supporting transmission facilities such as reactive power equipment, control and communication equipment.

Myth #4: The design of today’s electricity markets supports renewables.

Today’s electric power industry is deregulated in U.S. and other countries in the world, and electricity markets exist to support competition among various generation technologies. However, most of the rules in electricity markets are designed for conventional energy sources, without serious consideration under significant amount of renewables integrated into the system. Given that those rules have not been fully examined for the new era under renewables, it’s possible that renewables could have undesirable impacts on the market, or vice versa.