Policy & Regulation

US state governor argues passionately for cogeneration

Fri, 04 May 2012 12:01:00 GMT

The governor of the US state of Ohio, John Kasich has criticised the renewable-energy lobby in the state for an irresponsible self interest in objecting to cogeneration.

The Chicago Tribune reports that Gov. Kasich offered a most-passionate defence of his proposal to include cogeneration as an acceptable form of renewable energy in Ohio’s energy mix.

He singled out wind and solar power lobbyists as particularly culpable.

"All those who are in alternative energy and renewable standards believe in a cleaner environment, and that's just fantastic," Kasich said. "But don't lobby for your own industry to keep other industries out that result in a cleaner environment. And that happens.

So if I'm in the wind or the solar industry, I'm not so excited about waste heat or cogeneration because I get a nice big fat subsidy. OK.

That's just not the way it ought to be, because our goal ought to be a cleaner environment, and whatever moves us to a cleaner environment ought to be a part of it.

I'm a little disappointed when people lobby, and totally in self-interest."

The newspaper speculates that Kasich might have been referring to ongoing testimony related to Senate Bill 315, which would allow cogeneration --essentially the capture of waste heat --to be used to meet the state's energy-efficiency requirements.

A previous Senate-passed bill would add cogeneration to the definition of renewable energy, making it eligible for renewable-energy credits.

Last month, Columbus lobbyist Terrence O'Donnell testified before a Senate committee on behalf of wind-farm builder EDP Renewables of Houston against the "unqualified inclusion of cogeneration in the renewable-energy standard."

For more cogeneration policy news

Russian ministry paves way for CHP

Thu, 12 Apr 2012 10:29:00 GMT

Three combined heat and power plant (CHP) units owned by Finnish utility Fortum have been approved by the Russian Ministry for Economic Development has as joint implementation projects.

The projects include one Chelyabinsk CHP-3 unit and two Nyagan GRES units, which are part of Fortum's investment programme.

The units, which have a total capacity of 1,052MW electricity, are estimated to reduce greenhouse gas emissions by about 1.4 million tonnes by the end of 2012.

Fortum president and chief executive officer Tapio Kuula said by constructing modern, environmentally benign and energy-efficient energy production capacity in Russia, the company is contributing to the global reduction of greenhouse gas emissions.

"We are delighted that the Russian government is recognising the endeavour by approving again Fortum's new capacities in the country as Joint Implementation projects under the Kyoto Protocol," said Kuula, reported powertechnology.com.

Two enlargement projects - Pervomayskaya CHP-14 and Yuzhnaya CHP-22) of TGC-1 in St. Petersburg - were also approved as joint implementation projects.

For more combined heat and power news

US EPA proposes first carbon pollution standard for new power plants

Wed, 28 Mar 2012 16:06:00 GMT

Following a 2007 Supreme Court ruling, the US Environmental Protection Agency (EPA) today proposed the first Clean Air Act standard for carbon pollution from new power plants.

EPA’s proposed standard reflects the ongoing trend in the power sector to build cleaner plants that take advantage of American-made technologies, including even more efficient CHP technology of choice for new and planned power plants.

At the same time, the rule creates a path forward for new technologies to be deployed at future facilities that will allow companies to burn coal, while emitting less carbon pollution. The rulemaking proposed today only concerns new generating units that will be built in the future, and does not apply to existing units already operating or units that will start construction over the next 12 months.

“Today we’re taking a common-sense step to reduce pollution in our air, protect the planet for our children, and move us into a new era of American energy,” said EPA Administrator Lisa P. Jackson.

“Right now there are no limits to the amount of carbon pollution that future power plants will be able to put into our skies – and the health and economic threats of a changing climate continue to grow. We’re putting in place a standard that relies on the use of clean, American made technology to tackle a challenge that we can’t leave to our kids and grandkids.”

Currently, there is no uniform national limit on the amount of carbon pollution new power plants can emit. As a direct result of the Supreme Court’s 2007 ruling, EPA in 2009 determined that greenhouse gas pollution threatens Americans’ health and welfare by leading to long lasting changes in our climate that can have a range of negative effects on human health and the environment.

For more policy and regulation news

US military to invest $7bn in strategic investment in biofuels

Tue, 27 Mar 2012 09:12:00 GMT

The largest consumer of fuel in the US, the Pentagon, is seeking proposals as it plans an investment drive, targeting bio-fuels.

Oilprice.com reports that the US Army Energy Initiatives Task Force (AEITF) has issued a draft request for proposals (Draft RFP) for renewable energy contracts.

Driving the Pentagon’s green drive is Executive Order 13423, which mandates that the Department of Defense achieve a 30 per cent reduction in non-tactical fleet fossil fuel use by 2020, and over the next decade, an impressive $7bn has been set aside for the purpose.

A 2011 Pew Charitable Trusts report, "From Barracks to the Battlefield: Clean Energy Innovation and America's Armed Forces" reported that Department of Defense clean energy investments increased 300 per cent between 2006 and 2009 - from $400m to $1.2bn - and are projected at $10bn annually by 2030.

A second key piece of legislation driving the Pentagon’s mandate is the Renewable Fuel Standard, which Congress enacted in 2005 as part of the Energy Policy Act, amending it in the 2007 Energy Independence and Security Act.

The draft AEITF RFP marks the beginning of the AEITF's plan to develop a large, coordinated procurement process for renewables.

The AEITF's new program was developed in response to a National Defense Authorization Act that requires Department of Defense facilities to derive at least 25 per cent of the electricity they consume from renewable energy by 2025, and a Department of Defense "Net Zero Energy" initiative, which challenges DOD installations to produce more energy than they consume, with emphasis on the use of renewable energy and alternative fuels.

For more regulatory news

Re-thinking European CHP policy with a new energy efficiency directive

Thu, 01 Mar 2012 20:39:00 GMT

A proposed new directive on energy efficiency, which will replace the 2004 CHP Directive, is currently in the European policy melting pot. Now is the time for the CHP industry and its customers to play a part in the democratic process by making clear their views, writes COGEN Europe’s Fiona Riddoch.

The European Commission identified as early as 2009 that there was a gap emerging between its energy savings target and progress on energy savings in the 27 EU Member States. The Commission published its proposed Energy Efficiency Directive (EED) in June 2011 to plug the gap. The new Directive, which could come into force as early as 2013, repeals the CHP Directive and the Energy Savings Directive (ESD), and explicitly extends the scope of energy efficiency legislation along the energy supply chain. The current CHP Directive (2004/08/EC) will be repealed when the EED comes into force. The future European legislative framework for CHP is thus in the policy mixing bowl that is the Council, European Parliament and European Commission negotiation process.

The Commission’s EED proposal is for new binding measures to be adopted by the Member States to boost energy efficiency/savings across Europe. The new Directive is not a simple combination of the scope of the CHP Directive and the ESD, rather it extends the previous scope to include action across the full energy supply chain and proposes new electricity market elements. There are clear obligations on end use energy savings in buildings and in energy supply, and tighter scrutiny and additional reporting along the energy supply chain. In response to the Council’s constant protests that binding targets are not acceptable, the Commission proposes a set of binding measures, including around the development of CHP, to further encourage the development of CHP beyond the limited success of the CHP Directive.

NEED FOR A NEW ENERGY EFFICIENCY DIRECTIVE

In setting out its case for the new Directive the Commission reveals some interesting analysis of the current progress of Europe on energy efficiency and CHP. It identifies clearly that the greatest untapped energy savings potential is in the energy sector itself. This supports both the further strengthening of CHP and additional measures included in the EED along the energy supply chain – see Figure 1.

Going on to consider the effectiveness of the CHP Directive itself, the Commission concludes that: ‘The main objective of the CHP Directive is to promote the development of high-efficiency CHP as an energy saving measure. It requires Member States to establish via an analysis what their cogeneration potential is, evaluate barriers to realize this potential and report on progress in increasing the share of high-efficiency CHP. Yet focus on the Directive has been on evaluation and reporting. Only the setting up of a guarantee of origin (GO) system based on harmonized calculation methods and the priority dispatch obligation by transmission system operators can be considered as concrete operative action.’

The Commission also confirmed what has been clear from Eurostat data for some time – that CHP has not on average grown in Europe in the recent years. There is no discernible overall upward trend – rather an erratic progress which hides many setbacks and a few remarkable advances. Progress on CHP has been patchy across Europe; the Commission expresses this as 1.6% per annum (2004–2008) – see Figure 2.

Figure 1. Untapped energy saving potential across the sectors

The Commission notes the still high barriers to CHP, raising again the difficult situation surrounding connection and access to the grid for many operators and the wide range of tariff-setting processes still in operation. Operators launching a new CHP project will face very different charging schemes across Europe, with 40% of Member State transmission system operators still using deep rather than shallow charging approaches for CHP.

Figure 2. Electricity from CHP in EU-27 in TWh and required rate of increase - with CHP percentage share in gross generation

In assessing the impact of the EU Emissions Trading Scheme (ETS) on CHP, the Commission raises various points about the ETS in different phases of the scheme and notes: ‘Carbon prices alone (therefore) are not sufficient to remove market barriers unless they result in very high energy prices on a sustained basis, which is not optimal from a societal view point... A strong focus on energy efficiency and effective mechanisms to steer technological development and investment decision is key if Europe is to bring down its energy and resource intensity to the level in line with its 2020 objective and 2050 strategies on a low-carbon, resource-efficient energy system.’

The Commission goes on to point out that two thirds of electricity generation today is in fossil plants and all forecasts show this will remain at least 40% to 2030.

NEW ENERGY EFFICIENCY DIRECTIVE PROPOSALS

In its Directive, the Commission starts from the fundamental position that the 20% energy savings target for 2020 must be met. It requires EU Member States to set targets and states that if the voluntary progress thus achieved is insufficient, then mandatory targets must be considered. In the meantime, it sets out a range of obligations on Member States to implement specific energy savings measures including around CHP.

In Article 10 of the Commission’s proposal, all new electricity generating plant, all major refurbishments of existing plant and all new industrial plant over 20 MW thermal input must be CHP or connected to district heating, and local heat loads must be considered. Exemptions are allowed and criteria are proposed, including the use of a cost-benefit analysis as part of the process. Article 10 also requires Member States to produce a heat plan and requires TSOs to allow CHP plants to offer grid balancing services. In Article 12, CHP is explicitly granted the same priority access to the grid and dispatch that renewable electricity enjoys. It is the force of Article 10 and Article 12, relying on their mandatory and uncompromising nature, the Commission envisages will drive growth in CHP.

There are no additional targets or objectives for Member States. There is no reference to the overall savings target linked to CHP (Article 3). The planning exercise for the promotion of CHP links to requirements effecting local planning authorization, but is otherwise without quantified objective. The Commission thus came out with a strong support for further CHP deployment by simply saying all new utilities and large industrials must be CHP, staking out a strong position for negotiation. However, the method it chose in Article 10 to do this, although simple to explain, is difficult to implement in practice.

The European Parliament created for itself and pursued an aggressive timetable for delivering its position on the EED. However, the broad scope of the Directive has made this difficult to sustain. The European Parliament proposed well over 2000 amendments to the Commission text. For CHP, the Parliament declined to support the fully mandatory nature of the requirements of Article 10 – moving towards a compromise which weakens the heat planning aspects of the Commission’s proposal to a ‘roadmap’, a term lacking the force and resource application suggested by ‘plan’. The Parliament also weakened the mandatory requirements of Article 10 proposing the use of the cost-benefit analysis as the sole deciding criteria for new CHP and district heating associated with new utility and industrial plant. The methodology of the cost-benefit analysis will be developed by the Commission and should be produced by 1 January 2013. However, in the Parliament’s current proposals a positive result in the cost-benefit analysis means a new plant must include CHP or be linked to district heating as appropriate.

The Commission’s Article 12, granting equal grid access status to CHP and renewables, has had its wings clipped. Frequent references to renewables in the Parliament’s amendments to Article 12.5 stop short of creating a hierarchy between CHP and renewables, but the text is weaker than the Commission’s proposals. Article 12.5 is particularly important from the point of view of large industry-based CHP with extended operating hours driven by the industrial process. Such plants must follow the needs of the industrial process and the electrical output has a limited ability to respond to the electricity market signals. Without the guarantees of Article 12 for priority on the electricity network, investors in new plants will have to add into their calculation a quantification of the risk of having to modify generation.

The European Parliament has additionally proposed a new text which could be advantageous to CHP. There is support for action on CHP in capacities under 20 MW, an area neglected by the Commission, and explicit reference to improved operating conditions for small and micro-CHP, plus a set of new proposals in Article 12 to consider the need for a forward capacity market in electricity and to develop plans for a demand response market.

Elsewhere in the EED, the major discussion on target setting and the mandatory nature or otherwise of the target continues to be a point of significant debate between the European Commission, European Parliament and the 27 EU Member States (represented in the Council). The view remains that consensus will result in binding measures rather than a binding target. The major binding measure to achieve real improvement is emerging as Article 6, which requires energy distributors in Member States to achieve annual energy efficiency savings on end-use energy savings equal to at least 1.5% of their annual energy sales, by volume. The target is framed as end-use and, while traditionally space heat from CHP would have been included in such measures, there is a clear intention from both the Commission and the Parliament to exclude CHP from this Article.

THE NEXT STEPS

The co-decision process of agreeing a European Directive between the Council, European Parliament and European Commission will continue until at least June 2012. There is a strong desire in the Parliament to have it completed within this period, where the role of Denmark as President of the Council and a strong supporter of energy efficiency will help motivate discussions and keep the process on track.

The mood in the Council is to oppose strong action and has been since the Commission published its proposals in June 2011. The European financial crisis and major economic issues in Member States have diverted energy away from strong legislation at the European level. The Council is requiring more flexibility and less prescriptive language throughout the text. The appetite for strong legislation is minimal and the Parliament is distracted by economic affairs. The traditional pattern of the Council further diluting the parliamentary position is set to repeat itself again.

However, civil society and business also have a role to play in this democratic process. Those in the Council and Parliament, who will be debating the Directive over the coming months, need input from industry and civil society making clear their views on the key elements of the Directive. Failing to make clear at this point what the sector expects from this legislation and what the sector needs to do to grow, will result in a weakened policy environment around the sector in the years to come.

Particularly large industrial CHPs, which could be threatened by the changes in priority of dispatch, need to make their concerns known and to highlight the value of the sector in energy efficiency terms and the impact of failing to give CHP access for their electricity. It must further be made clear that CHP must be clearly linked to a requirement to action in Member States, and that any weakening in the binding nature of the articles supporting CHP growth must be compensated by strong links to the obligation and targets process.

Dr Fiona Riddoch is the Managing Director of COGEN Europe, Brussels, Belgium. Email: fiona.riddoch@cogeneurope.eu

COGEN Europe will be putting the industry view forward at its annual conference in Brussels on 3–4 May.

For more information, visit www.cogeneurope.eu

Emissions Control for gas turbine energy systems

Thu, 01 Mar 2012 16:44:00 GMT

Cogeneration and district energy, which formed the basis of the world’s very first power plant in New York, can be a prominent solution to energy security and environmental issues. And, as Manfred Klein writes, environmental policies for gas turbine CHP systems are evolving to advance sustainable energy objectives.

There are huge opportunities for industrial and commercial CHP systems. Previous articles in this magazine have discussed solutions to barriers, focusing on the business cases that often do not quantify the many benefits of CHP, and policy drivers that may discourage grid interconnection and local generation. One of these solutions is environmental regulatory policy, which is evolving but often not yet there to provide a balanced health benefit and the required incentives for expansion of ‘clean’ energy in on-site systems for various sectors.

So, what do we mean by ‘clean energy’ – is it just about carbon emissions, or health impacts? See Figure 1. Maybe both – there is more to this, as low air pollution and condenser water impacts have always been important to local regions. Air toxins and CFCs from these same energy systems must also be reduced, and back-end pollution controls have collateral impacts that often affect greenhouse gas (GHG) profiles. Pollution prevention and energy conservation, integrated with system efficiency, are key elements in arriving at balanced and cost-effective long-term solutions that address economic opportunities, energy security and environmental sustainability.

Gas turbine cogeneration systems fuelled by natural gas or synthetic gases have many attributes required by clean energy systems for thermal, electrical and mechanical energy with low air emissions. Smaller machines that can have most of the heat recovered often have the better CHP efficiency and GHG profiles. Best available technology (BAT) considerations will differ greatly, depending on the objectives and environmental issues to be mitigated, and the extent to which prevention and conservation is encouraged rather than controls and NOx emissions dilution. GHG issues may require a completely different environmental assessment (EA) approach than traditional air and water pollution control evaluations.

National guidelines and standards with comprehensive and consistent objectives applied in EAs or BAT determinations can give the best overall approaches. Until recently, GHG emissions and energy efficiency, as a balanced environmental issue, have rarely been studied in permitting and EA processes. Assessments may wish to consider the whole facility as a total energy system, rather than individual components, and may also include the various emissions and efficiency trade-offs in the surrounding region (for example to look for waste heat utilization potential, and water impacts).

Figure 1. Clean energy balancing act

A large fraction of the world’s energy production has been installed using various types of small and large gas turbine systems. Like other nations, Canada has many types of designs, in about 80 active gas turbine CHP plants and over 20 large gas turbine combined-cycle plants.

EMISSION STANDARDS FOR INDUSTRIAL GAS TURBINES

Gas turbines are thermodynamic engines which use a steady inflow of a gas (mostly air), compressed and fired with gaseous or liquid fuel. This high-pressure hot air mixture is expanded through a turbine to generate output power for thrust in an aircraft engine and for marine propulsion, or as shaft power for applications such as pipeline compression, electrical power and CHP heat production. Note that ‘gas turbine’ is a general term regardless of fuel used, as it is the large amount of clean air that produces the turbine power.

Most air pollution NOx measurements are done on a volumetric concentration basis, in parts per million by volume (ppmv) or in some cases in a weight/volume fraction such as mg/m³. Uncontrolled gas turbine NOx emissions are in the 150–300 ppmv range (about 300–600 mg/m³). Sometimes rules are based on a pollutant mass per unit heat input, such as lbs/MMBTU or grams/GJ.

There is little environmental stimulus to conserve energy, and plant output and system efficiency is not directly considered. To some degree they give an incentive to dilute the emission using airflow or stack height, although excess air can be limited by defining a standard oxygen content, such as 15% O2. Back-end controls also tend to encourage parasitic power losses, and plant efficiency objectives are not considered in the analysis. Traditional emission standards and assessment methods do not consider CO₂ emissions, a necessary product of heat release.

Energy conservation is clearly pollution prevention, and therefore waste heat recovery and CHP should be specifically recognized as an emission prevention technology. An alternative output-based standard such as kg per MWh allows the plant designer and operator to take advantage of all available system efficiencies to reduce fuel consumption, and parasitic losses, or to increase output to offset other emissions. Output-based criteria allow simple and clear comparisons with other technologies, and can readily be used in emissions trading scenarios.

Emission standards should also deal effectively in a balanced fashion with collateral emissions, such as CO, unburned hydrocarbons, particulate matter (PM) and air toxics, as well as GHG emissions of methane and nitrous oxide.

Canada

In 1992, Canadian emission guidelines for stationary combustion turbines were published through a national consultation to promote reasonable pollution prevention technology to achieve a sizeable reduction in NOx emissions. Energy efficiency to minimize CO₂ emissions was also deemed to be important, as well as considerations of operational reliability and cost-effectiveness. We developed an energy output basis for the guideline, with NOx levels directly tied to the demonstrated overall system efficiency. This spring marks the 20th anniversary of the development of that Canadian guideline.

This was the first regulatory standard for the gas turbine sector that used output energy, and helped to establish pollution prevention, combustion modifications and overall system CHP efficiency as ‘Best Available Technology’. The guideline uses an energy output basis for power and heat, in grams of NOx per GJ of energy output. It allows higher efficiency systems to have a higher exhaust ppm NOx concentration. The emission targets in Figure 2 were established at a certain efficiency range in each chosen size category, for gaseous and liquid fuels.

For large units greater than 20 MWe, the power output allowance at 140 g/GJ relates the mass of NOx emitted to the number of GJ or MW of power output (0.5 kg/MWh). This allowance results in large units, fired on natural gas, having to meet a full load NOx emission target of about 27–33 ppmv in simple cycle applications and 37–42 ppmv in a combined-cycle plant. A higher emission level is available through the 40 g/GJ heat recovery allowance to encourage cogeneration applications. Units of 3 to 20 MW have targets set about 70% higher (240 g/GJ, or 0.86 kg/MWh). Revisions are being developed this year to also deal with large gas turbine units in the 70 MWe and greater sizes.

United States

The US Environmental Protection Agency (EPA) has usually used concentration-based ppmv standards, coupled with some state daily, monthly or annual tonnage caps and emission offset rules. Best available control technology (BACT) practices included steam/water injection, dry low NOx combustion technology and add-on selective catalytic reduction (SCR) back-end emission controls. When the lowest achievable NOx emission rate became dominant, these ultra-low NOx control solutions with dry low NOx (DLN) plus SCR were often required, with regional levels set as low as 2 ppmv.

After some years of consultation, the US EPA released in July 2006 a new national NSPS regulation for gas turbines used for pipeline compressors, utility combined-cycle plants and industrial cogeneration plants. Instead of requiring ultra-low NOx stack concentration, the new rules would give a choice for using ppmv criteria, or a new output-based method in kg/MWh, at somewhat higher NOx levels to encourage more energy system efficiency (15–42 ppm, or 0.19 to 1.04 kg/MWh). Local state implementation may be held up by legal challenges due to perceived pitfalls in the loosening up of local NOx permit levels.

Europe

European countries have since 2005 revised the Large Combustion Plant Directive (LCPD), including ‘BAT Reference’ documents (BREFs). However, there is still much debate by industry and government on the various regulatory strategies in EU countries, and to what extent GHGs, system efficiency and other solutions are employed.

Europe has traditionally used concentration-based standards (mg/m³) or fuel input based levels (g/GJ fuel). The Large Combustion Plant Directive from 2005 has required limits for any fuel based plants with more than 50 MW thermal input capacity (between 15–20 MW output). For any gas-fired plants, this was set at a 50 mg/m³ level, but a 25 mg/m³ cogeneration efficiency allowance is a progressive incentive that allows this increased level. The European Commission in 2007 adopted new legislation on industrial emissions to strengthen these provisions, and a new Industrial Emissions Directive of 2011 may combine several impacts into an integrated policy.

AIR POLLUTION AND GHG EMISSIONS

Figure 3 compares approximate air pollution and CO₂ emissions from various fuel-based systems. The multiple pollution prevention benefits of gas turbine and biomass CHP are evident, along with gasification and carbon capture.

Some energy solutions have both low air pollution and low CO₂, including energy conservation, renewables, nuclear, hydro, as well as various industrial gas turbine systems. When GHG emissions are prevented in a system, one finds that all air pollution subsequently falls dramatically as well. There are many synergies and trade-offs in how air pollution and GHG emissions can be prevented and controlled. Some specific examples of balancing various issues are summarized below.

Figure 2. Canadian CCME gas turbine guideline, 1992

Water and steam injection for NOx reduction

One method of NOx reduction is the addition of clean water, at a water/fuel mass ratio about 1:1, into the combustion zone to lower the flame temperatures, achieving a 70% NOx reduction. Clean water treatment facilities and combustor maintenance can have high operating costs. Steam injection is often an option on combined cycles and cogeneration plants, where high-pressure steam at a ratio of 1.5:1 is readily available from the heat recovery steam generator (HRSG). Injection into the combustor while producing more power can, however, rob the high-pressure steam cycle of energy, thereby reducing plant efficiency in some cases.

Dry low NOx (DLN) combustors

A more cost-effective pollution prevention method for thermal NOx is to modify the combustion process itself, by changing the airflow and fuel mixture inside the combustor to minimize the occurrence of high local peak flame temperatures, in ‘lean pre-mix’ DLN combustors. Developments since 1990 have successfully resulted in NOx reductions of 60–90%, to a range near 0.7 kg/MWh (15-30 ppm)for small to medium-sized units, and as low as 0.2 kg/MWh (10 ppm) for some very large machines that have more physical combustor design volume and space. The fuel/air ratio must be closely controlled during off-design conditions to prevent instability, combustor pressure oscillations and flameout.

Gas turbine engine vibrations and thermal cracking of hot parts have always been a maintenance challenge, especially for high pressure ratio aeroderivative engines, and now with large gas turbine combined-cycle plants that must be cycled under part load conditions. Transient low fuel/air ratios during low power settings can create the need to bleed away compressor discharge air, or close inlet guide vanes, thereby losing efficiency. Difficulties are faced in designing a reliable fuel control system that maintains good combustion and low CO emissions over a wide range of ambient temperature and loading conditions.

NOx and CO₂ emissions from systems often increase in opposite ‘directions’, with high pressures and temperatures (for efficiency) creating more thermal NOx. Small high-pressure combustors may also have difficult challenges in lean pre-mix design. Smaller units, with smaller combustors, can be allowed a higher NOx level as they can often be more efficient in CHP applications, being able to use most of their exhaust heat output, with a high heat to power ratio.

Figure 3. Air pollution and CO₂ emissions from various fuel-based systems

Large gas turbines have lower NOx emission rates in large DLN combustors for combined-cycle plants. However, the required large steam condensers are an environmental problem for several reasons: large energy losses, thermal pollution of local water bodies, vapour plumes and noise impacts. Large gas turbine systems can be built very quickly, and consume large amounts of fuel from the natural gas delivery infrastructure. The remote siting of a large number of combined cycles will lead to more power transmission lines, condenser energy losses, and gas fuel supply and pricing uncertainty.

Selective catalytic reduction (SCR)

SCR systems use ammonia with a catalyst structure in the waste heat boiler to convert NOx in the exhaust stream to mostly nitrogen and water. Despite the demonstrated 70–80% reduction of NOx, there are several negative collateral issues with SCR systems, including increased fine particulate and ammonia emissions, problems with cycling operation, and the safety and health risks of ammonia handling and transportation. Back-end controls have generally been shown to be less cost-effective than pollution prevention measures, as they often give rise to other collateral air, water or safety impacts, as well as efficiency losses and increased GHGs. When employed after DLN combustion, the resulting safety issues, air emissions plus efficiency loss (more GHGs) can outweigh the marginal benefits of SCR.

Fine particulate and CO emissions

Fine particulate emissions (PM 10 and PM 2.5) can be a serious health issue. There has been discussion on fine PM emissions from gas-fired gas turbines (as per the US EPA AP42 rates of about 0.03 kg/MWh). However, with gas turbine engines swallowing millions of tonnes per year of air for their power output, some of that air may not go through combustion, but as combustor cooling bypass flow. The incoming air might have very fine airborne dust and volatile organic compound (VOC) oils. Can that air which gets by the inlet filter, avoiding combustion, pass through the machine and show up in the exhaust?

It may be that the modern gas turbine system, with higher efficiency air filtration, is cleaning the air from PM by over 99%, and the emission factor could be negative (unless there is an ammonia-based SCR). New DLN combustors also expose more of the airflow to high temperature combustion, possibly incinerating most particles which have survived the air filters.

Combustor design is greatly influenced by how carbon monoxide (CO) emissions are handled, especially for off-design, transient and cold ambient conditions. How important are CO emissions? These emission levels are often set at the same ppm level as NOx emissions. That may not be necessary, as they are much less harmful to human health, rising from an elevated high temperature exhaust stack to oxidize into CO₂ within a day or two.

But the combustor designer is faced with great challenges in mechanical airflow and mixing strategies, with the added complication of transient, start-up and shutdown operating modes. The necessary features of low CO emissions over these conditions will compromise the reliable dry low NOx performance over a suitable operating range.

Specific power

Gas turbine engines have varying amounts of shaft output per kg/sec of air mass flow. This seems to depend on engine size, number of compressor/turbine spools, pressure ratio and bleed air, combustor firing intensity, and the overall resulting efficiency. The value of air mass flow varies from about 200–400 kW per kg/sec air). Traditional gas turbine NOx emissions are measured and studied in term of concentration ppmv. In an efficient unit, at half the air mass flow for a certain power, the same concentration could have only half of the mass emissions.

HEAT RECOVERY STEAM GENERATORS (HRSGs)

HRSGs are critical to efficient gas turbine CHP systems. They can employ a duct burner at their intake from gas turbine exhaust that has a residual amount of oxygen (13–16%) needed for combustion. This ‘auxiliary firing’ can normally give a large boost to steam production by raising the gas temperature from about 450–500°C to around 900°C, especially for turbine units which have very efficient cycles and low exhaust temperatures. The available oxygen levels will decrease with firing in proportion to the fuel added. Because of the very high preheat from the gas turbine, duct burners are very effective in allowing the HRSG to act as a ~100% efficient ‘boiler’. Sometimes these burners are treated in permitting as a source of increased NOx emissions. There are however many benefits to having them:

avoiding additional traditional boiler fuel used at a 75–85% heat efficiency;
allowing smaller gas turbine engines for the CHP application;
providing good CHP opportunities for aeroderivative gas turbines with low exhaust gas temperatures;
for single-pressure drum units, the higher inlet temperature will increase heat transfer and lower the final stack temperature by 30–50°C, thereby improving overall thermal efficiency;
providing intermittent cycling flexibility for triple the steam production of unfired HRSG systems;
duct firing also allows for improved active control of steam conditions and process optimization.

SYSTEM EFFICIENCY

To evaluate system efficiency and GHG emissions, ‘fuel chargeable to power’ (FCP) is an energy allocation method that can be used for cogeneration calculations. FCP is defined as the net heat rate credited to electricity (or mechanical power) after the thermal load has been served, in GJ/MWh.

Figure 4. Quality of energy

Other more detailed analyses for heat may use ‘exergy’ methods, where the ‘quality’ of energy is determined depending upon temperature and pressure levels, and system losses – see Figure 4. Exergy analysis would allocate more emissions than FCP to the higher quality power portion of a system. Whether FCP or exergy, such methods would allow for a meaningful allocation of various emissions for cogeneration systems.

For fair comparisons, the use of higher heating value (HHV), rather than LHV, could also be considered for all energy systems that can use condensing heat recovery. CHP markets would also be better served if the MWth thermal values were recognized and described at the same time as MWe electrical totals.

GASIFICATION

IGCC and polygeneration should be considered for large projects where natural gas is at a premium, where coal or petcoke is abundant, and where CO₂ capture and storage can be linked to this technology. Because IGCCs are essentially coal plants, they will be unable to meet the very stringent NOx emission levels of natural gas-fuelled plants. Hydrogen-rich fuels must be reliably and safely burned to provide for effective carbon capture and system availability. They have significant flame speed, auto-ignition and flashback characteristics in high-pressure combustion, and are often used with nitrogen or steam dilution to minimize NOx emissions.

CONCLUSION

Identifying comprehensive environmental solutions for GHG and air pollution reductions, with energy reliability and security, make economic sense regardless of the degree of proof in anthropogenic climate change – what used to be termed ‘no regrets’ measures. Energy output, fuel combustion and emissions occur in real, physical facilities. Site visits, training and time spent in the field near actual equipment can be extremely valuable for all in understanding important linkages, collateral impacts and integrated systems.

Rational and clear energy output-based environmental standards can help encourage best practices for many efficient and clean energy opportunities. A balanced economic implementation will be a key consideration among the variety of energy choices that are needed for our long-term infrastructure and job creation needs.

Manfred Klein is a member of the Industrial Application of Gas Turbines Committee, Canada, a technical advisory group to Canadian industry and government. For further information, visit: www.iagtcommittee.com

COGEN Europe calls on ITRE to deliver clear EU policy on CHP

Fri, 24 Feb 2012 11:29:00 GMT

Ahead of the vote on the Energy Efficiency Directive on February 28th, COGEN Europe has called on the European Parliament’s ITRE Committee to deliver a clearly strengthened energy efficiency and CHP policy for Europe.

While the existing CHP Directive entered into force more than eight years ago, progresses have been slow at national level on designing a proper and supportive cogeneration framework.

COGEN added that one of the few positive outcomes deriving from the implementation of this directive has been the identification of a potential of 655 TWh of power supply and 211 GWe power capacity by 20201 at EU level, i.e. a doubling of the CHP market.

When voting on the proposal for an Energy Efficiency Directive, COM (2011) 370, Members of the ITRE Committee of the European Parliament shall send the strong political message that time has now come to improve the CHP policy leading to the realization of huge primary energy savings (notably via the implementation of the provisions contained in articles 10 & 12).

In addition, a bold Energy Efficiency Directive is central to meeting the strategic medium and long term energy and climate goals.

The European CHP sector, employing 100.000 workers in the manufacturing, servicing and supplying of CHPs, is looking forward to positive developments in the ITRE Committee and the weeks to come

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US Military wins awards for combined heat and power systems

Wed, 08 Feb 2012 21:55:00 GMT

The Environmental Protection Agency honored two Department of Defense facilities for achieving emissions reductions and energy savings with their combined heat and power systems at the 25th Annual IDEA Campus Energy Conference in Arlington, Va. Here are the details.

The Marine Corps Air Ground Combat Center in Twentynine Palms, California, US maintains its electricity and thermal energy needs with a solar combustion turbine generator that produces up to 7.5 MW of electricity and utilizes turbine exhaust to produce hot water that provides heat and domestic hot water to its many buildings.

The system allows the center to use 24 per cent less fuel than a conventional energy supply system and to avoid about 19,700 metric tons of CO2 emissions each year.

Annual energy costs from the use of the cogeneration plant are reduced by $5.8m the EPA reported.

In addition, the base is currently developing a micro-grid that will allow it to maintain power even in the case of grid outages.

At the 82nd Airborne Division Combined Heat and Power Plant at Fort Bragg, North Carolina, 18 per cent less fuel is consumed than a conventional energy supply system, the EPA reports.

The system used is avoiding emissions equal to that from the electricity of more than 1,500 homes each year and is saving the base about $1 million annually.

Powered by a 5 MW combustion turbine-generator, the system produces 27,000 pounds of steam each hour, which is used to provide heat and hot water to 10,000 soldiers, their families, and civilian base employees. An absorption chiller is also utilized, supplying cold water for air conditioning.

For more combined heat and power news

Christchurch’s $400m district energy scheme

Mon, 06 Feb 2012 14:49:00 GMT

Christchurch Hospital and the Christchurch Polytechnic Institute of Technology (CPIT) could be pivotal in getting an innovative $400m cogeneration energy scheme for Christchurch, New Zealand.

Three feasibility studies investigating aspects of a proposed district energy system (DES) say it is "very promising" and could be done in the rebuilt central city, reports the Fairfax News.

But they suggest a softly, softly approach, warning that key buildings need to be part of the scheme from its beginning and that temporary boilers on either side of the city would be needed while pipes were being laid.

The proposed project would provide space heating, water heating and air conditioning from a central power and heat co-generation plant fuelled by wood chips or wood waste.

A 10 kilometre network of pipes would transport hot and cold water from the plant into buildings. It would allow owners to dispense with their own boilers, air conditioners and chillers, and cut electricity use.

The idea was one of many put forward through the Christchurch City Council's Share an Idea campaign.

The technical study, by a consortium of Bizcat, Aurecon and FVB, recommended a "phased" scheme that could be expanded as the rebuild progresses, while the KPMG investment study said the project could be commercially successful using that phased approach.

For more district energy news

UK CHPA backs government on energy saving

Wed, 23 Nov 2011 11:17:00 GMT

The CHP industry body in the UK, the CHPA, has backed a commitment by the minister for Energy and Climate Change Greg Barker to make energy saving “an equal priority” with energy production.

CHPA director Graham Meeks has also welcomed Barker’s continued support for gas to feature strongly in the UK’s energy mix.

“He [Barker] has committed to making our homes and businesses less wasteful, and combined heat and power will be essential in securing this goal for the gas that we continue to use,” said Meeks.

The CHPA is also calling for a review on CHP incentives and action on exempting CHP fuel used for heat production from the Carbon Price Support Levy and retaining Climate Change Levy Exemption Certificates for CHP until the introduction of an alternative Feed-in Tariff incentive.

The industry body also wants to see the introduction of a tariff for micro-CHP of at least £0.15/kWh under the government’s existing Small-Scale Feed-In Tariff regime, and an extension of this scheme to include plant up to 50 kWe capacity.

Finally, the CHPA also wants a review of renewable CHP incentives, including extended eligibility for the Renewables Obligation until 2017, a dedicated CHP band in the Renewable Heat Incentive and retention of the single ROC band for energy-from-waste CHP.

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UK energy minister hints at growing role for CHP

Wed, 23 Nov 2011 10:09:00 GMT

Greg Barker, Minister of State for Energy and Climate Change, has set out his vision for CHP in the UK, claiming he has given officials “a mandate to be really ambitious.”

The minister also pointed to a series of forthcoming announcements that he says will reassure investors concerned over a perceived lack of certainty over the government’s vision for CHP.

“We intend to set out the importance of CHP with in our Autumn Statement and our report on the Fourth Carbon Budget.

“Be under no illusion there is more ambition for CHP, more determination to see this technology deployed at scale, than there has ever been before,” said Barker.

Addressing questions from the industry at the annual conference of the Combined Heat and Power Association, Barker argued:

“Were going to need industry to be competitive, especially if we’re going to achieve economic growth at the ambitious levels the Coalition has in mind. Energy efficiency will be of paramount importance and in that context a new ambitious role for CHP is very clear.”

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USDA to fund biomass projects

Tue, 22 Nov 2011 10:00:00 GMT

The US Department of Agriculture (USDA) is to fund a series of projects to convert biomass to energy through its Rural Energy for America programme (REAP).

Among the companies receiving funding is NC-CHP Owner 1, LLC, a business management consultancy company, which received project financing of $5 million for constructing CHP project serving a poultry producer in Montgomery County, Maryland.

The company will use wood chips as feedstock for generating electricity and the project will also generate steam with a boiler system. The project is expected to produce about 5.25 million kWh of electricity annually.

So far this year, the USDA has funded 52 biomass projects with just over $31 million in grant and loan note guarantees through the REAP programme. This support has helped to leverage $154.5 million of biomass project development in 26 states that will result in renewable heat and power for farms and small businesses in rural America.

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Californian legislation to benefit CHP newcomer

Fri, 28 Oct 2011 19:36:00 GMT

Leva Energy, a Californian cleantech start-up that can convert its current boiler into an efficient CHP system, is seeking to benefit from new regulations to be introduced in California that require operators to upgrade their boilers so they emit less nitrogen oxides (NOx).

Beginning next January in the counties that are part of the Bay Area Air Quality Management District (BAAQMD), operators of gas-fired boilers and steam generators have to conform to new clean air certification requirements.

Leva Energy plans to retrofit existing boilers with its power burner to generate cleaner and cheaper electrical power that Leva claims will normally pay for itself within two years.

"Most business owners believe their only options for lowering NOx are to spend money on new, ultra-low NOx burners that offer no payback or to buy expensive selective catalytic reduction systems.

In fact, these options often sacrifice energy efficiency or add operating costs in order to achieve lower NOx," said Franco Castaldini, president and co-founder of Leva Energy.

"You can upgrade your existing boiler to meet ultra-low NOx regulations and simultaneously generate clean electrical power that quickly pays you back for your low-NOx investment.

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COGEN Europe calls on lawmakers to 'unleash' CHP's potential

Fri, 21 Oct 2011 10:55:00 GMT

COGEN Europe, the European association for the promotion of cogeneration, is calling on European lawmakers to ‘unleash the potential of CHP’ as they meet to discuss plans for the proposed Energy Efficiency Directive.

COGEN Europe is calling on lawmakers to achieve the potential of CHP in order to bring much needed primary energy savings that will help to meet Europe’s 2020 and 2050 energy and climate targets.

The industry body says that data and analysis provided by the Member States show that the European Union (EU) has a large unexploited economical cogeneration potential of 655 TWh of power supply, which would double the electricity production compared to the baseline.

Furthermore, the CHP potential would also result in a 211 GWe of power capacity by 2020, corresponding to an extra 110 GWe compared to the 100.2 GW of installed CHP capacity in the EU in 2008, says COGEN Europe.

It also reports that the primary energy savings stemming from CHP uptake amounts to 35 Mtoe, representing around 2% of the 2008 gross inland consumption in the EU 27.

For more information on COGEN Europe.

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UK MEP visits CHP plant ahead of key EU vote

Wed, 12 Oct 2011 13:27:00 GMT

Ms Vicky Ford, MEP for the East of England, has visited the CHP system at British Sugar’s factory in Bury St Edmunds in the run up to the vote on the European Union’s (EU) Energy Efficiency Directive at the end of October.

The directive requires that by 1 January 2014, EU member states will have established a national heating and cooling plan including the use of CHP.

Although CHP is said to be 30 per cent more efficient in generating power than separate electricity and heat production, only 11 per cent of energy production currently uses it.

The new directive wants to raise this figure to 21 per cent by 2020.

British Sugar says its CHP facility helps the factory to be more than 70 per cent energy efficient, allowing it to transfer 50 MW of electricity back into the local power grid.

“I think everyone is so concerned about their energy bills and wants to be efficient but it is giving people the incentive to do it that is important, that is what the directive is about,” said Ford.

For more information on the Energy Efficiency Directive.

For more information on British Sugar.

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Texas streamlines CHP laws

Mon, 10 Oct 2011 10:23:00 GMT

In a boost for CHP in Texas, a new law requires the Texas Commission for Environment Quality (TCEQ) to create air-permitting regulations for CHP plants that recognize their emission reduction benefits.

The streamlined air permitting process is expected to reduce regulatory burdens and system costs especially for small on-site systems. Currently, CHP developers must follow the same permitting requirements as large utility-scale power plants.

The new permit would effectively reward CHP systems' net reductions in electricity use and emissions. Federal tax incentives encourage use of CHP helping reduce dependency on foreign fuels and promote growth of clean energy technology. CHP systems meet the requirements of Texas law regulating energy security for mission critical facilities and are considered a green building solution that drives emission reduction.

Dan Bullock, director of the US Department of Energy’s Gulf Coast Clean Energy Application Center, said, “While often overlooked, combined heat and power technologies are a significant part of the Texas clean energy story. Implementation of additional CHP is a logical step for Texas to comply with emerging environmental regulations while adding jobs and increasing the competitiveness of our industry.”

For more policy and regulation news click here

Canberra’s new energy plan targets cogen

Fri, 07 Oct 2011 10:05:00 GMT

Cogeneration is to be an important part of the Australian Capital Territory’s (ACT) plan to ensure that greenhouse gas emissions reductions targets are reached.

The policy will promote clean energy via an investigation into the feasibility of creating energy from waste, and an assessment of distributed generation technology in upcoming major building developments.

The deployment of distributed generation options, including cogeneration, trigeneration and large-scale, low emissions generation technologies, will also be encouraged.

To encourage the smarter use of energy, the development of secure and affordable energy, and the growth of the clean economy, the ACT Government has specified various measures, including: a target for the per capita usage of non-renewable electricity, a new energy savings initiative, stimulating the broad-scale energy efficiency improvements of homes and small businesses across the ACT.

The plan also looks to support national energy policy and market frameworks that integrate social, economic and environmental policy objectives and represent the interests of the ACT and continued support for capability development in ACT companies that are developing clean technology products and services.

For more policy news click here

Cogeneration sector responds to Energy Efficiency Directive

Mon, 26 Sep 2011 08:30:00 GMT

COGEN Europe says that for the new Energy Efficiency Directive (EED) could generate real growth in cogeneration in Europe.

To achieve this goal, COGEN Europe, the European association for the promotion of cogeneration, says that it should use the directive to support investor confidence and the smooth growth of the sector.

COGEN Europe also believes links between the Renewable Energy Directive and the CHP Directive including priority of dispatch should be included in the new directive.

The association is also backing moves that would require Member States to develop effective heat plans with clear enabling and support measures so that cogeneration rapidly becomes the default option for thermal electricity generation and industry is encouraged to generate electricity for its own and public use.

COGEN Europe is also keen that Member States commit to a timescale for implementing the identified growth plan for cogeneration while encouraging the deployment of micro-CHP by simplifying authorisation processes for metering and billing.

For more policy and regulation news click here

COGEN Europe welcomes Energy Efficiency Directive

Mon, 12 Sep 2011 07:18:00 GMT

The European cogeneration association COGEN Europe has published a position paper welcoming the European Commission's Energy Efficiency Directive (EED) proposals for reinforcing CHP.

“Measurable” progress is required to enhance heat and cooling plans, and to clarify possibilities for exemptions, said the association.

The industry group also calls for investors' confidence to be boosted by ensuring continuity of the legal framework and the technical specifications on CHP and securing priority of dispatch for cogeneration. Primary energy should remain the key measure for energy use, the association adds.

“Our sector welcomes supporting chapters about cogeneration in terms of continuity for industrial planning and removal of barriers," said COGEN Europe in its statement.

"The cogeneration measures in the new text signal a clear intention by the Commission to create a supportive environment for existing and new cogeneration operators, underpinning their investment certainty and the economic justification on the investment.”

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US DOE launches clean energy database

Fri, 29 Jul 2011 16:44:00 GMT

The US Department of Energy’s (DOE) Industrial Technologies Program has launched an online searchable database of project profiles on recycled energy projects across the US.

The database contains 130 project profiles and counting, all put together by the eight US DOE Regional Clean Energy Application Centers.

Each project profile, typically two pages in length, contains a project's site description, full technical details, reasons for installing recycled energy, unique aspects, results to date, lessons to share, and other relevant information.

The free online database allows searching for project profiles by market sector, state, technology type, system capacity, fuel type, thermal energy use, year installed, or any combination.

The DOE says the project profiles are written with the intent of showing other businesses in each market sector the benefits of recycled energy, educating policymakers about the economic benefits of clean energy in local districts, and showcasing local success stories.

You can access the database by click here.

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