American Made Wind Turbines

American Made Wind Turbines

Wind Power Technologies develops, acquires, owns and operates Wind Farms and Community Wind Farms and provides Carbon Dioxide Credits, Emissions Trading and Carbon Reduction Projects in the U.S. and Canada. We also provide Wind Energy Feasibility Studies and Wind Resource Assessments.

Nothing quite compares with the opportunities in renewable energy technologies, and in particular, wind energy and wind farm development.

As wind energy and wind farm developers, we are preparing to announce the location and details of the "world's largest wind farm." Watch for Press Release at our new website: 

Wind energy and wind farm development is big business, and this is only the beginning! Today, less than 1% of our energy comes from wind energy. 

President Bush and the U.S. government are calling for 20% of our nation's energy to come from wind energy by 2020. Hundreds of billions of dollars will be invested and made in wind energy! 

Now is the time to get in on the ground floor of the wind energy and wind farm development business! 

Look at the following facts about wind energy, according to the American Wind Energy Association (

  • The U.S. added nearly 1,400 megawatts of new wind energy capacity during the second quarter of 2008.
  • New wind turbines this year will generate 7,500 megawatts of additional electricity which surpasses the 5,249 megawatts installed in 2007.
  • Wind power accounted for more than one-third of the new electric generating capacity installed in the U.S. in 2007.
  • The wind industry is projected to grow at a 45 percent pace for the second straight year.
  • For every megawatt (MW) of wind energy produced, $1 million in economic development is generated. This includes revenue from planning, construction, etc. 
  • Wind energy revitalizes rural communities by providing steady income through lease and royalty payments to farmers and other landowners.
  • Supplemental income: It is estimated that the income to a landowner from a single utility-scale turbine is approximately $2000 per year. For a 250-acre farm with income from wind at $55 per acre, this translates into an annual income from wind leases of $14,000, with no more than 2-3 acres removed from production.

According to the American Wind Energy Association (

  • The U.S. added nearly 1,400 megawatts of new wind energy capacity during the second quarter of 2008. 
  • New wind turbines this year will generate 7,500 megawatts of additional electricity which surpasses the 5,249 megawatts installed in 2007.
  • Wind power accounted for more than one-third of the new electric generating capacity installed in the U.S. in 2007.
  • The wind industry is projected to grow at a 45 percent pace for the second straight year.
  • For every megawatt (MW) of wind energy produced, $1 million in economic development is generated. This includes revenue from planning, construction, etc. 
  • Wind energy revitalizes rural communities by providing steady income through lease and royalty payments to farmers and other landowners.
  • Supplemental income: It is estimated that the income to a landowner from a single utility-scale turbine is approximately $2000 per year. For a 250-acre farm with income from wind at $55 per acre, this translates into an annual income from wind leases of $14,000, with no more than 2-3 acres removed from production.
  • Jobs: Wind energy resources bring needed jobs to rural communities and bolster farm incomes against bad weather. Worldwide, wind and solar industries are likely to be one of the main sources of new manufacturing jobs in the 21st century.
  • Wind energy costs for consumers are low and stable. This is particularly beneficial for those on fixed incomes.
  • As wind energy production becomes more efficient, costs will decline, while fossil fuel prices are expected to rise. 
  • Wind energy is a widespread, inexhaustible resource: 46 of 50 states have wind resources that could be developed.
  • WIND ENERGY GENERATES CARBON FREE ENERGY & POLLUTION FREE POWER! Power generated from the wind reduces smog and eliminates a major source of acid rain. Wind energy has the potential to reduce Carbon Dioxide Emissions (one of the most potent of all Greenhouse Gas Emissions) by 1/3 in the U.S. and world Carbon Dioxide Emissions by 4%! 
  • Potential for growth: Development of just 10% of 10 of the windiest states could provide more than enough energy to displace emissions from coal-fired power plants.
  • Cleaner air means healthier air, especially for people with respiratory disabilities.

Wind Power Generation vs. Traditional Power Generation

Power generated from clean, green wind energy avoids numerous negative effects of traditional electricity generation from fossil fuels:

  • Emissions of mercury or other heavy metals into the air
  • Emissions associated with extracting and transporting fuels
  • Lake and streambed acidification from acid rain or mining
  • Water consumption associated with mining or electricity generation
  • Production of toxic solid wastes, ash, or slurry
  • Greenhouse Gas Emissions

The benefits of wind power generation go on – including the leading role wind energy provides in reducing Carbon Dioxide Emissions into the atmosphere – the leading cause of climate change and global warming. 

Today, Carbon Dioxide Emissions in the United States approaches 6 billion metric tons/year. 

39% of these Carbon Dioxide Emissions are produced when electricity is generated from fossil fuels.

If the United States obtained 20% of its electricity from wind energy, the country could avoid putting 825 million metric tons of CO2 annually into the atmosphere by 2030, or a cumulative total of 7,600 million metric tons by 2030.

A relatively straightforward metric used to understand the carbon benefits of wind energy is that a single 1.5 MW wind turbine displaces 2,700 metric tons of CO2 per year compared with the current U.S. average utility fuel mix, or the equivalent of planting 4 square kilometers of forest every year according to AWEA 2007.

2-Bladed Wind Turbines Versus 3-Bladed Wind Turbines

Why 3-Bladed Wind Turbines are Far Superior than 2-Bladed Wind Turbines

The argument has been settled and the debate is over. 

Today's "modern" 3-bladed wind turbines represent the latest technological improvements in wind turbine generators, and are superior to the 20-30 year old technology that 2-bladed wind turbines represent.

First of all, it is important to remember that 2-bladed wind turbines may generate only about 90% of the power of a 3-bladed wind turbine of comparable size. While a 2-bladed wind turbine saves the weight of one extra blade when compared with a 3-bladed wind turbine, engineers of the most efficient wind turbines have determined that the extra blade used on 3 bladed wind turbines provide the optimum wind turbine efficiency and wind turbine design for the "ideal" wind turbine generators of today. 

Secondly, the top-3 leading wind turbine manufacturers have standardized on the 3-bladed wind turbine. They do not manufacture any 2-bladed wind turbines. Plainly stated, a wind turbine with an even number of blades (2 blades or 4 blades) are NOT of optimum design or efficiency. In fact, this debate was settled years ago when the wind turbine engineers and designers began building wind turbines over 600 kW in power output.

The top-3 leading wind turbine manufacturers have standardized on the 3-bladed wind turbine. They do not manufacture any 2-bladed wind turbines. Plainly stated, a wind turbine with an even number of blades (2 blades or 4 blades) are NOT of optimum design or efficiency. In fact, this debate was settled years ago when the wind turbine engineers and designers began building wind turbines over 600 kW in power output. 

The leading wind turbine manufacturers and their engineers have decided that 3 bladed wind turbines are the optimum number of wind turbine blades due to the stability of the wind turbine as well as the significant wind loads and stresses placed on a 2-bladed wind turbine. A wind turbine that has an odd number of blades is similar to a disc when calculating the computational fluid dynamics of the wind turbine. Engineers have learned that wind turbines that have an even number of blades – such as the 2 bladed wind turbines of the past – have stability problems for a machine with a stiff structure. The reason for this problem is simple, engineers recognized that when a 2-bladed wind turbine's top blade bends backwards – when the wind turbine's 2 blades are in the vertical position – since it is now generating the maximum power from the wind – that the lower or bottom blade is now aligned with the tower and the blade is hidden or blocked from the wind – and this generates a huge amount of stress and loads on the wind turbine and its' primary components such as the bearings, shaft, transmission etc.

Because of the extreme wind loads and stresses placed on 2-bladed wind turbines, the remaining 2-bladed wind turbine manufacturers have had to resort to a "teetered hub" that helps remove some of the stress and loads placed on 2-bladed wind turbines. While there are some very fine 2-bladed wind turbines, of smaller power output, the bottom line is, 3 bladed wind turbines are inherently better and more efficient than 2-bladed wind turbines.

For these reasons, community wind farm owners and developers, along with utility-scale wind farm owners and developers, would be wise to only consider 3-bladed wind turbines. 

Renewable Energy Technologies, LLC. companies, strategic partners, joint venture partners and investors are developers of renewable energy power and energy projects that are environmentally-friendly and have above-average returns on capital. Our range of services (some provided by affiliated companies) include:

  • Engineering Feasibility and Economic Analysis Studies
  • Legal
  • Energy Service Agreements
  • Power Purchase Agreements
  • Interconnection Agreements
  • Build, Finance, Own, Operate/Maintain
  • Long Term Service Agreements
  • Project Finance
  • Engineering Procurement Construction
  • Mechanical Electrical Plumbing
  • Carbon Emissions and Carbon Credits, Greenhouse Gas Emissions Trading Credits and International Emissions Trading
  • Carbon Reduction Projects
  • Carbon Free Energy Projects
  • Pollution Free Power Projects
  • Carbon Capture and Sequestration
  • Transmission Superhighway development projects

Now seeking joint-venture partner(s) for multiple wind farms we are developing in Texas, Oklahoma, New Mexico, Colorado and Kansas. Our wind farms also include our own electric transmission lines. 

Our present and past projects include (some provided by affiliated companies);

  • Windpower Technologies, LLC is providing engineering and legal assistance in multiple wind farms and electric transmission lines that will move our wind power to major markets, and provide higher prices for the owners of the wind farms.
  • Windpower Technologies, LLC. is "vendor-neutral" as it relates to the brand of wind turbine we install. We have relationships with all major wind turbine manufacturers including; Vestas, G.E., and Siemens. We seek to match the right wind turbine to each wind farm development so as to maximize revenues and minimize expenses.
  • Biodiesel plants (one in operation at 30 million gallons/year and one in development at 102 million gallons/year)
  • (2) B100 Biodiesel fueled power plants that generate "green" electricity – 
  • Our first B100 Biodiesel power plant generates 5 MW and our second B100 Biodiesel power plant is rated at 25 MW). 
  • Our 3rd B100 Biodiesel power plant is now being developed. It will be rated at 25 MW.
  • Cogeneration and trigeneration plants (one 900 kW under construction) and a 100 MW cogeneration plant in development that will be fueled with B100 Biodiesel from our newest biodiesel plant.
  • Anaerobic digesters & Biogas plants and Biomethane production – Biomethane is the "Renewable Natural Gas"
  • Two "Natural Wastewaster Treatment plants built and in operation – replaces typical wastewater treatment plants and are significantly more "environmentally-friendly" than typical Publicly-owned Treatment Works and Wastewater Treatment Plants.

With energy prices very volatile, and recently ranging from $65 to almost $150/bbl for oil and $6.00 to over $18/mmbtu for natural gas – and with many parts of the U.S. and around the world paying more than $0.18/kWh for electricity, there simply has never been a better time to be in the energy industry, providing renewable energy and renewable fuel solutions!

We have answers and solutions for these high power and energy prices that include "Carbon Free Energy" and "Pollution Free Power" technologies. These technologies are; carbon-neutral, environmentally-friendly, sustainable and now, more affordable to operate than coal-fired power plants.

We Develop Utility Scale Wind Farms, Community Wind Farms,

& High Voltage Transmission Lines

and are "vendor neutral" in terms of wind turbine manufacturer. Our sole focus is in maximizing revenues and minimizing expenses for our clients.

Renewable Energy Technologies' focus is on renewable energy and developing projects that generate environmental credits such as Certified Emission Reductions, Verified Emission Reductions, Carbon Dioxide Credits, or other types of Greenhouse Gas Emissions credits. 

Our onsite power and energy projects produce the following benefits:

  • Reduced power and energy expenses for our customers
  • Healthy returns on investment for our investors, and
  • Significant savings for our environment

Windpower Technologies, LLC. is a Texas Limited Liability Company.

Windpower Technologies, LLC. develops, acquires, owns and operates Wind Farms and Community Wind Farms in the U.S. and Canada. 

We provide the following Wind Energy and Wind Power products and services, some through our strategic partners or company suppliers:

Mont Goodell, President of the Renewable Energy Institute, along with the Renewable Energy Institute's Scientific Advisory Board, which is comprised of our nation's leading experts, engineers, attorneys, professors and universities, is calling for our nation and all 50 states to adopt a Renewable Portfolio Standard (RPS) of at least 25% by 2025. According to Mr. Goodell, our nation is at a crossroads and we have been 'over the Middle Eastern barrel of their fossil fuels' long enough. We must shift from energy dependence to energy independence and place significant emphasis and investments in our national energy security and lower greenhouse gas emissions. In addition, we need to implement a "Feed In Tariff" in lieu of a Renewable Portfolio Standard and build the 'Transmission Superhighway' or 'Unified National Grid' and dramatically increase the nation's power supply as well as implement greater use of 'Energy Conservation Measures' and 'Demand Side Management' programs. Failure to move in these areas and to do so immediately increases the risks to our country, our national security and the climate" according to Mr. Goodell. 

One of the fastest paths to jump-start the renewable energy industry, according to the Renewable Energy Institute, is through a "Feed In Tariff. A Feed In Tariff is superior to a Renewable Portfolio Standard," according to Mr. Goodell. "Just look at Germany, they adopted a Feed In Tariff, are further north from the Equator than we are here in the U.S., and they are placing solar panels on every rooftop and wind turbine generators throughout their country. They are leading the world in renewable energy technologies, primarily due to their early adoption of a Feed In Tariff" 

Renewable energy, and renewable energy only provides significant economic and environmental dividends, whether this is through a Renewable Portfolio Standard, or through a Feed-in Tariff, some of the economic and environmental dividends include:

  • Creation of more than 3 million new jobs in the U.S.
  • Generate more than $1 trillion in economic impacts
  • Significant reductions of oil imports
  • Reduce energy prices and save consumers as much as $50 billion on their energy bills
  • Elimination of billions of pounds of carbon dioxide emissions and other greenhouse gas emissions
  • Stimulate rural economies
  • Conserve natural gas supplies 
  • Creates a clean, safe energy future
  • Position the US as a world leader in renewable energy technologies

According to the Energy Information Administration, the total US primary energy consumption is expected to increase from 100 quadrillion Btu (quads) in 2005 to 131 quads in 2030. However, the renewable electricity generation remains at 9% while use of coal increases 50 percent in 2030 to 57%. Ethanol use is expected to increase from 4 billion gallons in 2005 to 14.6 billion gallons in 2030, yet that is only about 8% of total gasoline consumption.

In January (2008) the National Climatic Data Center (NCDC) blamed the burning of fossil fuels as a key contributor to global warming and accelerating climate change. The NCDC warned that the rate of the warming is accelerating and that the rise in temperatures over the past 9 years is “unprecedented in the historical record." This was underscored in February (2008) in the consensus report by the Intergovernmental Panel on Climate Change that concluded with near certainty that human activity was the main contributor to global warming.

The renewable energy industry, single-handedly, provides a powerful argument and solutions for these problems. 

Global warming and climate change are symptoms of a sick planet and the results of unrestrained "dumping" of huge amounts of pollution – in the form of carbon dioxide emissions and greenhouse gas emissions into the atmosphere.

The vast majority of carbon dioxide emissions and greenhouse gas emissions comes from "dirty" fossil fuels (coal, oil, and natural gas) used in making electricity at power plants and dirty fuels (gasoline and petroleum diesel) that run our internal combustion engines in our cars, trains, planes, and trucks. Our planet is home to millions and millions of internal combustion engines that run on dirty fossil fuels – whether they are fueled with gasoline for running our cars and lawnmowers or running on diesel fuel in the engines of trucks and ships like the very large crude carriers that transport the crude oil all around the world…… every internal combustion engine that is running on dirty fossil fuels is dumping millions and millions of tons of carbon dioxide emissions and greenhouse gas emissions into our atmosphere – which is aggravating and exacerbating our sick planet – and making manmade climate change and global warming more difficult to resolve through manmade remedies and solutions.

Why We Need A "Unified Smart Grid" or "Transmission Superhighway

According to Mont Goodell, President of the Renewable Energy Institute, "our country desperately needs to upgrade its' national electric grid. The grid of today is a relic from the past, that is inefficient and costly. Originally built in the 1930's, it is costing our nation approximately $120 billion every year due to its' outdated and out-lived existence. The national power grid as designed and built in the 1930's does not have the efficiencies and capabilities to keep pace with the national power grid's demands of today." 

"What we need" according to Mr. Goodell, is what former Vice President Al Gore calls a "Unified Smart Grid" or what we prefer to call a "Transmission Superhighway."

A Transmission Superhighway would be buried underground and "wheels" renewable power ("green electricity") from the wind farms of the midwest, and solar farms of the southwest, and geothermal farms of the west, to load centers throughout every corner of the U.S."

According to many estimates, the "Unified Smart Grid" or "Transmission Superhighway" could be built for about $400 billion. Through its' increased efficiencies, savings and reliability improvements that it will provide, the nation's new "unified smart grid" will be paid in full, in less than 4 years. 

What is a Wind Resource Assessment?

A Wind Resource Assessment is defined as the process of characterizing the wind resource and its energy potential for a specific site or geographical area.

Wind Resource Assessment

Graphic wind maps of the state of Montana, USA, showing resource potential across the state.

All markets for wind turbines require an estimate of how much wind energy is available at potential development sites. Correct estimation of the energy available in the wind can make or break the economics of wind farm development. Wind maps developed in the late '70s and early '80s provided reasonable estimates of areas in which good wind resources could be found. But new tools and new data available from satellites and new sensing devices now allow researchers to create even more accurate and detailed wind maps of the world.

Wind mapping techniques developed by NREL and U.S. companies are being used to produce high-resolution projections of U.S. and foreign regions that are painting a whole new picture of wind potential. These maps are created using highly accurate GPS mapping tools and a vast array of satellite, weather balloon, and meteorological tower data, combined with much-improved numerical computer models. The higher horizontal resolution of these maps (1 km or finer) allows for more accurate siting of wind turbines and has also led to the recognition of higher-class winds in areas where none were thought to exist.

The ability to accurately predict when the wind will blow will help remove barriers to wind energy development by allowing wind-power-generating facilities to commit to power purchases in advance. NREL researchers work with federal, state, and private organizations to validate the nation's wind resources and support advances in wind forecasting techniques and dissemination. Wind resource validation is important for both wind resource assessment and the integration of wind farms into an energy grid. Validating new, high-resolution wind resource maps will provide an accurate reading of the wind resource at a particular site. Development of short-term (1 to 4 hours) forecasting tools will help energy producers proceed with new wind farm projects and avoid the penalties they must pay if they do not meet their hourly generation targets. In addition, validating new high-resolution wind resource maps will give people interested in developing wind energy projects greater confidence as to the level of wind resource for a particular site.

Renewable Energy Technologies provides the following power and energy project development services: 

  • Project Engineering Feasibility & Economic Analysis Studies
  • Engineering, Procurement and Construction
  • Environmental Engineering & Permitting 
  • Project Funding & Financing Options; including Equity Investment, Debt Financing, Lease and Municipal Lease
  • Shared/Guaranteed Savings Program with No Capital Investment from Qualified Clients 
  • Project Commissioning 
  • 3rd Party Ownership and Project Development
  • Long-term Service Agreements
  • Operations & Maintenance
  • Carbon Reduction Projects 
  • Carbon Emissions & Greenhouse Gas Emissions Credits (Renewable Energy Credit, Carbon Dioxide Credits, Emission Reduction Credits, Certified Emission Reductions, Verified Emission Reductions, Voluntary Emission Reductions) Consulting

We are specialists in Renewable Energy Technologies, Demand Side Management and in developing clean power/energy projects that will generate a Renewable Energy Credit, Carbon Dioxide Credits and/or Emission Reduction Credits. Through our strategic partners, we offer "turnkey" power/energy project development products and services that may include; Absorption Chillers, Adsorption Chillers, Automated Demand Response, Biodiesel Refineries, Biofuel Refineries, Biomass Gasification, BioMethane, Canola Biodiesel, Coconut Biodiesel, Cogeneration, Concentrating Solar Power, Demand Response Programs, Demand Side Management, Energy Conservation Measures, Energy Master Planning, Engine Driven Chillers, Solar CHP, Solar Cogeneration, Rapeseed Biodiesel, Solar Electric Heat Pumps, Solar Electric Power Systems, Solar Heating and Cooling, Solar Trigeneration, Soy Biodiesel, and Trigeneration.

Our company raises investment capital for Community Wind Farms and other renewable energy and power projects. For qualified clients, we provide "turnkey" renewable energy project development services, including; EPC (Engineering, Procurement, Construction), Investment/Funding, Permitting, and Emission Reduction Credits under the Kyoto Protocol's Clean Development Mechanism.

What are "Renewable Energy Technologies?"

Any technology that exclusively relies on an energy source that is naturally regenerated over a short time and derived directly from the sun, indirectly from the sun, or from moving water or other natural movements and mechanisms of the environment. A renewable energy technology does not rely on energy resources derived from fossil fuels, or waste products from inorganic sources. Renewable energy technologies include; Bioenergy (such as biomethane recovery from , landfills, animal operations and POTW's), Geothermal, Hydrogen, Hydropower, Ocean, Solar, and Wind power generation technologies. More information about these renewable energy technologies follows below beginning with the paragraph on "Bioenergy."

We provide Renewable Energy Technologies engineering and project development services. We incorporate many energy-saving technologies, products and services into our renewable energy power and energy projects that may include the use of; Absorption Chillers, Adsorption Chillers, Automated Demand Response, BioMethane, Cogeneration, Concentrating Solar Power, Demand Response Programs, Demand Side Management, Energy Master Planning, Energy Performance Contracting, Energy Savings Performance Contracting, Engine Driven Chillers, Geothermal Power Plants, Landfill gas to Energy, Ocean Thermal Energy Conversion, Quadgeneration, Solar CHP, Solar Cogeneration, Solar Trigeneration, Trigeneration and Energy Conservation Measures. 

Our company provides turn-key project solutions that include all or part of the following: 

  • Engineering and Economic Feasibility Studies 
  • Project Design, Engineering & Permitting
  • Project Construction
  • Project Funding & Financing Options
  • Shared/Guaranteed Savings program with no capital requirements. 
  • Project Commissioning 
  • Operations & Maintenance 


Bioenergy technologies use renewable biomass resources to produce an array of energy related products including electricity, liquid, solid, and gaseous fuels, heat, chemicals, and other materials. Bioenergy ranks second (to hydropower) in renewable U.S. primary energy production and accounts for three percent of the primary energy production in the United States.

Biomass (organic matter) can be used to provide heat, make fuels, and generate electricity. This is called bioenergy. Wood, the largest source of bioenergy, has been used to provide heat for thousands of years. But there are many other types of biomass—such as wood, plants, residue from agriculture or forestry, and the organic component of municipal and industrial wastes—that can now be used as an energy source. Today, many bioenergy resources are replenished through the cultivation of energy crops, such as fast-growing trees and grasses, called bioenergy feedstocks. 

Unlike other renewable energy sources, biomass can be converted directly into liquid fuels for our transportation needs. The two most common biofuels are ethanol and biodiesel. Ethanol, an alcohol, is made by fermenting any biomass high in carbohydrates, like corn, through a process similar to brewing beer. It is mostly used as a fuel additive to cut down a vehicle's carbon monoxide and other smog-causing emissions. Biodiesel, an ester, is made using vegetable oils, animal fats, algae, or even recycled cooking greases. It can be used as a diesel additive to reduce vehicle emissions or in its pure form to fuel a vehicle. 

Heat can be used to chemically convert biomass into a fuel oil, which can be burned like petroleum to generate electricity. Biomass can also be burned directly to produce steam for electricity production or manufacturing processes. In a power plant, a turbine usually captures the steam, and a generator then converts it into electricity. In the lumber and paper industries, wood scraps are sometimes directly fed into boilers to produce steam for their manufacturing processes or to heat their buildings. Some coal-fired power plants use biomass as a supplementary energy source in high-efficiency boilers to significantly reduce emissions. 

Even gas can be produced from biomass for generating electricity. Biomass Gasification systems use high temperatures to convert biomass into a natural gas, or BioMethane. The gas fuels a turbine, which is very much like a jet engine, only it turns an electric generator instead of propelling a jet. The decay of biomass in landfills also produces a BioMethane gas that can be burned in a boiler to produce steam for electricity generation or for industrial processes. 

New technology could lead to using biobased chemicals and materials to make products such as anti-freeze, plastics, and personal care items that are now made from petroleum. In some cases these products may be completely biodegradable. While technology to bring biobased chemicals and materials to market is still under development, the potential benefit of these products is great. 

Biomass Resources

The term "biomass" means any plant derived organic matter available on a renewable basis, including dedicated energy crops and trees, agricultural food and feed crops, agricultural crop wastes and residues, wood wastes and residues, aquatic plants, animal wastes, municipal wastes, and other waste materials. Handling technologies, collection logistics and infrastructure are important aspects of the biomass resource supply chain. 


Biopower technologies are proven electricity generation options in the United States, with 10 gigawatts of installed capacity. All of today's capacity is based on mature direct-combustion technology. Future efficiency improvements will include co-firing of biomass in existing coal fired boilers and the introduction of high-efficiency gasification combined-cycle systems, fuel cell systems, and modular systems. 


A variety of fuels can be made from biomass resources, including the liquid fuels ethanol, methanol, biodiesel, Fischer-Tropsch diesel, and gaseous fuels such as hydrogen and methane. Biofuels research and development is composed of three main areas: producing the fuels, finding applications and uses of the fuels, and creating a distribution infrastructure. 

Bio-based Chemicals and Materials

Bio-based chemicals and materials are commercial or industrial products, other than food and feed, derived from biomass feedstocks. Bio-based products include green chemicals, renewable plastics, natural fibers, and natural structural materials. Many of these products can replace products and materials traditionally derived from petrochemicals, but new and improved processing technologies will be required. 

Integrated Bio-energy Systems and Assessments

The economic, social, environmental, and ecological consequences in growing and using biomass are important to understand and consider when addressing technological, market, and policy issues associated with bioenergy systems. 


Geothermal energy technologies use the heat of the earth for direct-use applications, geothermal heat pumps, and electrical power production. Research in all areas of geothermal development is helping to lower costs and expand its use. In the United States, most geothermal resources are concentrated in the West, but geothermal heat pumps can be used nearly anywhere.

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma. 

Almost everywhere, the shallow ground or upper 10 feet of the Earth's surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger—a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water. 

In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk. 

Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth's surface and at lesser depths in certain areas. Access to these resources involves injecting cold water down one well, circulating it through hot fractured rock, and drawing off the heated water from another well. Currently, there are no commercial applications of this technology. Existing technology also does not yet allow recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy. 

  • Exploration

Geological, geochemical, and geophysical techniques are used to locate geothermal resources. 

  • Drilling

Drilling for geothermal resources has been adapted from the oil industry. Improved drill bits, slim hole drilling, advanced instruments, and other drilling technologies are under development. 

  • Direct Use

Geothermal hot water near the Earth's surface can be used directly for heating buildings and as a heat supply for a variety of commercial and industrial uses. Geothermal direct use is particularly favored for greenhouses and aquaculture. 

  • Geothermal Heat Pumps

Geothermal heat pumps, or ground-source heat pumps, use the relatively constant temperature of soil or surface water as a heat source and sink for a heat pump, which provides heating and cooling for buildings. 

  • Electricity Production

Underground reservoirs of hot water or steam, heated by an upwelling of magma, can be tapped for electrical power production. 

  • Advanced Technologies

Advanced technologies will help manage geothermal resources for maximum power production, improve plant operating efficiencies, and develop new resources such as hot dry rock, geopressured brines, and magma. 

  • Environmental

Geothermal technologies release little or no air emissions. Geothermal power production produces much lower air emissions than conventional energy technologies. 

  • Geothermal Resources

In the United States, geothermal resources are concentrated in the West, although low-temperature resources can also be found in the rest of the country. Geothermal heat pumps can be used nearly anywhere. 


Hydrogen is the third most abundant element on the earth's surface, where it is found primarily in water (H²O) and organic compounds. It is generally produced from hydrocarbons or water; and when burned as a fuel, or converted to electricity, it joins with oxygen to again form water.

Hydrogen is the simplest element; an atom consists of only one proton and one electron. It is also the most plentiful element in the universe. Despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas on the Earth—it is always combined with other elements. Water, for example, is a combination of hydrogen and oxygen (H²O). Hydrogen is also found in many organic compounds, notably the "hydrocarbons" that make up many of our fuels, such as gasoline, natural gas, methanol, and propane. 

Hydrogen can be made by separating it from hydrocarbons by applying heat, a process known as "reforming" hydrogen. Currently, most hydrogen is made this way from natural gas. An electrical current can also be used to separate water into its components of oxygen and hydrogen. Some algae and bacteria, using sunlight as their energy source, even give off hydrogen under certain conditions. 

Hydrogen is high in energy, yet an engine that burns pure hydrogen produces almost no pollution. NASA has used liquid hydrogen since the 1970s to propel the space shuttle and other rockets into orbit. Hydrogen fuel cells power the shuttle's electrical systems, producing a clean byproduct—pure water, which the crew drinks. You can think of a fuel cell as a battery that is constantly replenished by adding fuel to it—it never loses its charge. 

Fuel cells are a promising technology for use as a source of heat and electricity for buildings, and as an electrical power source for electric vehicles. Although these applications would ideally run off pure hydrogen, in the near term they are likely to be fueled with natural gas, methanol, or even gasoline. Reforming these fuels to create hydrogen will allow the use of much of our current energy infrastructure—gas stations, natural gas pipelines, etc.—while fuel cells are phased in. 

In the future, hydrogen could also join electricity as an important energy carrier. An energy carrier stores, moves, and delivers energy in a usable form to consumers. Renewable energy sources, like the sun, can't produce energy all the time. The sun doesn't always shine. But hydrogen can store this energy until it is needed and can be transported to where it is needed. 

Some experts think that hydrogen will form the basic energy infrastructure that will power future societies, replacing today's natural gas, oil, coal, and electricity infrastructures. They see a new hydrogen economy to replace our current energy economies, although that vision probably won't happen until far in the future.


Hydrogen is produced from sources such as natural gas, coal, gasoline, methanol, or biomass through the application of heat; from bacteria or algae through photosynthesis; or by using electricity or sunlight to split water into hydrogen and oxygen. 

Transport and Storage

The use of hydrogen as a fuel and energy carrier will require an infrastructure for safe and cost-effective hydrogen transport and storage. 

Fuel Cells

Hydrogen's potential use in fuel and energy applications includes powering vehicles, running turbines or fuel cells to produce electricity, and generating heat and electricity for buildings. The current focus is on hydrogen's use in fuel cells. 


Hydrogen has an excellent safety record, and is as safe for transport, storage and use as many other fuels. Nevertheless, safety remains a top priority in all aspects of hydrogen energy. The hydrogen community addresses safety through stringent design and testing of storage and transport concepts, and by developing codes and standards for all types of hydrogen-related equipment. 

The Hydrogen Economy

The vision of building an energy infrastructure that uses hydrogen as an energy carrier — a concept called the "hydrogen economy" — is considered the most likely path toward a full commercial application of hydrogen energy technologies. 


Hydropower (also called hydroelectric power) facilities in the United States can generate enough power to supply 28 million households with electricity, the equivalent of nearly 500 million barrels of oil. The total U.S. hydropower capacity—including pumped storage facilities—is about 95,000 megawatts. Researchers are working on advanced turbine technologies that will not only help maximize the use of hydropower but also minimize adverse environmental effects.

Flowing water creates energy that can be captured and turned into electricity. This is called hydropower. Hydropower is currently the largest source of renewable power, generating nearly 10% of the electricity used in the United States. 

The most common type of hydropower plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which, in turn, activates a generator to produce electricity. But hydropower doesn't necessarily require a large dam. Some hydropower plants just use a small canal to channel the river water through a turbine. 

Another type of hydropower plant—called a pumped storage plant—can even store power. The power is sent from a power grid into the electric generators. The generators then spin the turbines backward, which causes the turbines to pump water from a river or lower reservoir to an upper reservoir, where the power is stored. To use the power, the water is released from the upper reservoir back down into the river or lower reservoir. This spins the turbines forward, activating the generators to produce electricity. 

Types of Hydropower

  • Impoundment

An impoundment facility, typically a large hydropower system, uses a dam to store river water in a reservoir. The water may be released either to meet changing electricity needs or to maintain a constant reservoir level. 

  • Diversion

A diversion, sometimes called run-of-river, facility channels a portion of a river through a canal or penstock. It may not require the use of a dam. 

  • Pumped Storage

When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity. 

  • Sizes of Hydropower Plants

Facilities range in size from large power plants that supply many consumers with electricity to small and micro plants that individuals operate for their own energy needs or to sell power to utilities. 

  • Large Hydropower

Although definitions vary, DOE defines large hydropower as facilities that have a capacity of more than 30 megawatts. 

  • Small Hydropower

Although definitions vary, DOE defines small hydropower as facilities that have a capacity of 0.1 to 30 megawatts. 

  • Micro Hydropower

A micro hydropower plant has a capacity of up to 100 kilowatts (0.1 megawatts). 

Turbine Technologies

There are many types of turbines used for hydropower, and they are chosen based on their particular application and the height of standing water—referred to as "head"—available to drive them. The turning part of the turbine is called the runner. The most common turbines are as follows: 

  • Pelton Turbine

A Pelton turbine has one or more jets of water impinging on the buckets of a runner that looks like a water wheel. The Pelton turbines are used for high-head sites (50 feet to 6,000 feet) and can be as large as 200 megawatts. 

  • Francis Turbine

A Francis turbine has a runner with fixed vanes, usually nine or more. The water enters the turbine in a radial direction with respect to the shaft, and is discharged in an axial direction. Francis turbines will operate from 10 feet to 2,000 feet of head and can be as large as 800 megawatts. 

  • Propeller Turbine

A propeller has a runner with three to six fixed blades, like a boat propeller. The water passes through the runner and drives the blades. Propeller turbines can operate from 10 feet to 300 feet of head and can be as large as 100 megawatts. A Kaplan turbine is a type of propeller turbine in which the pitch of the blades can be changed to improve performance. Kaplan turbines can be as large as 400 megawatts. 

Environmental Issues and Mitigation

Current hydropower technology, while essentially emission-free, can have undesirable environmental effects, such as fish injury and mortality from passage through turbines, as well as detrimental effects on the quality of downstream water. A variety of mitigation techniques are in use now, and environmentally friendly turbines are under development. 

Legal and Institutional Issues

Legal and institutional issues include federal licensing as well as state and local permits, laws for historic and cultural preservation, and recreational requirements. 


Ocean energy draws on the energy of ocean waves, tides, or on the thermal energy (heat) stored in the ocean.

The ocean contains two types of energy: thermal energy from the sun's heat, and mechanical energy from the tides and waves. 

Oceans cover more than 70% of Earth's surface, making them the world's largest solar collectors. The sun warms the surface water a lot more than the deep ocean water, and this temperature difference stores thermal energy. Thermal energy is used for many applications, including electricity generation. There are three types of electricity conversion systems: closed-cycle, open-cycle, and hybrid. Closed-cycle systems use the ocean's warm surface water to vaporize a working fluid, which has a low-boiling point, such as ammonia. The vapor expands and turns a turbine. The turbine then activates a generator to produce electricity. Open-cycle systems actually boil the seawater by operating at low pressures. This produces steam that passes through a turbine/generator. And hybrid systems combine both closed-cycle and open-cycle systems. 

Ocean mechanical energy is quite different from ocean thermal energy. Even though the sun affects all ocean activity, tides are driven primarily by the gravitational pull of the moon, and waves are driven primarily by the winds. A barrage (dam) is typically used to convert tidal energy into electricity by forcing the water through turbines, activating a generator. For wave energy conversion, there are three basic systems: channel systems that funnel the waves into reservoirs, float systems that drive hydraulic pumps, and oscillating water column systems that use the waves to compress air within a container. The mechanical power created from these systems either directly activates a generator or transfers to a working fluid, water, or air, which then drives a turbine/generator. 

Wave Energy

The total power of waves breaking on the world's coastlines is estimated at 2 to 3 million megawatts. In favorable locations, wave energy density can average 65 megawatts per mile of coastline. 

Tidal Energy

Tidal energy traditionally involves erecting a dam across the opening to a tidal basin. The dam includes a sluice that is opened to allow the tide to flow into the basin; the sluice is then closed, and as the sea level drops, traditional hydropower technologies can be used to generate electricity from the elevated water in the basin. Some researchers are also trying to extract energy directly from tidal flow streams. 

Ocean Thermal Energy Conversion (OTEC) Systems

A great amount of thermal energy (heat) is stored in the world's oceans. Each day, the oceans absorb enough heat from the sun to equal the thermal energy contained in 250 billion barrels of oil. OTEC systems convert this thermal energy into electricity — often while producing desalinated water. 


Solar technologies use the sun's energy and light to provide heat, light, hot water, electricity, and even cooling, for homes, businesses, and industry. 

Sunlight—solar energy—can be used to generate electricity, provide hot water, and to heat, cool, and light buildings. 

Photovoltaic (solar cell) systems convert sunlight directly into electricity. A solar or PV cell consists of semiconducting material that absorbs the sunlight. The solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. PV cells are typically combined into modules that hold about 40 cells. About 10 of these modules are mounted in PV arrays. PV arrays can be used to generate electricity for a single building or, in large numbers, for a power plant. A power plant can also use a concentrating solar power system, which uses the sun's heat to generate electricity. The sunlight is collected and focused with mirrors to create a high-intensity heat source. This heat source produces steam or mechanical power to run a generator that creates electricity. 

Solar water heating systems for buildings have two main parts: a solar collector and a storage tank. Typically, a flat-plate collector—a thin, flat, rectangular box with a transparent covers—is mounted on the roof, facing the sun. The sun heats an absorber plate in the collector, which, in turn, heats the fluid running through tubes within the collector. To move the heated fluid between the collector and the storage tank, a system either uses a pump or gravity, as water has a tendency to naturally circulate as it is heated. Systems that use fluids other than water in the collector's tubes usually heat the water by passing it through a coil of tubing in the tank. 

Many large commercial buildings can use solar collectors to provide more than just hot water. Solar process heating systems can be used to heat these buildings. A solar ventilation system can be used in cold climates to preheat air as it enters a building. And the heat from a solar collector can even be used to provide energy for cooling a building. 

A solar collector is not always needed when using sunlight to heat a building. Some buildings can be designed for passive solar heating. These buildings usually have large, south-facing windows. Materials that absorb and store the sun's heat can be built into the sunlit floors and walls. The floors and walls will then heat up during the day and slowly release heat at night—a process called direct gain. Many of the passive solar heating design features also provide daylighting. Daylighting is simply the use of natural sunlight to brighten up a building's interior.

Solar Technologies

  • Photovoltaics (PV)

Photovoltaic solar cells, which directly convert sunlight into electricity, are made of semiconducting materials. The simplest cells power watches and calculators and the like, while more complex systems can light houses and provide power to the electric grid. 

  • Passive Solar Heating, Cooling and Daylighting

Buildings designed for passive solar and daylighting incorporate design features such as large south-facing windows and building materials that absorb and slowly release the sun's heat. No mechanical means are employed in passive solar heating. Incorporating passive solar designs can reduce heating bills as much as 50 percent. Passive solar designs can also include natural ventilation for cooling. 

  • Concentrating Solar Power

Concentrating solar power technologies use reflective materials such as mirrors to concentrate the sun's energy. This concentrated heat energy is then converted into electricity. 

  • Solar Hot Water and Space Heating and Cooling

Solar hot water heaters use the sun to heat either water or a heat-transfer fluid in collectors. A typical system will reduce the need for conventional water heating by about two-thirds. High-temperature solar water heaters can provide energy-efficient hot water and hot water heat for large commercial and industrial facilities. 


Solar Resources

Solar resource information provides data on how much solar energy is available to a collector and how it might vary from month to month, year to year, and location to location. Collecting this information requires a national network of solar radiation monitoring sites. 

Solar Access

The availability or access to unobstructed sunlight for use both in passive solar designs and active systems is protected by zoning laws and ordinances in many communities. 

Green Power

Consumer demand for clean renewable energy and the deregulation of the utilities industry have spurred growth in green power—solar, wind, geothermal steam, biomass, and small-scale hydroelectric sources of power. Small commercial solar power plants have begun serving some energy markets. 


Wind energy uses the energy in the wind for practical purposes like generating electricity, charging batteries, pumping water, or grinding grain. Large, modern wind turbines operate together in wind farms to produce electricity for utilities. Small turbines are used by homeowners and remote villages to help meet energy needs. Wind turbines capture the wind's energy with two or three propeller-like blades, which are mounted on a rotor, to generate electricity. The turbines sit high atop towers, taking advantage of the stronger and less turbulent wind at 100 feet (30 meters) or more aboveground. 

A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity. 

Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. Stand-alone turbines are typically used for water pumping or communications. However, homeowners and farmers in windy areas can also use turbines to generate electricity. For utility-scale sources of wind energy, a large number of turbines are usually built close together to form a wind farm. Several electricity providers today use wind farms to supply power to their customers.

Wind Energy Technologies

Modern wind turbines are divided into two major categories: horizontal axis turbines and vertical axis turbines. Old-fashioned windmills are still seen in many rural areas. 

Wind Turbine Use

Wind turbines are used around the world for many applications. Wind turbine use ranges from homeowners with single turbines to large wind farms with hundreds of turbines providing electricity to the power grid. 


Research advances have helped drop the cost of energy from the wind dramatically during the last 20 years. Research is carried out by research labs, universities, and utility organizations. 

Wind Resource

The wind is the fuel source for wind energy. The United States has many areas with abundant winds, particularly in the Midwest and Great Plains. Understanding the wind resource is a crucial step in planning a wind energy project. Detailed knowledge of the wind at a site is needed to estimate the performance of a wind energy project. 


Wind energy is considered a green power technology because it has only minor impacts on the environment. Wind energy plants produce no air pollutants or greenhouse gases. However, any means of energy production impacts the environment in some way, and wind energy is no different. 


The cost of energy from the wind has dropped by 85% during the last 20 years. Incentives like the federal production tax credit and net metering provisions available in some areas improve the economics of wind energy.

Forces Behind Wind Power


In the past several years, a number of new wind farms have begun commercial operation. Industry sources have estimated that more than 900 megawatts (MW) of wind capacity was under construction in 1999. A major portion of this capacity was constructed outside of California, the birth place of the wind power industry in the United States.(1) While the economics of wind turbine technology is improving, it is generally not yet competitive with fossil fuels.(2) Just as the outlook for wind improves, it can also improve for other energy sources. Thus, despite the encouraging portrayal of wind turbines, they face uncertainty in the future. This paper looks at the forces behind recent wind energy development.

Current Status and Recent Events

In 1997, wind power generation capacity of 1,579 MW produced 3,254,117 megawatthours (MWh) of electricity.(3) More than 99 percent of generation was by independent power producers, and nearly all of it was located in California. During 1998 and 1999, wind farm activity expanded into other States, motivated in part by financial and regulatory incentives and, in the case of Iowa and Minnesota, State mandates. Iowa, Minnesota, and Texas each had capacity additions exceeding 100 MW that came on line in 1999 (Table 1). During 1999, wind farm capacity that came on line consisted of state-of-the-art wind turbines manufactured primarily by Zond, a subsidiary of Enron Wind Corporation (392 MW); NEG Micon (325 MW); and Vestas (159 MW).(4) Less than 32 percent of new wind power construction was located in California in 1999.

Table 1. United States Wind Energy Capacity by State, 1998, and New Construction, 1999 and 2000 (Megawatts)


Existinga 1998

New Construction















































New Mexico




New York












South Dakota
































   a Defined as net summer capability.
   b Includes a substantial portion of repowered capacity.
   * = Less than 0.5 megawatts capacity.
   Sources: 1998 Capacity: Energy Information Administration, Renewable Energy Annual 1999 With Data for 1998, DOE/EIA-0603(99) (Washington, DC, March 2000) and New Construction: Based on data in American Wind Energy Association (AWEA), "Wind Energy Projects Throughout the United States," (July 7, 2000).

A number of recent events have triggered an interest in wind energy. Significant interest has arisen in the ability of renewable energy to survive as a viable energy source, compared with less expensive fossil fuels, as the electric power industry moves from a regulated to a competitive environment. Because renewable energy sources are generally perceived to be more environmentally benign than other energy sources, much recently enacted and/or proposed Federal and State legislation on electric competition contains provisions encouraging consumption of renewable energy. Hence, in those instances, electric restructuring may actually promote renewable energy use rather than restrain it. Wind energy, which is more economically competitive than most other renewable energy options, should benefit most from this effort.

Another event that increased interest in wind energy was the expiration of the federal production tax credit for any projects beginning operation after June 30, 1999. This tax credit was established by the Energy Policy Act of 1992 and provided a 1.5 cent per kilowatthour tax credit for the first 10 years of the project's life. Since all projects in operation by June 30, 1999, would be eligible for the tax credit, most of the capacity that came on line in 1999 came on by that date. Although the credit actually expired, it was reinstated in December 1999, it is retroactive to July 1999, and extends until the end of 2001. The current schedule for new capacity is less ambitious than 1999, but substantial (Table 1). A total of nearly 400 MW of new wind power construction (including a significant share of repowered capacity in California) was expected for 2000.

Additionally, in June of 1999, the Secretary of Energy announced the start of a new initiative, "Wind Powering America." The stated goal of this program is to have 80,000 MW of wind power generation capacity in place by 2020 and have wind power provide 5 percent of the Nation's electricity generation.(5) Year-end 1998 wind power capacity was about 1,698 MW,(6) so this goal represents an enormous increase in capacity additions. The initiative is mentioned here because of its potential importance and the attention it is drawing to wind energy. However, the full impact of the program on wind energy will be over the long-term future and is a concern more so for the Energy Information Administration's (EIA) Annual Energy Outlook, and less so for this paper, which covers the recent past and near-term future.(7)

Another long-term impact on renewable energy sources is concern over global warming and formulating a policy to reduce greenhouse gases in accordance with the Kyoto Protocol. A United Nations conference with representatives from more than 160 countries met in Kyoto, Japan, in 1997 to negotiate binding limits for greenhouse gas emissions for developed nations. Carbon dioxide is the major greenhouse gas. The target for the United States is to reduce carbon dioxide to 7 percent below 1990 levels in the 2008-2012 time frame. Adopting a carbon tax to accomplish this goal would increase the price of fossil fuels (particularly coal) but have little impact on the cost of renewables, which have zero or net zero carbon dioxide emissions. Assuming a carbon tax is imposed, analysis indicates that an increase in the consumption of renewable energy, led by wind, would make a significant contribution to achieving the targeted level of reduced emissions.(8) The next United Nations Conference of Parties (COP) meeting to develop strategies to achieve the goals of the Kyoto Protocol was held in November 2000 in the Hague, Netherlands.(9) No significant agreement was reached at that time, but future meetings are expected.

This paper is divided into two main sections followed by an appendix. The first section includes a technical discussion of expectations for wind turbine performance and efforts to improve it. The second section provides an overview of the world in which the wind power industry is developing. This discussion includes a broad view of the impact of electric power industry restructuring, as well as Federal and State incentives. These two main sections are supplemented by an Appendix of State Wind Profiles that takes a snapshot of the status of electricity restructuring in each State, the type of incentives or green power programs available to wind, and status of wind energy development through 2000. References are included so more current information can be obtained as needed.(10)

Wind Turbine Performance

The following sections provide an overview of the turbine technology being installed in today's wind farms. These turbines have generation capacities at or above 225 kilowatts (kW).(11) The discussion examines (1) wind resource issues and related siting considerations, (2) factors affecting wind turbine performance, (3) physical and operational characteristics of wind farm turbines and (4) operation and maintenance (O&M) considerations. The discussion focuses on wind farm turbines manufactured by NEG Micon, Vestas, and Zond, as they represent most of new installed capacity in the United States. The discussion indicates that each of their designs is equally adaptable to a variety of wind farm sites. The discussion shows how O&M considerations can be managed to ensure that the cost of O&M for a wind farm can be controlled and minimized.

A major caveat in evaluating information presented in this section is the availability of data. Performance data on operating wind turbines are frequently proprietary and extremely closely guarded. Thus, although some historical data are available, the data used in this chapter are often based upon engineering sources and not actual commercial operational performance data.

Factors Affecting Wind Turbine Performance

Wind Resources and Wind Turbine Machine Basics (12)

Winds are created by atmospheric temperature and pressure variations caused by the sun heating air during the day, so general wind patterns coincide well with electricity demand during the daytime. During nighttime, temperature variations are lessened; therefore, winds are less severe. Although geostrophic winds (or global winds) winds determine the prevailing direction and magnitude in an area, the surface winds (up to an altitude of 100 meters) such as sea breezes and mountain winds are key factors in calculating the usable energy content of the wind at a particular site. Wind direction is influenced by the sum of global and local effects; when larger scale winds are light, local winds may dominate the wind patterns.

The wind resource is seldom a steady, consistent flow. It varies with the time of day, season, height above ground, and type of terrain. An area's surface roughness and obstacles are also important determinants in wind resource. High surface roughness and larger obstacles in the path of the wind result in slowing the wind by creating turbulence. Wind speed generally increases with height above ground.

A wind turbine converts the force of the wind into a torque (turning force) that turns the turbine blades, which are connected to the shaft of an electric generator. The amount of energy that the wind transfers to the blades depends on the density of the air, the blade area, and the wind speed. Wind speed determines how much energy is available for conversion to electricity. For wind farm applications, developers seek sites with an annual average wind speed of at least 7.0 meters per second (15.7 miles per hour), measured at a wind turbine hub height above ground of 50 meters (164 feet).

Table 2. Definition of Classes of Wind Power Density for 50 Meter (164 Feet) Hub Height

Wind Power Class

Wind Power Density (W/m2)

Speeda m/s (mph)


400 – 500

7.0 (15.7)
– 7.5 (16.8)


500- 600

7.5 (16.8)
– 8.0 (17.9)


600- 800

8.0 (17.9)
– 8.8 (19.7)


> 800

> 8.8 (19.7)

   aMean wind speed is based on the Rayleigh speed distribution of equivalent wind power density. Wind speed is for standard sea-level conditions. To maintain the same power density, speed increases 3 percent /1000 m (5 percent/5000 ft) of elevation.
   W/m2 = Watts per square meter.
   Notes: Vertical extrapolation of wind speed from 10 meter baseline height based on the 1/7 power law.
   Source: D.L. Elliott, C.G. Holladay, W.R. Barchet, H.P. Foote, W.F. Sandusky, Wind Energy Resource Atlas of the United States, DOE/CH 10093-4 (Washington, DC, October 1986), Table 1.1.

Wind power density, measured in watts per square meter of blade surface, is used to evaluate the wind resource available at a potential site. The wind power density indicates how much energy is available for conversion by a wind turbine. The power available at a given wind speed varies with the cube (the third power) of the average wind speed.(13) Wind power developers think in terms of ranges of wind power density, termed wind power classes. Sites with a wind power class rating of 4 or higher are preferred for large-scale wind plants (see Table 2), which have installed capacity of at least 10 MW.(14) For any given wind power class, the wind power density range and wind speed range increases with hub height; a hub height of 50 meters is the approximate hub height for utility-scale turbines. For instance, NEG Micon turbine hub heights range from 40-55 meters for 600 kW and 750 kW turbines, to 49-80 meters for their 900 kW to 1.5 MW turbines.(15) Depending on rotor diameter, Vestas turbine hub heights range from 35-65 meters for their 600 kW and 660 kW models, to 60-100 meters for their 1.5 MW and 1.65 MW models.(16) The Zond turbine hub height is 53 meters for their 750 kW turbines, with an optional 65 meter height for the 48 meter and 50 meter rotor diameter versions of the 750 kW turbine.(17)

The goal of wind turbine design is to convert as much of the power in wind, illustrated by the wind power classes in Table 2, into turbine generator power output. The power curve for a wind turbine shows this relationship of wind speed to turbine power output by plotting turbine power output (e.g., kilowatts) as a function of wind speed (e.g., meters per second). Power curve values vary among turbines because turbine design approaches differ. The impact of design on power curve values is illustrated by comparing the wind speeds at which various turbines achieve rated power. For instance, the Zond Z-48 turbine achieves 750 kW rated power output at a lower wind speed (11.6 meters/second) than does the NEG Micon Multi-power 48 (16 meters/second) (Table 3). The shape of the power curve also varies with turbine design. For instance, the NEG Micon Multi-power 48, which uses a generator that operates at constant speed, produces less than 750 kW output at wind speeds less than or greater than 16 meters/second (Table 3), the speed at which it achieves rated power. In contrast, the variable speed generator used in the Zond Z-48 design enables the turbine to maintain rated output of 750 kW over the range of wind speeds listed in Table 3, starting with 11.6 meters per second (the speed at which it first achieves 750 kW output), because the generator speed varies with wind speed to maintain rated output. Power output per unit of rotor swept area offers a way to compare performance among wind turbines. Restated, the goal of wind turbine design is to obtain the highest value of power output per unit of rotor swept area (Table 3) for the lowest capital cost.

Table 3. Utility-Scale Wind Turbines–Performance Comparison

Turbine Manufacturer/Model (Rotor Diameter/Rated Power)

Rotor Swept Area (m2)

Power Output (kW)

Power Output/Rotor Swept Area (W/m2)

Wind Speed (meters/second)

Wind Speed (meters/second)











NEG Micon/Unipower 64
NM 1500C/64
(64 meters/1500 kW)













(66 meters/1650 kW)













NEG Micon/Multi-power 48
NM 750/48
(48.2 meters/750 kW)













(47 meters/660 kW)













(48 meters/750 kW)













   m2 = Square meters
   W/m2 = Watts per square meter
   Sources: NEG Micon, Vestas, and Zond wind turbine specification sheets for design information (rotor diameter, swept area, and rated power output). Power output at different wind speeds from manufacturer contacts, 1999.

Siting Factors Affecting Wind Turbine Performance

Several performance factors contribute to the selection of a wind farm site. Choosing a terrain with the least number of obstacles, least roughness, and the most expansive views is generally a good practice. The orientations of trees and shrubs and erosion patterns along a terrain provide clues to prevailing wind directions.

Meteorological data, preferably spanning periods greater than 20 years, are used to screen potential sites. Meteorologists collect wind data for weather forecasts and aviation, and that information is often used to assess an area's potential for wind energy. However, wind speeds and wind energy are not measured with great enough precision when monitored for weather forecasting to enable placement of turbines within a site. For example, wind speed is influenced by surface roughness, obstacles, and contours of the local terrain. The impact of these factors may be estimated when screening for potential wind farm sites.

Land conditions, which affect the cost of site preparation, are a factor in wind farm economics and in site selection. The earth must be able to withstand the combined weight of a tower foundation and the tower, turbine, and rotor. The earth and geography leading to and including the site must be accessible to large, heavy trucks and cranes used to haul wind turbine components on to the site and to install the turbines. The cost of building a road to the site must also be factored into site selection.

Connection to the electric grid presents other issues that must be addressed when choosing a wind farm site. Grid connection may be a component of total project cost, depending on the terms of the wind electricity purchase agreement between the wind farm developer and the electric utility. For example, the Southwest Mesa Wind Energy Project in Texas uses 700 kW NEG Micon turbines, which produce 600 volt electricity.(18) Electricity travels from the turbine to a field transformer to the wind farm substation to the utility transmission line. Therefore, the following transmission capital must be included in the project cost: field transformers, substation, and transmission lines to connect each element, ending with connection to the utility line. Congestion on the regional transmission system is also a consideration. It would be undesirable to locate a new wind farm where the transmission system would not accommodate the power generated.

Once a potential site is selected, meteorological data are measured at points within the site as part of wind turbine "micrositing." Micrositing refers to the actual placement of turbines within a wind farm site to optimize electricity production.

Capacity Factor

Capacity factor is defined as the actual annual wind farm energy output, in kilowatthours, divided by the rated maximum turbine output, in kilowatts, times 8,760 hours/year. For a 100 kW turbine producing 175,000 kWh in a year, the capacity factor would be:

Calculating the Capacity Factor

= ((175,000 kWh/year) /(100 kW x 8,760 hours/year)) x 100

= 20 percent

Factors affecting the magnitude of the capacity factor include wind resource intermittency, the wind farm site's wind speed distribution, turbine design, and turbine reliability. The degree of wind resource intermittency may vary both daily and seasonally. For a given turbine design, turbines sited where the wind resource is more intermittent will have a lower capacity factor. The wind farm site's wind speed distribution, and the associated average annual wind speed, affect annual electricity output. The annual electricity output for a wind turbine increases with average annual wind speed, since more hours of operation at a higher wind speed mean a higher average kilowatt power output from the turbine. Thus, for a given turbine design, wind farm sites with higher mean wind speeds have higher capacity factors. Historical data show wind farm capacity factors in the range of 25 percent to nearly 36 percent (Table 4). An objective of turbine design is to maximize annual power output, which would increase the capacity factor. Higher capacity factors, compared to Danish data and DOE 1997 baseline data for class 4 winds, are projected for the Zond Z-750 Series turbines (Table 4) because the Zond Z-750's variable speed generator design, taller tower, and larger rotor swept area enable a greater amount of wind energy to be converted to electrical energy. Finally, an increase in turbine reliability would be reflected in an increase in the capacity factor.

Table 4. Examples of Wind Farm Capacity Factors

Wind Farm Location (Developer)

Wind Farm Capacity(MW)

Turbine Manufacturer/Model

Turbine Description

Capacity Factor (percent)

Max. Power Output (kW)

Hub Height (m)

Rotor Swept Area (m2)







28.5 (historical)c







25.2 (historical)e

Hypothetical, Class 4 Windsf


DOE 1997 baseline technology




26.2 (based on historical)

Hypothetical, Class 6 windsg


DOE 1997 baseline technology




35.5 (based on historical)

Storm Lake II, Iowa (Enron)h


Zond Z-750




32 (historical)


38 (projected)

Lake Benton I, Minnesota (Enron)i


Zond Z-750




28 (historical)


35 (projected)

   a "Wind Turbine Performance Summary,"WindStats Newsletter, Vol. 11, No. 1 through 4, four consecutive quarters of data from winter 1998 through autumn 1998, wind farm section of tables with Danish data. During the winter 1998 and spring 1998 quarters, 46 turbines were operating. During the summer 1998 and autumn 1998 quarters, 48 turbines were operating.
   b NEG Micon. See website (November 1999). The 600 kW turbine comes in two rotor diameters: 48 meter (1810 m2 swept area) and 43 meter (1452 m2 swept area). Hub height options for the 48 meter model are 46 meters, 60 meters, and 70 meters. Hub height options for the 43 meter model are 40 meters, 46 meters, and 56 meters.
   c "Wind Turbine Performance Summary," WindStats Newsletter, Vol. 11, No. 1 through 4, four consecutive quarters of data from winter 1998 through autumn 1998, wind farm section of tables with Danish data. An annualized average capacity factor was calculated by averaging the four seasonal capacity factors provided in the WindStats Newsletter.
   dTurbine information for the Vestas 500 kW model from personal communication between Soren Christensen, Project and Sales Coordinator, Vestas-American Wind Technology, Inc., and William R. King, SAIC, November 1999. The 40-meter hub height is common in Denmark. The 500 kW turbine comes in three rotor diameters: 39 meters (1195 m2 swept area), 42 meters (1385 m2 swept area), and 44 meters (1521 m2 swept area).
   e "Wind Turbine Performance Summary, "WindStats Newsletter, Vol. 11, No. 1 through 4, four consecutive quarters of data from winter 1998 through autumn 1998, wind farm section of tables with Danish data. An annualized average capacity factor has been calculated by averaging the four seasonal capacity factors provided in the WindStats Newsletter.
   f U.S. Department of Energy (Office of Utility Technologies) and Electric Power Research Institute, Renewable Energy Technology Characterizations, TR-109496 (Washington, DC, December 1997), p. 6-12.
   g U.S. Department of Energy (Office of Utility Technologies) and Electric Power Research Institute, Renewable Energy Technology Characterizations, TR-109496 (Washington, DC, December 1997), p. 6-12.
   hAssumed Generation for Historical Capacity Factor: Energy Information Administration, Form EIA-900, "Monthly Nonutility Power Report,"Other Data: Enron Wind Corporation, See website (October 23, 2000). Note: Historical capacity factor is preliminary, calculated with preliminary generation data for 12 consecutive months during 1999 and 2000.
   i Assumed Generation for Historical Capacity Factor: Energy Information Administration, Form EIA-900, "Monthly Nonutility Power Report," Other Data: Enron Wind Corporation. See website (October 23, 2000).
   Note: Historical capacity factor is preliminary, calculated with preliminary generation data for 12 consecutive months during 1999 and 2000.
   Source: Energy Information Administration.


Annual electricity production can be estimated from the turbine's power curve, which plots kilowatt output as a function of wind speed.(19) Alternatively, electricity production from wind turbines may be estimated by statistical means.(20)

Contrary to conventional steam or nuclear power generation, the wind turbine with the larger capacity factor may not have an economic advantage over a wind turbine with a lower factor. For example, compare two wind turbines with the same rotor diameter but different generator capacities in a location with daily wind gusts or seasonal wind variations that are above the mean daily or seasonal speed. The turbine with the larger generator may be more economical because it enables higher power output, thus more electricity, when the wind turbine can take advantage of higher wind speeds. This strategy would tend to lower the capacity factor, using less of the available capacity of a larger generator. However, the strategy is economical if the value of the electricity production can be increased more than the incremental cost of the larger turbine over a smaller capacity turbine. The value of the electricity depends on daily or seasonal variations in electricity price. For instance, increased electricity production from a larger turbine has more value if produced during peak, rather than off-peak, periods of a utility's load curve.

Renewable Energy Credits

What is a "Renewable Energy Credit?"

One Renewable Energy Credit or "REC" represents one megawatt hour (MWh) of renewable energy that is physically metered and verified from the generator, or the renewable energy project. 

"REC's" are created when a Renewable Energy project is certified and begins producing renewable energy. Renewable energy projects create green power which helps reduce pollution. Renewable Energy Credits are the group of environmental benefits society benefits from in the production of green power. The green-power (electricity) is sold into the local electric grid where the renewable energy project is located. The REC's are sold separately as a commodity into the marketplace.

“In a REC deal, the power from the new renewable energy facility is not physically delivered to the customer, but the environmental benefits created by the facility are attributed to that customer, directly offsetting the environmental impact of the customer’s conventional energy use.” –Bonneville Environmental Foundation

REC Offset – An REC offset represents one megawatt hour (MWh) of renewable energy from an existing facility, which may be used in place of an REC to meet a renewable energy requirement imposed under this section. REC offsets may not be traded.

Renewable Energy Credit (REC or credit) – An REC represents one megawatt hour (MWh) of renewable energy that is physically metered and verified.

Renewable Energy Credit Account (REC account) – An account maintained by the renewable energy credits trading program administrator for the purpose of tracking the production, sale, transfer, purchase, and retirement of RECs by a program participant.

Renewable Energy Credit (trading program) – The process of awarding, trading, tracking, and submitting RECs as a means of meeting the renewable energy requirements.

Renewable Energy Resource – A resource that produces energy derived from renewable energy technologies.

Renewable Energy Technology – Any technology that exclusively relies on an energy source that is naturally regenerated over a short time and derived directly from the sun, indirectly from the sun, or from moving water or other natural movements and mechanisms of the environment. Renewable energy technologies include those that rely on energy derived directly from the sun, on wind, geothermal, hydroelectric, wave, or tidal energy, or on biomass or biomass-based waste products, including landfill gas. A renewable energy technology does not rely on energy resources derived from fossil fuels, or waste products from inorganic sources.


See important update on California Senate Bill 700 that impacts all California Animal Farming Operations

Some of the following information provided by the U.S. Environmental Protection Agency, the U.S. Department of Energy and the U.S. Department of Agriculture with permission and our thanks.

What is BioMethane and BioMethanation?

BioMethane is a renewable energy/fuel, with properties similar to natural gas, produced from "biomass." Unlike natural gas, BioMethane is a renewable energy. 

The cost of producing BioMethane, after installation of the BioMass Gasification equipment used to produce BioMethane (the process of making BioMethane is called "BioMethanation") is called is essentially free. 

Again, unlike the price of natural gas, which has been around $6.00/mmbtu for the past year. 

More About Biomass Gasification and BioMethanation Technology 

The process of Biomass Gasification produces BioMethane. BioMethane is also produced in anaerobic digesters, in the process called anaerobic digestion. BioMethane is a renewable energy resource, as opposed to natural gas (methane), which is a non-renewable energy resource. BioMethane has similar qualities of methane and both are used in interchangeably, and each may be a substitute for the other. 

The production and disposal of large quantities of organic and biodegradable waste without adequate or proper treatment results in widespread environmental pollution. Some waste streams can be treated by conventional methods like aeration. Compared to the aerobic method, the use of anaerobic digesters in processing these waste streams provides greater economic and environmental benefits and advantages.

As previously stated, Biomethanation is the process of conversion of organic matter in the waste (liquid or solid) to BioMethane (sometimes referred to as "BioGas) and manure by microbial action in the absence of air, known as "anaerobic digestion."

Conventional digesters such as sludge digesters and anaerobic CSTR (Continuous Stirred Tank Reactors) have been used for many decades in sewage treatment plants for stabilizing the activated sludge and sewage solids. 

Interest in BioMethanation as an economic, environmental and energy-saving waste treatment continues to gain greater interest world-wide and has led to the development of a range of anaerobic reactor designs. These high-rate, high-efficiency anaerobic digesters are also referred to as "retained biomass reactors" since they are based on the concept of retaining viable biomass by sludge immobilization.

Biomass Gasification and the Production of BioMethane

Biomass is a renewable energy resource which includes a wide variety if organic resources. A few of these include wood, agricultural residue/waste, and animal manure. 

Biomass Gasification is the process in which BioMethane is produced in the BioMass Gasification process. The BioMethane is then used like any other fuel, such as natural gas, which is not a renewable fuel.

Historically, biomass use has been characterized by low btu and low efficiencies. However, today biomass gasification is gaining world-wide recognition and favor due to the economic and environmental benefits. In terms of economic benefits, the cost of the BioMethane is essentially free, after the cost of the equipment is installed. BioMethane, probably the most important and efficient energy-conversion technology for a wide variety of biomass fuels. The large-scale deployment of efficient technology along with interventions to enhance the sustainable supply of biomass fuels can transform the energy supply situation in rural areas. 

It has the potential to become the growth engine for rural development in the country. 

Principles of Biomass Gasification

Biomass fuels such as firewood and agriculture-generated residues and wastes are generally organic. They contain carbon, hydrogen, and oxygen along with some moisture. Under controlled conditions, characterized by low oxygen supply and high temperatures, most biomass materials can be converted into a gaseous fuel known as producer gas, which consists of carbon monoxide, hydrogen, carbon dioxide, methane and nitrogen. This thermo-chemical conversion of solid biomass into gaseous fuel is called biomass gasification. The producer gas so produced has low a calorific value (1000-1200 Kcal/Nm3), but can be burnt with a high efficiency and a good degree of control without emitting smoke. Each kilogram of air-dry biomass (10% moisture content) yields about 2.5 Nm3 of producer gas. In energy terms, the conversion efficiency of the gasification process is in the range of 60%-70%.

Multiple Advantages of Biomass Gasification in Methane Production

Conversion of solid biomass into combustible gas has all the advantages associated with using gaseous and liquid fuels such as clean combustion, compact burning equipment, 

high thermal efficiency and a good degree of control. In locations, where biomass is already available at reasonable low prices (e.g. rice mills) or in industries using fuel wood, gasifier systems offer definite economic advantages. Biomass gasification technology is also environment-friendly, because of the firewood savings and reduction in CO2 emissions.

Biomass gasification technology has the potential to replace diesel and other petroleum products in several applications, foreign exchange.

Applications for Biomass Gasification

Thermal applications: cooking, water boiling, steam generation, drying etc.

Motive power applications: Using producer gas as a fuel in IC engines for applications such as water pumping Electricity generation: Using producer gas in dual-fuel mode in diesel engines/as the only fuel in spark ignition engines/in gas turbines.

Publicly Owned Treatment Works ("POTW's") or Wastewater Treatment Systems

More and more, cities, counties and municipalities are faced with greater environmental compliance issues relating to their municipally-owned landfills, Publicly Owned Treatment Works ("POTW's") or Wastewater Treatment Systems. 

A city's landfill and/or POTW provides an excellent opportunity for cities to reduce their emissions as well as provide an additional revenue stream. These facilities may have valuable gases that our company recovers and pipes to one of our clean, environmentally-friendly cogeneration or trigeneration energy systems. 

Our company provides economic and ecological solutions for cities and municipalities and provide a new cash flow simultaneously. We offer turn-key solutions for cities that includes the preliminary feasibility analysis, engineering and design, project management, permitting and commissioning. We provide very attractive financing packages for cities that does not add to a city's liability, yet provides a valuable new revenue stream. And, we are also able to offer a turn-key solution for qualified municipalities that includes our company owning, operating and maintaining the onsite power and energy plant.

At the heart of the system is a (Bio) Methane Gas Recovery system similar those used in Flare Gas Recovery or Vapor Recovery Units. Methane Gas Recovery, Flare Gas Recovery, Vapor Recovery, Waste to Energy and Vapor Recovery Units all recover valuable "waste" or vented fuels that can be used to provide fuel for an onsite power generation plant. Our waste-to-energy and waste to fuel systems significantly or entirely, reduces your facility's emissions (such as NOx , SOx, H2S, CO , CO2 and other Hazardous Air Pollutants/Greenhouse Gases) and convert these valuable emissions from an environmental problem into a new cash revenue stream and profit center.

Methane Gas Recovery and vapor recovery units can be located in hundreds of applications and locations. At a landfill, Wastewaster Treatment System (or Publicly Owned Treatment Works – "POTW") gases from the facility can be captured from the anaerobic digesters, and manifolded/piped to one of our onsite power generation plants, and make, essentially, "free" electricity for your facility's use. These associated "biogases" that are generated from municipally owned landfills or wastewater treatment plants have low btu content or heating values, ranging around 550-650 btu's. This makes them unsuitable for use in natural gas applications. When burned as fuel to generate electricity, however, these gases become a valuable source of "renewable" power and energy for the facility's use or resale to the electric grid. 

Additionally, if heat (steam and/or hot water) is required, we will incorporate our cogeneration or trigeneration system into the project and provide some, or all, of your hot water/steam requirements. Similarly, at crude oil refineries, gas processing plants, exploration and production sites, and gasoline storage/tank farm site, we convert your facility's "waste fuel" and environmental liabilities into profitable, environmentally-friendly solutions.

Our Methane Gas Recovery systems are designed and engineered for these specific applications. It is important to note that there are many internal combustion engines or combustion turbines that are NOT suited for these applications. Our systems are engineered precisely for your facility's application, and our engineers know the engines and turbines that will work as well as those that don't. More importantly, we are vendor and supplier neutral! Our only concerns are for the optimum system solution for your company, and we look past brand names and sales propaganda to determine the optimum system, which may incorporate either one or more; gas engine genset(s) or gas turbine genset(s), in cogeneration or trigeneration mode – in trigeneration mode, we incorporate absorption chillers to make chilled water for process or air-conditioning, fuel gas conditioning equipment and gas compressor(s). 

Our turn-key systems includes design, engineering, permitting, project management, commissioning, as well as financing for our qualified customers. Additionally, we may be interested in owning and operating the flare gas recovery or vapor recovery units. For these applications, there is no investment required from the customer.

For more information, please provide us with the following information about the flare gas or vapor: 

Type of gas being flared or vented (methane, bio-gas, digester, landfill, etc.).

Chromatograph Fuel/Gas analysis which provides us with the btu's (heating value) and the composition of the gas and its' impurities such as methane (and the percentage of methane), soloxanes, carbon dioxide, hydrogen, hydrogen sulfide, and any other hydrocarbons. 

Total amount of gas available, from all sources, at the facility. 

Waste Heat Recovery

Many industrial processes generate large amounts of waste energy that simply pass out of plant stacks and into the atmosphere or are otherwise lost. Most industrial waste heat streams are liquid, gaseous, or a combination of the two and have temperatures from slightly above ambient to over 2000 degrees F. Stack exhaust losses are inherent in all fuel-fired processes and increase with the exhaust temperature and the amount of excess air the exhaust contains. At stack gas temperatures greater than 1000 degrees F, the heat going up the stack is likely to be the single biggest loss in the process. Above 1800 degrees F, stack losses will consume at least half of the total fuel input to the process. Yet, the energy that is recovered from waste heat streams could displace part or all of the energy input needs for a unit operation within a plant. Therefore, waste heat recovery offers a great opportunity to productively use this energy, reducing overall plant energy consumption and greenhouse gas emissions. 

Waste heat recovery methods used with industrial process heating operations intercept the waste gases before they leave the process, extract some of the heat they contain, and recycle that heat back to the process. 

Common methods of recovering heat include direct heat recovery to the process, recuperators/regenerators, and waste heat boilers. Unfortunately, the economic benefits of waste heat recovery do not justify the cost of these systems in every application. For example, heat recovery from lower temperature waste streams (e.g., hot water or low-temperature flue gas) is thermodynamically limited. Equipment fouling, occurring during the handling of “dirty” waste streams, is another barrier to more widespread use of heat recovery systems. Innovative, affordable waste heat recovery methods that are ultra-efficient, are applicable to low-temperature streams, or are suitable for use with corrosive or “dirty” wastes could expand the number of viable applications of waste heat recovery, as well as improve the performance of existing applications. 

Various Methods for Recovery of Waste Heat

Low-Temperature Waste Heat Recovery Methods – A large amount of energy in the form of medium- to low-temperature gases or low-temperature liquids (less than about 250 degrees F) is released from process heating equipment, and much of this energy is wasted. 

Conversion of Low Temperature Exhaust Waste Heat – making efficient use of the low temperature waste heat generated by prime movers such as micro-turbines, IC engines, fuel cells and other electricity producing technologies. The energy content of the waste heat must be high enough to be able to operate equipment found in cogeneration and trigeneration power and energy systems such as absorption chillers, refrigeration applications, heat amplifiers, dehumidifiers, heat pumps for hot water, turbine inlet air cooling and other similar devices. 

Conversion of Low Temperature Waste Heat into Power –The steam-Rankine cycle is the principle method used for producing electric power from high temperature fluid streams. For the conversion of low temperature heat into power, the steam-Rankine cycle may be a possibility, along with other known power cycles, such as the organic-Rankine cycle. 

Small to Medium Air-Cooled Commercial Chillers – All existing commercial chillers, whether using waste heat, steam or natural gas, are water-cooled (i.e., they must be connected to cooling towers which evaporate water into the atmosphere to aid in cooling). This requirement generally limits the market to large commercial-sized units (150 tons or larger), because of the maintenance requirements for the cooling towers. Additionally, such units consume water for cooling, limiting their application in arid regions of the U.S. No suitable small-to-medium size (15 tons to 200 tons) air-cooled absorption chillers are commercially available for these U.S. climates. A small number of prototype air-cooled absorption chillers have been developed in Japan, but they use “hardware” technology that is not suited to the hotter temperatures experienced in most locations in the United States. Although developed to work with natural gas firing, these prototype air-cooled absorption chillers would also be suited to use waste heat as the fuel. 

Recovery of Waste Heat in Cogeneration and Trigeneration Power Plants

In most cogeneration and trigeneration power and energy systems, the exhaust gas from the electric generation equipment is ducted to a heat exchanger to recover the thermal energy in the gas. These heat exchangers are air-to-water heat exchangers, where the exhaust gas flows over some form of tube and fin heat exchange surface and the heat from the exhaust gas is transferred to make hot water or steam. The hot water or steam is then used to provide hot water or steam heating and/or to operate thermally activated equipment, such as an absorption chiller for cooling or a desiccant dehumidifer for dehumidification.

Many of the waste heat recovery technologies used in building co/trigeneration systems require hot water, some at moderate pressures of 15 to 150 psig. In the cases where additional steam or pressurized hot water is needed, it may be necessary to provide supplemental heat to the exhaust gas with a duct burner.

In some applications air-to-air heat exchangers can be used. In other instances, if the emissions from the generation equipment are low enough, such as is with many of the microturbine technologies, the hot exhaust gases can be mixed with make-up air and vented directly into the heating system for building heating.

In the majority of installations, a flapper damper or "diverter" is employed to vary flow across the heat transfer surfaces of the heat exchanger to maintain a specific design temperature of the hot water or steam generation rate. 

Typical Waste Heat Recovery Installation

In some co/trigeneration designs, the exhaust gases can be used to activate a thermal wheel or a desiccant dehumidifier. Thermal wheels use the exhaust gas to heat a wheel with a medium that absorbs the heat and then transfers the heat when the wheel is rotated into the incoming airflow.

A professional engineer should be involved in designing and sizing of the waste heat recovery section. For a proper and economical operation, the design of the heat recovery section involves consideration of many related factors, such as the thermal capacity of the exhaust gases, the exhaust flow rate, the sizing and type of heat exchanger, and the desired parameters over a various range of operating conditions of the co/trigeneration system — all of which need to be considered for proper and economical operation.