What is Renewable Energy
Renewable energy is a term used to describe energy that is derived from resources, like the sun and the wind — resources that are continually available to some degree or other all over the world. We never run out of them. And their use or capture does not inflict any material damage on the environment.
Sunlight is the source of most renewable energy power, either directly or indirectly. The sun can be harnessed to produce solar energy — electricity for heating, cooling, and lighting homes, offices, entertainment complexes, airports, and a variety of other industrial structures.
Heat from the sun also produces wind, whose energy is captured by wind turbines and turned into electricity capable of powering entire towns.
Hydroelectric power is produced from streams, rivers, and waterfalls that flow downhill, their tremendous power turning large turbines that convert the flow to electricity. Industrialized nations have already developed most of the world’s large hydroelectric resources, but small-scale technologies are being developed that will provide additional localized power in the future.
Organic plant matter, known as biomass, can be burned, gasified, fermented, or otherwise processed to produce electricity, heat and biofuels for transportation. Bioenergy is another term for energy that is produced from biomass for any of these purposes.
Geothermal energy taps the Earth’s internal heat in the form of steam for a variety of uses, including electric power production, and the heating and cooling of buildings. Some new systems are in development for harvesting even more power by injecting water back into underground heat sources to produce more steam.
Ocean energy can also be used to produce electricity. In addition to tidal energy, energy can be produced by the action of ocean waves, which are driven by both the tides and the winds. Because of their link to winds and surface heating processes, ocean currents are considered as indirect sources of solar energy.
- The U.S. is the leader in ethanol production (62 %) followed by Brazil (37.9%) followerd by the EU (6.0%) China (3.1%) and Thailand (2.5%).
- Corn ethanol production continues to expand rapidly in the U.S. (between 2000 and 2009 production increased more than 6 times), and in 2009 production grew about 20% to reach 10,750 million gallons / year
- Ethanol has steadily increased its percentage of the overall gasoline pool, and in 2009 was estimated to be 7.8%
- Since 2006, the U.S. has been the world’s leading ethanol producer. Between 2000 and 2009, production of corn ethanol increased by a factor of 6, and biodiesel production increased by a factor of more than 100. Use of ethanol in the U.S. has also grown substantially, and it accounts for 7.8% of the total U.S. gasoline pool, up from 1% in 2000.
- Total ethanol production increased nearly 21% to an estimated 13 billion gallons in 2010.
- The ethanol industry comprised approximately 200 plants in 26 states with nameplate capacity of 13.8 billion gallons
- An estimated 743 million gallons of new capacity were added in 2010, with 840 million gallons of new capacity under construction.
- $800 million of stimulus funds from the ARRA has been allocated in research and design in biofuels
- $1.3 billion was spend on biofuels R + D in 2009 – this figure rose to $1.5 billion in 2010.
- The ethanol industry supported more than 400,000 jobs in all sectors of the economy in 2010, and is estimated to have put $35 billion in to the pickets of Americans in 2010, and accounted for nearly $8.6 billion of revenue received by the Federal treasury in 2010.
- The production of 13 billion gallons of ethanol resulted in a reduction of 445 million barrels of imported oil in 2010. (This is roughly 13% of total US crude oil imports which is valued at $34 billion)
Beyond developing the technologies that will allow us to store solar and wind energy as effectively as we can store water in a dam or the earth stores heat in its core, we can also look at using innovative materials to generate our electricity. Trees, grasses, agricultural crops, and other biological materials are collectively known as biomass. Many people probably associate biomass with the manufacture of alternative fuels—ethanol and biodiesel. But here we’re talking about how wood waste, biogases, and even the scraps in your garbage—yard waste and paper that can’t be recycled into new paper products—potentially can be used as fuel in power plants (to make electricity) rather than taking up space in a landfill. Using biomass to produce power is called “biopower”. In the southeastern United States, as a matter of fact, biomass technology is already leading the region’s renewable power potential.
Wood is the most common form of biomass. In the United States, about 2 percent of the energy manufactured today comes from wood and wood waste, such as bark, sawdust, wood chips, and scraps, much of it from industries that use wood as a raw material and recycle the scrap to create their own energy supply. In landfills, when biomass rots, it produces methane, as does the manure at dairy and poultry farms; this gas can be collected and processed in tanks called digesters to produce power. Even your trash—known more formally as municipal solid waste (MSW)—contains food scraps, leaves, and lawn clippings that can become feedstock for power plants. But how much biomass can your lawn clippings and such really amount to? Right now, for example, the state of California produces more than 60 million tons of biomass each year. Less than 10 percent of that total is burned to make electricity, but if all 60 million tons were used, it could generate nearly 2,000 megawatts of electricity, enough to power 2 million homes!
Some studies estimate that in the entire United States there is an available biomass of 1.3 billion tons per year. 35 percent of the food purchased in Britain, and 50 percent in the United States, ends up rotting in a landfill, producing methane that contributes to global warming but that might be used for more constructive purposes.
Burning biomass is technically only one of many ways to produ ce biopower. To burn something, according to websters, it must undergo combustion. And combustion technically means a chemical reaction between oxygen an organic fuel—biomass, in this case. This reaction, as we know from watching a campfire, releases heat and light. But biomass can also be heated with limited oxygen in a process called gasification, or, can be heated in the complete absence of oxygen in a process called pyrolysis. These processes require attention and adaption to the different moisture content of different types of biomass feedstocks.
Additionally, biomass—because it’s composed of decomposing vegetation—contains carbon that it will release when it’s burned. But because the tree in your backyard, for instance, produces new carbon-eating leaves every year to replace the ones you’ve raked up and sent to the power plant, the level of carbon in the atmosphere remains ”carbon neutral” when biomass rather than coal is burned as a fuel. Furthermore, if trees are planted for the sole purpose of producing biopower, then the level of carbon in the atmosphere could be lowered to a level below what it originally was. In this case, biopower from these trees can potentially be “carbon negative”.
The word “geothermal” comes from the Greek geo, meaning “earth,” and therme, meaning “heat.” Geothermal energy systems make use of the heat that’s produced deep inside of the earth, at its core, 4,000 miles below the planet’s surface.
The earth’s core actually has two layers: an inner core of iron and an outer layer of very hot melted rock, called magma. On top of the magma layer comes the mantle, a layer of earth that’s about 1,800 miles thick, made of magma and rock. On top of the mantle is the earth’s crust, a layer that’s relatively thin—from three to five miles deep beneath the ocean and fifteen to thirty-five miles deep under landmasses. The earth’s crust is broken into pieces called plates, and it is at these broken places that heat manufactured in the magma layer by slowly decaying radioactive particles comes closest to the surface. The heat manifests itself as volcanoes, geysers, and hot springs—places where the Romans, Chinese, and Native Americans built their baths, and where today spas still draw enthusiastic patrons to their mineral-rich healing waters. It’s these same places that are, in general, the best locations for geothermal heating and electric-generating facilities.
All geothermal systems rely on two basic components: the heat beneath the earth’s crust and the subterranean waters that the earth’s heat will turn to steam. In most geothermal systems, accessing these components involves drilling up to two miles into the earth’s crust. In direct heating systems, the earth’s natural steam is piped directly into buildings to warm them in winter and—perhaps surprisingly—to cool them in summer.
How does that work? While the seasons change from cold to hot and back again out here on the surface of the planet, the temperature in the upper ten feet of the earth remains fairly constant, at between 50 and 60 F. The benefits of this constant temperature can be accessed by pumping the water of springs or reservoirs near the earth’s surface into buildings for interior climate control. In some cities in Iceland, a leader in using geothermal technology, the climate in nearly 95 percent of its buildings is managed in this manner.
Geothermal power can also be used to make electricity; it already supplies over twenty countries, including France, New Zealand, Russia, China, and the Philippines, with about 8 percent of the renewable energy generated globally. Though at the present time it costs between $4,000 and $5,000 to install 1 kilowatt, it has the potential to become a very cost-effective way to produce electricity, and its development potential is broad worldwide, so the technology deserves to be a little better understood.
There are four different ways to drive electric generators using geothermal energy. The first is called the dry steam method. First developed in 1904 by Prince Piero Ginori Conti at the Lardello field in Tuscany, this method uses the steam released directly from a geothermal reservoir to drive generator turbines.
A more technologically sophisticated method of geothermal electrical generation is called the flash steam system. This is the most common system in use today, and it works by taking advantage of the high pressure beneath the earth’s crust. Under this intense pressure, water remains liquid though it’s heated to what would be well over the boiling point were it at sea level. As the water is pumped from within the earth, an abrupt drop in pressure causes it to convert—in a flash—to steam, which more efficiently powers the turbines that energize the electrical generators.
Most geothermal facilities that are now in the planning stages incorporate a third, and even more efficient, technology to access geothermal power. Called the binary system, this method directs the earth’s hot water to a heat exchanger, where the heat is transferred to a second pipe containing a fluid with a much lower boiling point than water, usually either isobutane or isopentane gas, which is then vaporized to power the turbines. The advantage of this system is that it can make use of those geothermal reservoirs that have lower temperatures, which increases the places where geothermal systems can be located.
Finally, enhanced geothermal, or the hot dry rock system, may be yet another avenue into deep earth’s power potential. Rather than harvesting the heated water already in the earth, this method involves manufacturing steam by piping surface water into the hot but dry rocks in the earth’s crust. The benefit of this system is that it can be used anywhere on the planet simply by drilling a hole. The downside is that the hole has got to be dug deep—deeper than for any other geothermal system—and the environmental impacts of deep drilling aren’t yet fully understood.
- The first U.S. geothermal power plant, opened at The Geysers in California in
- 1960, continues to operate successfully.
- The United States, as the world’s largest producer of geothermal electricity, generates an average of 15 billion kilowatt hours of power per year, comparable to burning close to 25 million barrels of oil or 6 million shorttons of coal per year.
- A geothermal resource assessment shows that nine western states together have the potential to provide over 20 percent of national electricity needs.
- Although geothermal power plants, concentrated in the West, provide the third largest domestic source of renewable electricity after hydropower and biomass, they currently produce less than one percent of total U.S. electricity.
- Over 30 years, the period of time commonly used to compare the life cycle impacts from different power sources, a geothermal facility uses 404 square meters of land per gigawatt hour, while a coal facility uses 3632 square meters per gigawatt hour.
Like the sun and the wind, water has been serving the industry of humankind for at least as long as we’ve been recording history. In Himalayan villages in the twelfth century, small hydro systems powering waterwheels to grind grain would have been a common feature of the landscape. The first hydroelectric power plant was built in Appleton, Wisconsin, in 1882. It generated just 12.5 kilowatts of power, enough to provide lights for two small paper mills and one house. Today hydroelectric power is a form of renewable energy so mainstream that often it’s not even included in state or national tallies of renewable power capacity.
One of the reasons why hydroelectric power has such a comfortable niche in our contemporary energy mix is the lockstep progress of hydro technology and the electrification of developed countries. It’s been around for a long time: FDR, the father of American electrification, who called for hydroelectric power to be expanded in the 1930s as a source of cheap, clean electricity.
Nowadays hydroelectric giants, such as the 7,600-megawatt Grand Coulee power station on the Columbia River in the state of Washington and the 13,000-megawatt Itaipu Dam on the Paraná River in Brazil, combine to provide 24 percent of the world’s electricity. The global capacity from all hydroelectric facilities is 675,000 megawatts producing 2.9 trillion kilowatt-hours of power annually and—not incidentally—saving the world the equivalent of 1.7 billion barrels of oil each and every year.
Hydroelectric power works by converting the energy in flowing water to electric energy. The same physics lie behind the design of all hydroelectric systems: A dam is used to capture and store water; pipes, or penstocks, carry the water from a high reservoir, downhill, toward turbines in a power station, and the strength of the natural pressure of the surging water is often increased by nozzles affixed to the end of the pipes; the water strikes the turbines, rotating them and driving a generator that produces electricity.
Though the typical arrangement of all hydroelectric stations is similar, there are several variations in how the design can be implemented. First of all, the amount of electricity any hydro system can produce is determined by its “head”—the difference in height between the surface of the water in the high reservoir and how far it must fall to reach the turbines in the power station below. The greater the height, the more power that is achievable. The height of a system’s head is determined as much by engineering feats as it is by the natural geological features of the chosen site.
Second, the water’s flow can be utilized in a variety of ways. Conventional hydroelectric power plants use a one-way flow of water. These sometimes are called run-of-the-river plants, meaning that they rely solely on the native flow of the body of water. Consequently, they are significantly affected by the weather and by seasonal changes in rainfall and water levels that can cause fluctuations in the amount of electricity they produce. Conventional hydroelectric systems, with one-way water flow, can also be designed as “storage” plants, which reserve enough water in their dams to offset seasonal impact on their water flow. Large dams can, in fact, store several years’ worth of water.
Other hydroelectric systems are designed as pumped storage plants. This means that after the naturally flowing water has produced an initial quantity of electricity, it’s diverted from the turbines into a lower reservoir below the dam. During off-peak hours, or through dry-weather conditions, the water in this lower reservoir can be pumped back up and reused to supply a steady stream of electricity to the plant’s customers during peak use times. This characteristic of water—that it can be stored in dams or redirected for reuse—has probably also given hydroelectric power a historic advantage over the intermittent wind and sun and has likely contributed to its rapid acceptance and use as a mainstream power source.
- Hydropower is the most important and widely-used renewable source of energy.
- Hydropower represents 19% of total electricity production worldwide.
- Canada is the largest producer of hydroelectricity, followed by the United States and Brazil.
- Approximately two-thirds of the economically feasible potential remains to be developed.
- Untapped hydro resources are still abundant in Latin America, Central Africa, India and China.
Hydrogen is a universal fuel and the most abundant element in the universe. It is a light, odorless, colorless gas.
The universal nature of hydrogen means you have several choices to produce, store and use it. You can make hydrogen using wind, solar, hydropower, biomass, natural gas, coal, nuclear energy and other resources. Hydrogen can then be stored in a tank, distributed in a pipeline or used directly where it is produced. It can also be used in a variety of different ways: combined with cooking oil to make chocolate, peanut butter and other foods; burned to power an engine with no carbon emissions; to remove dirty sulfur from gasoline; combined with nitrogen to make fertilizer; and combined with oxygen in a fuel cell to make electricity for vehicles, homes and personal electronics with zero emissions–only water vapor.
Whether hydrogen is renewable or not depends on how it is produced. If it is produced from water, using renewable sources of electricity, or from many different kinds of biomass, hydrogen is completely renewable. If hydrogen is produced from natural gas, coal or water, using nuclear energy, hydrogen is not renewable (although these resources have many benefits when linked with hydrogen that they do not have when used on their own). Most of the hydrogen in the U.S. today is made from natural gas because it’s the cheapest to make fertilizer and to remove sulfur from gasoline. However, as more hydrogen is used to make clean electricity to power our homes, personal electronics and vehicles, the use of renewables to make hydrogen will grow.
Hydrogen is a key enabler for the wider use of renewables, because excess electricity can be stored as hydrogen. Then the hydrogen can be used to make electricity later, when the sun isn’t shining and the wind isn’t blowing. When used in combination with other renewables this way, hydrogen can help increase the reliability of renewable electricity as a whole. It’s a great way that hydrogen and renewables can help each other to improve our environment, reduce our dependence on imported fuels and grow the economy.
- The world produces enough hydrogen right now to fuel 180 million fuel cell-electric vehicles (FCEVs)
- More than 56 billion kilograms of hydrogen are produced globally each year (the equivalent of 56 billion gallons of gasoline).
- 53% of the hydrogen produced in North America is already dedicated to transportation, enough to fuel 21 million FCEVs. It’s used to make gasoline cleaner by removing sulfur from petroleum at refineries.
- A large hydrogen production site exists today near almost every major U.S. and European city.
- If we use current technology to make hydrogen, it can cost the equivalent of $3 to $6 per gallon of gasoline at the pump, not including taxes. Hydrogen can be delivered at the pump within this equivalent price range when made from natural gas, water (using electricity from wind), plants and coal. (This assumes that a fuel cell is twice as efficient as a gasoline engine.)
- The U.S. Department of Energy’s target for total hydrogen cost is $2.00 – $3.00 per gallon of gasoline equivalent. There are several strategies that have potential to meet this target.
- A system of hydrogen fueling stations may not be as expensive as you think. A $10 – $15 billion investment would put you within two miles of the nearest hydrogen station in the top 100 metro areas (where 70% of the population lives). This is one-half the cost of the Alaskan pipeline in today’s dollars. This infrastructure could support 1 million FCEVs, assuming there are 240 stations in L.A. and 240 in New York City. By comparison, in 2007, 324,318 gasoline electric hybrid vehicles were sold in the U.S.
- A fuel cell vehicle using hydrogen produced from water using renewable energy produces no exhaust emissions.
Ocean & Tidal Energy
With the oceans covering over 70% of the earth’s surface, they are the world’s largest collector and retainer of the sun’s vast energy – and the largest powerhouse in the world. Jacques Cousteau said it was equivalent to 16,000 nuclear plants. This energy is continually renewed and is available 24/7.Just a small portion of the energy conveniently stored in the oceans could power the world.
For over 60 years, several forms of tapping energy from the ocean have been researched and implemented, and now with fossil fuels running out and becoming increasingly expensive, they are more than competitive in costs – and the ‘fuel’ from the ocean is both free and clean.
The massive oceanic surface currents of the world are untapped reservoirs of energy. Their total energy flux has been estimated at 2.8 ¥ 1014 (280 trillion) watt-hours. Because of their link to winds and surface heating processes, the ocean currents are considered as indirect sources of solar energy. If the total energy of a current was removed by conversion to electric power, that current would cease to exist; but only a small portion of any ocean current’s energy can be harnessed, owing to the current’s size.
One of the primary advantages of this technology is the energy density. While solar and wind systems are well-suited for remote off grid locations, ocean energy is ideal for large-scale developments in the multiple gigawatt range. Sea water is 832 times as dense as air, providing a 5 knot ocean current with more kinetic energy than a 350 km/h wind.
Ocean currents are one of the largest untapped renewable energy resource on the planet. Preliminary surveys show a global potential of over 450,000 MW, representing a market of more than US$550 billion.
Areas that typically experience high marine current flows are in narrow straits, between islands and around headlands. Entrances to lochs, bays and large harbours often also have high marine current flows (EECA,1996). Generally the resource is largest where the water depth is relatively shallow and a good tidal range exists. In particular, large marine current flows exist where there is a significant phase difference between the tides that flow on either side of large islands.
There are many sites world-wide with velocities of 5 knots (2.5 m/s) and greater. Countries with an exceptionally high resource include the UK (E&PDC, 1993), Ireland, Italy, the Philippines, Japan and parts of the United States. Few studies have been carried out to determine the total global marine current resource, although it is estimated to exceed 450 GW (Blue Energy, 2000).
In the US, the Florida Current and the Gulf Stream are reasonably swift and continuous currents moving close to shore in areas where there is a demand for power. If ocean currents are developed as energy sources, these currents are among the most likely. But most of the wind-driven oceanic currents generally move too slowly and are found too far from where the power is needed.
Electricity also can be generated by tidal water flowing both into and out of a bay. As there are two high and two low tides each day, electrical generation from tidal power plants is characterized by periods of maximum generation every twelve hours, with no electricity generation at the six hour mark in between. Alternatively, the turbines can be used as pumps to pump extra water into the basin behind the barrage during periods of low electricity demand. This water can then be released when demand on the system is greatest, thus allowing the tidal plant to function with some of the characteristics of a “pumped storage” hydroelectric facility.
- Wave energy contains roughly 1000 times the kinetic energy of wind, allowing much smaller and less conspicuous devices to produce the same amount of power in a fraction of the space
- Wave energy varies as the square of wave height, whereas wind power varies with the cube of air speed. Water being 850 times as dense as air, this results in much higher power production from waves averaged over time
- Because wave energy needs only 1/200 the land area of wind and requires no access roads, infrastructure costs are less
Solar energy is the cleanest, most abundant, renewable energy source available. And the U.S. has some of the richest solar resources shining across the nation. Today’s technology allows us to capture this power in several ways giving the public and commercial entities flexible ways to employ both the heat and light of the sun.
The greatest challenge the U.S. solar market faces is scaling up production and distribution of solar energy technology to drive the price down to be on par with traditional fossil fuel sources.
Solar energy can be produced on a distributed basis, called distributed generation, with equipment located on rooftops or on ground-mounted fixtures close to where the energy is used. Large-scale concentrating solar power systems can also produce energy at a central power plant.
There are four ways we harness solar energy: photovoltaics (converting light to electricity), heating and cooling systems (solar thermal), concentrating solar power (utility scale), and lighting. Active solar energy systems employ devices that convert the sun’s heat or light to another form of energy we use. Passive solar refers to special siting, design or building materials that take advantage of the sun’s position and availability to provide direct heating or lighting. Passive solar also considers the need for shading devices to protect buildings from excessive heat from the sun.
As global climate change impacts the way the U.S. addresses environmental policy, conducts business and harnesses energy, the solar energy industry is leading the way with a renewable energy source that creates economic growth and reduces carbon emissions. Solar is an emission-free source of electricity and hot water that can be immediately deployed to reduce the nation’s growing carbon footprint.
- New solar installations nationwide increased by more than 40 percent from 2006 to 2007.
- In that timeframe, expansions of solar energy companies resulted in 6,000 new jobs, 265 megawatts of energy and more than $2 billion of investment in the U.S. economy by Wall Street firms such as JP Morgan, Chase and Goldman Sachs.
- A recent study from Navigant Consulting found that more 115,000 jobs and nearly $19 billion in U.S. investment could be lost in 2009 alone if Congress does not extend the solar and wind tax credits. In the solar energy segment 39,400 of those jobs and $8 billion in investment are put at risk.
- The National Renewable Energy Laboratory (NREL) estimates that an additional thirty gigawatts of solar energy would result if the Investment Tax Credit is extended for 8 years. This is enough energy to power more than five million homes!
Waste to Energy
Waste-to-energy is considered a renewable because its fuel source—garbage—is sustainable and non-depletable. According to the U.S. EPA, waste-to-energy is a “clean, reliable, renewable source of energy.” In addition, the Energy Policy Act of 2005, the Federal Power Act, the Public Utility Regulatory Policies Act, the Biomass Research and Development Act of 2000, the Federal Energy Regulatory Commission’s regulations, and fifteen states all recognize waste-to-energy power as renewable.
The U.S. has 87 waste-to-energy plants nationwide that dispose of more than 90,000 tons of trash each day while generating enough clean energy to supply electricity to about 2.3 million homes nationwide.
Municipal waste consists of products that are combusted directly to produce heat and/or power and comprises wastes produced by the residential, commercial and public services sectors that are collected by local authorities for disposal in a central location. Hospital waste is included in this category.
The modern waste-to-energy plant turns garbage into energy using materials that range in size from the size of a pea to the size of a tree limb. The fuel can be wet or dry, and it varies greatly in energy content.
The process of producting energy from trash starts at the receiving building, where the trash is deposited onto the floor or into a large concrete pit. In many facilities, trash is then loaded directly into the furnaces. In other facilities, the trash is processed and shredded to produce a fuel before putting it into the boilers. Air for the combustion process in the furnaces is drawn from within the receiving building so that air is always flowing into the building from the outside. This creates a “negative pressure” within the building that prevents dust and odors from escaping the building.
The plant’s high temperature combustion furnace completely destroys viruses, bacteria, rotting food and other organic compounds found in household garbage that could potentially impact human health. The heat from the burning garbage boils water flowing inside the boiler tubes and turns the water into steam. The steam can be used directly in a heating system or a factory but it is usually used to turn a turbine-generator to make electricity. After any uncombustible residue (ash) cools, magnets and other mechanical devices pull metals from the ash for recycling. This is an important step, since a waste-to-energy plant can recycle thousands of tons of metals from its ash.
The Integrated Waste Services Association (IWSA) was formed in 1991 to promote integrated solutions to municipal solid waste management challenges. IWSA encourages the use of waste-to-energy technology as an integral component of a comprehensive, integrated solid waste management program.
- Waste-to-energy plants annually recover for recycling more than 700,000 tons of ferrous metals on-site. These facilities annually recycle more than 3 million tons of glass, metal, plastics, batteries, ash and yard waste. More than one-third of all ash is being reused as an aggregate material in roads and as landfill cover.
- Waste-to-energy technology prevents the emission of eleven million metric tons of greenhouse gases (methane and carbon dioxide) that would otherwise be released into the atmosphere on an annual basis.
- America’s waste-to-energy facilities today meet some of the most stringent environmental standards in the world and employ the most advanced emissions control equipment available including scrubbers to control acid gas, fabric filters to control particulate, selective non-catalytic reduction (SNCR) to control nitrogen oxides, and carbon injection to control mercury and organic emissions.
- Waste-to-energy serves as an alternative to land disposal and power generation from fossil fuels, which prevents the release of more than 20,000 tons of nitrogen oxides and 2.2 million tons of volatile organic compounds.
- Waste-to-energy reduces the volume of trash by about 90%, resulting in a 90% decrease in the amount of land required for garbage disposal.
In reality, wind energy is a converted form of solar energy. The sun’s radiation heats different parts of the earth at different rates-most notably during the day and night, but also when different surfaces (for example, water and land) absorb or reflect at different rates. This in turn causes portions of the atmosphere to warm differently. Hot air rises, reducing the atmospheric pressure at the earth’s surface, and cooler air is drawn in to replace it. The result is wind.
Air has mass, and when it is in motion, it contains the energy of that motion (“kinetic energy”). Some portion of that energy can converted into other forms mechanical force or electricity that we can use to perform work.
A wind energy system transforms the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical use. Mechanical energy is most commonly used for pumping water in rural or remote locations- the “farm windmill” still seen in many rural areas of the U.S. is a mechanical wind pumper – but it can also be used for many other purposes (grinding grain, sawing, pushing a sailboat, etc.). Wind electric turbines generate electricity for homes and businesses and for sale to utilities.
There are two basic designs of wind electric turbines: vertical-axis, or “egg-beater” style, and horizontal-axis (propeller-style) machines. Horizontal-axis wind turbines are most common today, constituting nearly all of the “utility-scale” (100 kilowatts, kW, capacity and larger) turbines in the global market.
Electricity generated by a utility-scale wind turbine is normally collected and fed into utility power lines, where it is mixed with electricity from other power plants and delivered to utility customers. Today turbines with capacities as large as 5,000 kW (5 MW) are being tested.
- New wind projects added in 2007 account for about 30% of the entire new power-producing capacity added nationally in the year.
- By reducing the use of natural gas and other fuels used for electricity generation, and lowering the pressure on their price, wind can save consumers money, even in regions with low or no wind
- To generate the same amount of electricity using the average U.S. power plant fuel mix would cause over 28 million tons of carbon dioxide (CO2) to be emitted annually.
- Shattering all its previous records, the U.S. wind energy industry installed 5,244 megawatts (MW) in 2007, expanding the nation’s total wind power generating capacity by 45% in a single calendar year and injecting an investment of over $9 billion intothe economy.
- The U.S. wind power fleet now numbers 16,818 MW and spans 34 states.
- American wind farms will generate an estimated 48 billion kilowatt-hours (kWh) of wind energy in 2008, just over 1% of U.S. electricity supply, powering the equivalent of over 4.5 million homes.
- Texas consolidated its lead in terms of installed wind power capacity. The states with the most cumulative wind power capacity installed are: Texas, with 4,356 MW; California, with 2,439 MW; Minnesota, with 1,299 MW; Iowa, with 1,273 MW; and Washington with 1,163 MW.
- At least fourteen new manufacturing facilities opened or were announced in2007.
- GE Energy continued to lead in wind turbine sales, with 45% of the market in terms of new capacity installed.
- FPL Energy remained atop the list of wind project developers, with 956 MW of new development in 2007 alone.
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