Renewable Energy Terms
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Alternative Fuel
The following fuels are defined as alternative fuels by the Energy Policy Act (EPAct) of 1992: pure methanol, ethanol, and other alcohols; blends of 85% or more of alcohol with gasoline; natural gas and liquid fuels domestically produced from natural gas; liquefied petroleum gas (propane); coal-derived liquid fuels; hydrogen; electricity; pure biodiesel (B100); fuels, other than alcohol, derived from biological materials; and P-Series fuels. In addition, the U.S. Department of Energy (DOE) is authorized to designate other fuels as alternative fuels, provided that the fuel is substantially nonpetroleum, yields substantial energy security benefits, and offers substantial environmental benefits. For more information about the alternative fuels defined by EPAct 1992 as well as DOE’s alternative fuel designation authority, visit the EPAct Web site. (Reference 42 U.S. Code 13211)
Alternative Fuel Definition – Internal Revenue Code
The Internal Revenue Service (IRS) defines alternative fuels as liquefied petroleum gas, compressed natural gas, liquefied natural gas, liquefied hydrogen, liquid fuel derived from coal through the Fischer-Tropsch process, liquid hydrocarbons derived from biomass, and P-Series fuels. Biodiesel, ethanol, and renewable diesel are not considered alternative fuels by the IRS. While the term “hydrocarbons” includes liquids that contain oxygen, hydrogen, and carbon and as such “liquid hydrocarbons derived from biomass” includes ethanol, biodiesel, and renewable diesel, the IRS specifically excluded these fuels from the definition. (Reference 26 U.S. Code 6426)
Anaerobic digestion
Anaerobic digestion (AD) is, simply put, the naturally occurring breakdown of organic materials by microorganisms when oxygen is not present. During this process, methane gas is created. An anaerobic digester is a man-made system that allows this process to happen more quickly and captures the methane that is released. This gas can be utilized to create heat and power. Learn more how anaerobic digestion is used in energy creation.
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Biodegradable
The ability of a material to be broken down or to decompose by natural processes.
Biodiesel
Biodiesel is a domestically produced, renewable fuel that can be manufactured from vegetable oils, animal fats, or recycled restaurant greases. Biodiesel is cleaner burning, safe, biodegradable, and reduces air pollutants such as particulates, carbon monoxide, hydrocarbons, and air toxics.
Pure, or 100-percent, biodiesel fuel is referred to as B100 or “neat” biodiesel. A biodiesel blend is pure biodiesel blended with petrodiesel. Biodiesel blends are referred to as BXX. The XX indicates the amount of biodiesel in the blend (i.e., a B20 blend is 20 percent biodiesel and 80 percent petrodiesel). All vehicles that run on diesel can be fueled with a small percentage of biodiesel, but the quantity will depend on the engine type.
Biodiversity
A large variety of different species represented in a certain area.
Biofuel
Fuel that is produced from renewable sources.
Biomass
Biomass energy is derived from three distinct energy sources: wood, waste, and alcohol fuels. Wood energy is derived both from direct use of harvested wood as a fuel and from wood waste streams. The largest source of energy from wood is pulping liquor or “black liquor,” a waste product from processes of the pulp, paper and paperboard industry. Waste energy is the second-largest source of biomass energy. The main contributors of waste energy are municipal solid waste (MSW), manufacturing waste, and landfill gas. Many types of crops can be used in the production of alcohol. In the U.S. biomass alcohol fuel, or ethanol, is derived almost exclusively from corn, while Brazil, for example gets 30% of its automotive fuel from ethanol distilled from sugar cane. Its principal use is as an oxygenate in gasoline. Other methods of production are looking at such items as cellulose found in grasses, agricultural wastes, and algae.
Biopower
Biopower, or biomass power, is the use of biomass to generate electricity. Biopower system technologies include direct-firing, cofiring, gasification, pyrolysis, and anaerobic digestion.
Most biopower plants use direct-fired systems. They burn bioenergy feedstocks directly to produce steam. This steam drives a turbine, which turns a generator that converts the power into electricity. In some biomass industries, the spent steam from the power plant is also used for manufacturing processes or to heat buildings. Such combined heat and power systems greatly increase overall energy efficiency. Paper mills, the largest current producers of biomass power, generate electricity or process heat as part of the process for recovering pulping chemicals.
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Concentrating Solar Power
Concentrating solar power (CSP) technologies use mirrors to reflect and concentrate sunlight onto receivers that collect the solar energy and convert it to heat. This thermal energy can then be used to produce electricity via a steam turbine or heat engine driving a generator.
Concentrating solar power technologies can generate electricity at relatively low cost and deliver power during periods of peak demand. In addition, integration with low-cost thermal storage adds significant value to the energy delivered from CSP plants. The public is becoming more familiar with the availability, benefits, and economic feasibility of CSP. And researchers are continuing to discover ways to reduce costs and improve efficiencies. Consequently, many utilities are including concentrating solar power in their power-generation portfolio, helping our nation reduce its dependence on fossil fuels.
CSP is one of four subprograms within the Solar Energy Technologies Program (SETP), along with Photovoltaics, Market Transformation, and Systems Integration. The SETP subprograms focus on accelerating the advancement of solar energy technologies to make solar electricity more cost competitive with conventional forms of electricity. For more informatiom, visit the U.S. Department of Energy website.
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Ecosystem
The interconnectedness of organisms (plants, animals, microbes) with each other and their environment.
Emission Controls
Any measure that limits and reduces the release of emissions.
Emissions
The release of any gas, liquid or solid.
Environmental Footprint
The environmental impact of a company or person, measured by the raw materials and nonrenewable resources or products it wastes.
Environmental Impact
Any change to the environment whether it is harmful or helpful.
Environmentally Preferable Purchasing (EPP)
A federal government program that helps government agencies purchase environmentally friendly products and services and stimulates other companies to “buy green.”
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Fossil Fuel
Any fuel that was created by decomposed plants and animals. Burning fossil fuels create carbon dioxide and are a large contributor to pollution.
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Geothermal Energy
Geothermal energy is defined as heat from the Earth. It is a clean, renewable resource that provides energy in the U.S. and around the world in a variety of applications and resources. Although areas with telltale signs like hot springs are more obvious and are often the first places geothermal resources are used, the heat of the earth is available everywhere, and we are learning to use it in a broader diversity of circumstances. It is considered a renewable resource because the heat emanating from the interior of the Earth is essentially limitless. The heat continuously flowing from the Earth’s interior, which travels primarily by conduction, is estimated to be equivalent to 42 million megawatts (MW) of power, and is expected to remain so for billions of years to come, ensuring an inexhaustible supply of energy.
Gray Water
Any dish, shower, sink, or laundry water that has been used in the home is called gray water and may be reused for other purposes, especially landscape irrigation.
Greenhouse Gas (GHG) Offsets
A greehouse gas (GHG) offset, sometimes referred to as a carbon offset, is a tradable commodity representing a unit of GHG emissions reduction or avoidance. Typically, a GHG offset represents a reduction or avoidance of one metric ton of carbon dioxide equivalent (CO2e). GHG offsets may be purchased by consumers and businesses to “offset” their own emissions, such as those associated with electricity consumption, product manufacturing processes, automobile use, and air travel. GHG offsets can be derived from a variety of project types that reduce or avoid GHG emissions, with diverse methods for measuring these reductions. Examples of GHG reduction projects include renewable electricity generation, energy efficiency measures, methane capture at landfill sites, soil carbon sequestration, and reforestation projects. Developers of these project types can sell GHG offsets to consumers or businesses to help finance their projects.
All of the GHG offset providers and products presented on the Green Power Network are available nationally and derived at least in part from U.S.-based renewable energy generation projects.
Green Design
Incorporates environmental principles, such as durability, efficiency, and renewability, into constructing a building or designing a product.
Green Power
”Green power” refers to electricity generated from renewable energy sources such as wind and solar power, geothermal (steam), various forms of biomass (organic waste), landfill gas and hydroelectric power. While these resources provide an unlimited supply of environmentally friendly energy, they also are more expensive than conventional energy sources such as coal and natural gas.
Green Tags
Tradable commodities which represent that a certain amount of energy (1 megawatt hour) was generated from a renewable energy resource.
Green
A movement incorporating environmental awareness, social responsibility, bioregionalism, and nonviolence.
Hydroelectric Energy obtained from water, usually by damming a river or by using tidal power. ([Click here] to learn more about renewable energy).
Ground-level Ozone
Ground-level ozone is formed by a chemical reaction between volatile organic compounds and oxides of nitrogen in the presence of sunlight. Ozone concentrations can reach unhealthful levels when the weather is hot and sunny with little or no wind. High concentrations of ozone near ground level are harmful to people, animals, crops, and other materials.
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Haze
Haze consists of sufficient smoke, dust, moisture, and vapor suspended in air to impair visibility. The term regional haze means haze that impairs visibility in all directions over a large area.
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Industrial Air Pollution
This term refers to the emissions of the following pollutants: sulfur oxides, nitrogen oxides, mercury, and carbon dioxide. These air emissions contribute to such environmental concerns as urban smog; acid deposition; excessive nutrient loads to important bodies of water, such as the Chesapeake Bay; haze in national parks and wilderness areas; and global climate change.
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(Large) Hydroelectric Power
The process of generating electricity by harnessing the power of moving water is called hydroelectricity. Hydroelectric power (hydropower) is generated by forcing water that is flowing downstream, often from behind a dam, through a hydraulic turbine that is connected to a generator. The water exits the turbine and is returned to the stream or riverbed. Much of the hydroelectricity in the United States is generated at large facilities and in the Pacific Northwest, where it meets about two-thirds of the electricity demand. In the U. S., hydroelectricity contributes about 10 percent of the total electricity supply.
Line Losses
The amount of energy lost during transmission and distribution of electricity, including unaccounted for uses.
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Mercury/Mercury Compounds
Mercury is a toxic heavy metal that is a byproduct of thermo combustion of fossil fuels, especially coal. Mercury and compounds containing mercury can accumulate in the environment and are highly toxic to humans and animals if inhaled or swallowed. Exposure can permanently damage the brain, kidneys, and fetuses.
Methane (CH4)
A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 23 times that of carbon dioxide (CO2). Methane is produced through anaerobic (without oxygen) decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and distribution of natural gas and petroleum, coal production, and incomplete fossil fuel combustion. The global warming potential (GWP) is from the Intergovernmental Panel on Climate Change’s (IPCC’s) Third Assessment Report (TAR).
Municiple Solid Waste
MSW is primarily composed of residential solid waste but also includes some types of non-hazardous commercial, institutional and industrial wastes. MSW can be problematic to discard because of its large volume: one commonly adopted solution is to combust the MSW, which both decreases the volume of material and creates energy that can be recovered in the form of heat or steam. Because some materials have higher heat content than others, the amount of energy that can be produced by combusting MSW is a function of the composition of the waste stream. For example, certain types of plastics have more than three times the heat content of yard trimmings or organic textiles. In general, combustible non-biogenic materials are characterized by higher heat contents per unit weight than combustible biogenic materials. Thus, the ratio of biogenic to non-biogenic material volumes can have a considerable effect on the heat content of the waste stream.
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Natural Gas
Underground deposits of gases consisting of 50 to 90 percent methane (Ch3) and small amounts of heavier gaseous hydrocarbon compounds such as propane (C3H8) and butane (C4H10).
Nitrogen Oxides (NOX)
Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced in the emissions of vehicle exhausts and from power stations. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), can impair visibility, and have health consequences; they are thus considered pollutants
Nonrenewable Resource
A natural resource that can’t be replenished because the rate of formation is slower than the rate of consumption. Fossil fuels, metals, minerals, and groundwater are nonrenewable.
Nuclear Energy
Nuclear energy originates from the splitting of uranium atoms in a process called fission. At the power plant, the fission process is used to generate heat for producing steam, which is used by a turbine to generate electricity. Because nuclear power plants do not burn fuel, they do not emit air pollutant emissions. All of the nuclear power plants in the United States collectively produce about 2,000 metric tons per year of radioactive waste. Abandoned uranium mines contaminated with high-level radioactive waste can continue to pose radioactive risks for as long as 250,000 years after closure. There are more than 60 nuclear power plants currently in operation in the U.S., which accounts for approximately 20 percent of the country’s electricity production. No nuclear power plants have been built since 1996, mostly due to economic factors and environmental concerns.
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Oil
A liquid fossil fuel, is formed from layers of buried plants and animals that have been subjected to geologic heat and pressure over a long period of time. The energy that the plants and animals originally obtained from the sun is stored in the oil in the form of carbon. In addition to carbon, oil contains elements such as nitrogen, sulfur, mercury, lead, and arsenic. Oil is a nonrenewable resource because it cannot be replenished on a human time frame.
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Renewable Energy
Renewable energy resources are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy resources include biomass, hydropower, geothermal, solar, wind, ocean thermal, wave action, and tidal action. In 1850, about 90% of the energy consumed in the United States was from renewable energy resources. Now the United States is heavily reliant on the non-renewable fossil fuels: coal, natural gas, and oil. In 2007, about 6% of all energy consumed and about 9% of total electricity production was from renewable energy resources.
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Small Hydro
In addition to very large hydro plants in the West, the United States has many smaller hydro plants. Like large plants, small-scale hydroelectric systems capture the energy in flowing water and convert it to electricity. Although the potential for small hydroelectric systems depends on the availability of suitable water flow, these systems can provide cheap, clean, reliable electricity where the resource exists.
Smog
Smog is the brownish haze that pollutes our air, particularly over cities in the summertime. Smog can make it difficult for some people to breathe and it greatly reduces how far we can see through the air. The primary component of smog is ozone, a gas that is created when nitrogen oxides react with other chemicals in the atmosphere, especially in strong sunlight
Socially Responsible Investing
Investing money in companies that abide by sustainability guidelines.
Solar Power
The technology that we use to obtain energy from sunlight. ([Click here] to learn more about renewable energy).
Sulfer Dioxide
High concentrations of sulfur dioxide affect breathing and may aggravate existing respiratory and cardiovascular disease. Sensitive populations include asthmatics, individuals with bronchitis or emphysema, children, and the elderly. Sulfur dioxide is also a primary contributor to acid rain, which causes acidification of lakes and streams and can damage trees, crops, historic buildings, and statues. In addition, sulfur compounds in the air contribute to visibility impairment in large parts of the country. This is especially noticeable in national parks. Sulfur dioxide is released primarily from burning fuels that contain sulfur (such as coal, oil, and diesel fuel). Stationary sources such as coal- and oil-fired power plants, steel mills, refineries, pulp and paper mills, and nonferrous smelters are the largest releasers
Sustainability
A characteristic of a process that can be maintained indefinitely.
Sustainable Development
Meeting the needs of the present while planning and growing without compromise to the future environmental state.
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Tidal Power
Power obtained by catching the energy of moving water masses from tides. ([Click here] to learn more about renewable energy).
Total Environmental Impact
The total change on the environment from humans, industry and natural disasters.
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Volatile Organic Compound (VOC)
Organic chemical compounds which vaporize under normal conditions, such as methane. The can damage soil and groundwater and contribute to air pollution.
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Wind Power
Winds are created by uneven heating of the atmosphere by the sun, irregularities of the Earth’s surface, and the rotation of the Earth. As a result, winds are strongly influenced and modified by local terrain, bodies of water, weather patterns, vegetative cover, and other factors. The wind flow, or motion of energy when harvested by wind turbines, can be used to generate electricity. Wind-based electricity generating capacity has increased markedly in the United States since 1970, although it remains a small faction of total electric capacity.
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