Last updated on: 7/29/2009 | Author:


Terms Definitions
Alternative Energy The term “alternative energy” has numerous definitions. On this website “alternative energy” refers to any form of energy that is not derived from fossil fuels (oil, coal, or natural gas). Under this definition nuclear energy is an alternative energy even though it is not considered a renewable energy like solar or wind energy. [To learn more about the terms alternative energy and renewable energy, please visit our webpage titled What are alternative energies?]
Anthropogenic Something made or generated by humans.
Arsenic A semi-metal element that occurs naturally and can cause human health problems including cancer. Arsenic is used in the production of some types of photovoltaic cells.
Baseload Power The amount of electricity that utilities must produce constantly in order to meet the minimum estimated customer needs.
Biodiesel A type of biofuel produced from soybean, canola, palm, or other vegetable oils. It can also be produced from animal fats and recycled grease. Biodiesel is a substitute for conventional diesel fuel made from petroleum.
Bioethanol A type of biofuel produced by converting the starch and sugar from plants into alcohol. Corn and sugarcane are two common plants used to make ethanol. Bioethanol is a substitute for conventional gasoline.
Biomass Organic non-fossil materials, such as wood, peat, grass, etc. that are used as fuel for things such as heating, cooking, electricity generation, or biofuel production.
British Thermal Unit (Btu) An energy measurement unit that represents the amount of energy it takes to raise the temperature of 1 pound of liquid water by 1 degree Fahrenheit at the temperature at which water has its greatest density (approximately 39 degrees Fahrenheit). The Btu allows for comparisons among fuels that are measured in different units.
Cadmium An extremely toxic metal commonly found in industrial workplaces. Cadmium is used in the production cadmium telluride – a component of certain types of photovoltaic cells.
Cadmium Telluride A crystalline compound formed from cadmium and tellurium with a zinc blend. It is used in the production of thin film photovoltaic cells.
Cap and Trade A program that caps greenhouse gas emissions at a certain level and requires utilities or other entities to hold permits, or allowances, for their emissions of greenhouse gases. Because the permits/allowances are tradable, a utility could buy them if it exceeded the emission cap or sell them if it emitted less than the cap allowed.
Carbon Cap An imposed limit on the amount of carbon that any individual industry or business may release into the atmosphere.
Carbon Capture and Storage (CCS) Also known as CO2 sequestration, it is a process whereby CO2 is captured from gases produced by fossil fuel combustion, compressed, transported and injected into underground geologic formations. Research efforts focus on systems for capturing CO2 from coal-fired power plants due to their large CO2 emissions.
Carbon Credit A credit given to an entity (government, industry, carbon-producing business, etc.) that has reduced its carbon emissions to a level below the carbon cap. Credits represent a specific amount of carbon emissions, and they can be bought and sold between entities. For example, an oil refinery that expects to produce more carbon emissions than it is allowed under its cap could buy carbon credits from a steel manufacturer that has reduced its emissions.
Carbon Cycle The movement of carbon through the environment. One example is the release of carbon from a burned fossil fuel; absorption by a plant through photosynthesis; and its reformation into woody plant material.
Carbon Sink A reservoir for carbon, such a forest or ocean, which absorbs carbon from the atmosphere and stores it in the form of plant material. The oceans act as a carbon sink because algae and other ocean plants absorb carbon from the atmosphere.
Catalytic Process A refining process using heat and pressure with catalysts to rearrange certain hydrocarbon molecules and reform them into other substances. The conversion of coal or natural gas into hydrogen is a catalytic process.
Cellulose The primary structural component of green plants. This material can be converted into biofuel through chemical or enzymatic processes.
Cellulosic Ethanol Ethanol made from the cellulosic material of plants rather than the starch or sugar portions. For example, cellulosic ethanol is made from corn stalks and husks, rather than the kernel.
Chlorofluorocarbons (CFCs) A variety of compounds used in refrigeration, air conditioning, packaging, insulation, solvents, and aerosol.
Cogeneration The simultaneous production of heat and power. One example is an electricity generation plant that uses its steam output to provide heat. In Manhattan, cogeneration plants provide both electricity and piped steam for home and business heating needs.
Copper Indium Gallium Selenide A semiconductor material made from copper, indium, gallium, and selenium that is used in the production of certain types of thin film photovoltaic cells.
Copper Indium Diselenide A semiconductor material made from copper, indium, and selenium that is used in the production of certain types of thin film photovoltaic cells.
Crude Oil Unrefined petroleum (oil) containing impurities such as sulfur and various metals.
Distillation The process of using heat to seperate alcohol from water. This process is used to produce ethanol for use as a biofuel.
E85 A fuel composed of 85 percent ethanol and 15 percent gasoline.
Electrolysis A method of separating chemically bound compounds by passing electricity through them. Electrolysis can be used to produce hydrogen fuel by sending electricity through water to split the hydrogen from the oxygen.
Ethanol The form of alcohol found in liquor. It is produced by fermentation of the starches and sugars found in plants.
Fermentation The process by which yeast break down starches and sugars into alcohol and carbon dioxide.
Fossil Fuels Petroleum (oil), coal, and natural gas. Fossil fuels are composed of the decayed fossilized remains of plants and animals.
Halocarbons Any chemical compound containing the element carbon and one or more of the halogens bromine, chlorine, fluorine, or iodine. Halocarbons are considered greenhouse gases that can damage the ozone layer.
Hydrocarbon An organic compound comprised of hydrogen and carbon.
Hydrofluorocarbons An organic compound comprised of hydrogen, fluorine, and carbon. These compounds do not deplete the ozone layer but may be greenhouse gases.
Life Cycle Analysis A technique used to assess the environmental impacts associated with a process by taking into account all relevant material inputs and releases and evaluating their potential environmental impacts.
Light Water Reactor A type of nuclear power plant that is cooled with ordinary water.
Mandate A formal order given by a court or government official or body. Many states in the US have mandated that a certain percentage of energy must come from alternatives to fossil fuels.
Methane An odorless, colorless, flammable gas (CH4). It is the major component of natural gas. The primary source of methane is from underground wells.
Methanol Also known as wood alcohol or rubbing alcohol. It is highly poisonous if consumed. It can be produced synthetically from fossil fuels or from biomass. It is used as an additive in gasoline and bioethanol.
Net Energy Balance The total amount of energy that goes into and comes out of a system. A system has a negative net energy balance if it takes more energy to make a fuel than one gets from the finished product.
Nitrous Oxide A colorless gas, naturally occurring in the atmosphere. It is also produced from industrial and agricultural activities.
Nuclear Fission The process by which atoms are split apart. This process releases energy and is used to produce electricity in nuclear power plants.
Nuclear Reactor Devices that contain and control nuclear reactions (the splitting of atoms). The heat generated in the reactor is used to turn water to steam which is then used to power a turbine and produce electricity.
Oil Shale Any rock that contains large amounts of the hydrocarbon kerogen. A petroleum like substance can be extracted from oil shale through a high heat process called pyrolysis. The processing of oil shale releases significantly more CO2 than the processing of conventional crude oil.
Oxidation The process by which a substance is chemically transformed by exposing it to oxygen. Rust on metal is a common example of oxidation.
Peak Oil The point at which global oil production reaches its maximum output and begins a permanent decline.
Perfluorocarbons A group of chemicals composed of one or two carbon atoms and four to six fluorine atoms. Perfluorocarbons are man made and do not exist in nature. They are emitted as a byproduct of certain industrial processes and have a high global warming potential.
Petroleum Also known as oil. It is a liquid hydrocarbon used for a number of industrial purposes including the production of gasoline.
Photoelectrolysis The process of using light for electrolysis. Hydrogen fuel can be made in a photoelectrochemical cell by using light to create an electric current that is then passed through water to split it into hydrogen and oxygen.
Photovoltaic Cell A device made from a variety of semiconductor materials, such as silicon or cadmium telluride, that converts sunlight directly into electricity.
Radiation Energy (heat) that travels by means of electromagnetic waves. Radiation that is strong enough to break chemical bonds in molecules or remove electrons from atoms is called ionizing radiation. This is the type of radiation produced during the production of nuclear power.
Radiative Forcing The measure of how incoming solar radiation influences and is influenced by changes in the earth’s atmosphere.
Renewable Energy Any form of energy produced from non finite resources. Solar, wind, and biomass are examples of renewable energy.
Renewable Portfolio Standard A policy that requires electricity providers to produce a percentage of their power from renewable energy resources.
Shale Oil A petroleum like substance that can be extracted from oil shale through a high heat process called pyrolysis.
Silicon A material produced from silica that is used as a semiconductor in certain types of photovoltaic cells.
Stratosphere The upper layer of the earth’s atmosphere where the ozone layer is found.
Subsidies A type of financial assistance given by governments to encourage certain activities. The US federal government provides many different subsidies to speed the development and implementation of alternative energy.
Sulfur Dioxide A gas produced when materials containing sulfur, such as coal and crude oil, are burned. Sulfur dioxide mixes with the air to create sulfates which can be harmful to humans and the environment.
Tar Sands Natural sands that contain the hydrocarbon bitumen that can be processed into a liquid petroleum product.
Thermal Energy Heat. Many types of power generation stations use thermal energy to generate electricity. Geothermal plants use the heat of the earth, and solar thermal plants use the heat of the sun, to generate electricity.
Transesterfication A process whereby a base solution and alcohol are added to vegetable or animal oil to initiate a chemical reaction that produces biodiesel fuel.
Troposphere The lowest layer of atmosphere surrounding the earth’s surface. It extends to the upper layer – the stratosphere. The troposphere is where much of the earth’s weather takes place.
Turbine A machine that generates electricity by the turning of a rotary mechanism. Turbines are spun by a fluid stream such as water (as in hydroelectric plants) or steam (as in coal fired plants).