Alternative Fuel - A popular term for "non-conventional" transportation fuels made from natural gas (propane, compressed natural gas, methanol, etc.) or biomass materials (ethanol, methanol).

Biodiesel - An alternative fuel that can be made from any fat or vegetable oil. It can be used in any diesel engine with few or no modifications. Although biodiesel does not contain petroleum, it can be blended with diesel at any level or used in its pure form.

Biofuels - Liquid fuels and blending components produced from biomass (plant) feedstocks, used primarily for transportation.

Bioreactor - A landfill where the waste actively decomposes rather being simply buried in a "dry tomb."

Biomass - Any organic (plant or animal) material which is available on a renewable basis, including agricultural crops and agricultural wastes and residues, wood and wood wastes and residues, animal wastes, municipal wastes, and aquatic plants.

Energy Efficiency - Refers to activities that are aimed at reducing the energy used by substituting technically more advanced equipment, typically without affecting the services provided. Examples include high-efficiency appliances, efficient lighting programs, high-efficiency heating, ventilating and air conditioning (HVAC) systems or control modifications, efficient building design, advanced electric motor drives, and heat recovery systems.

Ethanol - A colorless liquid that burns to produce water and carbon dioxide. The vapor forms an explosive mixture with air and may be used as a fuel in internal combustion engines.

Flat-Plate Solar Connector - A device designed to capture the suns energy and produce low temperature heat energy. They are commonly used as collectors in solar heating systems.

Generator - A device that turns mechanical energy into electrical energy. The mechanical energy is sometimes provided by an engine or turbine.

Geothermal Energy - The heat energy that is produced by natural processes inside the earth. It can be taken from hot springs, reservoirs of hot water deep below the ground, or by breaking open the rock itself.

Global Warming - An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is today most often used to refer to the warming some scientists predict will occur as a result of increased anthropogenic emissions of greenhouse gases.

Greenhouse Effect - The effect of the Earth's atmosphere, due to certain gases, in trapping heat from the sun; the atmosphere acts like a greenhouse.

Greenhouse Emissions - Waste gases given off by industrial and power plants, automobiles and other processes.

Green Pricing - In the case of renewable electricity, green pricing represents a market solution to the various problems associated with regulatory valuation of the nonmarket benefits of renewables. Green pricing programs allow electricity customers to express their willingness to pay for renewable energy development through direct payments on their monthly utility bills.

Heat Exchanger - Any device that transfers heat from one fluid (liquid or gas) to another or to the environment.

Heliostat - Flat sun-tracking mirrors used to reflect and concentrate the suns' energy onto a central receiver tower.

Hydroelectric Power Plant - A power plant that uses moving water to power a turbine generator to produce electricity.

Hydrogen - A colorless, odorless, highly flammable gaseous element. It is the lightest of all gases and the most abundant element in the universe, occurring chiefly in combination with oxygen in water and also in acids, bases, alcohols, petroleum, and other hydrocarbons.

Hydropower - Energy that comes from moving water. Liquefied Petroleum Gas (LPG) -A group of hydrocarbon-based gases derived from crude oil refining or natural gas fractionation. They include ethane, ethylene, propane, propylene, normal butane, butylene, isobutane, and isobutylene. For convenience of transportation, these gases are liquefied through pressurization.

Methane -A colorless, flammable, odorless hydrocarbon gas (CH4) which is the major component of natural gas. It is also an important source of hydrogen in various industrial processes. Methane is a greenhouse gas.

Municipal Solid Waste (MSW) - Residential solid waste and some nonhazardous commercial, institutional, and industrial wastes. Nonrenewable - Fuels that cannot be easily made or "renewed." We can use up nonrenewable fuels. Oil, natural gas, and coal are nonrenewable fuels.

Organic Waste - Waste material of animal or plant origin.

Parabolic Trough - A type of solar concentrator collector that has a linear parabolic shaped reflector that focuses the sun's radiation on a receiver at the focus of the reflector.

Passive Heating System - A means of capturing, storing, and using heat from the sun.

Peak Load Plant - A plant usually housing old, low-efficiency steam units, gas turbines, diesels, or pumped-storage hydroelectric equipment normally used during the peak-load periods.

Penstock - A large pipe which carries moving water from the reservoir to a turbine generator in a hydropower plant.

Petrochemicals - Organic and inorganic petroleum compounds and mixtures that include but are not limited to organic chemicals, cyclic intermediates, plastics and resins, synthetic fibers, elastomers, organic dyes, organic pigments, detergents, surface active agents, carbon black, and ammonia.

Photovoltaic Cells - A device, usually made from silicon, which converts some of the energy from light (radiant energy) into electrical energy. Another name for a solar cell.

Prime Mover - The engine, turbine, water wheel, or similar machine that drives an electric generator; or, for reporting purposes, a device that converts energy to electricity directly (i.e. photovoltaic solar and fuel cells).

Receiver Panel (Solar) - A panel that contains a battery of solar cells.

Recycling - The process of converting materials that are no longer useful as designed or intended into a new product.

Renewable Energy Sources - Fuels that can be easily made or "renewed." We can never use up renewable fuels. Types of renewable fuels are hydropower (water), solar, wind, geothermal, and biomass.

Semiconductor - Any material that has a limited capacity for conducting an electric current. Semiconductors are crystalline solids, such as silicon, that have an electrical conductivity between that of a conductor and an insulator.

Solar Cell - An electric cell which changes radiant energy from the sun into electrical energy by the photovoltaic process.

Solar Dish - A device that receives radiation collected by motorized collectors which track the sun. The collectors focus the radiation the energy at a focal point of the dish.

Solar Energy - The radiant energy of the sun, which can be converted into other forms of energy, such as heat or electricity.

Solar Power Tower - The conceptual method of producing electrical energy from solar rays. It involved the focusing of a large number of solar rays on a single source (boiler), usually located on an elevated tower, to produce high temperatures. A fluid located in or passed through the source changes into steam and used in a turbine generator to produce electrical energy. Solar spectrum - The total distribution of electromagnetic radiation emanating from the sun.

Solar Thermal Heating System - Systems using concentrating collectors to focus the sun's radiant energy onto or into receivers to produce heat.

Steam - Water in vapor form; used as the working fluid in steam turbines and heating systems.

Steam Generator - A generator in which the prime movers (turbines) are powered by steam.

Transmission (Electric) - The movement or transfer of electric energy over an interconnected group of lines and associated equipment between points of supply and points at which it is transformed for delivery to consumers or is delivered to other electric systems. Transmission is considered to end when the energy is transformed for distribution to the consumer.

Transmission Line - A set of conductors, insulators, supporting structures, and associated equipment used to move large quantities of power at high voltage, usually over long distances between a generating or receiving point and major substations or delivery points.

Transmission System (Electric) - An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers or is delivered to other electric systems.

Turbine - A device with blades, which is turned by a force, e.g. that of wind, water , or high pressure steam. The mechanical energy of the spinning turbine is converted into electricity by a generator.

Transportation Sector (of the Economy) - The part of the economy having to do with the how people and goods are transported (moved) from place to place.. The transportation sector is made up of automobiles, airplanes, trucks, and ships. trains, etc.

Utility Generation - Generation by electric systems engaged in selling electric energy to the public.

Waste - Municipal solid waste, landfill gas, methane, digester gas, liquid acetonitrile waste, tall oil, waste alcohol, medical waste, paper pellets, sludge waste, solid byproducts, tires, agricultural byproducts, closed loop biomass, fish oil, and straw.

Waste Energy - Municipal solid waste, landfill gas, methane, digester gas, liquid acetonitrile waste, tall oil, waste alcohol, medical waste, paper pellets, sludge waste, solid byproducts, tires, agricultural byproducts, closed loop biomass, fish oil, and straw used as fuel.

Water Cycle - Water constantly moves through a vast global cycle, in which it evaporates from lakes and oceans, forms clouds, precipitates as rain or snow, then flows back to the ocean. The energy of this water cycle, which is driven by the sun, is tapped most efficiently with hydropower.

Water Turbine - A turbine that uses water pressure to rotate its blades. Primarily used to power an electric generator.

Wind - The term given to any natural movement of air in the atmosphere. A renewable source of energy used to turn turbines to generate electricity.

Wind Machine - Devices powered by the wind that produce mechanical or electrical power.

Wind Tower - Devices, some as tall as 120 feet, which lift wind turbine blades high above the ground to catch stronger wind currents.

Wood and Waste (as used at electric utilities) - Wood energy, garbage, bagasse (sugarcane residue), sewerage gas, and other industrial, agricultural, and urban refuse used to generate electricity for distribution.

Wood Energy - Wood and wood products used as fuel, including round wood (cord wood), limb wood, wood chips, bark, sawdust, forest residues, charcoal, pulp waste, and spent pulping liquor. 

Source:Energy Information Administration