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.
Liquid fuels and blending components produced from biomass (plant) feedstocks, used primarily for transportation.
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.
A medium Btu gas containing methane and carbon dioxide, resulting from the action of microorganisms on organic materials such as a landfill.
Organic non-fossil material of biological origin that is a byproduct or a discarded product. Biomass waste includes municipal solid waste from biogenic sources.
British thermal unit (Btu)*:
The quantity of heat required 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).
A colorless, odorless noncombustible gas with the formula CO2 that is present in the atmosphere. It is formed by the combustion of carbon and carbon compounds (such as fossil fuels and biomass) and by respiration, which is a slow combustion in animals and plants, and by the gradual oxidation of organic matter in the soil.
Refers to the un-encapsulated semi-conductor components of the module that convert the solar energy to electricity.
A term used to refer to all forms of climatic inconsistency, but especially to significant change from one prevailing climatic condition to another. In some cases, "climate change" has been used synonymously with the term "global warming"; scientists, however, tend to use the term in a wider sense inclusive of natural changes in climate, including climatic cooling.
A fossil fuel formed by the breakdown of vegetable material trapped underground without access to air.
The production of electrical energy and another form of useful energy (such as heat of steam) through the sequential use of energy.
An electric generating technology in which electricity is produced from otherwise lost waste heat exiting from one or more gas (combustion) turbines. The exiting heat is routed to a conventional boiler or to a heat recovery steam generator for utilization by a steam turbine in the production of electricity. This process increases the efficiency of the electric generating unit.
Concentrating solar power or solar thermal power system*:
A solar energy conversion system characterized by the optical concentration of solar rays through an arrangement of mirrors to generate a high temperature working fluid. Concentrating solar power (but not Solar thermal power) may also refer to a system that focuses solar rays on aphotovoltaic cell to increase conversion efficiency.
Conventional hydroelectric plant*:
A plant in which all of the power is produced from natural streamflow as regulated by available storage.
A pv cell made of either a single crystalline or poly crystalline structure which have a controlled direction of structure.
A fuel composed of distillates obtained in petroleum refining operation or blends of such distillates with residual oil used in motor vehicles. The boiling point and specific gravity are higher for diesel fuels than for gasoline.
This is the ratio of power put in verses power outputted. Usually shown as a percentage.
The amount of energy produced per second. The power produced by an electric current.
The system of power distribution from power generating plants to the customers. Usually operated by a public utility.
A form of energy characterized by the presence and motion of elementary charged particles generated by friction, induction, or chemical change.
The process of producing electric energy or the amount of electric energy produced by transforming other forms of energy, commonly expressed in kilowatthours (kWh) or megawatthours (MWh).
A discharge or something that is given off; generally used in regard to discharges into the air. Or, releases of gases to the atmosphere from some type of human activity (cooking, driving a car, etc). In the context of global climate change, they consist of greenhouse gases (e.g., the release of carbon dioxide during fuel combustion).
The ability to do work or the ability to move an object. Electrical energy is usually measured in kilowatthours (kWh), while heat energy is usually measured in British thermal units (Btu).
The use of energy as a source of heat or power or as a raw material input to a manufacturing process.
Agricultural crops grown specifically for their energy value.
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.
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.
Benefits or costs, generated as a byproduct of an economic activity, that do not accrue to the parties involved in the activity. Environmental externalities are benefits or costs that manifest themselves through changes in the physical or biological environment.
The biomass used in the creation of a particular biofuel (e.g., corn or sugarcane for ethanol, soybeans or rapeseed for biodiesel).
Fossil fuel plant*:
A plant using coal, petroleum, or gas as its source of energy.
An energy source formed in the Earth's crust from decayed organic material. The common fossil fuels are petroleum, coal, and natural gas.
Any material that can be burned to make energy.
(1) A non-solid, non-liquid (as hydrogen or air) substance that has no fixed shape and tends to expand without limit. (2) A state of matter in which the matter concerned occupies the whole of its container irrespective of its quantity. Includes natural gas, coke-oven gas, blast furnace gas, and refinery gas.
Gas to liquids (GTL):
A process that combines the carbon and hydrogen elements in natural gas molecules to make synthetic liquid petroleum products, such as diesel fuel.
Gas turbine plant*:
A plant in which the prime mover is a gas turbine. A gas turbine consists typically of an axial-flow air compressor and one or more combustion chambers where liquid or gaseous fuel is burned and the hot gases are passed to the turbine and where the hot gases expand drive the generator and are then used to run the compressor.
A chemical or heat process used to convert carbonaceous material -- coal, petroleum, biomass -- into its gaseous components, carbon monoxide and hydrogen.
A complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, blended to form a fuel suitable for use in spark-ignition engines.
The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in kilowatthours.
Hot water or steam extracted from geothermal reservoirs in the earth's crust. Water or steam extracted from geothermal reservoirs can be used for geothermal heat pumps, water heating, or electricity generation.
One billion watts or one thousand megawatts.
One billion watthours.
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.
The result of water vapor, carbon dioxide, and other atmospheric gases trapping radiant (infrared) energy, thereby keeping the earth's surface warmer than it would otherwise be. Greenhouse gases within the lower levels of the atmosphere trap this radiation, which would otherwise escape into space, and subsequent re-radiation of some of this energy back to the Earth maintains higher surface temperatures than would occur if the gases were absent.
Waste gases given off by industrial and power plants, automobiles and other processes.
Gases that trap the heat of the sun in the Earth's atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapor and carbon dioxide. Lesser greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrogen oxides.
The layout of an electrical distribution system.
The point at which alternative means of generating electricity is equal in cost, or cheaper than grid power.
Any device that transfers heat from one fluid (liquid or gas) to another or to the environment.
Flat sun-tracking mirrors used to reflect and concentrate the suns' energy onto a central receiver tower.
A power generating system that has more than one power source such as: photovoltaic, wind or hydro.
Hydroelectric power plant*:
A power plant that uses moving water to power a turbine generator to produce electricity.
The use of flowing water to produce electrical energy.
Energy that comes from moving water.
Sunlight, either direct or reflected which is usually measured in watts per square meter.
A unit of power, usually used for electric power or to energy consumption (use). A kilowatt equals 1000 watts. See our brief section on Measuring Electricity and our Energy Calculator.
A measure of electricity defined as a unit of work or energy, measured as 1 kilowatt (1,000watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu.
The energy of a body which results from its motion.
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.
One million watts of electricity.
One thousand kilowatt-hours or 1million watt-hours.
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.
Particles that normally consist of two or more atoms joined together. An example is a water molecule that is made up of two hydrogen atoms and one oxygen atom.
An odorless, colorless, tasteless, non-toxic clean-burning fossil fuel. It is usually found in fossil fuel deposits and used as a fuel.
Natural gas hydrates*:
Solid, crystalline, wax-like substances composed of water, methane, and usually a small amount of other gases, with the gases being trapped in the interstices of a water-ice lattice. They form beneath permafrost and on the ocean floor under conditions of moderately high pressure and at temperatures near the freezing point of water.
Nuclear electric power (nuclear power)*:
Electricity generated by the use of the thermal energy released from the fission of nuclear fuel in a reactor.
Energy that comes from splitting atoms of radioactive materials, such as uranium.
The raw material that petroleum products are made from. A black liquid fossil fuel found deep in the Earth. Gasoline and most plastics are made from oil.
One axis tracking:
A pv system where the modules track the sun from East to West and return to East in the morning.
Aiming the pv module(s) to a compass heading, usually to true South in the Northern Hemisphere.
A high-temperature solar thermal concentrator, generally bowl-shaped, with two-axis tracking.
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.
Peak load /peak demand:
The most power consumed at a given moment in the day.
Peak sun hours:
The number of hours in the day when solar irradiance (or insolation) averages 1000 watts per square meter - also known as full sun.
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.
Generally refers to crude oil or the refined products obtained from the processing of crude oil (gasoline, diesel fuel, heating oil, etc.) Petroleum also includes lease condensate, unfinished oils, and natural gas plant liquids.
A particle of light that acts as an individual unit of energy.
The process by which green plants make food (carbohydrates) from water and carbon dioxide, using the energy in sunlight.
An electronic device consisting of layers of semiconductor materials fabricated to form a junction (adjacent layers of materials with different electroniccharacteristics) and electrical contacts and being capable of converting incident light directly into electricity (direct current).
The process by which radiant (light) energy is changed into electrical energy.
An integrated assembly of interconnected photovoltaic cells designed to deliver a selected level of working voltage and current at its output terminals, packaged for protection against environmental degradation, and suited for incorporation in photovoltaic power systems.
Photovoltaic cells that have semi-random orientation of the structure. They look like broken sheets.
The loss of power when electricity is sent over long distances.
A facility where power, especially electricity, is generated.
The rate of producing, transferring, or using energy, most commonly associated with electricity. Power is measured inwatts and often expressed in kilowatts (kW) or megawatts (mW). Also known as "real" or "active" power.
The percentage of the total energy content of a power plant’s fuel which is converted into electric energy. The remaining energy is lost to the environment as heat.
Any form of energy radiating from a source in waves.
Any high-speed transmission of energy in the form of particles or electromagnetic waves.
The process of converting materials that are no longer useful as designed or intended into a new product.
Refined petroleum products*:
Refined petroleum products include but are not limited to gasoline, kerosene, distillates (including No. 2 fuel oil), liquefied petroleum gas, asphalt, lubricating oils, diesel fuels, and residual fuels.
An industrial plant that heats crude oil (petroleum) so that is separates into chemical components, which are then made into more useful substances.
Renewable energy resources*:
Energy resources that are naturally replenishing but flow-limited. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy resources include biomass, hydro, geothermal, solar, wind, ocean thermal, wave action, and tidal action.
The primary material in most photovoltaic modules. Commonly found in sand and quartz.
An electric cell which changes radiant energy from the sun into electrical energy by the photovoltaic process.
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.
The radiant energy of the sun, which can be converted into other forms of energy, such as heat or electricity.
Solar power tower*:
A solar energy conversion system that uses a large field of independently adjustable mirrors (heliostats) to focus solar rays on a near single point at the top of a fixed tower (receiver). The concentrated energy may be used to directly heat the working fluid of a Rankine cycle engine or to heat an intermediary thermal storage medium (such as a molten salt).
A general term for the visible and near visible (ultraviolet and near-infrared) electromagnetic radiation that is emitted by the sun. It has a spectral, or wavelength,distribution that corresponds to different energy levels; short wavelength radiation has a higher energy than long-wavelength radiation.
The total distribution of electromagnetic radiation emanating from the sun.
Solar thermal collector*:
A device designed to receive solar radiation and convert it to thermal energy. Normally, a solar thermal collector includes a frame, glazing, and an absorber, together with appropriate insulation. The heat collected by the solar collector may be used immediately or stored for later use. Solar collectors are used for space heating; domestic hot water heating; and heating swimming pools, hot tubs, or spas.
Solar thermal heating system*:
Systems using concentrating collectors to focus the sun's radiant energy onto or into receivers to produce heat.
Solar thermal parabolic dishes*:
A solar thermal technology that uses a modular mirror system that approximates aparabol a and incorporates two-axis tracking to focus the sunlight onto receivers located at the focal point of each dish. The primary applications include remote electrification, waterpumping, and grid-connected generation.
Water in vapor form; used as the working fluid in steam turbines and heating systems.
A generator in which the prime movers (turbines) are powered by steam.
Temperature coefficient (of a solar photovoltaic cell)*:
The amount that the voltage, current, and/or power output of a solar cell changes due to a change in the cell temperature.
A non-crystaline semiconductor material that is used in "thin-film" photovoltaic modules such as those made by Uni-Solar and some of the earlier Solarex modules.
The chemical process in which an alcohol reacts with the triglycerides in vegetable oil or animal fats, separating the glycerin and producing biodiesel.
An electromagnetic device which steps up or steps down an alternating current.
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.
High-temperature concentrator with one axis-tracking.
A machine for generating rotary mechanical power from the energy of a stream of fluid (such as water, steam, or hot gas). Turbines convert the kinetic energy of fluids to mechanical energy through the principles of impulse and reaction, or a mixture of the two.
Variable-speed wind turbines*:
Turbines in which the rotor speed increases and decreases with changing wind speed, producing electricity with a variable frequency.
Vertical-axis wind turbine*:
A type of wind turbine in which the axis of rotation is perpendicular to the windstream and the ground.
The volt is the International System of Units (SI) measure of electric potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance. Reduced to SI base units, 1 V = 1 kg times m2 times s-3 times A-1 (kilogram meter squared per second cubed per ampere).
The difference in electrical potential between any two conductors or between a conductor and ground. It is a measure of the electric energy per electron that electrons can acquire and/or give up as they move between the two conductors.
A thin sheet of semiconductor (photovoltaic material) made by cutting it from a single crystal or ingot.
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.
The unit of electrical power equal to one ampere under a pressure of one volt. A Watt is equal to 1/746 horse power.
The electrical energy unit of measure equal to one watt of power supplied to, or taken from, an electric circuit steadily for one hour.
The distance, measured in the direction of progression of a wave, from any given point to the next point in the same phase.
The term given to any natural movement of air in the atmosphere. A renewable source of energy used to turn turbines to generate electricity.
Kinetic energy present in wind motion that can be converted to mechanical energy for driving pumps, mills, and electric power generators.
Devices which lift wind turbine blades high above the ground to catch stronger wind currents.
Saw dust compressed into uniform diameter pellets to be burned in a heating stove.