| A | B |
|---|
| active solar heating system | System that uses solar collectors to capture energy from the sun and store it as heat for space heating and water heating. Liquid or air pumped through the collectors transfers the captured heat to a storage system such as an insulated water tank or rock bed. Pumps or fans then distribute the stored heat or hot water throughout a dwelling as needed. |
| biofuel | Gas or liquid fuel (such as ethyl alcohol) made from plant material (biomass).
cogeneration Production of two useful forms of energy, such as high-temperature heat or steam and electricity, from the same fuel source. |
| CHP | combined heat and power |
| energy conservation | Reducing or eliminating the unnecessary waste of energy. |
| energy efficiency | Percentage of the total energy input that does useful work and is not converted into low-quality, usually useless heat in an energy conversion system or process. |
| geothermal energy | Heat transferred from the earth's underground concentrations of dry steam (steam with no water droplets), wet steam (a mixture of steam and water droplets), or hot water trapped in fractured or porous rock. |
| hydroelectric power plant | Structure in which the energy of falling or flowing water spins a turbine generator to produce electricity. |
| hydropower | Electrical energy produced by falling or flowing water. |
| kilowatt (kW) | Unit of electrical power equal to 1,000 watts. |
| life-cycle cost | Initial cost plus lifetime operating costs of an economic good. |
| micropower systems | Systems of small-scale decentralized units that generate 1[[endash]]10,000 kilowatts of electricity. Examples include microturbines, fuel cells, and household solar panels and solar roofs. |
| passive solar heating system | System that captures sunlight directly within a structure and converts it into low-temperature heat for space heating or for heating water for domestic use without the use of mechanical devices. |
| photovoltaic cell (solar cell) | Device that converts radiant (solar) energy directly into electrical energy. |
| solar collector | Device for collecting radiant energy from the sun and converting it into heat. See active solar heating system, passive solar heating system. |
| superinsulated house | House that is heavily insulated and extremely airtight. Typically, active or passive solar collectors are used to heat water, and an air-to-air heat exchanger is used to prevent buildup of excessive moisture and indoor air pollutants. |
| watt | Unit of power, or rate at which electrical work is done. |
| wind farm | Cluster of small to medium-sized wind turbines in a windy area to capture wind energy and convert it into electrical energy. |
