A system in which a working fluid is used over and over without introduction of new fluid, as in a hydronic heating system or mechanical refrigeration system.

The number of cycles through which an alternating current passes per second; in the U.S. the standard for electricity generation is 60 cycles per second (60 Hertz).

Water heated for residential washing, bathing, etc.

The lowest wind speed at which a wind turbine begins producing useable power.

The push or pull that alters the motion of a moving body or moves a stationairy body; the unit of force is the dyne or poundal; force is equal to mass time velocity divided by time.

The process of converting municipal solid waste to energy and/or recovering materials for recycling.

The device in an air conditioner or heat pump in which the refrigerant condenses from a gas to a liquid when it is depressurized or cooled.

One millionth of a meter (10-6 m).

A term for the process of transmitting electricity over transmission lines not owned by the supplier of the electricity to a retail customer of the supplier. With retail wheeling, an electricity consumer can secure their own supply of electricity from a b ...

The amount of conditioned air to be supplied by a cooling system; usually the maximum amount to be delivered based on a specified number of cooling degree days or design temperature.

A heat exchanger in a solar water heating system that has two distinct walls between the heat transfer fluid and the domestic water, to ensure that there is no mixing of the two.

In reference to solar photovoltaic cell manufacure, a method of growing a large-size, high-quality crystal whereby coils heat a polycrystalline ingot placed atop a single-crystal seed. As the coils are slowly raised the molten interface beneath the coils ...

A power plant that produces electricity by the force of water falling through a hydro turbine that spins a generator.

Pounds/force per square inch gauge.

An energy band in a semiconductor in which electrons can move freely in a solid, producing a net transport of charge.

A type of combustion heating system in which combustion air is drawn directly from outside and the products of combustion are vented directly outside. These features are beneficial in tight, energy-efficient homes because they will not depressurize a home ...

A particle of light that acts as an individual unit of energy.

A method of depositing thin semiconductor photovoltaic) films. With this method, physical processes, such as thermal evaporation or bombardment of ions, are used to deposit elemental semiconductor material on a substrate.

Any wholly or partially enclosed space in which combustion takes place.

The relative extent that energy is required for a process.