Air that is returned from a heated or cooled space, reconditioned and/or cleaned, and returned to the space.

The component of a central receiver solar thermal system where reflected solar energy is absorbed and converted to thermal energy.

An electromagnetic device that changes the voltage of alternating current electricity. It consists of an induction coil having a primary and secondary winding and a closed iron core.

Parasitic resistance to current flow in a cell due to mechanisms such as resistance from the bulk of the semiconductor material, metallic contacts, and interconnections.

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

Caulking and weatherstripping to reduce air infiltration and exfiltration into/out of a building.

A tank used in a closed-loop solar heating system that provides space for the expansion of the heat transfer fluid in the pressurized collector loop.

An electrical generator that runs at a constant speed and draws its excitation from a power source external or independent of the load or transmission network it is supplying.

A mechanism used by electric utilities to determine prices for electricity; typically defines rates according to amounts of power demanded/consumed during specific time periods.

A clear, colorless, very mobile liquid that is flammable and poisonous; used as a fuel and fuel additive, and to produce chemicals.

The shape of the phase power at a certain frequency and amplitude.

A chemical compound produced in a reaction between ethanol and isobutylene (a petroleum-derived by-product of the refining process). ETBE has characteristics superior to other ethers: low volatility, low water solubility, high octane value, and a large re ...

Electrical energy lost due to inherent inefficiencies in an electrical transmission and distribution system under specific conditions.

The pressure equivalent of the velocity of a fluid.

A window glass that has been coated with a reflective film and is useful in controlling solar heat gain during the summer.

For a wind turbine, the ratio of the speed of the tip of a turbine blade for which the power coefficient is at maximum.

A wall with high thermal mass used to store solar energy passively in a solar home. The wall absorbs solar energy and transfers it to the space behind the wall by means of radiation and by convection currents moving through spaces under, in front of, and ...

A heat engine of the reciprocating (piston) where the working gas and a heat source are independent. The working gas is compressed in one region of the engine and transferred to another region where it is expanded. The expanded gas is then returned to the ...

A device used to remove particulate matter from the waste gasses of a combustion power plant.

One horsepower provided over one hour; equal to 0.745 kilowatt-hour or 2,545 Btu.