The first law states that energy can not be created or destroyed; the second law states that when a free exchange of heat occurs between two materials, the heat always moves from the warmer to the cooler material.

An electrochemical battery that uses lead and lead oxide for electrodes and sulfuric acid for the electrolyte.

In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into contact with the wind.

A measure of air purity that is equal to one complete air change (in an interior space).

A total life cycle cost divided into equal amounts.

The sum of all the costs both recurring and nonrecurring, related to a product, structure, system, or service during its life span or specified time period.

The force that pulls a wind turbine blade, as opposed to drag.

A description of how well people in a lighted space can see to do visual tasks and how visually comfortable they feel in that space.

The trapping of light inside a semiconductor material by refracting and reflecting the light at critical angles; trapped light will travel further in the material, greatly increasing the probability of absorption and hence of producing charge carriers.

Defects, such as dangling bonds, induced in an amorphous silicon semiconductor upon initial exposure to light.

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

A solar heating system that uses a liquid as the heat transfer fluid.

A heat exchanger that transfers the heat contained in a liquid heat transfer fluid to air.

A heat exchanger that transfers heat contained in a liquid heat transfer fluid to another liquid.

A battery that uses lithium in the negative electrode and a metal sulfide in the positive electrode, and the electrolyte is molten salt; can store large amounts of energy per unit weight.

Steam available directly from a boiler under full pressure.

The demand on an energy producing system; the energy consumption or requirement of a piece or group of equipment.

A curve that displays load values on the horizontal axis in descending order of magnitude against the percent of time (on the vertical axis) that the load values are exceeded.

The ratio of average energy demand (load) to maximum demand (peak load) during a specific period.

An estimate of power demand at some future period.