A type of (geothermal) heat pump that uses well (ground) or surface water as a heat source. Water has a more stable seasonal temperature than air thus making for a more efficient heat source.

The measure of seasonal or annual efficiency of a heat pump operating in the heating mode. It takes into account the variations in temperature that can occur within a season and is the average number of Btu of heat delivered for every watt-hour of electri ...

A heat storage system that uses a heat storage medium, and where the additional or removal of heat results in a change in temperature.

In a wind energy conversion system, to pitch the turbine blades so as to reduce their lift capacity as a method of shutting down the turbine during high wind speeds.

A group of wind turbines interconnected to a common utility system through a system of transformers, distribution lines, and (usually) one substation. Operation, control, and maintenance functions are often centralized through a network of computerized mo ...

A substance(s) or pollutant emitted as a result of a process.

see Peak Power

The process in which a solid fuel is converted into a gas; also known as pyrolitic distillation or pyrolysis. Production of a clean fuel gas makes a wide variety of power options available.

A raw material that can be converted to one or more products.

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

Solid fuels made from primarily wood sawdust that is compacted under high pressure to form small (about the size of rabbit feed) pellets for use in a pellet stove.

The amount of visible light that passes through the glazing material of a window, expressed as a percentage.

Under the First Law of Thermodynamics, efficiency is the ratio of work or energy output to work or energy input, and cannot exceed 100 percent. Efficiency under the Second Law of Thermodynamics is determined by the ratio of the theoretical minimum energy ...

An air heater in which air is blown over electric resistance heating coils.

Air brought into a building from outside to replace exhaust air.

A federal agency established in 1933 to develop the Tennessee river valley region of the southeastern U.S., and which is now nation's largest power producer.

A device that tracks the movement of the sun; used to orient solar concentrating systems.

A diagram that indicates the average percentage of time that the wind blows from different directions, on a monthly or annual basis.

A thermal storage wall is a south-facing wall that is glazed on the outside. Solar heat strikes the glazing and is absorbed into the wall, which conducts the heat into the room over time. The walls are at least 8 in thick. Generally, the thicker the wall, ...

A curve that indicates the number of hours per year that specific wind speeds occur.