Glossary G to L


Generation (Electricity) - Process of producing electric energy by transforming other forms of energy.

Generator - Machine used to convert mechanical energy into electrical energy.

Gigawatt (GW) - The unit of electrical power equal to one thousand-million watts, or one thousand megawatts.

Grid - Matrix of an electrical distribution system, the National Grid in the UK.


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Installed capacity - The total generating units' capacities in a power plant or on a total utility system. The capacity can be based on the nameplate rating or the declared net (dependable) capacity (DNC).

Intermittent resources - Resources whose output depends on some other factor that cannot be controlled by the utility e.g. wind or sun. Thus, the capacity varies by day and by hour.


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Kilowatt (kW) - The electrical unit of power equal to 1,000 watts.

Kilowatt-hour (kWh) - The basic unit of electric energy equal to one kilowatt of power supplied to or taken from an electric circuit for one hour.


Load - The amount of electric power delivered or required at any specified point or points on a system. Load originates primarily at the power consuming equipment of the customer.

Load factor - The ratio of the average load supplied to the peak or maximum load during a designated period. Similar to capacity factor, but more often used when describing conventional plant.

Losses - The general term applied to energy (kWh) and capacity (kW) lost in the operation of an electric system. Losses occur principally as energy transformations from kWh to waste-heat in electrical conductors and apparatus.