ELECTRICITY AND POWER DEFINITION

Heat rate
A form of expressing efficiency of an engine or turbine. The fuel heating value consumed per unit of useful output (usually electrical output). Common unit is kJ/kWh. To convert to efficiency divide by 3600 and invert.

Heat Rate (Generated) (kJ/kWh)
Quantity fuel (kg) * higher heating value of fuel consumed (kJ/kg) divided by:
Total energy generated (kWh)
Heat Rate (gen) is related to Efficiency (gen) by:
Heat Rate (gen) (kJ/kWh) = 3600 * 100 divided by:/ Efficiency (gen) (%)

Heat Rate (Sent Out) (kJ/kWh)
Quantity fuel (kg) * higher heating value of fuel consumed (kJ/kg) divided by:/ Total energy generated (kWh) - Total auxiliary energy (kWh)
Heat Rate (s/o) is related to Efficiency (s/o) by
Heat Rate (s/o) (kJ/kWh) = 3600 * 100 ./ Efficiency (s/o) (%)

Heat Recovery Steam Generator
A boiler that uses waste heat (such as gas turbine or reciprocating engine exhaust gas) to produce steam or hot water.

Higher Heating Value (HHV)
The amount of heat recovered when the products of complete combustion of a unit quantity of a fuel are cooled to the initial temperature of the air and fuel (kJ/kg).
For Natural Gas, the relationship between Higher Heating Value (HHV) and Lower Heating Value (LHV) is (approximately):
HHV = 1.1 * LHV

Industrial gas turbine
Heavier, more robust, and cheaper than aeroderivative gas turbines. Generally have lower thermal efficiency and higher exhaust gas temperatures than aeroderivative gas turbines.

Isentropic
Constant entropy, or effectively zero loss. Used in the context of steam turbine ability to convert steam energy into mechanical energy, as opposed to leaving the turbine as exhaust steam energy at the exhaust steam pressure.

ISO conditions
Ambient conditions stated in the ISO Standard 2314 = 15°C, 0 metres ASL, (i.e. at average sea level) and 60% Relative Humidity (RH).

Load factor (%)
(Also called Output Factor) - total energy produced for a specified period relative to the total possible amount of energy that could have been produced for the operating hours during the same period. It can be thought of as the load (% MCR) that would have produced the same total energy over the same operating hours.
Total energy generated during the period (MWH) * 100
Total installed capacity (MW) * operating hours

Lower Heating Value (LHV)
The amount of heat recovered when the products of complete combustion of a unit quantity of a fuel are cooled to just above the dew point of the water vapour it contains (kJ/kg).
For Natural Gas, the relationship between Lower Heating Value (LHV) and Higher Heating Value (HHV) is (approximately):
LHV = HHV/1.1