Power Plants  Performance Efficiencies
Power plants heat rates, thermal efficiencies, capacity factors, load factors, economic efficiencies, operational efficiencies and energy efficiencies.
The performance of a power plant can be expressed through some common performance factors:
 heat rate (energy efficiency)
 thermal efficiency
 capacity factor
 load factor
 economic efficiency
 operational efficiency
Heat Rate (Energy Efficiency)
Overall thermal performance or energy efficiency for a power plant for a period can be defined as
φ_{hr} = H / E (1)
where
φ_{hr} = heat rate (Btu/kWh, kJ/kWh)
H = heat supplied to the power plant for a period (Btu, kJ)
E = energy output from the power plant in the period (kWh)
Thermal Efficiency
Thermal efficiency of a power plant can be expressed as
μ_{te} = (100) (3412.75 Btu/kWh) / φ (2)
where
μ_{te} = thermal efficiency (%)
 1 kWh = 3412.75 Btu
Capacity Factor
The capacity factor for a power plant is the ratio between average load and rated load for a period of time and can be expressed as
μ_{cf} = (100) P_{al} / P_{rl} (3)
where
μ_{cf} = capacity factor (%)
P_{al} = average load for the power plant for a period (kW)
P_{rl} = rated capacity for the power plant (kW)
Load Factor
Load factor for a power plant is the ratio between average load and peak load and can be expressed as
μ_{lf} = (100) P_{al} / P_{pl} (4)
where
μ_{l}_{f} = load factor (%)
P_{pl} = peak load for the power plant in the period (kW)
Economic Efficiency
Economic efficiency is the ratio between production costs, including fuel, labor, materials and services, and energy output from the power plant for a period of time. Economic efficiency can be expressed as
φ_{ee} = C / E (5)
where
φ_{ee} = economic efficiency (cents/kW, euro/kW, ...)
C = production costs for a period (cents, euro, ..)
E = energy output from the power plant in the period (kWh)
Operational Efficiency
Operational efficiency is the ratio of the total electricity produced by the plant during a period of time compared to the total potential electricity that could have been produced if the plant operated at 100 percent in the period.
Operational efficiency can be expressed as
μ_{oe} = (100) E / E_{100%} (6)
where
μ_{eo} = operational efficiency (%)
E = energy output from the power plant in the period (kWh)
E_{100%} = potential energy output from the power plant operated at 100% in the period (kWh)
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