Factors Affecting Power Plant Economic Efficiency

The economic efficiency of a power plant can be expressed through some common performance factors:
heat rate (energy efficiency)
thermal efficiency
capacity factor
load factor
operational efficiency

Heat Rate (Energy Efficiency)

Overall thermal performance or energy efficiency for a power plant for a period can be defined as
φhr = H / E
φhr = 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
μte = (100) (3412.75 Btu/kWh) / φ
μte = 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
μcf = (100) Pal / Prl
μcf = capacity factor (%)
Pal = average load for the power plant for a period (kW)
Prl = 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
μlf = (100) Pal / Ppl
μlf = load factor (%)
Ppl = peak load for the power plant in the period (kW)

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
μoe = (100) E / E100%
μeo = operational efficiency (%)
E = energy output from the power plant in the period (kWh)
E100% = potential energy output from the power plant operated at 100% in the period (kWh).