# Power Plants - Performance 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)

## Related Topics

### • Thermodynamics

Thermodynamics of steam and condensate systems.

### • Thermodynamics

Work, heat and energy systems.