Heat Rate & Power Plant Efficiency Calculator
Calculate the thermodynamic efficiency and heat rate of your power generation facility.
kg/h
lb/h
SCF/h (Gas)
kJ/kg
BTU/lb
BTU/SCF
Megawatts (MW)
Kilowatts (kW)
System Performance Analysis
Heat Rate (kJ/kWh)
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Heat Rate (BTU/kWh)
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Thermal Efficiency
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Total Heat Input
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What is Heat Rate in Power Plants?
Heat rate is a standard measure used in the power generation industry to define the efficiency of a power plant. It represents the amount of thermal energy (fuel) required to produce one unit of electrical energy. Essentially, it is the inverse of efficiency: the lower the heat rate, the more efficient the power plant.
The Heat Rate Formula
The fundamental calculation for Heat Rate (HR) is:
Heat Rate = (Total Heat Input per Hour) / (Net Electrical Output)
Depending on the region, heat rate is commonly expressed in BTU/kWh (British Thermal Units per kilowatt-hour) or kJ/kWh (kilojoules per kilowatt-hour).
Thermal Efficiency vs. Heat Rate
Thermal efficiency is the percentage of energy from fuel that is successfully converted into electricity. The relationship is defined by constants based on energy units:
- Efficiency (%) = (3,412.14 / Heat Rate in BTU/kWh) × 100
- Efficiency (%) = (3,600 / Heat Rate in kJ/kWh) × 100
Typical Heat Rate Values by Technology
| Plant Type | Average Heat Rate (BTU/kWh) | Average Efficiency (%) |
|---|---|---|
| Natural Gas Combined Cycle | 6,400 – 7,500 | 45% – 53% |
| Supercritical Coal | 8,500 – 9,500 | 36% – 40% |
| Simple Cycle Gas Turbine | 9,500 – 11,500 | 30% – 36% |
| Older Steam Turbines | 10,500 – 12,500 | 27% – 32% |
Practical Example
Imagine a natural gas power plant consuming 12,000 kg of fuel per hour. The gas has a heating value of 48,000 kJ/kg. The plant produces 60 MW of net power.
- Total Heat Input: 12,000 kg/h × 48,000 kJ/kg = 576,000,000 kJ/h
- Convert Power to kW: 60 MW = 60,000 kW
- Heat Rate: 576,000,000 / 60,000 = 9,600 kJ/kWh
- Efficiency: (3,600 / 9,600) × 100 = 37.5%