Heat Rate & Thermal Efficiency Calculator
Calculate the heat rate of a power plant or engine based on fuel consumption and power output.
Understanding Heat Rate in Power Generation
In the power generation industry, Heat Rate is a critical performance metric used to measure the efficiency of a power plant or internal combustion engine. It represents the amount of thermal energy required to produce one unit of electrical energy.
What is Heat Rate?
Simply put, the heat rate tells you how much fuel energy you need to burn to get one kilowatt-hour (kWh) of electricity. Because heat rate measures input per unit of output, a lower heat rate indicates a more efficient system. Conversely, a higher heat rate means the system is consuming more fuel to produce the same amount of power.
The Mathematical Formula
The standard formula used in this calculator is:
Heat Rate = (Fuel Flow × Heating Value) / Net Power Output
- Fuel Flow: The mass or volume of fuel consumed per hour.
- Heating Value: The energy content of the fuel (Higher Heating Value or Lower Heating Value).
- Net Power Output: The actual electricity delivered to the grid (after subtracting house loads).
Heat Rate to Efficiency Conversion
To convert heat rate into a percentage (Thermal Efficiency), we compare it to the theoretical energy content of a kilowatt-hour:
| Unit System | Constant Value (1 kWh) | Efficiency Formula |
|---|---|---|
| Metric (kJ) | 3,600 kJ | (3,600 / Heat Rate) × 100 |
| Imperial (BTU) | 3,412.14 BTU | (3,412.14 / Heat Rate) × 100 |
Realistic Example
Imagine a natural gas turbine with the following specs:
- Fuel Flow: 8,000 kg/hr
- Heating Value: 45,000 kJ/kg
- Power Output: 40,000 kW
Calculation: (8,000 × 45,000) / 40,000 = 9,000 kJ/kWh.
Efficiency: (3,600 / 9,000) × 100 = 40% Thermal Efficiency.