Cofiring hydrogen with natural gas in power plants generally has a modest positive effect on efficiency, though the impact can vary depending on the plant type and operating mode.
Efficiency Impact of Hydrogen Cofiring
- Gas Turbine Power Plants: Studies show that cofiring hydrogen with natural gas can improve thermal efficiency in gas turbine power plants. For example, hydrogen cofiring enhanced efficiency by about 1.42% in open-cycle mode and 0.42% in combined-cycle mode at a turbine inlet temperature of 1650 °C using a M501JAC gas turbine. This improvement is due to hydrogen’s higher flame speed and calorific value compared to natural gas.
- Combined Cycle Plants: While efficiency gains are smaller in combined-cycle plants than in open-cycle, hydrogen blending still contributes to efficiency improvements.
- Effect Depends on Hydrogen Percentage: Real-world tests at existing plants show cofiring hydrogen at volumes ranging from 5% to 44% with natural gas. Such blending not only reduces CO2 emissions but can also slightly affect efficiency, though detailed efficiency change numbers vary by report.
- Boiler Efficiency Considerations: For traditional boilers cofiring hydrogen and coal, there may be a slight decrease in boiler efficiency, roughly 1% to 2% for 20% hydrogen co-firing. This is mainly due to changes in combustion characteristics and heat loss dynamics. However, boiler efficiency reductions can be as high as 5% when firing 100% natural gas compared to coal.
- High Efficiency Hydrogen-Compatible Turbines: Some modern hydrogen-ready turbines can run on hydrogen blends with high efficiency. For example, Siemens Energy reports fuel efficiencies up to 93% for combined heat and power plants running on hydrogen-natural gas blends. They also estimate CO2 reductions with increased hydrogen share at stable or improved efficiency levels, e.g., 11-23% CO2 savings with 30-50% hydrogen blends while maintaining high thermal efficiency around 64% or above.
Summary
| Plant Type | Hydrogen Cofiring Ratio | Efficiency Effect | Notes |
|---|---|---|---|
| Gas turbine (open-cycle) | ~up to 44% | Efficiency increase ~1.4% | Higher flame speed and calorific value |
| Combined cycle | up to 20-44% | Efficiency increase ~0.4% | Smaller gain vs open-cycle |
| Boilers (coal/hydrogen) | ~20% | Slight decrease (1-2%) | Due to combustion and heat loss changes |
| Modern turbines (Siemens) | 30-50% | High efficiency (~64-93%), CO2 reduced | Advanced hydrogen-ready turbines |
In conclusion, cofiring hydrogen with natural gas can slightly improve the thermal efficiency of power plants, particularly gas turbines, while also significantly reducing CO2 emissions. The exact efficiency impact depends on the plant technology, cofiring ratio, and combustion conditions. Boilers cofiring hydrogen with coal may see a slight efficiency penalty, while modern hydrogen-adapted turbines maintain high efficiency at high hydrogen blends.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-cofiring-hydrogen-and-natural-gas-affect-the-efficiency-of-power-plants/
