Enhancing Thermal Power Plant Flexibility to Accommodate Renewable Energy

Strategic Insights -

Researchers at Xi'an Jiaotong University have conducted a study on the operational flexibility of thermal power plants to accommodate high levels of photovoltaic and wind power within the power grid. The study highlights the need to improve the energy efficiency of thermal power plants under ultra-low power load ratio conditions to reduce carbon emissions. The research, funded by the National Key R & D Program of China and the Science and Technology project of China Huaneng Group Co., LTD, focused on developing off-design condition models for coal-fired power plants and evaluating the influences of degradation factors on energy consumption characteristics.

Key Takeaways:

  • The study emphasizes the importance of enhancing thermal power plant flexibility to accommodate renewable energy sources, such as photovoltaic and wind power.
  • The energy efficiency of thermal power plants deteriorates heavily under ultra-low power load ratio conditions, leading to increased carbon emissions.
  • The research developed off-design condition models for coal-fired power plants to simulate the thermal system regulation under below 30% power load ratio conditions.
  • The study found that the degradations of turbines' internal efficiencies are the main source of internal losses, while the degradation of boiler's efficiency and the increase of auxiliary power ratio are the main sources of external losses.
  • The total carbon emission rate of power generation decreases by 21.98 g/(kW h) with the power load ratio of CFPP decreasing from 30% to 20% due to increased accommodation of renewable power.
  • The research evaluated the energy saving potential under ultra-low power load ratio conditions, finding a net coal consumption rate of 298.56 g/(kW h) and 522.39 g/(kW h) when the thermal power plant operates under 100% and 20% power load ratio conditions, respectively.
  • The maximal energy saving potential under ultra-low power load condition are 87.25, 29.47, 25.05, 2.33, and 1.05 g/(kW h) for the degradation of isentropic efficiency of turbine, the degradation of boiler's efficiency, the increase of auxiliary power ratio, the additional drainage water of the boiler, and the switching action of BFPT's supply steam, respectively.

Statistics:

  • 21.98 g/(kW h): decrease in total carbon emission rate of power generation when the power load ratio of CFPP decreases from 30% to 20%.
  • 298.56 g/(kW h): net coal consumption rate when the thermal power plant operates under 100% power load ratio conditions.
  • 522.39 g/(kW h): net coal consumption rate when the thermal power plant operates under 20% power load ratio conditions.
  • 87.25 g/(kW h): maximal energy saving potential for the degradation of isentropic efficiency of turbine.
  • 29.47 g/(kW h): maximal energy saving potential for the degradation of boiler's efficiency.
  • 25.05 g/(kW h): maximal energy saving potential for the increase of auxiliary power ratio.
  • 2.33 g/(kW h): maximal energy saving potential for the additional drainage water of the boiler.
  • 1.05 g/(kW h): maximal energy saving potential for the switching action of BFPT's supply steam.

Sources:

  • [1] NewsRx. Findings on Renewable Energy Reported by Investigators at Xi'an Jiaotong University (Energy Consumption Characteristics and Energy Saving Potential of Thermal Power Plants Under Ultra-low Power Load Ratio Conditions). Global Warming Focus. September 1, 2025; p 235.
  • [2] Liu, M., Du, Z., Zhao, Y., Yan, J., Wang, Y., & Zhou, Y. (2025). Energy Consumption Characteristics and Energy Saving Potential of Thermal Power Plants Under Ultra-low Power Load Ratio Conditions. Energy, 330.