An efficient solar/lignite hybrid power generation system based on solar-driven waste heat recovery and energy cascade utilization in lignite pre-drying

Solar-aided power generation (SAPG) is a promising way to achieve clean and efficient production of electricity. An efficient solar/lignite hybrid power generation system was proposed in the paper, in which solar energy was amplified in solar-driven heat pump cooperating with waste heat recovery and two-stage drying was applied for energy cascade utilization. By absorbing waste heat in solar-driven heat pump and integrating with lignite pre-drying, the solar energy is amplified and converts into the heating value of fuel, leading to a high solar utilization efficiency. Thermodynamic and economic analysis of the proposed SAPG was conducted. The results reveal that, for a typical 660 MW lignite-fired power plant, the proposed SAPG generates 50.3 MWe of additional power with 3.47% of thermal efficiency increase. The COEs of the proposed SAPG are 0.045 USD/kWh, which is significantly lower than that of the conventional SAPG. The off-design performance reveals that the fluctuation of solar energy could be dealt by dried coal storage, leading to stable power output of the proposed SAPG.