A Typical Solar-coal Hybrid Power Plant in China

Abstract

This paper proposes a 330 MW coal-fired power plant hybridized with solar heat, which will be demonstrated in Sinkiang province of China. In this solar hybrid plant, solar heat at around 300 °C is used to replace the steam extracted from the high- pressure turbine, to pre-heat the feed water before the economizer of the boiler. In this way, the replaced high-temperture and pressure steam can be further expanded in the turbine, boosting output work of the coal-fired power plant. At the same time, compared to present solar-only thermal power technology, the solar heat at around 300 °C here can be converted into electricity by the aid of larger capacity units of the coal-fired plant with higher turbine internal efficiency. Furthermore, this kind of solar hybrid power plant can be operated at a fully rated output during periods of low solar radiation such as the evening and overcast days without storage device. As a result, the annual net solar-to-electric efficiency could reach up to 21%, with the improvement of nearly 3 percentage points, compared to the state-of-the art parabolic trough plants, such as SEGSs. And the levelized cost of electricity generation (LCOE) could be reduced to 0.8-1.0/kWh, about 20-30% lower than that of the solar-only thermal power plant (1.1-1.3/kWh). This kind of solar-coal hybrid power plant would offer a promissing approach to the cost-effective and scalable utilization of mid-temperature solar heat in the near and mid term.