Proposed Partial Repowering of a Coal-Fired Power Plant Using Low-Grade Solar Thermal Energy
In this paper, a hybrid power-generation system with integration of solar heat at approximately 300 ⁰C was proposed for a coal-fired power plant. The system was investigated with the aid of energy-utilization diagram methodology (EUD methodology). In this research, instead of steam, low-grade solar heat was utilized to heat the feed water, leading to an improvement in the plant thermodynamic performance. The net annual solar-to-electric efficiency was recorded as over 15%. Solar feed-water heaters can operate in line with previously used feed-water heaters during the solar off-design period. A preliminary economic evaluation demonstrated that the increased capital cost of the solar collectors may be approximately $2,007/kWe. The promising results indicated that the proposed thermal cycle offers an approach that integrates mid-temperature solar heat to partially repower existing coal-fired power plants.