Exergy-Based Analysis and Optimization of an Integrated Solar Combined-Cycle Power Plant

The transition towards higher shares of electricity generation from renewable energy sources is shown to be significantly slower in developing countries with low-cost fossil fuel resources. Integrating conventional power plants with concentrated solar power may facilitate the transition towards a more sustainable power production. In this paper, a novel natural gas-fired integrated solar combined-cycle power plant was proposed, evaluated, and optimized with exergy-based methods. The proposed system utilizes the advantages of combined-cycle power plants, direct steam generation, and linear Fresnel collectors to provide 475 MW baseload power in Aswan, Egypt. The proposed system is found to reach exergetic efficiencies of 50.7% and 58.1% for day and night operations, respectively. In economic analysis, a weighted average levelized cost of electricity of 40.0 $/MWh based on the number of day and night operation hours is identified. In exergoeconomic analysis, the costs of thermodynamic inefficiencies were identified and compared to the component cost rates. Different measures for component cost reduction and performance enhancement were identified and applied. Using iterative exergoeconomic optimization, the levelized cost of electricity is reduced to a weighted average of 39.2 $/MWh and a specific investment cost of 1088 $/kW. Finally, the proposed system is found to be competitive with existing integrated solar combined-cycle plants, while allowing a significantly higher solar share of 17% of the installed capacity.