Air Bottoming Cycle for Hybrid Solar-Gas Power Plants

Abstract

Several solar-gas hybrid power plants based on the parabolic trough system are under construction in the MENA region and in Spain. The thermodynamic cycle of these plants is divided into topping cycle and bottoming cycle according to their temperature range. Since the solar collectors supply heat at a medium temperature level, up to 400°C, the existing technology uses a steam bottoming cycle (steam turbine). The present study aimed at investigating the thermodynamic feasibility of using air bottoming cycle (gas turbine) instead of the steam bottoming cycle. A thermodynamic scheme of solar air bottoming cycle was proposed. The case study considered an existing small size capacity gas turbine (<50 MW) as a topping cycle. The thermodynamic performance of the proposed solar air bottoming cycle was compared to two reference cases, without solar energy, a steam bottoming cycle and a conventional air bottoming cycle.