Low-CO2 Emission Solar/methanol Hybrid Power System

This paper proposes and analyzes a novel gas/steam combined cycle power system integrated with low/mid temperature solar heat thermo-chemical conversion and CO2 capture. The power system uses methanol as the input fuel. Methanol reformation is highly endothermic and can achieve over 90% conversion into H2-rich syngas at temperatures around 250°C. The high conversion rate at relatively low temperature enables the following configuration arrangement, (1) solar heat collected at 200-300°C can be used to heat the endothermic methanol reformation and is thereby converted into syngas chemical energy; (2) the produced syngas is enriched with H2 and CO2 (24.4% CO2 and 74.7% H2 by volume), thus is ready for pre-combustion decarbonization. The processed CO2- lean syngas is used to fuel a gas/steam combined cycle. In form of the fuel chemical exergy, the collected low level (low temperature) solar heat is released as high temperature thermal energy for power generation, achieving a highefficiency heat-power conversion in the advanced combined cycle system. The hybrid system is simulated with Aspen Plus code and analyzed. The results show that with 91% CO2 captured, the system attains a net exergy efficiency of ∼55%. Fossil fuel saving ratio of 30.5% is achievable with a solar thermal share of 21.5%.