Thermodynamic analysis of solar-assisted hybrid power generation systems integrated with thermochemical fuel conversion

Solar-assisted hybrid power generation systems integrated with thermochemical fuel conversion are of increasing interest because they offer efficient use of lower temperature solar heat, with the important associated advantages of lower emissions, reduction of use of depletable fuels, production of easily storable fuel to alleviate the variability of solar heat, and relatively low cost of the use of lower temperature solar components. This paper examines thermodynamic features and performance of thermochemical hybridization of power generation systems, and demonstrates it for two previously proposed and analyzed specific systems, SOLRGT that incorporates reforming of methane, and SOLRMCC that incorporates reforming of methanol, both of which using lower temperature solar heat (at ∼220 °C) to help reform the fuel input to syngas, which is then burned for power generation. This analysis resulted in an equation for the power system performance in terms of the energy level (exergy to enthalpy change ratio) of the syngas produced by the thermochemical process. It was found that the solar-to-electricity efficiency is higher by up to 42% in the investigated cases if lower temperature solar heat is used in the thermochemical hybrid systems, compared to using the solar-only power generation systems with the same turbine inlet temperature. - Highlights: • Efficient use of lower temperature solar heat. • Reducing emissions, use of depletable fuels, and cost. • Integrated production of easily storable fuel. • Equations for efficiency competitiveness of the hybrid with a solar-only system. • Such thermochemical hybrid systems have higher solar-to-electricity efficiency than solar-only ones.