Low CO2 emissions chemically recuperated gas turbines fed by renewable methanol

Steam reforming of the fuel in chemically recuperated gas turbine (CRGT) plants allows performing a heat recovery of the gas turbine exhausts, boosting the plant performance. Power-to-liquids technologies are a very interesting solution for storing the excess of renewable electricity into liquid fuels. Among the renewable fuels, methanol is well-known as a hydrogen carrier and an energy feedstock. Indeed, methanol can be stored, transported, and used in an easier way than hydrogen. In this paper a CRGT fed by renewable methanol produced in power-to-liquids plant through the CO2 hydrogenation process was studied. The hydrogen needed to synthesize methanol is produced in an alkaline electrolyser, while the CO2 is captured from the CRGT exhausts. The opportunity of introducing an organic Rankine cycle (ORC) to enhance the energy production was also investigated. Dedicated simulation models of the single sections and of the overall system were developed through the commercial software Aspen Plus. The overall system was sized to generate about 350 kg/h of methanol, resulting in a power production in the order of 600–750 kW. The study demonstrated that the integrated system based on a CRGT plant fed by renewable methanol can effectively store RES surplus and produce electricity with very low CO2 emissions. The overall system shows a power-to-power efficiency of about 0.23 that can be slightly increased with the introduction of an ORC system to better exploit the heat released by the CRGT.