Unlocking Energy Flexibility: MGT with Integrated Power-to-Heat-to-Power Technology

Abstract

The rising integration of renewable energy sources leads to a more volatile power grid. At the same time, limited grid expansion forces more efficient use of existing infrastructure and the integration of decentralized flexible energy storages. Solutions like Power-to-Heat-to-Power offer a cost-effective approach: while their electrical round-trip efficiency is lower than that of batteries, combined heat and power integration ensures high overall efficiency. An additional key factor is system resilience. Sector-coupled concepts - including co-firing of hydrogen and other renewable fuels - enable continued operation even when stored heat becomes insufficient. Therefore, we propose a new concept that integrates a ceramic high-temperature energy storage (HTES) directly into the high-pressure path of an MGT between the recuperator and combustor. In times of low electricity prices, the HTES will be heated via a high-temperature induction heater. Heating the ceramic storage to the regular turbine inlet temperature (TIT) of about 1000°C allows for efficient reconversion to electricity and process heat. When the outlet temperature of the HTES decreases, the combustor keeps the TIT constant, providing a gradually increasing temperature rise, starting from minimal fuel input and ramping up to the regular temperature lift required when the HTES is depleted. To enable this wide operating range of air-to-fuel ratios with low pollutant emissions, a novel variable-geometry combustor is developed. In this presentation, we introduce the overall concept, with its main advantages and technical challenges. This is followed by an overview of key component development, namely the variable-geometry combustor, the high-temperature induction heater and the solid media HTES, including initial experimental results from laboratory-scale tests. The presentation concludes with an overview of the ongoing work to virtually couple the MGT test rig with the integrated induction heater and HTES system, which is scheduled for completion early next year. Finally, we present initial plans for an industrial-scale demonstration.