Integrated ORC-SOEC system for green hydrogen production from incineration of solid fuels

In the present paper, green hydrogen production from biomass and municipal solid waste is evaluated, targeting circular economy and green energy transition objectives pursued through waste-to-energy valorisation. In particular, the study consists in designing and modelling a hydrogen production system that integrates a solid oxide electrolyser (SOEC) and an organic Rankine cycle (ORC) powered by the combustion of biomass or municipal solid waste (MSW). The resulting efficiency, corresponding to 100.70 kg/h of hydrogen production in the optimal scenario, varies between 15.44% and 22.70% depending on operating conditions considered. Although on the one hand, this efficiency is far from the cold gas efficiency of an alternative gasification process, on the other, incineration shows a larger processing capacity and fewer restrictions in the waste categorization. Moreover, unlike traditional gasification treatments, the proposed concept can yield three outputs, namely pure hydrogen, electricity, and heat, allowing greater flexibility according to the end users’ requests and achieving a cogeneration efficiency greater than 80% in every operating mode. Furthermore, some fairly simple preliminary treatments, aiming to reduce biomass or MSW water content, can increase the green hydrogen production rate.