Electricity and Hydrogen Co-Production From Coal and Biomass

Abstract

This paper presents and discusses the results of a complete thermoeconomic analysis of an integrated power plant for co-production of electricity and hydrogen via pyrolysis and gasification processes, applied to an existing large steam power plant (ENEL Brindisi power plant-660 MWe). The two considered technologies produce syngas with different characteristics in terms of temperature, pressure and composition, and this has a significant effect on the layouts of the complete systems proposed in the paper. Moreover, the proximity of a hydrogen production and purification plants to an existing steam power plant favour the inter-exchange of energy streams, mainly in the form of hot water and steam, which reduces the costs of auxiliary equipment. Various coals (Ashland, South African and Sardinian Sulcis coal) and mixtures of South African coal and biomass (Poplar) are considered in this study, in order to explore the real potential of mixed fuels in terms of impact on plant economics and reducing CO2 emissions. Furthermore, the high quality of the hydrogen, produced through a Pressure Swing Adsorption unit or a dense Membrane unit, allows it to be used for distributed generation (e.g. by microturbine, Stirling engine, etc.) as well as public transport (using PEM fuel cells). The results were obtained using WTEMP thermoeconomic software [9], developed by the TPG (Thermochemical Power Group) of the University of Genoa, and this project has been carried out within the framework of the FISR National project “Integrated systems for hydrogen production and utilization in distributed power generation” [10]. The complete systems proposed here can represent an attractive approach to flexible hydrogen-electricity co-production.