Standardized techno-economic assessment of synthetic natural gas and synthetic hydrogen natural gas production for the transport sector and gas grid

Abstract

As CO2-emission hit new records, immediate emission reductions have to be achieved, especially in the transport and industrial sector an in domestic heat. As important backbone of the industrial and private sector, the existing natural gas grid is capable of storing and transporting large amounts of energy. Admixing synthetic natural gas to the gas grid could have an immediate impact on CO2-safings. Furthermore, admixing up to 30 % renewable H2 to the gas grid could improve resilience, lower costs, compared to synthetic natural gas, and could have positive impacts on the use in the transport sector. Based on rigorous process simulations in Aspen Plus V14 a techno-economic analysis for two production processes: high temperature TREMP and low temperature isothermal, has been carried out. The product quality has been set to the overlap of the requirements of the gas grid and the transport sector. Furthermore, three different higher hydrogen concentrations have been assessed. The TREMP process has a power-to-fuelefficiency of about 57 % compared to 55 % for the isothermal process, resulting in net production costs in 2018 of 185 €2018 MWhLHV -1 for TREMP versus 189 €2018 MWhLHV -1 for isothermal. An increase from 2 % to 30 % mol H2 reduces the NPC by about 2.6 % for TREMP and 2.7 % for the isothermal process in comparison to synthetic natural gas. Technical constraints and costs within the gas grid suggest a sweet spot of hydrogen admixture of up to 20 % vol. H2.