Hybrid systems integrating advanced SOEC for co-electrolysis and supercritical CO2 heat pump for renewable natural gas production

Synthetic natural gas (SNG) will play a pivotal role in the decarbonization process, especially concerning the hard-to-abate sectors. This work proposes a techno-economic analysis of different innovative plant configurations for the so-called Renewable Natural Gas (RNG) production, starting from various biogas compositions. The proposed layouts are based on hybrid systems, by coupling vacuum pressure swing adsorption (VPSA), electrolysis, co-electrolysis and a supercritical CO2 heat pump (SCO2HP). Such innovative systems aim at increasing the RNG production by exploiting CO2 as byproduct of the VPSA process. The scope of the present work is to investigate on the viability of different RNG production pathways, by evaluating strengths and weaknesses of each configuration. Additionally, the potential coupling of SCO2HPs with them has been evaluated. The technical options are compared in terms of RNG production ratio and levelized cost. The results show that, by employing such innovative plants, the annual RNG production can be increased by about 60 %. Yet, the RNG production cost increases by 100 %. Moreover, it emerges that SCO2HPs could be a valid solution for electrifying the heat demand, in terms of steam, for industry sectors.