Techno-economic assessment of the Synthetic Natural Gas production using different electrolysis technologies and product applications

Power to Methane (PtM) systems are considered an attractive alternative for power generation, renewable sources' potential harnessing, and atmospheric carbon dioxide (CO2) utilization. This study analyzes the potential use of Synthetic Natural Gas (SNG) for electrical power generation or its direct injection into the currently available Natural Gas Transportation infrastructure. A simulation approach using Aspen Plus v14 software was employed to assess various PtM configurations. Six different systems were analyzed for methanation processes, utilizing three types of electrolysis systems: Alkaline (AE), Proton Exchange Membrane (PEME), and Solid Oxide (SOE). Two primary methane applications were considered: integrated into a combined cycle for power generation and a standalone gas treatment stage for grid injection. As a result, the PEME-based system showed the highest generated-to-fed power ratio, larger than SOE (1.45% higher) and AE (20.66% higher). In addition, PEME technology reports the largest generation of SNG per power supply, exceeding 3.4% and 16.4% of those of SOE and AE, respectively. However, the SOE technology showed a larger efficiency than PEME technology by 8.2% and a PtM efficiency larger than PEME by 12.4%. Fixed capital investment for the PtM systems is around 8.6 and 13.9 million USD$, and their total earnings are between -8.2 and 20.9 thousand USD$ a year, depending on the electrolysis technology, methane application, and carbon credits scenario. According to these results, the PEME-based system is the most suitable option regarding technical and economic criteria.