STUDY OF THE ENERGY EFFICIENCY OF A RENEWABLE POWER TO METHANE STORAGE PROCESS INCLUDING SOEC- SOFC
Résumé
In the current global development of sustainable energy resources, a new storage need is rising. Solutions already exist but address the issue of short period storage and then small energy quantities are concerned. This implies storage on batteries or on Compressed Air Energy Storage systems. As shown on figure 1, natural gas offers the highest energy capacity. Moreover systems involving natural gas are able to deliver very high power during long periods instead of batteries for instance which deliver small power during short periods. Consequently storing renewable power on natural gas means a gigantic energy storage volume capacity due to the use of the existing natural gas network and will provide a high power during long periods as several months. The herein process is reversible and converts renewable electric power to synthesis methane produced with H2 and CO2, the latter coming from Carbon Capture from fossil power plants or from bio-gaspowerplants. Itoffersameansofstoringelectricalpowerfromrenewableresourceswhen consumption does not match with production and of delivering this power when consumption is very high regarding the production. It will also participate to CO2 valorization. Processes involving low temperature water electrolysis already exist and achieve an energy efficiency higher than 60% for the storage part. An up-to 60% efficient combined heat and power plant is used to produce power from synthetic fuel, as illustrated on figure 2, leading to a global efficiency of 36% for the whole line.