Seasonal storage and grid balancing through power-to-methanol and a “Biomass Battery”

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The world is witnessing a rise in the use of renewable energy sources for electricity generation. However, these sources rely on weather and seasonal conditions, affecting grid stability and energy supply security. This study introduces a system enabling seasonal energy storage and synthesis of e-methanol using biomass as an energy reservoir. Biogas drives an oxy-fuel combustion power cycle, generating electricity during periods with low wind/solar electricity production. The captured biogenic CO 2 is stored and later used to produce e-methanol, with a solid oxide electrolyzer providing hydrogen when there is excess grid electricity. The feasibility of the system is examined from a techno-economic standpoint, including calculations of exergy efficiency and the Levelized Cost of Methanol (LCOM). The LCOM is estimated to be about €900/ton for conditions applicable in 2023 using a multi-objective optimization method. It is predicted to reach approximately €500/ton by 2040, based on various assumptions about future developments in green electricity costs and the technologies involved. With projected electricity prices, the proposed system can become economically attractive by 2040, as the profits can outweigh the electricity costs. The CO 2 tax thresholds required for e-methanol to be economically competitive with traditional fossil-based methanol under various electricity tariff models are also analyzed. It is found that by 2040, a CO 2 tax of €258/tCO 2 would match the production cost of e-methanol compared to its non-renewable counterpart, assuming a grid variable tariff model expected in that year.