Role of power to liquids and biomass to liquids in a nearly renewable energy system

In order to achieve significant greenhouse gas emission reductions, decarbonisation of all economic sectors must be considered. Here, the authors study the provision of renewable energy for the power, district heating, transport and industrial sectors in nine North European countries by integrating a large amount of wind and solar power into the system with power-to-gas and power-to-fuel plants enabling balancing and sector coupling. Simultaneous optimisation of plant capacities and operation was performed. Two different synthetic liquid fuel production pathways were compared. The cost of synthetic liquid fuel remained, depending on the production pathway and amount, 30-120% higher than estimated fossil alternative cost. Biomass potential emerged as a limiting factor with high shares of biomass-based synthetic liquid fuel production. The need for energy storage system was estimated. The total optimal capacity of synthetic natural gas, hydrogen, synthetic liquid fuel, and heat storages varied between 37 and 54 TWh (1.7-2.5% of energy demand) depending on the scenario, when emergency stocks were not included. The cost of energy storages remained small compared to the total system cost, with heat storages exhibiting the highest cost.