Electrofuels from biological processes – A knowledge synthesis

About the project

Sweden aims to have a 100% renewable power production by 2040. This will primarily be achieved by largely expanding the intermittent power production with for example wind power. However, an increased proportion of wind power also requires increased access to energy storage and balance and/or regulating power. Sweden also has other environmental and cli­mate goals and ambitions to strive for, such as a fossil-independent transport sector in 2030, a car­bon-neutral society in 2045 and acheiving a leading position in taking care of and recycling waste in a circular economy.

The combination power-to-gas and biogas production can contribute to reach these goals in different ways. By enabling for a more flexible electricity system and, at the same time utilize the available biomass (e.g. manure and bio-degradable waste) more efficiently, more renewable fuels and/or chemicals can be produced from the same amount of biogas substrate. The concept is based on converting low-cost renewable electricity, via electrolysis, into hydrogen (power-to-gas). In turn, hydrogen is further reacted with carbon dioxide in raw biogas in so-called electro­fuel processes.

There are both thermochemical and biological electrofuel processes for methane production. There are also biological gas fermentation for the production of liquid electrofuels, i.e. bio-alcohols. Among today’s biogas producers the interest in electrofuel processes is growing because of their potential to open up for more profitable biogas plants at the same time as the plants could become more product flexible and less susceptible to market fluctua­tions. However, it is difficult to get a grip on what the techno-economic performance and degree of maturity of the pro­cesses really are, particularly concerning biological electrofuel processes.

This knowledge synthesis has aimed to meet this need. It includes in-situ, ex-situ biological methanation and gas fermentation, and uses thermochemical methanisation as a reference. The possibilities to combine and/or to replace conventional biogas upgrading with the different electrofuel processes are also investigated and discussed.

The report is written in Swedish with an English summary.