Surplus electricity to biomethane via intermittent hydrogen injection in post-digestion systems

In the route to mitigate global warming and phase out fossil energy sources, solar and wind power represent an increasing share of the produced electricity. These sources are difficult to plan for as they are weather dependent, resulting in fluctuating electricity prices. But in situations with high production without matching demand it is possible to use the cheap, surplus electricity to produce hydrogen (H₂) through electrolysis of water (power2gas). Yet, infrastructure for H2 is expensive and instead H₂ can be added to existing biogas plants.

This project will focus on developing an affordable and novel method to insert H₂ to biogas plants for conversion into bio-methane. The technique proposed in the project will be in-situ methanation in post digesters, where we hypothesize that it can be efficiently converted without risking the overall biogas process.

In-situ methanation in post digestion is not well studied yet, and more knowledge are needed to create a cost- efficient process.