The growing share of electricity from wind and solar increases variability in energy supply. During periods of high production and low demand, renewable electricity cannot always be used, leading to curtailed wind turbines. At the same time, certain industries require stable, high-temperature energy that electricity alone cannot easily provide. This creates a mismatch between fluctuating power generation and continuous energy needs. In Sønderborg, addressing this imbalance is part of a broader ambition to phase out fossil fuels and transition to a fully renewable energy system by 2029.

In 2023, a Power-to-Gas facility was integrated into the biogas plant in Glansager, owned by Shell. The system converts surplus electricity into hydrogen through electrolysis. The hydrogen is then combined with CO₂ from biogas in a biological methanation process. Using a trickle filter with naturally occurring microorganisms, the process produces methane (e-methane).

The solution upgrades the biogas by converting CO₂ into additional methane through an integrated Power-to-Gas process. By combining biogas production with electrolysis and methanation, the gas composition shifts to up to 90 % methane and 10 % CO₂, increasing the energy value of the biomass while utilising CO₂ as part of the process. By converting excess electricity into gas, the facility supports better integration between the power and gas grids and reduces renewable energy curtailment.