Gasum starts expansion project at Riihimaki biogas plant

Gasum, a Nordic energy company, on February 8 announced a €7.5mn ($8mn) investment to expand and improve its existing biogas plant in Riihimaki, Finland. The plant, operational since 2016, currently contributes approximately 45 GWh/year of biomethane to the gas transmission network, catering to industrial and transportation needs for renewable energy.

The expansion is expected to be operational by May 2025, and the project has received a grant covering 40% of the investment sum from the Finnish ministry of the environment.

The project's primary goal is to implement an evaporation system to enhance the removal of liquid from the digestate generated during biogas production. This addition to the plant's process is expected to improve operational efficiency while allowing for the recovery of nitrogen in the form of valuable ammonium water.

Ari Suomilammi, Gasum’s head of renewable gas, highlighted that the plant primarily processes biowaste, sewage sludge, and industrial side streams. The resulting digestate has traditionally been used in agriculture as fertilizer. However, challenges have arisen due to revised fertilizer regulations.

In the context of emission reductions, the investment involves the production of an ammonia solution containing organic nitrogen. This solution is designed to replace nitrogen of fossil origin, specifically urea. Using this substitute is crucial in reducing carbon dioxide emissions, with an estimated decrease of about 1,000 tonnes/year compared to traditional urea production.

Gasum aims to increase the output of existing biogas plants in alignment with its goal to bring 7 TWh/year of renewable gas to the market by 2027.