Leeuwarden, September 27, 2022 – Starting in 2024, verge grass from Frisian and national roads will be processed into biomethane and sustainable potting soil in Leeuwarden. A consortium consisting of D4, HoSt Groep, and Kekkilä-BVB has received a European LIFE subsidy of €2,261,231 for this initiative. The project provides local Frisian authorities with a green and local alternative to natural gas, currently supplied by Gazprom.

The verge grass digester will be constructed at the Energiecampus Leeuwarden and will convert 30,000 tons of roadside and natural grass into four products: biomethane, sustainable potting soil, biogenic CO2, and green fertilizer. Annually, the consortium will produce 2.7 million cubic meters of green gas, equivalent to the gas consumption of 2,300 households. The grass will be sourced from Rijkswaterstaat, the province of Fryslân, Frisian municipalities, nature reserves, and water authorities.

In this project, D4 is responsible for project development, bio-energy company HoSt handles the design and construction of the digester, and Kekkilä-BVB processes the sustainable potting soil into consumer bags.

From grass to gas and beyond

Through the digestion of roadside grass, biomethane is produced with the same quality as natural gas but sustainably. The digestate is the residual product remaining after the digestion process. Research by Wageningen University & Research has shown that digestate from verge grass is particularly suitable as a component in potting soil. Peat is a significant component in potting soil and is currently excavated in Finland and the Baltic states under strict environmental regulations. Incorporating the residual product into potting soil can help reduce the CO2 footprint, as peat has a relatively high carbon footprint.

In addition to green gas and potting soil, biogenic CO2 is produced for sustainable horticulture, and green fertilizer is manufactured as a replacement for fossil fertilizers. This method of verge grass processing is highly sustainable and circular, resulting in the avoidance of approximately 11,000 tons of CO2 emissions annually.

Self-supply model

It is possible to establish a circular chain in Friesland where the Province of Fryslân and local authorities and nature conservation organizations supply verge grass to the facility and receive biomethane in return. This enables public buildings, such as the provincial government building or a local swimming pool, to be sustainably heated using locally sourced verge grass. This aligns with the Frisian self-supply model of the Frisian energy procurement collective OVEF, providing a local and green alternative to natural gas, currently supplied by Gazprom.

LIFE subsidy

The project is made possible in part by a European LIFE subsidy. The subsidy program contributes to the realization of European environmental, energy, and climate policies, such as the European Green Deal. In 2021, LIFE allocated 327 million euros in subsidies across the EU, with just under 2 percent going to 13 projects involving Dutch participation.