Weltec Biopower Constructs Cutting-Edge Biomethane Plant in Wisconsin
In February 2025, German biogas specialist Weltec Biopower completed the commissioning and handover of a state-of-the-art dairy RNG (renewable natural gas/biomethane) plant in Barron County, Wisconsin, USA. This facility, operational after a brief four-month construction period, is strategically designed to produce 2.36 million standard cubic metres of RNG/biomethane annually. The advanced plant operates above typical gas grid specifications, using cutting-edge membrane-based gas upgrading technology, achieving an output of 272 standard cubic metres per hour. This output is subsequently compressed, bottled, and dispatched to a gas grid injection point, bolstering the sustainability traits of buyer transportation fleets.
Currently, the farm tends to a herd of 3,400 cattle, versed mainly of Holsteins, alongside sel ect Swiss cows. With prior ventures into AD plants to generate electricity for on-site needs, the transition to RNG was fluid. “For years, we have utilized cattle manure to generate biogas, catering to our farm’s electricity and heating needs while fertilizing our fields with digestate,” claimed the owner. “The new RNG facility allows us to upscale digestate utilization substantially, now stored efficiently in our dedicated lagoon for optimal land application.”
Weltec Biopower deployed three 6,850 cubic metre duplex stainless steel digesters for the biomethane plant set near Rice Lake. "We adopted a ring-by-ring assembly approach in tank construction, culminating in installing a gas-tight membrane storage roof,” shared Carsten Hesselfeld, COO of Weltec Biopower North America. The tanks, each with a gas storage volume of 3,320 cubic metres, highlight Weltec’s modular construction method, instrumental in the abbreviated construction timeline. The facility has the capacity to process 207,000 metric tonnes of cattle manure yearly, adaptable for potential herd increase.
The plant design ensures efficient processing, where manure transitions fr om barns into a 1,543 cubic metre stainless steel pre-storage tank before proceeding to digesters. With a digestion retention time of 34 days, the biogas is further upgraded through an integrated, contract-specified, membrane-based system into RNG aligned with gas grid standards.
Post processing, the digestate feeds into existing lagoons, while strategic design and key component supply by the company, including pre-assembled containerized systems, heating, boiler containers, and prefabricated control containers, underpin a streamlined construction and operational deployment.
Utilizing biomethane as a fuel source incurs substantial environmental benefits, contributing to a reduction of approximately 11,200 tonnes of carbon dioxide equivalents annually. Financial incentives, like RNG tax credits and allowances, add economic benefits to environmental gains. Such endeavors play a pivotal role in de-carbonizing agriculture and expanding the carbon-neutral fleet ethos across North American territories.
