WELTEC BIOPOWER Completes Commissioning, Handover of RNG Plant

WELTEC BIOPOWER successfully commissioned and delivered a dairy RNG plant in Barron County, WI, after four months of construction. The dairy farm produces 86,600 MMBTU per year of RNG/biomethane and is processed using advanced membrane-based gas upgrading technology. From here, the RNG is compressed, bottled, and transported to a gas grid injection point, which is then drawn off the gas grid elsewhere.

“For years, we have been utilizing cattle manure to generate biogas, meeting our farm’s electricity and heating needs while also fertilizing our fields with digestate,” said the dairy farm owner. “With the new RNG facility, we have expanded our digestate utilization on a larger scale and now store it in our dedicated lagoon for optimal land application.”

By utilizing biomethane as a fuel source, the farm reduces carbon emissions by approximately 11,200 tons of CO₂ equivalents per year, with the plant owners capitalizing on RNG tax credits and fuel tax allowances. This project demonstrates the potential for biogas/RNG development at small-scale dairy farms, as its carbon-negative RNG, fast construction time, and the relatively low CAPEX can decarbonize North American agriculture and truck fleets.

Dairy RNG plant; image credit: WELTEC BIOPOWER

The Facility & Construction

The facility leverages a streamlined process flow, with manure fed from the barns into a 1,543 m³ stainless steel pre-storage tank before being pumped into the digesters. The digestion system has a retention time of 34 days, before the biogas is upgraded into high-quality RNG at gas grid specifications—digestate is pumped into the existing lagoons. WELTEC BIOPOWER designed and supplied digesters, a prefabricated containerized pump-block system, heating and boiler containers, and a prefabricated factory-tested control container.

“We constructed the tanks using a ring-by-ring assembly approach, with the final step involving the installation of a gas-tight membrane storage roof,” said Carsten Hesselfel, WELTEC BIOPOWER North America COO. “Our modular construction method, tried and tested worldwide over the past 20+ years, contributed significantly to the short construction time of the plant.”

It can process 207,000 metric tons of cattle manure annually, with some flexibility to incorporate future increases in herd size.

RNG in the News

In mid-January 2025, Brightmark RNG achieved a first gas milestone at 10 RNG projects in Iowa, Michigan, South Dakota, Wisconsin, and Ohio, increasing its ownership and operation to 15 RNG projects in Midwestern region. Brightmark has reduced methane emissions via anaerobic digestion by over 1.2 million tons of CO₂ equivalent at its RNG circularity centers.

The company’s anaerobic digestion process produces RNG in partnership with farmers: It collects and digests organic waste to extract methane and upgrades it into RNG for transportation fuel. The methane emissions reduction is equivalent to the carbon sequestered by planting and growing approximately 20 million trees over 10 years. With these first gas milestones, Brightmark RNG owns and operates 15 RNG projects in the U.S. Midwest. This region generates almost 43% of the country’s agricultural products.

In October 2024, Synthica Energy put first shovels in the ground at a new RNG facility in Rome, GA, just north of Atlanta. The facility, named Synthica Rome, is the first of its kind in the Greater Atlanta region and is expected to divert approximately 250,000 tons of waste from local landfills per year. Synthica Rome is the company’s third RNG facility under development and, last year, construction began on the first facility developed by Synthica in Cincinnati, OH, which is scheduled for operation in 2025.