The Mill Valley RNG Center In Focus

South Dakota’s dairy industry is growing, and with that growth comes new opportunities. In Grant County, the Mill Valley RNG Center is one of a handful of pioneering dairies that have found a way to increase their revenue and make the planet a better place for future generations.

And Brooks Construction played a key role in making Mill Valley’s renewable energy facility come to fruition.

What Is the Mill Valley RNG Center?

Milbank is known for its dairy industry. With dairy production facilities dating back almost 100 years, the community surrounding the Mill Valley Dairy is a perfect place for a renewable natural gas facility.

Mill Valley’s 600-cow facility is just one of many farms in the area. Another facility, Boadwine Farms, partnered with Mill Valley to help build the RNG center they would both start using in early 2023 to produce the carbon-negative fuel their cattle slurry can create.

Mill Valley RNG Center

The Mill Valley RNG Center is one of the first manure digesters in South Dakota, alongside the Full Circle RNG Digester in Hurley, SD, and the Athena Circularity Center near Baltic, SD. While not as large as these two facilities, it still offers plenty of room for RNG and fertilizer production.

The Facility

The Mill Valley RNG Center is a 2-tank system, plus a receiving tank and a digestate tank. The site is connected by underground piping that then connects to the California Natural Gas transportation pipeline.

• Two 105-foot diameter, 26-foot tall concrete digestion tanks
• One 36-foot diameter, 15-foot tall concrete receiving tank
• One 36-foot diameter, 15-foot tall concrete digestate tank

Digester Capacity

There are more than 2,500 cows between Mill Valley Dairy and Boadwine Farms. With that much cattle, waste management becomes critical. But with the 2-tank digestion system, the farms can easily manage all the cattle slurry produced each year while converting methane into green energy.

• 178,000+ tons of cattle slurry processed annually
• 70,226 MMBTUs of renewable natural gas annually

Construction and Timeline

Mill Valley worked with several different companies to bring the project to completion. Technology vendor Biogest provided the biogas collection components, while Brightmark, in partnership with Chevron, provided infrastructure and funding. With Stockwell Engineering at the helm of construction, we utilized special radial gangforms from EFCO to build the four tanks on site. After 6 months of construction, the facility was ready to start production.

• Groundbreaking in April 2022
• 6 months of construction
• First gas produced in Q1 of 2023

Economic Benefits for the Dairy Farms Served by Milly Valley RNG Center

The Mill Valley RNG Center joins a handful of other South Dakota farms in bolstering their revenue with biogas. But there are more benefits to RNG production than renewable fuel.

Renewable Energy Economy

Through Brightmark’s renewable natural gas infrastructure, Mill Valley Dairy adds RNG to both regional and national supply chains. This additional biofuel replaces fossil fuels and improves the economy through a plentiful renewable resource.

Organic Fertilizer

The communities near Mill Valley and Boadwine Farms benefit from the RNG production through the byproducts of that process: digestate. This organic fertilizer can be sold regionally to replace chemical fertilizers and keep local money in local operations.

Cooperative Agreements with Farms and Investors

The land where the digesters are built is leased by the investors. This allows the farms connected to the Mill Valley RNG center to gain additional revenue on top of the natural gas and the fertilizer.

Elimination of Dangerous Lagoons

Lagoon maintenance is both costly and dangerous. By moving the cattle slurry out of lagoons and into receiving tanks and digesters, farms like Mill Valley see less risk, less maintenance, and better operations.

Strengthening South Dakota’s Green Economy

Renewable energy is still a relatively new industry in South Dakota. Along with biofuels like ethanol, RNG is helping make South Dakota farms greener.

Carbon-Negative Fuel

Solar power and many biofuels are carbon neutral, but very few can boast a carbon-negative effect on the environment. Renewable natural gas is one of these carbon-negative fuels because it both prevents greenhouse gas emissions and replaces carbon-heavy fuels.

Fewer Methane Emissions

Methane is a potent greenhouse gas. By capturing and collecting methane, RNG centers like Mill Valley keep approximately 23,000 tons of Co2eq from entering the atmosphere each year—roughly the equivalent of 28,000 acres of forest in reduction.

Environmentally Friendly Fertilizer

The digestate left after the methane collection provides an organic alternative to chemical fertilizers. Local farms can reduce runoff pollution and improve the carbon footprint of their crops while supporting the local economy in a responsible way.

What’s Next?

As Brooks continues construction on other digester projects in and around the Sioux Falls area, we’re on the lookout for new partnerships with other dairy farms. With partners like Stockwell, Biogest, and Brightmark, we’re helping the next generation of dairy farmers create a greener future for our communities.
If you’re interested in building a circularity center for your dairy farm, contact us today. We’ll be glad to help you create a greener farm with our extensive experience in the industry!