Digesters fuel dairy forward

Boadwines install technology to capture methane gas

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BALTIC, S.D. – When dairyman Lynn Boadwine glances out the window of his farm office, he sees two structures that are not only aiding his farm but the environment too.
“I feel good about doing something for the environment,” Boadwine said.
He’s talking about the two new manure digesters that were recently completed on his home dairy farm.
The base of each digester measures 120-feet across. Situated mostly underground beneath each of the digesters is a round pit that is 20-feet deep. Manure from Boadwine’s herd of 2,300 dairy cows is pumped into the circular pits. Stainless steel pipes that are connected to a boiler heat the manure to 100 degrees. Anaerobic bacteria feast on the warm manure and produce methane.
Brightmark Energy, of San Francisco, California, designed and oversaw the construction of the digesters and will be in charge of managing their ongoing operation. When the manure is in the digesters, it belongs to the company; once it leaves the digesters, the manure’s ownership returns to Boadwine.
After the impurities are removed from the methane, it will be injected into the local natural gas pipeline.
“The manure digesters won’t make or break me financially,” Boadwine said. “But they were a good way to do something for the planet without the financial burden.”
Methane is commonly known as natural gas. Natural gas is burned in everything from utility-sized power plants to the small cooktop burners of residential stoves. According to the University of Missouri, the manure from one 1,200-pound dairy cow has the potential to produce 22.7 cubic feet of harvestable gas per day. The average U.S. household uses 196 cubic feet of natural gas per day.
Natural gas is also used as a feedstock in the manufacture of nitrogen fertilizer.
“Consumer organizations, processors and retailers are increasingly focused on climate change,” Boadwine said. “The carbon footprint of agriculture is front and center. Making methane on the farm is low-hanging fruit. It just makes sense to capture the methane from our manure. It’s similar to producing ethanol or biodiesel. As with the start of the ethanol industry, being among the first in to adopt a process can be scary. But someone has to take on the challenge and be a risk-taker.” 
The soaring costs of fossil fuels and fertilizer, along with the brittleness of the global supply chain, are recent developments that have been deeply troubling for many farmers.
“Fertilizer prices have doubled,” Boadwine said. “There won’t be any loss of crop nutrients contained in our manure after it has gone through the digesters. In fact, the nutrients will be made more available thanks to the work being done by the microbes in the digesters. We are constantly working to improve our soil health. Using manure as fertilizer improves the soil’s structure and increases its water holding capacity. I think the digesters will enable us to be more efficient with our nutrients and stretch our manure over more acres.”
Boadwine inked an agreement with Brightmark Energy in December 2019.
“Construction took a lot longer than anticipated due to the COVID outbreak and the ensuing supply chain issues,” Boadwine said. “And as every dairy farmer knows, it has been extremely difficult to find and retain good employees.”
Just a few yards away from the digesters sits a facility that contains a maze of pipes and a trio of large white tanks. It looks like a refinery because that is exactly what it is.
Clyde Scott is a construction manager who worked on the Boadwine Dairy manure digester project. Scott was recently ironing out the final operational wrinkles of Boadwine Dairy’s digesters and getting them ready to start pumping purified natural gas into the local pipeline.
“Lynn beds his cow with sand, and one of our biggest challenges has been figuring out how to keep fine sand out of the digesters where it could accumulate,” Scott said. “But we’re learning how to deal with it. We’ll try something, and if it doesn’t work, we’ll try something else.”
Boadwine Dairy uses both a sand lane and a mechanical separator to recover waste sand from their manure.
“The raw gas goes from the digesters to our scrubber,” Scott said. “We use an iron sponge to extract most of the hydrogen sulfide. The gas is then pumped through a media filter that removes moisture, carbon dioxide and the rest of the hydrogen sulfide. The final step is a membrane separation system that gives us natural gas that’s more than 98% pure methane.”
Boadwine said manure digesters on dairy farms will become more common as time goes on.
“The industry is trying to find more ways for smaller operations to participate in methane production,” he said. “The ingenuity, resourcefulness and experience of the people in the dairy industry will help make these things possible. Dairy farms can become a carbon offset for those who don’t have an offset.”
Producing a green source of energy is not the only factor behind Boadwine’s decision to install manure digesters.
“Our dairy operation is located in one of the most populous areas of South Dakota,” Boadwine said. “For us, the digesters were a good opportunity to help reduce odors. That was actually one of our greatest incentives. We have to be aware that dairies have odors. We are trying our best to reduce the impact that we are having on our neighbors by using common sense and the best technology available.”
Boadwine is enthusiastic about what the future holds for the dairy industry and its ability to supply nutritious food for a hungry world along with a source of renewable energy to help power it.
“I think it’s neat that agriculture can accomplish something meaningful in the area of climate change while continuing in our role as food producers,” he said.

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