MAURICE, Iowa — After two years of planning and construction, the West Branch project of Novilla RNG LLC has two renewable natural gas digesters in operation and is now injecting RNG into the city of Sioux Center’s lines.
The digesters receive manure from four dairy farms. The first is Maassen dairy, a 2,000-cow dairy operated by Aaron Maassen and partners, Adam, Stefan and Lee Maassen, near Maurice. The other three sites are operated by the Hoogland family. Two of the Hoogland dairies are located near Orange City and one is located near Maurice. There are a total of 4,500 cows milked at the Hoogland family’s three sites.
One digester is located on Maassen’s farm, which processes manure from his cows and one of the Hoogland farms. The other is located at one of the Hoogland dairies.
“I’m just happy that we’ve gotten to this point and it’s operating and producing gas,” Maassen said. “That’s exciting. I give Novilla RNG a lot of credit for following through with it and how they’ve gone through the construction phase.”
Digesters were originally used in water treatment plants. Dairies started utilizing digesters in the 1970s but became popular on dairies beginning in the 1990s. At first the gas was used to run an engine to generate electricity.
Now they have evolved into making purified renewable natural gas to power cities.
Mark Hill, co-CEO of Novilla RNG, said the West Branch project has been operating smoothly since they started it last fall. Novilla RNG has been around for three years and is run by Hill and Jared Williams.
Novilla RNG is currently in the process of building five more RNG sites. The first step taken is going out to the farm to understand how the producer handles manure so they know what they will need to make it successful.
The company has four operating systems and partnerships with nine dairy farms. The latest partnership is the dairies of the West Branch project.
“In December 2024, 99% of the time we were injecting gas into the pipeline to Sioux Center,” Hill said. “It takes a couple of months to get the digester warmed up and get the bugs right in there that are eating the manure and releasing the biogas.”
The pipeline and gas are closely monitored by Novilla RNG and people in Sioux Center. Hill said they have fewer emissions with the methane gas collected from the digesters than normal geological gas.
As production goes into full swing, the digesters will be producing over 140,000 million British thermal units a year. The natural gas captured by these digesters is utilized to power the digesters themselves and the excess is brought to Sioux Center with the use of a six-inch natural gas pipeline. According to the U.S. Department of Energy, a household will average 77 million Btu a year, meaning the digesters could provide natural gas to around 2,000 homes.
“I think the biggest positive right now is the size and scope of the project between multi-sites and all the different things that had to come together to make it work,” Maassen said.
The day-to-day operations of the RNG digesters are fully operated by employees of Novilla RNG who communicate with the dairies so they can make adjustments to ensure the proper functioning of the digesters.
“The (start-up has) been smooth,” Maassen said “There’s some adjustments about water that needs to be added to help the sand get cleaned (out of the manure). It’s just a day-to-day operation of maintaining the bacteria and digester.”
At the dairies, most of the water from the manure is drained out and gets cycled back to the dairy to be reused to remove sand from the manure. In Maassen’s case, this is used to charge his sand settling lane.
“We’ve always had a sand lane, so essentially, they just rerouted the flow from the end of the sand lane into their facility to dewater it and separate the solids out to go into the digester.”
Once the digested manure, called digestate, is returned to the farm, the farmers can utilize it in the manner they always have. There are several positives of using digestate.
“One of the big benefits at the farms is we help reduce odors that would be coming out of the lagoon because … the manure goes to the lagoon and sits there and in the summer months it will get hot and release gas and some of those gasses can be smelly,” Hill said.
The digestate also offers more plant-available nutrients since it has already been digested once.
Hill said the project has come together due to the cooperation of everyone involved.
“It has been great working with the city of Sioux Center,” Hill said “It is neat when you have a local community looking at unconventional ways of getting gas through their lines. Our project would not have happened if we were not able to work cooperatively with Sioux Center.”
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