Mills County landfill gas being processed into renewable energy
A $35 million, state-of-the-art renewable natural gas (RNG) processing facility is up and running at the Loess Hills Regional Sanitary Landfill northwest of Malvern.
Two years in the making, the facility houses a complex, multi-step processing plant that converts gas from the landfill into methane which gets injected into a nearby natural gas pipeline. The facility is the first-of-its kind in western Iowa and one of only a handful across the state.
“We started two years ago and we probably should have started it three years ago,” said Waste Connections Division Landfill Manager Kelly Danielson. “We had a deadline of Oct. 1 and we got it online Sept. 29.”
The process begins with landfill gas being extracted from the ground by 76 landfill gas wells scattered across the landfill. From the well, the gas is piped to the processing plant where various compounds are separated and removed during a sophisticated, multi-step process.
“There’s a series of filters and systems that extracts,” Danielson said. “Basically, you take landfill gas and you separate everything that’s not methane. Methane is about 55 percent of landfill gas. The rest is mostly carbon dioxide, nitrogen, oxygen, hydro sulfides, siloxanes, non-meth organic compound, stuff like that.
“There’s a series of things they do to take that out. This is just cleaning it so it’s 99.9 percent methane. You just keep forcing the gas through with pressure until at the end you have 99.9 percent methane.”
Up to this point, the landfall gas collected at the site was being burned and destroyed through a combustion flare.
Bret Stephens, Environmental Manager for the landfill, said the facility is required to operate under the air compliance rules of the Environmental Protection Agency (EPA).
“If you’re not using it (landfill gas) for energy, it has to be destroyed,” Stephens said. “Once the plant is fully online, our flare will go away.”
Landfill officials note that methane being processed at the facility is considered a “green gas” that will “displace natural gas derived from fossil fuels, reducing carbon emissions in the heat, power and transport sectors.”After the methane is processed at the landfill, the gas goes through an interconnect station owned by energy infrastructure giant Kinder Morgan. From the interconnect, the methane is pushed into a British Petroleum (BP) natural gas pipeline near Highway 34. The methane produced at the landfill mixes with the existing natural gas already inside the BP pipeline.
Stephens said specific standards must be met before the methane gets injected into the pipeline.
““We have to continually sample our gas to make sure it’s good enough to put into the pipeline,” he said. “They have monitors at the interconnect, too, so if for some reason we had something failing here and had a bunch of bad gas, they would shut us off.”
Danielson noted that gas being produced in Mills County can be sold to companies anywhere in the country.
“Typically, big companies like the Googles and the Pepsis, they go out and buy because they want to help the environment,” he said. “They go out and buy landfill gas at a premium. You couldn’t fund this facility on the price of natural gas.”
Initially, the facility will be processing 1,500 standard cubic feet of landfill gas into RNG every minute. Landfill officials project that within 15 years, the production rate will increase to 4,000 standard cubic feet per minute, generating enough renewable energy to meet the needs of nearly 14,000 Iowa homes every year.
At some point, carbon dioxide gathered during the production process could be sold, Danielson said, but that can’t happen without a carbon pipeline.
Carol Vinton, a member of the Mills County Board of Supervisors, came away impressed after getting a tour of the facility in mid-October, along with Mills County Chamber Of Commerce Executive Director Jennie Davis.
“What an undertaking,” Vinton said. “I’m so excited. It’s going to be great, not only for these guys (Waste Connections), but for recycling and it’s good for the county.”
Area residents are invited to get a first-hand look at the facility when Waste Connections and the Mills County Chamber of Commerce host a luncheon open house at the processing plant on Thursday, Nov. 16, from noon – 1 p.m.
The processing facility is located near the main entrance to the landfill at 59722 290th St.
Loess Hills Regional Sanitary Landfill Environmental Manager Bret Stephens said as of February 2023, the constructed acreage of the landfill was 84.7 acres, with 257.9 acres permitted.
On average, 650,000 tons of waste is collected annually at the landfill. Approximately 60% of the waste is degradable, while the other 40% is plastics, etc. that don’t degrade into natural gas readily like organic material (food waste, etc.).