By Zach Jensen,
Pictured is a Novilla biodigester facility in West Branch (Submitted)
Rural Ridgeway may soon be the home of a new biodigester facility.
A public hearing was held during a July 9 Winneshiek County Planning and Zoning Commission meeting to listen to the public’s concerns about rezoning a piece of property for the purpose of constructing one biodigesting facility. Novilla RNG, LLC, a Michigan-based renewable natural gas company, submitted the rezoning application and hopes to construct the new facility on land owned by Craig Bohr and Deb Storlie, near the intersection of 275th Street and Iowa Highway 9.
A biodigester contains microorganisms which break down manure in an oxygen-free environment, producing renewable natural gas, according to the U.S. Environmental Protection Agency – the facilities are also sometimes called anaerobic digestion systems or anaerobic digesters.
Novilla co-CEOs Jared Williams and Mark Hill said the proposed facility, the company’s second in Iowa, would produce approximately 1.5 million gallons of renewable natural gas per year.
All manure from two local dairy herds would be transported via pipeline into the proposed digester, where it would be heated and stirred to produce biogas consisting of 55 percent methane and 45 percent carbon dioxide. That biogas would then be transported into the biogas upgrading plant via a membrane, which separates the gases. Natural gas is then injected into a pipeline, leaving behind what’s known in the industry as a tail, which itself is then burned off in a thermal oxidizer or incinerator. Liquid from the digester, known as digestate, along with the leftover manure fiber, is then pumped back to the farms’ manure lagoons.
The digesters are expected to be placed on a three-inch-thick concrete base, according to the July 9 meeting’s unofficial minutes, and before holding manure, the digesters will be filled with 70 feet of water to test for leaks. Additionally, the digester’s pipelines will be tested for leaks.
The Decorah Leader contacted specialists from the Iowa State University Extension and Outreach Office, the Iowa Department of Natural Resources Environmental Protection Division and U.S. EPA for comment on potential dangers of biodigesters, and none of the specialists expressed concerns. According to information on the EPA’s website, “A properly designed and operated system is very safe. Anaerobic digesters are designed to meet local and national codes for safety.”
Decorah residents Tim Wagner and Christine Erickson suggested the commission table its decision on whether to grant the zoning change in order to ensure the environment is protected.
According to Novilla’s website, the digesters’ seams are sealed with rubber silicone, and there have been no leaks in the 26 years such digesters have used that type of sealant. The presenters also said no hazardous materials are stored on site.
Kevin Lee of Freeport expressed concern regarding what is done with the other gases produced during the digester’s process, what volatile organic compounds are on site and what would happen in the event of an explosion or other mishap. Novilla’s co-CEO’s reiterated that no hazardous materials are stored on site – they said the only volatile organic compound involved in the process is methane, which is not stored on site. They said the methane is injected into the pipelines, and hydrogen sulfide is converted to sulfur dioxide and released at levels considered safe. Additionally, carbon dioxide is safely discharged from the facility.
The proposed facility would be regulated by the state and required to record all emissions and submit that data to the state. The state also conducts regular on-site inspections for such facilities — sometimes unannounced.
Winneshiek County Engineer Michael Kueny reportedly recommended denial of the rezoning request. However, his concerns were related to a conditional use permit regarding manure pipelines and cleanouts, according to the unofficial meeting minutes, which Planning and Zoning Director Tony Phillips said is separate from the information needed for the zoning request.
The commission agreed to table its decision after the lengthy discussion — the commission ultimately adjourned shortly after 10 p.m. — and take up the issue again during a special meeting the night of July 16. If the commission approves the request, the proposal will then be brought before the Winneshiek County Board of Supervisors during a public hearing, which will be announced at a later date.
Submit A Comment
Fill out the form to submit a comment. All comments require approval by our staff before it is displayed on the website.