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gen-free digester where manure from the dairy is pumped and held for about three weeks. Naturally occurring microorganisms break down the organic material, producing methane-rich biogas while leaving behind nutrient-rich digestate that is returned to the farm as fertilizer and bedding.
“ We have sensors all over so we can monitor gas pressure, liquid levels, the dome height— just to make sure that everything’ s correlating to how we want it to run,” Torborg said.
The raw biogas then moves to an upgrader, where moisture, hydrogen sulfide, carbon dioxide and other impurities are removed, increasing the methane content from about 60 % to nearly 100 %.
“ The kindergarten-level explanation is essentially we make fizzy water, and then we de-fizz the water,” Torborg said.“ The different pressures at which we release the bubbles, the different molecules just stick to the water at those different pressures, so that’ s how we end up with pure natural gas.”
The finished renewable natural gas
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is compressed into trailers operated by Dooley’ s Petroleum Inc. Every other day, loaded trailers leave the dairy for Paynesville, where the gas is injected into the natural gas distribution system for homes and businesses.
The Malecha project is one of two BioGasCo facilities currently operating in central Minnesota. The company is also developing additional projects while focusing on dairies that larger developers often overlook.
“ We’ re just a local Stearns County-based Central Minnesota company,” Evens said.“ We’ re not huge... we just got our small team, and we run these two plants, hopefully working on the third here.”
BioGasCo builds, owns and operates anaerobic digestion and renewable natural gas projects, serving as both developer and general contractor. Company officials said they assemble proven technologies from around the world to reduce construction costs while making projects economically feasible for midsized dairies. AURI officials said anaerobic digestion
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can provide additional farm income, create renewable energy, reduce greenhouse gas emissions and recycle nutrients back into crop production.
The digester partnership does not change the day-to-day realities of dairy farming. But it gives the operation another revenue stream while turning a constant byproduct of the dairy into renewable energy.
As trucks continue leaving the farm every other day carrying renewable natural gas instead of simply hauling away waste, the towering dome and steel column have become visible reminders of how traditional agriculture and new technology can work together.
“ What we’ re doing is nothing special,” Todd said.“ The only thing special about us is just the people who work with us and for us.”
Louise agreed, praising the partnership that allows each side to focus on its strengths.
“ The dairy takes care of what it needs to, and they take care of what they need to,” she said.
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Jeffrey Hage / Stories of the Heartland
The biogas upgrading tower removes carbon dioxide, hydrogen sulfide and other impurities from raw biogas, producing renewable natural gas.
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