As the buzzword of the year seems to be sustainability, the addition of anaerobic digesters on dairy farms across the U.S has been making headway. In a Michigan State University extension article, assistant professor Jaime Luke explained how Michigan is taking legislative steps to make it easier for farms to incorporate digesters into their operations. However, it isn’t that easy as economic and regulatory challenges continue to get in the way of the adoption process. Recently, two bills were passed by the Michigan House Agriculture Committee. “Included in the bills are training and recordkeeping standards for anaerobic digester operators and a 180-day deadline for anaerobic digester permitting decisions within the state, among other regulatory provisions,” Luke noted.

Anaerobic digesters break down livestock manure and other feedstocks like food waste in an oxygen-free environment. Because of this, two by-products are created: digestate, which can be used as fertilizer, and biogas, which can be converted into electricity or renewable natural gas. These by-products can serve as an energy source and are also environmentally friendly, making them the perfect combo for a dairy farmer who may be looking to capitalize on what they have as margins continue to tighten. Because of this, more anaerobic digesters are beginning to pop up around the U.S. “According to AgSTAR data, there were 400 operating anaerobic digesters in the country in June 2024, with an additional 73 under construction. Of the 400 operational anaerobic digesters, 86% serviced dairies, 13% hog operations, 2% poultry operations, and 2% beef operations,” she said.

Figure 1. Number of manure-based anaerobic digesters operating in the U.S. (updated through June 2024)

California leads the nation in terms of the number of digesters, with 31% of all systems found in the state. Wisconsin ranks second and is home to 11% of the country’s digesters, with most being for dairy farm use. Michigan has nine anaerobic digesters in operation. Seven of those are used by dairy farms, while the other two process both dairy and swine manure. Altogether, these Michigan systems handle manure from an estimated 22,240 dairy cows and 25,000 hogs throughout the state.

Figure 2. Map of manure-based anaerobic digesters operating in the U.S.

While useful as a tool, installing an anaerobic digester can come at a hefty price, and not just in terms of dollars. A digester is a large upfront investment, and not everyone can afford to install one without the support from grants, subsidies, or off-farm income. Even for farms ready to invest, the rules and regulations required to install a digester are time-consuming.

Because of this, the goal of the bills is to emphasize expectations and hold agencies to permitting deadlines, making the process more streamlined and accessible. Still, experts agree that policy change alone may not be enough. “Ultimately, economic incentives must be aligned for producers to adopt,” Luke warned.

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