U.S. dairy production has continued its decades-long consolidation into fewer, larger operations[1],[2]. Recent news coverage has suggested that the growth in anaerobic digester adoption over the past decade may have encouraged this expansion[3],[4]. Whether digesters influence herd-size decisions, however, has not been well documented.
To test that claim and understand what drives adoption, Cornell researchers surveyed U.S. dairy producers who operate digesters about the factors behind their adoption decisions and future farm investments. Of 352 surveys delivered, 63 were returned (an 18 percent response rate), representing 15.8 percent of dairy digesters in the U.S. EPA AgSTAR database[5].
Key findings:
- 95 percent of farms did not increase herd size because of their digester.
- Cost share programs remain a top driver of adoption and future investment.
- Long-term markets for renewable energy and carbon credits matter most for new digesters.
- 44 percent of producers plan to reinvest in or build new digester infrastructure.
Producers ranked expected dairy business profit as the most important factor in decisions to expand their herds, followed by the interests of the next generation and labor availability. Digester net revenues played little to no role, and 95 percent of farms did not increase herd size because of their digester. Figure 1 from the peer-reviewed publication shows how producers weighted six factors in these decisions[5].
All digester types, including those that accept other feedstocks with dairy manure (19 percent co-digested other feedstocks with manure), and biogas utilization pathways were represented in the responses received. Just over half (52 percent) of the systems are managed or operated by a third party, and most of those were installed in 2017 or later. Annual milk production per cow among respondents averaged 28,196 pounds, exceeding the U.S. average by nearly 15 percent, which aligns with higher productivity among larger dairy farms[6].
A statistically significant positive correlation between larger herd size and renewable natural gas (RNG) production for off-farm sale suggests that larger operations are more likely to adopt biogas to RNG pathways, rather than biogas to electricity pathways. Most dairy manure digesters generate more biogas energy than is used on the farm, resulting in some off-farm use whether electricity or RNG is produced.
