Anaerobic digesters are a hit among the renewable energy crowd, but do they make economic sense on dairies? Researchers at the University of Vermont took a look at that question, and published a case study on the Central Vermont Public Service (CVPS) Cow Power program in the October Journal of Dairy Science.

They examined the mechanism for CVPS, dairy farms, electricity customers and government agencies to develop and operate the program since 2004. The case-study reviewed the cost and return for the participating dairy farms, and assessed their cash-flow over a period of seven years under different scenarios.

With six dairy farms in the program generating about 12 million kilowatt-hours of electricity per year and more than 4,600 CVPS electricity customers voluntarily paying premiums of $0.04 per kilowatt-hour, or a total of $470,000 per year, the Cow Power program does represent a successful and locally sourced renewable energy project.

However, the study also confirms that while it is technically feasible to convert manure to energy on farms, the economic returns are highly dependent on the base electricity price, premium rate, financial support from government agencies and other organizations and sales of the byproducts of methane generation.