The Vermont Methane Pilot Program
Since the 1970s, anaerobic methane-digester systems have been installed - not always successfully - on farms to provide electrical power from animal wastes. The Vermont Methane Pilot Program was federally funded from 1999-2004, a six-year period, to explore the potentially more effective new uses of methane recovery technology on Vermont dairy farms.
Project funds were provided by the U.S. Department of Energy and administered by the Vermont Department of Public Service (VDPS), in partnership with the Vermont Agency of Agriculture, Food and Markets (VAAFM). BERC provided grant management services, along with assessment of renewable energy potential.
At the start the project divided its budgeted funds and its work into three areas: 1) project oversight and function; 2) research; and 3) cost share. There was also a broad "outreach" component of the project throughout its six year history. In general, "research" was looked at as the exploration and development of new, not-yet-commercial methane recovery technology solutions. "Cost share" was intended to be the allocation of project funds to support new digester construction projects on specific farms, using commercially available technology. Over time, the importance of providing cost share for demonstration of both commercially mature and new digester technologies became obvious.
The project carried out a number of research tasks. Research by VAAFM looked at methane digesters installed on farms across the U.S. since the 1970s, and found that many of these older-generation systems had failed, and/or were no longer in use. Experiments by a contracted researcher demonstrated that "attached growth" media could speed the digestion of screened manure, while significantly reducing odors. Statewide resource assessment found that, in Vermont, dairy cow manure is the most plentiful of methane feedstocks - all of which might support 28 megawatts of electric-energy generating capacity.
Outreach work and preliminary economic analysis on seven farms suggested that four would have reasonable cash flow with a new methane system, while three would not generate acceptable return on investment. The project found that:
- systems on farms with fewer than 500 cows would be unlikely to be economic;
- odor control and other factors may be as important as economics and energy in farmer decisions;
- with methane systems generating a low rate of economic return, other investments may be more attractive to farmers; and
- new, less costly, faster, and more "user friendly" technology needs to be developed, so that more farms - including smaller operations - can realize attractive benefits from methane recovery technology.
The project funded the non-profit Intervale Foundation to work on development of a small scale digester which, it is hoped, will be scaled up to become an affordable technology for small dairy farms and to develop a standardized test protocol that will be implemented on farms that received project cost share funds. The project also studied the prospect of a manure cooperative and it provided assistance to improve the system at Vermont's sole operating manure digester system, at the Foster Brothers Farm in Middlebury.
The three demonstration systems under construction with help from project cost-share funds involved:
- The 300-cow Hinsdale farm in Charlotte. The innovative design for this system employs a manure grinder, heat exchangers to capture and use waste heat and speed digestion, and steam heat to pre-heat the manure.
- The 1,200-cow Blue Spruce Farm in Bridport. The proprietary commercial system designed and being installed here, by GHD, Inc., uses a whole-manure, mixed plug-flow digester. Solids remaining from the process will be dried for use as bedding, land application, or compost (a potential sales product).
- The 300-cow system at North Williston Cattle Company. This experimental system incorporates existing nutrient-management technology into the design of a factory-built liquid manure digester. The methane produced will be used to make hot water; the farmers and partners hope to add an electricity generator in the near future.
Overall, the project partners realized that successful farm digesters are not just energy-producing systems that happen to use manure - in fact, it may be better to look at them as manure-management systems that produce energy. This view underscores the importance of looking at the digester as one part of the overall farm operation, addressing and impacting multiple issues - including nutrient management, energy, odor, labor, and cash flow.
There is a clear need to make methane digester systems cheaper to install and simpler to operate. Instrumentation and testing are needed to quantify the costs and savings of installed systems, so that farmers are more sure to build systems that make money.
The state agencies involved with the project are continuing to work on making cost-effective farm digesters a reality on more Vermont dairy farms. VAAFM has increased staffing in this area, and intends to further develop new technologies that simplify methane recovery and reduce system costs. VAAFM, VDPS, and BERC are helping Vermont's largest utility design and implement a digester program for farms in its service territory.