Agricultural Digesters and Paul Percy of Stowe, Vermont ask questions about Paul’s future digester
to Brenden Williams of technology provider Biogest.

Although Vermont has 14 operating farm digesters, many questions remain. Much of this comes from northern Vermont’s geographic isolation from suppliers who provide generators and the digester itself. When issues occur, especially with the CHP (combined heat and power unit), suppliers must travel many hours from places like Lancaster County, PA. This means costly operation interruptions and travel charges.

In addition to this, most of Vermont’s digesters were built ten years ago during a unique period of large state grants. Along with two established American manufacturers, inexperienced developers, some who had never launched a digester, appeared. Since all manufacturers are headquartered far from Vermont, farmers did not have a good sense of their capabilities and a few defective systems were built.

Time has passed and biogas technology has advanced from ten years ago. Highly experienced international manufacturers like Biogest and MAN/Clarke generators have entered the North American market greatly improving the farmers’ options. Energy output has been increased, digesters can be remotely monitored by smart phone and new treatments for H2S build-up are available. (H2S problems effected Vermont’s digesters for years and in one case, caused a digester to be shut down).

In addition to this, the Inflation Reduction Act of 2022 has stimulated the industry and developers like Agricultural Digesters LLC to increase their outreach. In fact, our headquarters is just outside Burlington, Vermont. Conveniently located to service the many dairy farms in Vermont and the northeast.

(:26) Basic insulation of digester is described.

(1:00) Biogest maintains internal heat by utilizing a boiler or heat from the CHP. Their systems work in Idaho with winters as severe as Vermont.

(2:32) A key issue for existing Vermont digesters is maintenance, especially of the generator. For this reason, Agricultural Digesters has established a separate, direct business relationship with the CHP supplier Clarke, with offices in northern Massachusetts. This means either Biogest or Clarke can respond promptly to the needs of our farms.

(1:31) Recent industry improvements include carbon filtration for H2S mitigation and improved agitation from “long shaft” stirring blades leading to better mixing and energy production. Not mentioned is visual monitoring of conditions so issues can be identified before becoming problems. Remotely by the farmer, manufacturer or smart phone.