FARM DIGESTER PROGRESS IN WISCONSIN

DAIRY POWER

Casebook provides information on 17 anaerobic digester systems operating in the state, as of June 2008.

Part I

WISCONSIN continues to be one of the leading states in operating farmbased anaerobic digester systems. The Wisconsin Agricultural Biogas Casebook gives a snapshot with some history of the 17 operating anaerobic digester systems in Wisconsin as of June 2008. Information was provided by digester owners, technology suppliers and utilities. General details on the farms covered in Part I are presented in Table 1.

This casebook represents an early step in a larger and ongoing effort to provide coordinated and consistent digester performance information to the general public using uniform methods. The Association of State Energy Research and Technology Transfer Institutions (ASERTTI), USDA Rural Development and EPA AgSTAR program have worked together to produce a standardized performance protocol. Focus on Energy (Focus) has instituted contracting measures in its grant language to enable monitoring and collection of more detailed information for current grant recipients, e.g. system economics, biogas production and electricity production, which can be included in future editions of the Casebook. This twopart article, excerpted from the Casebook, highlights these farm digester operations.

SUMMARY OF THE 17

Herd sizes for operational digester systems in Wisconsin range from about 800 to 4,000 head. Several system types are being installed. A total of seven different digester design companies have active systems in Wisconsin. Table 2 lists details on individual systems and design companies for the farms included in Part I.

Table 3 covers digester ownership and utility contracts. Most digester owners utilize the biogas through an engine generator to produce electricity for sale. Farm-scale biogas systems in Wisconsin have a total installed generation capacity of about 7.3 megawatts. In addition to generating electricity, one farm is flaring the biogas and another is selling it to a third party. Owners of these two operations are part of a group that has plans to install a gas pipeline linkage to allow them to upgrade their biogas …