King County wins grant to plan manure digester

System would improve dairy waste management, capture methane for energy

Cow power on the Enumclaw Plateau is getting a boost thanks to a $93,900 federal grant for King County's efforts to help family-run dairies, improve manure waste management and generate a new source of energy.

King County Executive Ron Sims said the U.S. Department of Agriculture Rural Business Enterprise Grant will be used to address the technical challenges of developing and building a system to collect and process the tens of thousands of gallons of manure that dairy cows produce each day on the Enumclaw Plateau.

"We are excited about the possibility of bringing new technology to the Enumclaw Plateau in this pilot project," Sims said. "By focusing our efforts on reducing nutrients, reducing odor, creating electricity and safeguarding water quality, we are taking significant steps toward ensuring the future of family dairies in King County."

The heart of any system is a manure "digester" that converts methane gas from cow manure into electricity. The digester also creates a marketable fiber that is an excellent composting material. The remaining liquid that is separated from the gas and solids during processing will continue to be used as fertilizer for farmers' crops but with significantly less odor.

Sims said the federal grant funding will be used to identify which manure digester system is most appropriate for the Enumclaw Plateau, to map out a system to aggregate the manure, and to identify the best site for such a facility. The work is expected to be completed by the end of the year.

"This project is very good for agriculture, very good for economic development, very good for the environment and it is a source of both renewable energy and sustainable development," said Chris Cassidy, rural business and cooperative programs director and Renewable Energy Coordinator for Rural Development at the USDA's Washington office.

Dairy cow manure is currently stored in lagoons or large tanks on individual farms and later sprayed onto fields as a fertilizer. This practice can lead to complaints from neighbors about excessive odors. Runoff from sprayed fields can also deteriorate local ground water and create problems for salmon and other fish species.

Sims said King County's initial goal is to build a centralized waste digester that is connected via pipes to six to eight dairy farms. Once it is built, the system could easily be modified to handle manure from additional dairy farms.

King County has had a number of important partners during this initial stage of the manure digester project, including the dairy farmers of the Enumclaw Plateau Energy Northwest and its team, Washington State University, Seattle City Light, the USDA's Natural Resource Conservation Service in Renton, the King Conservation District, and the Department of Community Trade and Economic Development .

"Our partners deserve so much credit for their efforts in keeping this project moving forward," Sims said. "We are grateful for their continued support."

The King County Department of Natural Resources and Parks (DNRP) is already involved in projects to turn methane gas from its wastewater treatment plants and solid waste landfill into electricity. The dairy biogas digester project builds on those successes.

For more information about this project , contact Doug Howell in the DNRP Director's Office, at 206-263-6295 , or e-mail doug.howell@kingcounty.gov.