Energizing Michigan

Overview

Anaerobic digesters are designed to compost organic waste in the absence of oxygen, an anaerobic process. In process methane and carbon dioxide are the main products generated by microbes that are digesting the waste. This gas from the digester can be used in several ways including burning for heat and using in an engine to turn a generator to make electricity.

A common source of organic waste used in digesters is animal manure. Other sources of organic materials include waste from food processing plants, sewage sludge, and yard waste. After the organic waste has been run through the digester, most of the nutrients needed to fertilize crops are still available for use. If operating correctly, a digester can reduce the order originating from manure.

There are several types of digesters with the more common ones being slurry, complete mix, plug-flow and lagoon. The Ag-Star project of the U.S. Environmental Agency is a good source of information on digesters.

Because of their potential to address organic waste problems and be a renewal energy source, Michigan State University has an ongoing research/outreach project on a dairy farm using a digester.