Economic and Environmental Manure Solutions

co-generation

Technology Description (from Wright, 2001)
The biogas produced in anaerobic digestion of dairy manure is expected to be about 60% methane and 40% carbon dioxide, with approximately 0.2 – 0.4% hydrogen sulfide.  In general biogas from manure digestion is considered a low quality gas due to its relatively low heating value (40% less BTU value than pure methane) and its corrosive qualities (the hydrogen sulfide converts to sulfuric acid at low temperatures).  Nonetheless, digeser biogas can be used to generate both electricity and heat on site through engine generator sets designed to run on this type of fuel. 

Sale of energy to the power grid in NY State is governed under ‘Net Metering’ regulations.  In the event of excess energy sales back to the grid, an induction generator will be needed that will run off the signal from the utility and allow parallel hook up with the utility. 

Generator electric production depends on the amount and quality of the biogas as well as the efficiency of the engine generator.  Typically, 33-38 kWh/day will be produced per 1,000 ft3/day of biogas produced (Koelsch et. al. and EPA). 

Sources of Additional Information
A guide to technology providers (including engine manufacturers) can be found at the USEPA AgStar website www.epa.gov/agstar

References
EPA.  “A Manualfor Developing Biogas Systems at Commercial farms in the United States.”  1997.  U.S. Environmenal Protection Agency.  EPA-430-B-97-015.

Koelsch, R.K., E.E. Fabian, R.W. Guest, J.K. Campbell.  “Experience with Three Anaerobic Digestion Systems on Commercial Dairies.”  1989. ASAE Meeting Presentation. ASAE, 2950 Niles Rd., St. Joseph, MI  49085-9659.  Paper No. 896550.

Wright, P. E..  “Overview of Anaerobic Digestion Systems for Dairy Farms.”  Proceedings from “Dairy manure Systems:  Equipment and Technology” Rochester, NY  March 20-22, 2001  NRAES Publication No. NRAES-143  pp. 93-109

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Cornell University

Department of Biological and Environmental Engineering

Ithaca, NY 14853

Fax: 607.255.4080