Amana Farms makes electricity from manure

An Amana Farms project to turn animal waste into electricity is generating results and reducing greenhouse gases.

Members of the Iowa Power Fund board and officials of the Iowa Office of Energy Independence on Wednesday toured the Amana Farms anaerobic digester system. The $4.9 million facility near West Amana produces methane biogas that powers four electric generators.

John Peterson, Amana Society president and chief executive officer, told Power Fund board members Wednesday that the system produces about 2.6 megawatts of power or 15 percent of Amana Service Co.'s base load electricity in the winter and 10 percent of its power in the summer.

The digester uses feeder cattle manure from Amana Farms and industrial and food processing waste from such industries as Genencor International, Cargill and International Paper's Cedar River Mill in Cedar Rapids.

“Most of the anaerobic digesters that have been constructed in the Midwest use manure from dairy cattle,” Peterson said. “We don't know of any other digester that uses industrial waste for 75 percent or 80 percent of the mix.”

John McGrath, Amana Farms manager, said getting the right recipe of manure and industrial waste has been a challenge. The waste works its way through the digester over a 21-day cycle, generating methane gas and heat as byproducts.

“Iowa State University has agreed to build three scale anaerobic digesters that will use a 60-day cycle,” McGrath said. “If an industry offers us a new waste product, we can test it using the smaller digesters to assure there is no toxicity or adverse effect on the process.”

The moisture content of the methane is substantially reduced to improve its performance as a fuel. The excess 100-degree heat is used to heat buildings housing the renewable energy facility and a nearby house.

McGrath said the heat, which could reach 180 degrees, may eventually be used for such farm tasks as grain drying.

Fred Hubbell, chairman of the Power Fund board, said the Amana Farms anaerobic digester system will help Iowa deal with manure disposal.

“If we can find an economical way to convert manure into energy, it's a great benefit for the state,” Hubbell said. “Using food and industrial waste that would go to the landfill is an added benefit.”

McGrath said Amana Farms will qualify for carbon credits because it is removing methane - a greenhouse gas - from the atmosphere. The carbon credits would repay the state for a portion of the Power Fund financial assistance.

The Power Fund board approved $1 million for Amana Farms to construct the anaerobic digester. The project's required $3.8 million in matching funds was provided by $3.5 million from the Amana Society Inc. and $500,000 from the U.S. Department of Agriculture.