Food Engineering

Turn organic waste into energy

May 1, 2010
With help from Cargill, Bettencourt Dairy’s B6 farm installed a digester/generation system, which will generate between 1 and 1.3 million kilowatt hours per month. Source: Mark Luinenberg, photographer.


According to the US EPA, one full-size dairy cow, depending on the breed, will put out somewhere between 120 to 150 lbs. of manure on a daily basis. Multiply this number times 6,000 cows, and the result is the amount of manure being processed by an anaerobic digester at Bettencourt Dairy’s B6 farm in Jerome, ID. It all adds up to 1 million kW-hours of electricity each month.

Farms aren’t the only winners with this technology. Any processing plant with a large amount of organic waste (BOD) can turn it into clean energy.

Cargill, which has digesters at 11 of its meat processing plants, partnered with Bettencourt to design and build the dairy’s second digester/power generation system. The digester breaks down the waste and feeds methane to a series of generators that create one million kilowatt-hours of electricity per month. The electricity is fed into the power grid and is enough to continuously supply about 1,100 homes.

The digester from Cargill’s Environmental Finance group operates by feeding manure into a large, sealed, oxygen-free vessel. Bacteria in the tank break down the waste, creating methane. The Jerome project follows the successful implementation of an anaerobic digester operating since 2008 on a 10,000-cow Bettencourt Dairy farm located nearby in Wendell. The Wendell digester creates 1.3 kW-hours of power per month, which is sold back into the power grid. Co-products from the process are being made into organic fertilizer and solids for animal bedding.

Along with generating the electricity to feed back into the power grid, the Jerome project will generate carbon credits from reduced methane emissions into the atmosphere. Cargill is currently in the process of selling the first 28,000 tons of emissions offsets generated by the initial Wendell digester.

At peak capacity, the Jerome digester/generation facility is expected to produce 1.3 million kilowatt-hours per month. The two Bettencourt Dairy digester projects and a third digester project on a 5,500-cow dairy near Idaho Falls are all part of a broader initiative by Cargill Global Emissions, which seeks to enhance direct participation in renewable energy projects.

Cargill processing plants use biogas generated by anaerobic digester systems to fuel plants’ boilers and decrease natural gas demand. The processor estimates more than 20% of all the energy consumed in its North American beef operations is created by this renewable resource.