Anaerobic Digesters article in Courier Press

Well, you can't get much further from my last blog post than this. Still, be sure to look for a copy of the Prairie du Chien Courier Press Newspaper (not up on the website yet) and my article, "Anaerobic digesters may not always be the solution," which is about a talk I attended regarding anaerobic digesters.

My original title was "Methane Digesters Offer Benefits and Challenges" to reflect somewhat the title and purpose of the talk: “Methane Digesters: Fact and Fiction.” The speaker was James Poehling, a Leadership in Engineering and Environmental Design (LEED) certified and registered professional engineer in Wisconsin for over 30 years. Poehling discussed the science behind digesters-which can convert waste without oxygen (anaerobically) into energy-and talked about the pros and cons of such systems on “concentrated animal feeding operation” or CAFO farms as well as smaller opperations.

Anaerobic digesters are used throughout the world. They are usually under or over ground sealed containers which hold waste and vent methane gas through a pipe at the top. Methane, a greenhouse gas, can be destroyed by “flaring” or burning the chemical as it escapes out the end of the pipe. In China (see image) and India where energy and sanitation infrastructure can be lacking, millions of digesters are used to convert waste products, including animal waste, to fertilizer and energy for home heating and cooking use. Poehling noted that Germany gets 10% of its energy from digesters that run not on manure but on crop waste.

Here in the US, there are about 1,600 digesters at use in industrial settings and around 200 on farms. Some flare the methane to cash in on carbon offset credits. Others find ways to convert methane to energy and send it back into the grid, in essence selling electricity. The City Brewery in La Crosse has had a digester for about 12 years. In January, Gunderson Lutheran announced plans to work with City Brewery to pipe the methane to an engine to generate electricity which could power up to 280 homes. Wisconsin Governor Jim Doyle announced in March he wants to spend $6.6 million in state money on manure digesters in Waunakee and Middleton. The Waunakee digester will be a regional digester, not a single farm affair. It will also remove phosphorous from the waste, helping to prevent water pollution.

Poehling, who had been asked a few years back by a manufacturer to help them determine the heating needs of a small portable digester system that could be used for farms with 100 dairy cows, drew much of his data from USDA’s AgStar website. AgStar is a program jointly sponsored by the U.S. Environmental Protection Agency (EPA), the U.S. Department of Agriculture, and the U.S. Department of Energy to encourage the use of methane recovery (biogas) technologies. As to whether he thought anaerobic digesters were a good idea, Poehling said, “I want people to decide for themselves. Understanding is needed. It takes a lot of talk.”(The photo is of the digester at Wild Rose Dairy in Vernon County).

The Coulee Region Sierra Club's Clean Energy Coalition will sponsor a talk on this topic by Mr. Poehling and the owner of the Wild Rose Dairy, Art Thelen, as well as Niel Kennebeck of Dairyland Power, on April 30, 2009 at 7p.m. in the Ho-Chunk Three River's House (basement) 8th and Main St. in La Crosse.