Viability of Methane Production by Anaerobic Digestion on Iowa Swine Farms

and Implications Energy production and use has long been a major policy issue in Iowa. The 1990 Comprehensive Energy Plan for Iowa established two statewide goals around which current energy policy is structured: • to meet all future demand for energy by increasing efficiency rather than supply, and • to increase the use of alternative energy resources from 2% of Iowa's total energy consumption to 5% by the year 2005 and 10% by 2015. A currently available and potential alternative energy source that can move Iowa nearer these goals is methane recovery. It is projected that about 5 MW of energy are produced from methane gas in Iowa (8). This represents a minuscule amount of the energy produced in Iowa. Most of this energy comes from methane recovery at landfills and municipal sludge digesters, but some is produced by methane recovered from anaerobic digestion at industrial sites such as meat packing plants.. Chapter 473.3 of the Iowa Code states that the goal of Iowa energy policy should be to develop and promote programs that promote energy efficiency and conservation " through the development of indigenous energy resources that are economically and environmentally viable. " The purpose of this report is to evaluate the economic viability of methane production from anaerobic digestion of swine manure. This analysis will use a series of budgets to accomplish this purpose. However, with the stated purpose of Iowa's energy policy in mind, this report also will identify potential environmental viability issues related to the economics of methane production by anaerobic digestion. Anaerobic digestion occurs when bacteria produce biogas by decomposing an organic matter in an environment without air (14). Interest in on-farm biogas generation is hardly a recent phenomenon. Prompted by the energy crisis of the 1970s, several farm operations throughout the country—including Iowa—experimented with anaerobic digesters. This experimentation was frequently marked by dissatisfied operators and/or system failure. The technology was frequently concluded to be a promising idea, but only technically and economically feasible to those who were willing to spend a great deal of time tinkering with the technology on the farm. Like many other alternative energy technologies, the rate of anaerobic digester failure is high. Historically, there is a 63% chance in the United States for a farm to install a presently nonoperating digester (11). Many of the digesters that failed were those installed during the energy crisis of the 1970s. This failure …