Abstract

Livestock's manure can be a valuable resource or an environmental pollutant. In fact, the tons of manure excreted daily can't be always used as fertilizer because of their high nitrogen content. The solution to this problem can be in the manure itself: a waste-processing system - essentially a small power plant - installed on farms and which uses bacteria to digest the waste and burns methane to produce electricity. This process is called anaerobic digestion, which, by defi nition, is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. It is used for industrial or domestic purposes to manage waste and/ or to release energy. Studies have estimated that converting manure from the 95 million animal units in the United States would produce renewable energy equal to 1% of the total energy consumption in the nation. Because more and more farmers and communities are interested in generating renewable energy from farm waste, there is a growing need for information on the economic feasibility and sustainability of such programs.