Methane is an odorless, tasteless, and colorless gas. Lagoons produce about 2,300,000 tonnes per year, with around 40 percent of this mass coming from hog farm lagoons. Methane is combustible at high temperatures and explosions and fires are a real threat at, or near, lagoons. Additionally, methane is a greenhouse gas. The U.S. EPA estimated that 13 percent of all the methane emissions came from livestock manure in 1998, and this number has grown in recent years. Recently there has been interest in technology which would capture methane produced from lagoons and sell it as energy.