What is the energy potential from manure produced by livestock?
Most references on bomb calorimeter studies of manure indicate about 7,500 BTU/lb of manure dry matter. This value is similar to the energy in raw feedstuffs. One finishing pig will consume about 600 lb of feed. The energy content of the feed is about 5 million BTU. The pig will excrete about 150 lb of manure dry matter. Energy content of the manure is about 1 million BTU.
The water in manure must be vaporized before the manure will burn. About 1,000 BTU of energy are required to vaporize 1 lb of water. The energy in 1 lb of manure dry matter can vaporize about 7.5 lb of water. This suggests a “break-even” moisture content of 88% w.b. Most manures have an “as-excreted” moisture content in this range.
Moisture content / Available energy,
95% / (11,500) BTU/lb dm
90% / (1,500) BTU/lb dm
88% / 0 BTU/lb dm
75% / 4,500 BTU/lb dm
50% / 6,500 BTU/lb dm
25% / 7,200 BTU/lb dm
0% / 7,500 BTU/lb dm
lb dm: Pound of Dry Matter
Author: John Lory, University of Missouri, based on presentation by Dr. Charles Fulhage, a former faculty member at the University of Missouri based upon information from Dr. Charles Fulhage, former faculty member at University of Missouri