Converting livestock manure into a domestic renewable fuel source could generate enough electricity to meet up to 3% of North America's entire consumption needs and lead to a significant reduction in greenhouse gas emissions, according to research published July 24 in the Institute of Physics' Environmental Research Letters.
The journal paper, "Cow Power: The Energy & Emissions Benefits of Converting Manure to Biogas," has implications for all countries with livestock as it is the first attempt to outline a procedure for quantifying the national amount of renewable energy that herds of cattle and other livestock can generate and the concomitant GHG emission reductions.
Livestock manure, left to decompose naturally, emits two particularly potent GHGs: nitrous oxide and methane. According to the Intergovernmental Panel on Climate Change, nitrous oxide warms the atmosphere 310 times more than carbon dioxide; methane does so 21 times more.
Through anaerobic digestion, similar to the process by which compost is created; manure can be turned into energy-rich biogas, which standard microturbines can use to produce electricity. The hundreds of millions of livestock inhabiting the U.S. could produce approximately 100 billion kilowatt hours of electricity, enough to power millions of homes and offices, according to the paper.
Since manure left to decompose naturally can have a damaging effect on the environment, this new waste management system has a net potential GHG emissions reduction of 99 million metric tons, wiping out approximately 4% of the country's GHG emissions from electricity production.
Authors of the paper, Dr. Michael E. Webber and Amanda D. Cuellar from the University of Texas at Austin, noted that the "logistics of widespread biogas production, including feedstock and digestates transportation, must be determined at the local level to produce the most environmentally advantageous, economical, and energy efficient system."