Cow dung: The answer to fuel supply?
Manure from livestock could be a beneficial renewable energy supply
Thursday, 24, Jul 2008 08:02
Turning animal faeces into a fuel source could generate enough electricity to meet up to three per cent of North America's entire energy needs, scientists claim.
A study in the Institute of Physics' journal Environmental Research Letters says that fuel from livestock manure could also help to bring about a significant reduction in greenhouse gas emissions (GHGs).
The research is the first attempt to quantify how much electricity can be generated by livestock manure.
Left to decompose naturally, livestock manure emits two particularly potent GHGs – nitrous oxide and methane.
The study created two hypothetical scenarios and quantified them to compare energy savings and GHG reducing benefits.
The first is 'business as usual', with coal burnt for energy and manure left to decompose naturally.
The second is one where manure undergoes a process called anaerobic digestion to create biogas and is then burnt to offset coal.
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 US could produce approximately 100 billion kilowatt hours of electricity, enough to power millions of homes and offices, the study said.
Commenting on their findings, researchers Dr Michael Webber and Amanda Cuellar from the University of Texas at Austin, said: "In light of the criticism that has been levelled against biofuels, biogas production from manure has the less controversial benefit of re-using an existing waste source and has the potential to improve the environment.
"Nonetheless, 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."