Cows: a source of natural gas?

13th February, 2014 by Anonymous

Argentinian researchers believe rural communities could use methane from ruminants as an alternative energy source.

Greenhouse gas emissions associated with livestock supply chains account for 14.5% of all human-caused GHG releases, according to a report published by the UN Food and Agriculture Organisation in 2013. Of this, 39% is produced by ruminants – mammals that acquire nutrients from plant-based food by fermenting it in a specialised stomach prior to digestion. The average cow produces 1,100 litres of gas each day, of which around one-fifth is methane.

Previously, scientists have looked at ways to minimise the amount of gas ruminants produce, with nutritional additives a popular approach. But researchers at Argentina’s National Institute of Agricultural Technology (INTA) have come up with a novel solution: harvesting the gas as a renewable energy source. The team at INTA has shown that it is possible to capture the gas by inserting a tube into a cow’s stomach (using what they stress is a pain-free procedure) and storing the gas produced by its digestive system in a balloon-like bag on the animal’s back.

Methane has a high calorific value (the amount of heat produced by its complete combustion), meaning it is a potentially valuable source of renewable energy. Over a 24-hour period, one cow produces the methane equivalent of 300ml of oil, or enough to power a refrigerator for a day, according to Guillermo Berra, Head of Argentina’s National Institute of Agricultural Technology (INTA) animal physiology group.

Berra suggests that capturing the gas and using it at as an energy source could benefit rural communities where conventional energy is difficult to access, or appeal to developed countries eager to reduce their carbon footprint. “As an energy source it is not very practical at the moment”, he admits, “but if you look ahead to 2050, when fossil fuel reserves are going to be in trouble, it is an alternative.”

A significant barrier to scale is animal welfare, given that the process involves the surgical placement of a tube into an animal. “I doubt public opinion would be in favour of this on welfare grounds”, says Dr Jon Moorby, Principal Investigator at the Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, who is currently developing nutritional additives to reduce methane emissions from ruminants. – Rohan Boyle

Photo credit: National Institute of Agricultural Technology

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