Backpack-Wearing Cows: A New Alternative Energy Source?

April 19, 2017

If you’ve been paying attention to environmental news, you may have seen that methane gas has been a rather controversial topic in the last year. In March 2017, the EPA announced that it has withdrawn its request that oil and gas operators report their methane gas emissions to the agency.[1] On the other side of the spectrum, just six months ago California signed into law Senate Bill 1383, which set forth goals for significant methane gas emission reductions in a variety of industries operating in the state.[2] Both of these actions have received substantial criticism and have made it clear that methane gas is a polarizing issue at the moment. Given this contentious debate, I thought a more lighthearted, but related, topic of interest might be of some interest: cows wearing backpacks. More specifically, cows wearing backpacks designed to capture the methane gas that cows emit through eructation and flatulence. The designers of the “methane backpack” hope to use the captured methane as a biofuel to help power the farms on which the cows live and reduce methane emissions in the cattle industry.


First off, a rough explanation of enteric fermentation helps to understand the current situation regarding cattle and methane. Enteric fermentation is the process by which methane is produced by the cow. In the most basic terms, enteric fermentation is microbial fermentation that takes place in the digestive system of cows when they eat.[3] This process is used to breakdown the cellulose of cell walls of certain grasses and vegetation into digestible nutrients.[4] Within the cow, enteric fermentation takes place in the rumen, which is the first and largest chamber of the cow’s stomach.[5] The rumen is where the majority of the digestion takes place and is home to a host of microorganisms including bacteria, protozoa, and fungi.[6] These microorganisms cause the fermentation that breaks down the carbohydrates into soluble products that can be metabolized by the cow. Enteric fermentation is important because methane gas is produced as a byproduct during the process, which is either exhaled, eructated, or released in flatulence by the cow into the atmosphere.[7]


Why should we care about methane being emitted into the atmosphere? In summary, methane gas is the second most prevalent greenhouse gas emitted by human activity (the livestock industry’s methane emissions are considered part of human activity by the EPA).[8] While less prevalent than carbon dioxide, methane gas has a significantly higher greenhouse effect and it is estimated that methane contributes more than one-third of today’s anthropogenic warming.[9] However, as mentioned earlier, the EPA has made it clear that methane is not a top priority for the agency at the moment. Nevertheless, this may not always be the case. If the politics in Washington shift again, which they inevitably will, we may see the EPA reverse itself on its stance towards methane emissions. Further, in recent years several states have taken action to reduce methane gas emissions, including emissions in the livestock industry and the oil and gas industries. So, methane emissions regulations will likely be relevant in the coming years and successful mitigation techniques in one industry may be relevant in others. For example, if new developments can significantly reduce methane emissions in the livestock industry, then the state may not see the need to place harsh regulations on other methane-producing industries, e.g. oil and petroleum operations.


On top of the environmental concerns, the methane backpacks also serve the purpose to provide power “for activities such as cooking, lighting a home or even driving a car on the farm.”[10] So, the methane backpacks serve the dual function as an alternative energy source and a method for greenhouse gas mitigation.


Now, how do these backpacks work? Researchers at the Argentina National Institute of Agricultural Technology (INTA) designed the backpack to attach to a cow’s digestive tract and collect the gasses emitted.[11] The backpack connects directly to the cow’s rumen (chamber of the stomach) and collects the methane before it is emitted into the atmosphere.[12] Although the methane backpack is still in development, researchers at INTA report that the backpack collects around 300 liters of methane a day, which is condensed into a usable biofuel.[13] According to INTA, 300 liters of methane is enough to power a refrigerator or car for 24 hours.[14] So, for now the methane backpacks are only really effective as an additional power source for smaller farms. However, the researchers hope that this technology will lead to further methane capturing techniques that can be implemented on a larger scale.[15]


In conclusion, methane backpacks on cows may be a bit absurd looking, provide only a small mitigating effect on methane gas emissions, and might not be a revolutionary new power source, but it is certainly a great representation of creativity in the alternative energy world and may be a stepping stone to significant developments in the future.



[1] Environmental Protection Agency, (last visited Mar. 27, 2017).

[2] Sharon Bernstein, California Restricts Pollutants from Cow Flatulence to Diesel Emissions, Reuters (Sep. 19, 2016),

[3] Environmental Protection Agency, Emissions Factors & AP 42, Compilation of Air Pollutant Emission Factors, Chapter 14.4 Enteric Fermentation (2008).

[4] Fuller, M.F., Encyclopedia of Farm Animal Nutrition 488 (2004).

[5] Fuller, supra note 3, at 488.

[6] Id.

[7] Andy Thorpe, Enteric Fermentation and Ruminant Eructation: the Role (and Control?) of Methane in the Climate Change Debate, 93 Climatic Change 407, 411 (2009).

[8] Environmental Protection Agency, view-greenhouse-gases#methane (last visited Nov. 28, 2016).

[9] Global Methane Initiative,

analysis_fs_en.pdf (last visited Nov. 28, 2016). (Other sources have estimated methane’s contribution slightly lower. For example, The Environmental Defense Fund lists methane as contributing 25% of today’s man-made global warming. Environmental Defense Fund,

methane-other-important-greenhouse-gas (last visited Nov. 28, 2016)).

[10] Teodora Zareva, This Is How You Turn Cow Fart Gas Into Energy, Big Think (2015),

[11] Jason L Strongin, Could Less Gassy Livestock Be a Cash Cow?, Bloomberg (Aug. 18, 2016),

[12] Zareva, supra note 8.

[13] Id.

[14] Ben Schiller, These Backpacks for Cows Collect Their Fart Gas and Store it for Energy, Fast Company (Apr. 15, 2014),

[15] Id.

Brantley Smith is a second year law student at The University of Texas School of Law. He graduated with honors from The University of Texas in 2014, and will be heading to Dallas after this summer to clerk with Gardere Wynne Sewell.