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While carbon dioxide tends to be a significant focus of controlling climate-affecting emissions, methane produced by livestock such as bovines is also considered a major contributor to climate change and is a considerable focus of emissions research.
A new clean technology system based on the red algae Asparagopsis taxiformis has recently emerged as a potential solution for addressing the large amounts of methane emissions produced by the livestock industry. A US-based start-up company called Symbrosia has developed a seaweed supplement that is said to be capable of significantly reducing a cow's methane emissions.
How Does Methane Affect Climate Change?
Methane is the main ingredient in what is called 'natural gas' and is dozens of times more effective at trapping heat in the atmosphere than carbon dioxide. Even though the amount of methane in the atmosphere is much smaller than the amount of carbon dioxide, methane has a considerable impact on climate change.
In addition to being a greenhouse gas on its own, methane also has problematic effects after it enters the atmosphere. Specifically, it affects the amounts of atmospheric water vapor, ozone, and carbon dioxide present in the atmosphere.
Although data from direct atmospheric measurements of methane only goes back a few decades, climate researchers have been able to track levels through the fossil record. Studies have found there has been a significant increase in atmospheric methane since the dawn of the Industrial Revolution in the middle of the 18th century.
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Annual emissions from the livestock industry are equal to more than 7 gigatons of carbon dioxide, which is approximately the same as emissions from transportation. Around 40% of this is generated during digestion.
The digestive systems of cattle and other livestock is based on a process called enteric fermentation. Digestive tract microbes digest and acquire energy from the grasses that these animals eat. However, the same method also produces hydrogen, which another group of microorganisms consumes, and this generates methane as a by-product. Approximately 95% of the methane released by livestock escapes through their nose and mouth.
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According to the United Nations Food and Agriculture Organization, livestock represents about 14% of all human-created greenhouse gas emissions, with 39% of that coming from the enteric fermentation process.
Fighting Methane Production with Seaweed
Scientists are working on ways to reduce methane emissions from livestock, including placing microbes from low-methane-emitting animals into bovine intestinal tracts and breeding animals based on low methane emissions.
The most promising research so far has been associated with feed additives. In particular, a 2016 study published in the journal Animal Production Science revealed that incorporating a small amount of supplement made from the red algae Asparagopsis taxiformis into a cow's diet could lower methane production by 99%.
Awarded the prestigious 2019 MIT Water Innovation Prize for their work, Symbrosia has leveraged the findings of that study to develop a system that grows the methane-reducing algae. The system is based on a symbiotic relationship between the algae and shrimp. One of the system's two tanks contains algae while the other contains shrimp. Waste produced by the shrimp flows into the other tank, where it functions as a fertilizer for the algae. In turn, the algae filter the water in their tank, and the clean, oxygenated water is sent to the shrimp. The system has minimal water loss and does not produce waste.
Video Credit: HATCH/YouTube.com
In addition to producing methane-reducing algae, the Symbrosia system also has the bonus of growing organic shrimp. According to a report from MIT, Symbrosia plans to sell the algae to companies that make livestock feed for $1.60 (€1.44) per pound and sell shrimp to restaurants for $24 (€22) per pound.
With a pilot project just getting underway, Symbrosia has said it plans to place commercial operations of its system close to major livestock areas to minimize the carbon footprint of the company.
Symbrosia is not the only start-up looking to take advantage of the connection between a particular type of red algae and lower methane emissions. A Vietnam-based project called Greener Grazing by a company called Australis Aquaculture is also said to be developing a different kind of algae-growing system.
Video Credit: Australis Barramundi/YouTube.com
In the Greener Grazing system, algae would be grown off the coast of Vietnam in plastic netting suspended around one meter underwater. This is near enough to the surface to allow for photosynthesis but deep enough to avoid issues caused by waves.
Incidentally, a Dutch-based company called DSM is developing a synthetic methane-inhibiting supplement called Bovaer, which has been found to reduce an equivalent of 1 ton of carbon dioxide per cow per year.
Video Credit: DSM/YouTube.com
Continuing Research into Methane Reduction
While many companies are looking to commercialize the research that shows a connection between red algae and lower methane emissions, there are also ongoing research efforts looking to perform a more in-depth investigation of that same study.
The University of California is trying to determine if "more potent" strains of red algae can be used to reduce the amount of supplement needed to cut emissions significantly.
The UC Davis effort is particularly motivated by a California law passed in 2016 that mandated a 40% reduction in the Golden State's methane emissions. The law has placed pressure on farms and businesses while simultaneously creating opportunities for organizations such as the UC Davis lab.
In their research with Asparagopsis taxiformis, the California researchers discovered that the supplement appeared to lower the appetites of cattle. This is a significant issue because eating less means the cows produce less meat and milk. Figuring the cows found the seaweed too salty, the UC Davis team said they were able to come up with a solution: adding molasses to sweeten the supplement.
Having to add this extra ingredient inspired the team's current work of trying to find a more potent seaweed supplement that can be effective at smaller doses. The team has been working with two dozen beef cattle to find out if a more potent strain of algae can lower emissions while not affecting cows' weight, milk production, meat production, and quality.
The UC Davis team noted that blocking the production of methane could have a benefit for farmers as more consumed carbohydrates would stay in the cows instead of being emitted as a waste product.
References and Further Reading
Winn, Z. (2019) Water Innovation Prize goes to startups targeting methane and wastewater. [Online] MIT News. Available at: https://news.mit.edu/2019/water-innovation-prize-methane-wastewater-0423 (Accessed on 21 April 2020).
Temple, J. (2018) Seaweed could make cows burp less methane and cut their carbon hoofprint. [Online] MIT Technology Review. Available at: https://www.technologyreview.com/s/612452/how-seaweed-could-shrink-livestocks-global-carbon-hoofprint/ (Accessed on 21 April 2020).
Mernit, J. (2018) How Eating Seaweed Can Help Cows to Belch Less Methane. [Online] Yale Environment 360. Available at: https://e360.yale.edu/features/how-eating-seaweed-can-help-cows-to-belch-less-methane (Accessed on 21 April 2020).
Dean, J. (2018). Methane, Climate Change, and Our Uncertain Future. [Online] Eos. Available at: https://eos.org/editors-vox/methane-climate-change-and-our-uncertain-future (Accessed on 21 April 2020).