Our project focuses on reducing emissions of methane and ammonia from the cattle livestock sector. Where does our choice come from? You might be wondering why there is interest in reducing the emission of these two gasses. So, in this piece we will cover the background of our project and look at what environmental and societal events made us decide to work on our SynBio solution: the Cattlelyst biofilter.
Methane and ammonia are two gaseous compounds produced in large amounts from the agricultural sector.
Approximately 78% of the air consists of dinitrogen, an odorless and harmless gas. However, nitrogen can react with other elements to form reactive compounds. The most important reactive nitrogen forms are: ammonia (NH3) and nitrogen oxides (NOx) [1]. Emissions of NH3 and NOx contribute to climate change, biodiversity loss, acid rain, soil acidification and degradation of ecosystem services [2, 3].
At this moment, there is a huge excess of fixed nitrogen in the atmosphere, surpassing earth’s safe operating space, due to the excessive release of nitrogen from human activities [4]. Primary causes for distortion of the N-cycle are large-scale manufacturing of fertilizer and cultivation of leguminous crops [5]. A major part of the nitrogen species from fertilizer and legumes is consumed by livestock, which release this again in the form of ammonia [4].
Ammonia therefore mainly comes from livestock, where the manure is used by the farmers as fertilizer for their land. The ammonia from the manure partly evaporates and is released into the atmosphere. Through precipitation, the ammonia is deposited in the soil over large areas and ends up in groundwater. Excessive nitrogen is a global environmental problem that exceeds the national borders. Reactive nitrogen deposition is quantified through emission density, i.e. the amount of nitrogen emitted per square area. The Netherlands is a tiny, densely populated country, with a gigantic dairy sector. The intensive livestock sector is one of the key reasons why the Netherlands emits four times the average emission of fixed nitrogen per hectares in Europe. Larger countries, like France, house a smaller amount of cows per square kilometer. As a consequence, The Netherlands, having extensive agricultural and livestock sectors, faces the environmental consequences of ammonia excess more heavily [6]. Dramatic issues are emerging: the soil becomes enriched with nutrients, causing plants that normally thrive in nutrient-poor soil to disappear. This in turn leads to a loss of biodiversity, which is especially a problem in the nature reserves such as the dunes and heather fields. Out of a total of 161 Dutch nature reserves protected under EU guidelines, 118 have nitrogen deposition levels that exceed the critical deposition value [7].
Furthermore, ammonia also plays a significant role in acid deposition. ‘Acid rain’ has been recognized as an issue in Europe and North America since the late 1960s and in Asia since the 1980s [8, 9]. Now however, more is known about the negative effects that ammonia has on the environment. The ammonia deposited in the soil, where it is converted into an acid. When this acid is leached into deeper soil layers, it displaces other ions like calcium and potassium. This is not only detrimental for plants, but also for animals which can get calcium deficiencies due to the demineralization of the soil. There have been reports of birds born with broken legs due to this [10].
Given the great impact of nitrogen excess that the Netherlands have been facing and the need to comply to EU rules on acceptable nitrogen levels, the Dutch government issued rules to reduce the nitrogen emission. This was done with a series of measures that were put in place from the 80s and continue being updated in the current days that lead to the so called “Dutch Nitrogen Crisis”.
Since May 2019, the Dutch news channels have been captivated by the nitrogen excess and environmental issues associated. Even the global pandemic could not make the Dutch forget about large-scale deposition of nitrogenous compounds. The largest polluters are traffic, agriculture, construction and industry. This crisis affects citizens in more ways than they had previously realized. In order to tackle such a multi-angular problem, in-depth knowledge of the problem is required. As an iGEM team, we were able to understand the breadth and depth of the nitrogen crisis by linking causes with consequences and conducting interviews.
Once we knew that the livestock sector was the largest contributor to the issue, we decided to focus on ammonia emissions specifically. This choice was particularly relevant as farmers have received substantial scrutiny recently, yet, not only because of their contribution to the nitrogen crisis. Farm animals, cattle in particular, produce considerable amounts of methane (CH4), a greenhouse gas. Methane has a global worming potential (GWP) approximately 30 times larger than the GWP of carbon dioxide over 100 years and directly contributes to climate change [11]. Globally, CH4 emissions from the livestock sector (27%) are second only to methane emissions from the fossil fuel industry (33%) as shown in the figure below from United Nations Economic Commission for Europe (UNECE) [11].
Global methane emission chart per source sector. Note the large contribution to the increase in emissions from the Fossil fuel and the Livestock sectors. (Figure adapted from UNECE [11])
Approximately, 90% of GHG emissions (in carbon dioxide equivalents) in livestock farming comes from the digestion of food in livestock and during manure storage. More than two thirds of all methane emissions in the Netherlands still originate from the agricultural sector today [12-14]. Within the livestock sector, cattle are the biggest producer of CH4: 44% of the livestock CH4 emissions can be attributed to cattle.
The European Commission has proposed a European Climate Law to reduce the GHG emissions by 50-55% by 2030 compared to 1990 levels [15]. Methane emission in the Netherlands need to be reduced of approximately 40% to achieve this goal [16]. All the sectors responsible for methane emission have to cut their CH4 emission of the same percentage according to the regulations. However, the task is quite hard for cattle farmers as emissions from animals cannot easily be tuned.
Although both the levels of methane and ammonia emissions are concerning, the challenges surrounding methane did not get the title of a “societal crisis” as the nitrogen problems did. The nitrogen issue directly involved the general public by implementation of sudden measures and policy changes. Nevertheless, methane emissions are still a big concern. Despite the economic and industrial slow-down caused by the global pandemic, the largest annual increase of methane was recorded in 2020 since 1983, the year in which annual measurements started [17, 18]. Methane emission should be reduced to alleviate its effect on the environment. We cannot afford to reduce methane emissions and neglect ammonia emissions. This way we committed to design Cattlelyst, destined to convert both methane and ammonia.
With Cattlelyst we want to serve nature and citizens. To do so, we integrated ideas, wishes and needs of people affected by the crisis. We have taken our project to farmers, legislators, experts, and ethicists, and with their involvement we have been able to shape our project. If you are wondering what the advantage of our biofilter is compared to the existing solutions of reducing the emissions of these two gasses, stay tuned, because that’s exactly what will talk about in our next blog post. Any questions? Get in touch at igem@wur.nl. If you want to keep up to date with our project, click this link to register to our monthly newsletter!
References
H. Steinfeld and T. Wassenaar, “The Role of Livestock Production in Carbon and Nitrogen Cycles,” Annu. Rev. Environ. Resour., vol. 32, no. 1, pp. 271–294, Nov. 2007, doi: 10.1146/annurev.energy.32.041806.143508.
TNO. (2019). Factsheet Emissies en depositie van stikstof in Nederland. 1–16.
Morseletto, P. (2018). Confronting the nitrogen challenge: Options for governance and target setting. https://doi.org/10.1016/j.gloenvcha.2018.10.010
J. Rockström et al., “A safe operating space for humanity,” Nature, vol. 461, no. 7263. Nature Publishing Group, pp. 472–475, Sep. 2009, doi: 10.1038/461472a.
Tian, D., Wang, H., & Sun, J. (2015). Environmental Research Letters A global analysis of soil acidification caused by nitrogen addition Related content Global evidence on nitrogen saturation of terrestrial ecosystem net primary productivity. https://doi.org/10.1088/1748-9326/10/2/024019
Sikkema, A. (2019). The nitrogen problem in five questions. Resource, WUR. Retrieved from https://resource.wur.nl/en/show/The-nitrogen-problem-in-five-questions.htm
J. W. Remkes et al., “Niet alles kan overal: Eindadvies over structurele aanpak op lange termijn.” Adviescollege Stikstofproblematiek, Jun. 08, 2020, Accessed: Apr. 14, 2021. [Online]. Available: https://research.wur.nl/en/publications/niet-alles-kan-overal-eindadvies-over-structurele-aanpak-op-lange.
P. Grennfelt, A. Engleryd, M. Forsius, Ø. Hov, H. Rodhe, and E. Cowling, “Acid rain and air pollution: 50 years of progress in environmental science and policy,” Ambio, vol. 49, no. 4. Springer, pp. 849–864, Apr. 01, 2020, doi: 10.1007/s13280-019-01244-4.
L. Duan et al., “Acid deposition in Asia: Emissions, deposition, and ecosystem effects,” Atmos. Environ., vol. 146, pp. 55–69, Dec. 2016, doi: 10.1016/j.atmosenv.2016.07.018.
A. van den Burg, “Rammelende eieren en brekebenen bij de koolmees: verzuring terug bij af?” Accessed: Apr. 21, 2021. [Online]. Available: https://edepot.wur.nl/418194.
UNECE, “Methane management: The Challenge.” https://unece.org/challenge (accessed Apr. 20, 2021).
CLO. (2020). Emissies broeikasgassen, 1990-2019. Retrieved September 7, 2020, from https://www.clo.nl/indicatoren/nl0165-broeikasgasemissies-in-nederland
RVO. (2016). De Nederlandse landbouw en het klimaat. Retrieved from https://www.rvo.nl/sites/default/files/2016/12/RVO_De Nederlandse landbouw en het klimaat_Broch_def.pdf
Calderón-Chagoya, R., Hernandez-Medrano, J. H., Ruiz-López, F. J., Garcia-Ruiz, A., Vega-Murillo, V. E., Montano-Bermudez, M., … Román-Ponce, S. I. (2019). Genome-wide association studies for methane production in dairy cattle. Genes, 10(12), 995. https://doi.org/10.3390/genes10120995
European Commission, Impact Assessment, accompanying Communication ’Steppingup Europe’s 2030 climate ambition -Investing in a climate-neutral future for the benefit of our people -part 1/2, 2020.
European Parliament and Council of the European Union, Regulation (EU) 2018/842 of 65 the European Parliamanet and the Council of 30 May 2018, Off. J. Eur. Union. (2018) 26–42. https://eur-lex.europa.eu/eli/reg/2018/842/oj
Ed Dlugokencky, NOAA/GML (www.esrl.noaa.gov/gmd/ccgg/trends_ch4/)
NOAA Research, “Despite pandemic shutdowns, carbon dioxide and methane surged in 2020 ,” Apr. 07, 2021. https://research.noaa.gov/article/ArtMID/587/ArticleID/2742/Despite-pandemic-shutdowns-carbon-dioxide-and-methane-surged-in-2020 (accessed Apr. 23, 2021).
Credits for title image to @Jenny Bakker
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