Project Team
Student(s)
Louise Shaffer
Chemical Engineering
Penn State University
Mentor(s)
Civil and Environmental Engineering
Project Video
Project Abstract
The world’s growing population will require food production to increase by up to 70% by 2050 (1). Dairy products are a large source of food for many people, with milk being the highest consumed animal protein in the world. Worldwide, 46.4 kg of milk is consumed per capita each year, while only 37.9 kg of all meats is consumed per capita (2). The animal agriculture industry can create detrimental impacts not only to local land use and water consumption, but also to the world through greenhouse gas (GHG) emissions and eutrophication of water bodies. In fact, 15% of the world’s total GHG emissions come from raising farm animals, which has a significant impact on global warming (3). Much of the impact of dairy farms comes from the cultivation of crops to feed dairy cattle. The reuse of waste nutrients to grow feed can help farms move toward a more sustainable circular bioeconomy. Duckweed, an aquatic plant, can be the bridge to creating this circular bioeconomy at the dairy farm level since it can recover waste nutrients from manure and then upcycle those nutrients into a high-protein feed alternative for dairy cattle. However, the sustainability of growing duckweed on dairy farms needs to be investigated. To holistically determine the environmental impacts of such a duckweed system, a life cycle assessment (LCA) is needed to calculate potential impacts to human health, water consumption, land use, and eutrophication potential. To determine the potential benefit of using duckweed as a feed substitute, an LCA was conducted on a dairy farm in Central Pennsylvania that raises about 3,000 cows and is located in the Chesapeake Bay watershed. This study also investigated the environmental impact of different techniques for growing duckweed on dairy farms: conventional pond systems vs. vertical farming systems in which duckweed is grown in long trays illuminated by LED lights stacked on top of each other. When comparing duckweed to conventionally farmed soybeans as a protein source, there are improvements when using duckweed in the categories of human non-carcinogenic toxicity as well as water consumption. In an initial LCA of the vertical farming system, the trays were assumed to be made from plywood lined with recycled polyethylene, the structure was made of wood, and low voltage electricity was powering the LEDs. In this configuration, with 6 trays, vertical farming exhibited more detrimental environmental impact than a conventional pond system due to the amount of materials and energy required. Further research should be done to identify the best materials for construction of a vertical farming system to minimize the impact. Therefore, although there are benefits to implementing duckweed on dairy farms, further materials and economic analyses will be necessary to optimize the system and complete the evaluation.
References
1. Diaz-Ambrona, C.G.H., Maletta, E. Achieving Global Food Security through Sustainable Development of Agriculture and Food Systems with Regard to Nutrients, Soil, Land, and Waste Management. Curr Sustainable Renewable Energy Rep 1, 57–65 (2014). https://doi.org/10.1007/s40518-014-0009-2
2. Andrew W. Speedy, Global Production and Consumption of Animal Source Foods, The Journal of Nutrition, Volume 133, Issue 11, November 2003, Pages 4048S–4053S, https://doi.org/10.1093/jn/133.11.4048S
3. Hawken, P. (2017). Drawdown. Penguin. Page 39
Project Poster
https://sites.psu.edu/drawdownscholars/files/formidable/13/Poster_final-1.pdf