Life Cycle Assessment of a large commercial kelp farm in Shandong, China

Ji Li; Kristina Bergman; Jean-Baptiste E Thomas; Yonghui Gao; Fredrik Gröndahl

doi:10.1016/j.scitotenv.2023.166861

Life Cycle Assessment of a large commercial kelp farm in Shandong, China

Sci Total Environ. 2023 Dec 10:903:166861. doi: 10.1016/j.scitotenv.2023.166861. Epub 2023 Sep 9.

Authors

Ji Li¹, Kristina Bergman², Jean-Baptiste E Thomas³, Yonghui Gao⁴, Fredrik Gröndahl³

Affiliations

¹ School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China. Electronic address: liji81@sjtu.edu.cn.
² KTH Royal Institute of Technology, Department of Sustainable Development, Environmental Science and Engineering Teknikringen 10B, SE-100 44 Stockholm, Sweden. Electronic address: krbergm@kth.se.
³ KTH Royal Institute of Technology, Department of Sustainable Development, Environmental Science and Engineering Teknikringen 10B, SE-100 44 Stockholm, Sweden.
⁴ School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China.

PMID: 37673254
DOI: 10.1016/j.scitotenv.2023.166861

Abstract

The environmental benefits of seaweed cultivation have gained a lot of attention, both in policy strategies and by private companies. Sustainability evaluations of seaweed farming have however focused on a very small part of global production of seaweed - on European cultivations at research and pilot-scales although Asia stands for 99 % of global production with China alone producing 60 %. In this study, we use Life Cycle Assessment (LCA) to evaluate the environmental performance of a 400-hectare Chinese kelp farm with a yearly harvest of 60,000 tons. Primary data from the farm was used to assess impacts up until harvest for the functional unit of 1 ton of fresh-weight kelp. Included in the LCA were impact on climate change, acidification terrestrial and marine eutrophication, and use of land water and energy. In addition, we calculated nutrient uptake. Further, we extracted inventory data of four published LCA studies of farmed kelp and recalculated environmental impacts, applying the same background data and method choices with the aim to compare the effects of scale and cultivation system. The results of the hotspot analysis showed that the plastic ropes and buoys dominated impacts on climate change, freshwater and marine eutrophication, and energy consumption. Consequently, the most effective improvement action was recycling after use. The yearly harvest of the Chinese farm was 1000-4000 times larger than previously evaluated farms compared. Results suggest that streamlined and mature production in the large-scale Chinese kelp farm led to lower electricity and fuel consumption compared to small-scale production, thus placing the Chinese farm with a climate impact of 57.5 kg CO₂ eq. per ton fresh-weight kelp on the lower end when comparing the carbon footprint. There was a large variation in carbon footprints, which implies that the kelp cultivation sector has considerable room for optimization.

Keywords: Commercial production; Environmental impact; LCA; Saccharina japonica; Seaweed aquaculture.