Life cycle assessment of heterotrophic algae omega-3

Abstract

Fish oil has traditionally been the primary source of long chain omega-3 fatty acids, which are essential nutrients for human diets as well as many aquaculture and animal feeds. The demand for fish oil is growing rapidly, due to an expanding aquaculture sector as well as rising demand in pet and livestock feeds, while the availability of fish oil from wild caught fish has leveled off over the past decade. Fish oil is not easily replaced and alternative sources are required to meet the growing global demand. One of the most promising alternatives is microalgae - the original source of long chain omega-3s. To understand the environmental impacts of omega-3s produced by heterotrophic algae, a comprehensive Life Cycle Assessment (LCA), assessing six impact categories, was conducted for two algae omega-3 DHA (docosahexaenoic acid) products, in powder and liquid suspension formats. These products are manufactured at industrial scale using sugarcane for both feedstock and a renewable energy source. The life cycle impact assessment results for algae omega-3 DHA indicate that sugarcane cultivation has the largest contribution for most of the categories. A sensitivity analysis revealed that the sugarcane yield, and the sugar to omega-3 DHA yield, were the most relevant parameters, and that the choice of allocation methodology did not have a strong influence on the results. A comparison with fish oil, using data publicly available in LCA databases, indicated that the two formats of the commercial algae omega-3 DHA product offer about 30–40% lower impact on climate change than fish oil.