Environmental impact and water footprint of biofuel production from microalgae biomass based on life cycle assessment

Abstract

Algae is a promising raw material for producing biofuels, which has sparked a lot of interest in the utilization process. Taking three pyrolytic utilization processes into consideration, this paper conducted three pyrolytic experiments of Chlorella (CV) to accurately evaluate the environmental impact and water resource consumption. The pyrolysis catalyzed by ZSM catalyst exhibited the smallest global warming potential (GWP: 25711.158 kg CO₂ eq/t biofuel) and water resource consumption (WCP: 1716.010 m³/t biofuel). All the three processes integrated with hydrogenation process, which requires hydrogen. However, hydrogen production from pyrolytic gas has the greatest portion GWP at the three processes. Instead, if the hydrogen was meted by green hydrogen from renewable electricity, GWP and WCP can be reduced by up to 16 % and 4 %, respectively. In order to comprehensively evaluate the impact on the environment and water consumption, a reasonable plan for preparing biofuels in provinces with high algae yields was calculated and evaluated. Xinjiang, Heilongjiang, Jiangsu, Guangdong, Guangxi, and Hubei are selected as the oil producing provinces in each region in the article. The whole life cycle assessment results of this paper can be used as a reference for the subsequent algal oil production program in China.