LCA of an Algal Biomass Plant

Abstract

The depletion of fossil fuels and the pace of climate change sparked our quest for alternative energy sources such as microalgae is a prospective third-generation biofuel source. A life cycle assessment (LCA) of microalgae biomass harvesting, HTL conversion, and bio-oil stabilization is undertaken to analyze the overall environmental implications of the process. This process also involves “Carbon Sequestration.” This book chapter will compare three fuels and two conversion pathways. With four microalgae cultivation pathways and three biofuel types, SimaPro 8.0.3 software is used to assess life cycle. Functional unit of the study is 1 kg of bio-oil produced by the plant. “ReCiPe method of life cycle assessment is undertaken in this book chapter to show the total impact of fuel production and also provide the best option.” Result indicates 13.074 kg CO2 equivalent Global Warming Potential (GWP) from bio-oil production through HTL process, which is around 60% less than the nearest alternative, pyrolysis process with a net energy ratio (NER) around 0.9, which states in the favor of HTL process as our goal of the study indicates. Combination of open pond and flue gas injection as carbon source gave the best sustainability results for cultivation processes, with a 1.37 kg CO2 equivalent, and its simplicity of use and low capital cost also gave it an advantage. For different biofuels, bio-oil emits least greenhouse gases (GHGs), around 255 kg CO2 equivalent, followed by biomethane 393 kg CO2 equivalent and biodiesel 425 kg CO2 equivalent.