(587c) Harvesting and Extraction Technologies Contributing to Algae Biofuel Environmental Viability-Life Cycle Analysis of Naabb Developed Novel Technologies

Authors: 
Shi, R., University of Illinois at Urbana-Champaign
Handler, R., Michigan Technological University
Shonnard, D. R., Michigan Technological University
There are many challenges and technical barriers to implementation of a thorough life-cycle assessment of algae-based biofuels. Biofuels made from algae must typically go through a complicated cultivation, harvesting, dewatering, oil extraction, and conversion process, involving many unit operations. Feedbacks between unit operations often depend on the particular operations being performed, so selection of a particular technology will have upstream as well as downstream consequences in the value chain. The National Alliance for Advanced Biofuels and Bioproducts (NAABB) project was established to produce and evaluate new technologies that can be implemented by the algal biofuel industry and establish the overall process sustainability. The goal of our LCA is to determine greenhouse gas (GHG) emissions and fossil energy demand associated with harvesting and extraction of algae. Four harvesting technologies and two extraction technologies within the NAABB group were evaluated. These include: Chitosan Flocculation, Electrolytic Flocculation, Membrane Harvesting, Acoustic Harvesting, Acoustic Extraction, and Wet fractionation. The scope will be limited in the sense that our focus is only on inputs of harvest and extract technologies, not including the materials and chemicals used to cultivate algae. The functional unit for harvesting technologies study is 1 kg dry algae output. Harvesting technologies will be normalized to this unit, while extraction technologies will be normalized on the basis of 1 kg algae oil output. Input/output data on the industrial operations being investigated was used to construct LCA models of the unit operations. Using the input data from multiple resources, the harvesting and extraction processes were all placed on an equivalent basis for comparison and the GHG emissions impacts were analyzed using SimaPro LCA software. In order to assess the magnitude of each technology in a similar fashion as the other unit operations, the gate-to-gate results for these unit operations were placed in the context of our previous LCA baseline modeling and the results for these unit operations are presented in g CO2eq / MJ renewable diesel using the assumptions detailed in the Baseline Harmonized Report and GREET model.