1067563 (Colosi). The goal of this research is to develop a meta-model of existing algae-to-energy life cycle analyses (LCAs) in order to evaluate the impact of emerging technologies in this burgeoning sector. The model will be analogous to two other widely influential energy meta-models: Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) developed for petroleum at Argonne National Lab; and ERG Biofuel Assessment Meta-Model (EBAMM) for ethanol production from the University of California at Berkeley. Both of these have become enormously useful tools for setting policy and directing engineering research. The proposed Meta-Model of Algae Bio-Energy Life Cycles (MABEL) is targeted to overcome seeming disparities among the current body of algae LCA knowledge. Many of these disparities reflect key differences in modeling strategies among authors such that standardization of functional unit, system boundaries, and key model parameters will provide more definitive estimates of energy use, greenhouse gas emissions, land use, and water use associated with energy production from algae. MABEL will facilitate more direct, data-driven comparisons among proposed algae cultivation/conversion mechanisms and between algae-derived energy and energy from terrestrial crops. The model will be open-source and freely available via download from a website hosted by the Office of the Vice President for Research at the University of Virginia (UVA). Users will be able to manipulate the model to investigate processes of interest in a flexible manner. In light of the large amount of economic and research activity that is currently being dedicated to algae-based energy, and the vigorous debate over the merits of these technologies, such a model is clearly needed by the bioenergy community. The project will compile and normalize six existing life cycle assessments into an open-source modeling platform. It will be the first open-source meta-model of the LCA impacts of algae-to-energy systems. MABEL will be stochastic so that it can capture the uncertainty inherent to this rapidly changing sector. This model will also be reconfigurable such that users will be able to use it for their own purposes. This tool will be a contribution to the industrial ecology community because it will demonstrate the usefulness of LCA as a proactive design tool. Once it is complete and fully functional, MABEL will be used by the PIs to answer key questions about algae farming, algae conversion, and algae financial considerations. The broader impact of this research will be to disseminate the MABEL platform via a freely accessible website, conference presentations, and academic publications. The model website will offer extensive documentation on policy-relevant scenarios that will be developed during this work to demonstrate the capabilities of the model and also to serve as a template for others hoping to modify the model. The project will combine the expertise of an environmental engineer and chemist with extensive experience in LCA, an environmental biochemist specializing in the environmental impacts of emerging contaminants, and a finance professor from the McIntire School of Commerce at UVa who is an expert in ecosystem services and costing models.
The project had two main goals related to intellectual merit: 1) quantitatively summarize what is known about the environmental impacts of large-scale algae-to-biodiesel systems, and 2) anticipate the effects that emerging algae technologies could have on these systems. In order to fulfill these goals, a meta-model for algae-to-energy technologies was created; whereby, data from six existing life cycle assessment (LCA) studies was integrated into a single quantitative framework for evaluation of "what if" scenarios. The resulting meta-model was referred to as MABEL (the Meta-Model of Algal Bio-Energy Life Cycles). It was used to ask and answer interesting questions related to the environmental and economic sustainability of algae-derived biodiesel and other fuels. All told, this body of work yielded ten manuscripts in top scientific journals, including: six papers published, two accepted, and two in review. Several research highlights are summarized in the following paragraphs. The MABEL analyses revealed that first-generation algae-to-energy systems, which produce biodiesel via lipid transesterification and bioelectricity via anaerobic digestion of non-lipid residuals, have roughly the same environmental performance as selected terrestrial benchmarks; i.e., slightly less energy use and greenhouse gas (GHG) emissions than corn ethanol but slightly more energy use and GHG emissions than soybean biodiesel for the same amount of energy delivered. These comparisons are noteworthy, since it was impossible to compare algae LCA papers to themselves or external benchmarks without first subjecting the previously published results to the meta-model standardization process. Additionally, use of recycledcarbon dioxide (as from flue gas) with full digestion of non-lipid algal matter to make bioelectricity would make algae-derived energy sources much more desirable than either the corn or soy benchmarks, but these approaches are still unproven at large scale. Other interesting questions that can be asked and answered using MABEL pertain to algae cultivation configuration and financial considerations. Regarding cultivation configuration, a combination of LCA and life cycle costing (LCC) approaches was used to compare open pond (OP) systems versus horizontal tubular photobioreactors (PBRs). From LCA, OPs have substantially lower energy consumption and GHG emissions than PBRs per fixed amount of fuel production. From LCC, OP and PBRs are currently financially unattractive, though OPs are less so than PBRs. Sensitivity analyses suggest that improvements in certain cultivation parameters, conversion parameters, and market factors could alter these results, with the latter having the most significant effects; however, OPs are always expected to be more environmentally and economically attractive than PBR systems for cultivation of algae biomass to produce energy. Regarding financial considerations, economic meta-analysis reveals that first-generation algae fuels are less financially viable than commercially available benchmarks without significant technological improvements. Still, there is significant potential for improvement in financial performance as new technologies and/or optimized operations come online. Ongoing current and future work is moving towards evaluation of second-generation algae conversion technologies (i.e., hydrothermal liquefaction) and optimization of algae-mediated ecosystem services (e.g., removal of man-made organic contaminants from partially treated wastewaters) as means to improve the environmental and economic sustainability of algae-to-energy systems. There were also two main objectives related to broader impacts: 1) recruiting qualified graduate students from traditionally under-represented minorities; and 2) integrating sustainability content, particularly LCA, into a two-course series within the Department of Civil and Environmental Engineering at the University of Virginia (UVA), as means to stimulate interest in Sustainability Engineering. Regarding recruitment, this work supported five female graduate students, four of which were recruited specifically for this project. Three PhD dissertations and one MS thesis were completed. Two of the graduating doctoral students are now assistant professors at academic institutions, while the third is a post-doctoral research associate at a government research laboratory. Regarding course content development, the principal investigator (PI) and co-PI successfully revised a two-course sequence related to sustainability ("Introduction to Green Engineering" followed by "Introduction to Environmental Engineering") for use in the Civil and Environmental Engineering curriculum at UVA. This sequence was first taught in the 2012-2013 academic year. It was also taught in the 2013-2014 academic year. It is currently being revised to better accommodate the evolving second-year curriculum, but the overall structure will remain mostly intact.
