Engineering system modeling for sustainability assessment
Date
2016
Authors
Barlow, Jay, author
Quinn, Jason C., advisor
Willson, Bryan, committee member
Reardon, Kenneth F., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
The increase in global greenhouse gas emissions has driven interest in the development of renewable energy sources. The commercial development of emerging renewable technologies like algal biofuels requires the identification of an economically viable production pathway. This study examined the sustainability of generating renewable diesel via hydrothermal liquefaction (HTL) of algal biomass from an attached growth architecture. Pilot-scale growth studies and laboratory-scale HTL experiments validated an engineering system model, which facilitated analysis of economic feasibility and environmental impact of the system at full scale. Techno-economic analysis (TEA) results indicate an optimized minimum fuel selling price (MFSP) of $11.90 gal-1, and life-cycle assessment (LCA) found a global warming potential (GWP) of -44 g CO2-e MJ-1 and net energy ratio of 0.33. Results from this work identified current gaps in sustainability assessment through TEA and LCA. Two needs were identified to improve sustainability assessment: the internalization of a carbon emission price into TEA and the consideration of the time-value of carbon emissions in LCA. With these effects considered, MFSP and GWP increase by 23% for the modeled biofuels system. Results from a harmonized model of an array of energy technologies indicate that prices for fossil-based energy increase 200% and GWP increases 25% when these factors are considered, whereas low-emitting technologies increase minimally in both metrics. Based on these findings, the development of improved sustainability assessment methodology is proposed.