(99b) Sustainability Metrics for Biofuel Production Via Thermochemical and Biochemical Conversion Platforms

The National Renewable Energy Laboratory (NREL) is developing technologies to convert biomass to biofuels via biochemical and thermochemical conversion processes. Three environmental sustainability metrics?greenhouse gas (GHG) emissions, consumptive water use, and fossil energy demand?are quantified using process engineering models. Currently, NREL is working to identify technology improvements in the conversion processes that will reduce these environmental emissions. This effort will improve our understanding of the environmental tradeoffs between conversion technology options. For example, in the NREL biochemical conversion process design, ammonium hydroxide has replaced overliming as for conditioning the hydrolysate. The GHG tradeoffs associated with this technology change will be examined. Aspen Plus software is used to evaluate process enhancements and to quantify the emissions, as well as to calculate the cost of such a reduction. Furthermore, developing annual state-of-technology (SOT) sustainability assessments for the conversion platforms is critical to the overarching goal of developing a sustainable biofuels industry. Both the current SOT and process modifications to the current technology have been assessed and will be updated based on the latest conversion SOT for their relative sustainability.