Printed on paper containing at least 50% wastepaper, including 10% post consumer waste.iii Executive SummaryThe U.S. Department of Energy (DOE) promotes the production of ethanol and other liquid fuels from lignocellulosic biomass feedstocks by funding fundamental and applied research that advances the state of technology in biomass collection, conversion, and sustainability. As part of its involvement in the program, the National Renewable Energy Laboratory (NREL) investigates the production economics of these fuels.This report describes in detail one potential biochemical ethanol conversion process, conceptually based upon core conversion and process integration research at NREL. The overarching process design converts corn stover to ethanol by dilute-acid pretreatment, enzymatic saccharification, and co-fermentation. Ancillary areas-feed handling, product recovery, wastewater treatment, lignin combustion, and utilities-are also included in the design. Detailed material and energy balances and capital and operating costs were developed for the entire process, and they are documented in this report and accompanying process simulation files, which are available to the public.As a benchmark case study, this so-called technoeconomic model provides an absolute production cost for ethanol that can be used to assess its competitiveness and market potential. It can also be used to quantify the economic impact of individual conversion performance targets and prioritize these in terms of their potential to reduce cost. Furthermore, by using the benchmark as a comparison, DOE can make more informed decisions about research proposals claiming to lower ethanol production costs.Building on design reports published in 2002 and 1999, NREL, together with the subcontractor Harris Group Inc., performed a complete review of the process design and economic model for the biomass-to-ethanol process. This update reflects NREL's current vision of the biochemical ethanol process and incorporates recent progress in the conversion areas (pretreatment, conditioning, saccharification, and fermentation), optimizations in product recovery, and an improved understanding of the ethanol plant's back end (wastewater and utilities). The major process updates in this design report are the following:• Feedstock composition is updated to a carbohydrate profile closer to the expected mean.• Pretreatment reactor configuration is revised with significant new detail.• Whole-slurry pH adjustment of the pretreated biomass with ammonia replaced the previous conditioning practice of overliming, eliminating a solid-liquid separation step.

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The U.S. Department of Energy (DOE) promotes the production of a range of liquid fuels and fuel blendstocks from lignocellulosic biomass feedstocks by funding fundamental and applied research that advances the state of technology in biomass collection, conversion, and sustainability. As part of its involvement in this program, the National Renewable Energy Laboratory (NREL) investigates the conceptual production economics of these fuels.Between 1999 and 2012, NREL conducted a campaign to quantify the economic implications associated with measured conversion performance for the biochemical production of cellulosic ethanol, with a formal program between 2007-2012 to set cost goals and to benchmark annual performance toward achieving these goals, namely the pilot-scale demonstration by 2012 of biochemical ethanol production at a price competitive with petroleum gasoline based on modeled assumptions for an "n th " plant biorefinery. This goal was successfully achieved through NREL's 2012 pilot plant demonstration runs, representing the culmination of NREL research focused specifically on cellulosic ethanol, and a benchmark for industry to leverage as it commercializes the technology. This important milestone also represented a transition toward a new Program focus on infrastructure-compatible hydrocarbon biofuel pathways, and the establishment of new research directions and cost goals across a number of potential conversion technologies.This report describes in detail one potential conversion process to hydrocarbon products by way of biological conversion of lignocellulosic-derived sugars. The pathway model leverages expertise established over time in core conversion and process integration research at NREL, while adding in new technology areas primarily for hydrocarbon production and associated processing logistics. The overarching process design converts biomass to a hydrocarbon intermediate, represented here as a free fatty acid, using dilute-acid pretreatment, enzymatic saccharification, and bioconversion. Ancillary areas-feed handling, hydrolysate conditioning, product recovery and upgrading (hydrotreating) to a final blendstock material, wastewater treatment, lignin combustion, and utilities-are also included in the design. Detailed material and energy balances and capital and operating costs for this baseline process are also documented.This benchmark case study techno-economic model provides a production cost for a cellulosic renewable diesel blendstock (RDB) that can be used as a baseline to assess its competitiveness and market potential. It can also be used to quantify the economic impact of individual conversion performance targets and prioritize these in terms of their potential to reduce cost. The analysis presented here also includes consideration of the life-cycle implications of the baseline process model, by tracking sustainability metrics for the modeled biorefinery, including greenhouse gas (GHG) emissions, fossil energy demand, and consumptive water use.Building on prior design reports for bioch...

in Wiley Online Library (wileyonlinelibrary.com).This article addresses the optimal design and planning of cellulosic ethanol supply chains under economic, environmental, and social objectives. The economic objective is measured by the total annualized cost, the environmental objective is measured by the life cycle greenhouse gas emissions, and the social objective is measured by the number of accrued local jobs. A multiobjective mixed-integer linear programming (mo-MILP) model is developed that accounts for major characteristics of cellulosic ethanol supply chains, including supply seasonality and geographical diversity, biomass degradation, feedstock density, diverse conversion pathways and byproducts, infrastructure compatibility, demand distribution, regional economy, and government incentives. Aspen Plus models for biorefineries with different feedstocks and conversion pathways are built to provide detailed techno-economic and emission analysis results for the mo-MILP model, which simultaneously predicts the optimal network design, facility location, technology selection, capital investment, production planning, inventory control, and logistics management decisions. The mo-MILP problem is solved with an econstraint method; and the resulting Pareto-optimal curves reveal the tradeoff between the economic, environmental, and social dimensions of the sustainable biofuel supply chains. The proposed approach is illustrated through two case studies for the state of Illinois.We note that both distance variable costs and distance fixed costs are taken into account in the feedstock and fuel ethanol

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