Abstract
AbstractThe 2011 US Billion‐Ton Update estimates that by 2030 there will be enough agricultural and forest resources to sustainably provide at least one billion dry tons of biomass annually, enough to displace approximately 30% of the country's current petroleum consumption. A portion of these resources are inaccessible at current cost targets with conventional feedstock supply systems because of their remoteness or low yields. Reliable analyses and projections of US biofuels production depend on assumptions about the supply system and biorefinery capacity, which, in turn, depend upon economic value, feedstock logistics, and sustainability. A cross‐functional team has examined combinations of advances in feedstock supply systems and biorefinery capacities with rigorous design information, improved crop yield and agronomic practices, and improved estimates of sustainable biomass availability. A previous report on biochemical refinery capacity noted that under advanced feedstock logistic supply systems that include depots and pre‐processing operations there are cost advantages that support larger biorefineries up to 10 000 DMT/day facilities compared to the smaller 2000 DMT/day facilities. This report focuses on analyzing conventional versus advanced depot biomass supply systems for a thermochemical conversion and refinery sizing based on woody biomass. The results of this analysis demonstrate that the economies of scale enabled by advanced logistics offsets much of the added logistics costs from additional depot processing and transportation, resulting in a small overall increase to the minimum ethanol selling price compared to the conventional logistic supply system. While the overall costs do increase slightly for the advanced logistic supply systems, the ability to mitigate moisture and ash in the system will improve the storage and conversion processes. In addition, being able to draw on feedstocks from further distances will decrease the risk of biomass supply to the conversion facility.
Highlights
Biofuels have the potential to reduce dependence on fossil fuels, enhance energy security, provide environmental benefits, and stimulate rural econo mies.[1,2] In the United States, these objectives are supported by the Energy Independence and Security Act of 2007 (EISA), with the goal of producing and using 136 billion liters (36 billion gallons) of renewable fuels by 2022.To commercialize biofuels, significant tradeoffs are acknowledged between improved economies of scale associated with increased biorefinery size, and higher feedstock price that may be associated with supply chains needed to satisfy increased feedstock demand
An earlier study reported the influence of biorefinery size and biomass logistics supply system design on process economics and environmental sustainability metrics for herbaceous bio mass converted to ethanol in a biochemical process.[3]
Techno-economic analyses of the thermochemical proc ess for making ethanol from woody biomass via gasifi cation were performed by scaling the process design as detailed in a report developed at the National Renewable Energy Laboratory (NREL) in collaboration with The Dow Chemical Company and Idaho National Laboratory (INL).[7]
Summary
Significant tradeoffs are acknowledged between improved economies of scale associated with increased biorefinery size, and higher feedstock price that may be associated with supply chains needed to satisfy increased feedstock demand. Advanced feedstock supply chain strategies can potentially play a key role in optimizing biorefinery size. The results from the previ ous study determined that increasing biorefinery size (up to 10 000 dry metric tonnes day–1) can achieve lower minimum ethanol selling prices (MESP). This proved true even after accounting for increased delivered feedstock cost associated with additional pre-processing operations required to achieve commodity feedstock characteristics
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