A previous Iowa State University (ISU) analysis published in 2010 investigated the technical and economic feasibility of the fast pyrolysis and hydroprocessing of biomass, and concluded that the pathway could produce cellulosic biofuels for a minimum fuel selling price (MFSP) of $2.11/gal. The 2010 ISU study was largely theoretical in that no commercial-scale fast pyrolysis facilities were being constructed at the time of publication.The present analysis expands upon the 2010 ISU study by performing an updated techno-economic analysis of the fast pyrolysis and hydroprocessing pathway. Recent advances in pathway technology and commercialization and new parameters suggested by the recent literature are accounted for. The MFSP for a 2000 MTPD facility employing fast pyrolysis and hydroprocessing to convert corn stover to gasoline and diesel fuel is calculated to quantify the economic feasibility of the pathway.The present analysis determines the MFSP of gasoline and diesel fuel produced via fast pyrolysis and hydroprocessing to be $2.57/gal. This result indicates that the pathway could be competitive with petroleum, although not as competitive as suggested by the 2010 ISU study. The present analysis also demonstrates the sensitivity of the result to process assumptions. Keywords fast pyrolysis, hydroprocessing, catalytic pyrolysis, techno-economic analysis, Bioeconomy Institute, Mechanical Engineering Disciplines Industrial Engineering | Mechanical Engineering | Systems EngineeringComments NOTICE: This is the author's version of a work that was accepted for publication in Fuel. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently publishedin in Fuel, 106, April (2013) NOTICE: This is the author's version of a work that was accepted for publication in Fuel. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently publishedin in Fuel, 106, April (2013)

We estimate the profi tability of producing biochar from crop residue (corn stover) for two scenarios. The fi rst employs slow pyrolysis to generate biochar and pyrolysis gas and has the advantage of high yields of char (as much as 40 wt-%) but the disadvantage of producing a relatively low-value energy product (pyrolysis gas of modest heating value). The second scenario employs fast pyrolysis to maximize production of bio-oil with biochar and pyrolysis gas as lower-yielding coproducts. The fast pyrolysis scenario produces a substantially higher value energy product than slow pyrolysis but at the cost of higher capital investment.We calculate the internal rate of return (IRR) for each scenario as functions of cost of feedstock and projected revenues for the pyrolysis facility. The assumed price range for delivered biomass feedstock is $0 to $83 per metric ton.The assumed carbon offset value for biochar ranges from $20 per metric ton of biochar in 2015 to $60 in 2030.The slow pyrolysis scenario in 2015 is not profi table at an assumed feedstock cost of $83 per metric ton. The fast pyrolysis scenario in 2015 yields 15% IRR with the same feedstock cost because gasoline refi ned from the bio-oil provides revenues of $2.96 per gallon gasoline equivalent. By 2030, the value of biochar as a carbon offset is projected to increase to $60 per metric ton and the price of gasoline is expected to reach $3.70 per gallon, which would provide investors with an IRR of 26%.

In contrast to a few years ago, when cellulosic ethanol via enzymatic hydrolysis was the only widely recognized technology for commercially producing cellulosic biofuels, a diversity of approaches are currently under commercial development. While no commercial‐scale (≥20 million gallons per year) cellulosic biofuel facilities are operating at present, at least ten biorefinery projects employing six different pathways are expected to begin operations by 2014. These biorefineries will employ the following pathways: (i) catalytic pyrolysis and hydrotreating to hydrocarbons; (ii) gasification and Fischer‐Tropsch synthesis to hydrocarbons; (iii) gasification and methanol‐to‐gasoline synthesis; (iv) dilute acid hydrolysis, fermentation to acetic acid, and chemical synthesis to ethanol; (v) enzymatic hydrolysis to ethanol; and (vi) consolidated bioprocessing (single‐step enzyme production, hydrolysis, and fermentation) to ethanol. This review provides an overview of the six pathway technologies, comprehensive descriptions of each of the ten biorefinery projects, and a discussion of the current direction of cellulosic biofuel commercialization efforts and its implications for the revised Renewable Fuel Standard. © 2013 Society of Chemical Industry and John Wiley & Sons Ltd

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