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Biorenewables Systems Analysis

BEI’s thermochemical program conducts biorenewables systems analysis.

Here is a listing of some of our more significant published papers in this area. Click on title to view article in a new window from the publication Website.

Techno-economic analysis of biomass fast pyrolysis to transportation fuels

Mark M. Wright, Daren E. Daugaard, Justinus A. Satrio, Robert C. Brown (2010), Fuel

[DIAGRAM] Biomass fast pyrolysis and bio-oil upgrading
Biomass fast pyrolysis and bio-oil upgrading.

This techno-economic study examines fast pyrolysis of corn stover to bio-oil with subsequent upgrading of the bio-oil to naphtha and diesel range fuels. Two 2000 dry tonne per day scenarios are developed: the first scenario separates a fraction of the bio-oil to generate hydrogen on-site for fuel upgrading, while the second scenario relies on merchant hydrogen.

The modeling effort resulted in liquid fuel production rates of 134 and 220 million liters per year for the hydrogen production and purchase scenarios, respectively. Capital costs for these plants are $287 and $200 million. Fuel product value estimates are $3.09 and $2.11 per gallon of gasoline equivalent ($0.82 and $0.56 per liter). While calculated costs of this biofuel are competitive with other kinds of alternative fuels, further research is required to better determine the effect of feedstock properties and process conditions on the ultimate yield of liquid fuel from bio-oil. Pioneer plant analysis estimates capital costs to be $911 and $585 million for construction of a first-of-a-kind fast pyrolysis and upgrading biorefinery with product values of $6.55 and $3.41 per gge ($1.73 and $0.90 per liter).

Techno-economic analysis of biobased chemicals production via integrated catalytic processing

Tristan R. Brown, Yanan Zhang, Guiping Hu,  and Robert C. Brown (2012), Biofuels, Bioproducts and Biorefining


[DIAGRAM] Five scenarios for Integrated Catalytic Processing (ICP)
Five scenarios for Integrated Catalytic Processing (ICP).

We evaluate the economic feasibility of a fast pyrolysis facility producing biobased commodity chemicals based on various manifestations of Integrated Catalytic Processing (ICP). Five scenarios are analyzed: fluid catalytic cracking (FCC) of whole pyrolysis oil (WPO); one-stage hydrotreating and FCC of WPO; FCC of the aqueous phase of pyrolysis oil (APPO); one-stage hydrotreating and FCC of the APPO; and two-stage hydrotreating followed by FCC of the APPO.

We calculate the internal rate of return (IRR) for each scenario as functions of the costs of feedstock, hydrogen, and catalyst, and projected revenues for the facility. The assumed feedstock cost is $83/MT for mixed wood. The assumed hydrogen cost is $3/kg. Catalyst costs are based on December 2010 prices and projected revenues are based on August 2010 petrochemical prices.

The analysis indicates that a facility employing FCC of WPO or APPO without hydrotreating is unable to generate a positive IRR. Employment of two-stage hydrotreating significantly increases the facility IRR, although IRRs in excess of 10% are only attained when higher pyrolysis oil yields (70 wt%) are assumed.

© 2012 Society of Chemical Industry and John Wiley & Sons, Ltd

Techno-economic analysis of two bio-oil upgrading pathway

Yanan Zhang, Tristan R. Brown, Guiping Hu, and Robert C. Brown (2013), Chemical Engineering Journal

[DIAGRAM] Two pathways
Generalized process diagram for the two pathways.

We evaluate the economic feasibility for two bio-oil upgrading pathways: two-stage hydrotreating followed by fluid catalytic cracking (FCC) or single-stage hydrotreating followed by hydrocracking. In the hydrotreating/FCC pathway, two options are available as the hydrogen source for hydrotreating: merchant hydrogen or hydrogen from natural gas reforming. The primary products of the hydrotreating/FCC pathway are commodity chemicals whereas the primary products for the hydrotreating/hydrocracking pathway are transportation fuels and hydrogen. The two pathways are modeled using Aspen Plus® for a 2000 metric tons/day facility. Equipment sizing and cost calculations are based on Aspen Economic Evaluation® software.

The bio-oil yield via fast pyrolysis is assumed to be 65% of biomass. We calculate the internal rate of return (IRR) for each pathway as a function of feedstock cost, fixed capital investment (FCI), hydrogen and catalyst costs, and facility revenues. The results show that a facility employing the hydrotreating/FCC pathway with hydrogen production via natural gas reforming option generates the highest IRR of 13.3%. Sensitivity analysis demonstrates that product yield, FCI, and biomass cost have the greatest impacts on facility IRR. Monte-Carlo analysis shows that two-stage hydrotreating and FCC of the aqueous phase bio-oil with hydrogen produced via natural gas reforming has a relatively low risk for project investment.

Techno-economics of advanced biofuels pathways

Tristan R. Brown and Robert C. Brown (2013),  Royal Society of Chemistry Advances

[DIAGRAM] Fast pyrolysis
Fast pyrolysis system biomass conversion.

Techno-economic analysis enables researchers to quickly and inexpensively assess the technical and economic feasibility of biorenewable pathways. This mini-review article covers Iowa State University’s techno-economic analyses since 2007, which includes two distinct methodologies: one based on adapting existing analyses found in the literature and the other based on constructing detailed process models.

Techno-economic analysis of biomass to transportation fuels and electricity via fast pyrolysis and hydroprocessing

Tristan R. Brown,Rajeeva Thilakaratne, Robert C. Brown, and Guiping Hu (2013), Fuel


[DIAGRAM] Schematic of FP and hydroprocessing system
Schematic of FP and hydroprocessing system.

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.

Life cycle assessment of the production of hydrogen and transportation fuels from corn stover via fast pyrolysis

Yanan Zhang, Guiping Hu, and Robert C Brown (2013), Environmental Research Letters

[DIAGRAM] Corn stover fast pyrolysis
Process diagram for fast pyrolysis of corn stover and upgrading of the resulting bio-oil to hydrogen, gasoline and diesel fuel (adapted from Wright et al 2010a).

This life cycle assessment evaluates and quantifies the environmental impacts of the production of hydrogen and transportation fuels from the fast pyrolysis and upgrading of corn stover. Input data for this analysis come from Aspen Plus modeling, a GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model database and a US Life Cycle Inventory Database. SimaPro 7.3 software is employed to estimate the environmental impacts. The results indicate that the net fossil energy input is 0.25 MJ and 0.23 MJ per km traveled for a light-duty vehicle fueled by gasoline and diesel fuel, respectively. Bio-oil production requires the largest fossil energy input. The net global warming potential (GWP) is 0.037 kg CO2eq and 0.015 kg CO2eq per km traveled for a vehicle fueled by gasoline and diesel fuel, respectively. Vehicle operations contribute up to 33% of the total positive GWP, which is the largest greenhouse gas footprint of all the unit processes. The net GWPs in this study are 88% and 94% lower than for petroleum-based gasoline and diesel fuel (2005 baseline), respectively. Biomass transportation has the largest impact on ozone depletion among all of the unit processes. Sensitivity analysis shows that fuel economy, transportation fuel yield, bio-oil yield, and electricity consumption are the key factors that influence greenhouse gas emissions.