Gasoline from Woody Biomass via Thermochemical Gasification, Methanol Synthesis, and Methanol-to-Gasoline Technologies: A Technoeconomic Analysis

Abstract

This work describes a technoeconomic analysis of the feasibility of making gasoline using biomass-derived syngas that was completed at the National Renewable Energy Laboratory (NREL). The process includes the following steps: (1) biomass gasification of woody residues, which produces a syngas rich in hydrogen and carbon monoxide; (2) syngas cleanup by means of tar reforming and scrubbing, followed by the removal of acid gases; (3) synthesis of methanol from clean syngas by passing it over a copper/zinc oxide/alumina catalyst; (4) conversion of methanol to gasoline using a ZSM-5 zeolite catalyst, first developed by Exxon Mobil as the methanol-to-gasoline (MTG) technology; and (5) multiple gasoline separation and finishing processes. The process was modeled in Aspen Plus, and information taken from the Aspen Plus simulation was used to complete a discounted cash flow rate of return (DCFROR) analysis. The results of the DCFROR, using a poplar wood feedstock cost of $55.89/dry metric tonne ($50.70/dry U.S. ton), give an estimated plant gate price (PGP) of $15.73/GJ ($16.60/MMBtu) (2007 U.S. dollars) for gasoline and LPG (liquefied petroleum gas). The corresponding unit prices for gasoline and LPG are $0.52/L ($1.95/gal) and $0.40/L ($1.53/gal), respectively, with yields of 229.9 L of gasoline and 38.8 L of LPG per metric tonne of dry biomass (55.1 gal of gasoline and 9.3 gal of LPG per short ton of dry biomass). This report is a future look at the potential of the biomass-to-gasoline process, based on calculations for an nth plant and 2012 technology targets for clean syngas from biomass as established in the Multi-Year Program Plan of the U.S. Department of Energy (DOE) Office of the Biomass Program.

A techno-economic review of thermochemical cellulosic biofuel pathways

“…This versatile intermediate product is known as syngas and can be converted to heat and power via combustion or upgraded over catalysts to liquid transportation fuels such as ethanol (Zhu and Jones, 2009), methanol (Andersson et al, 2014;Phillips et al, 2011), gasoline (Phillips et al, 2011), diesel and jet fuels (Swanson et al, 2010;Zhu et al, 2012). More recently a novel Clostridium bacterium has been identified as being capable of fermenting switchgrass-derived syngas to ethanol (Datar et al, 2004;Piccolo and Bezzo, 2009), combining the thermochemical and biochemical platforms to yield cellulosic biofuel.…”

“…Finally, the methyl acetate is hydrogenated to yield methanol, which is recycled, and ethanol. The MTG pathway instead reacts the DME over a zeolite catalyst to yield alkenes and ultimately a blend of aromatics and alkanes belonging primarily in the gasoline boiling range (Phillips et al, 2011). The S2D pathway combines the methanol dehydration and hydrocarbon synthesis steps by reacting the syngas-derived methanol with the catalysts responsible for both in a single reactor.…”

“…Phillips et al (2011) uses an Aspen Plus model to calculate a TPI of $217 million for a MTG biorefinery with a hybrid poplar feedstock capacity of 2000 MTPD. A feedstock cost of $60.63/MT and 10% IRR yields a MFSP of $2.12/ gge ($0.56/lge).…”

“…A sensitivity analysis reveals that the MFSP is most sensitive to assumptions regarding the feedstock, capacity, and economic factors (IRR and TPI). Trippe et al (2013) arrives at a much higher estimate than Phillips et al (2011) despite considering syngas rather than biomass feedstock, calculating TPIs of $287 million and $301 million and MFSPs of $6.26/gge ($1.65/lge) and $6.10/gge ($1.61/lge) for its 4 MPa and 8 MPa syngas MTG scenarios, respectively. While both analyses assume a 10% IRR, Trippe et al (2013) employs a syngas cost that translates to a feedstock cost that is roughly twice that employed by Phillips et al (2011).…”

“…Trippe et al (2013) arrives at a much higher estimate than Phillips et al (2011) despite considering syngas rather than biomass feedstock, calculating TPIs of $287 million and $301 million and MFSPs of $6.26/gge ($1.65/lge) and $6.10/gge ($1.61/lge) for its 4 MPa and 8 MPa syngas MTG scenarios, respectively. While both analyses assume a 10% IRR, Trippe et al (2013) employs a syngas cost that translates to a feedstock cost that is roughly twice that employed by Phillips et al (2011). Haro et al (2013b) expands upon Trippe et al (2013) by comparing the MTG pathway with variations in which either only alkenes or both alkenes and gasoline are produced.…”