Synthesis Energy Systems Options Up to 15 Methanol-to-Gasoline Technology Licenses for Coal-to-Gasoline Projects
Synthesis Energy Systems, Inc. (SES), a gasification company, has entered into an agreement with ExxonMobil Research and Engineering Company that provides SES the option to execute up to 15 Methanol-to-Gasoline (MTG) technology (earlier post) licenses at its U-GAS coal gasification plants globally.
MTG is one of several pathways for converting syngas to transportation fuels, the Fischer-Tropsch process being another. The MTG technology converts crude methanol directly to low-sulfur, low-benzene 87 octane gasoline that can be sold directly or blended with conventional refinery gasoline. The gasoline yield from the process is about 89%; LPG yield is about 10%, and fuel gas, about 1%.
SES plans to utilize the MTG technology at its coal gasification projects under development in North America with partners in West Virginia, Mississippi and North Dakota. The Company believes that each of these projects, if completed, will produce approximately 100M gallons of gasoline per year.
By coupling the ExxonMobil proven MTG technology with our proprietary U-GAS process, we believe that we have completed the technology suite to fully execute our vision to convert low cost, abundant coal resources, including lignites and waste streams, into high value transportation fuels.—Tim Vail, President and CEO of SES
This approach to converting coal to gasoline first gasifies the coal, then converts the resulting syngas to methanol for use by the MTG process. The conversion of methanol to hydrocarbons and water is virtually complete and essentially stoichiometric in the MTG process. The reaction is exothermic with the reaction heat managed by splitting the conversion in two parts. In the first part, methanol is converted to an equilibrium mixture of methanol, dimethyl ether (DME), and water.
In the second part, the equilibrium mixture is mixed with recycle gas and passed over a shape-selective catalyst to form hydrocarbons and water. Most of the hydrocarbon product boils in the gasoline boiling range.
ExxonMobil calculates that a feed of around 4.6 million t/year of coal can produce about 1.4 million t/a gasoline—about 36,000 barrels per day. Yield and capital costs are dependent on the coal quality: ash content, moisture content, sulfur and heating value.
According to the technical analysis for California’s Low Carbon Fuel Standard published by UC Davis in 2007, total lifecycle greenhouse gas emissions for all energy products produced by the MTG process (without carbon capture and storage, CCS) are comparable to the high estimates for average coal-to-liquids process emissions (about 48.7 gCeq/MJ of refined product). However, emissions per MJ of gasoline delivered are much higher (64.69 gCeq/MJ of gasoline), according to the report.
By contrast, the report describes total emissions of gasoline produced from conventional oil as around 25.7 gCeq/MJ, and fuel derived from tar sands or extra heavy oil ranging from 29.4 to 35.9 gCeq/MJ. Estimates for oil shale fuels range from 33 to 70 gCeq/MJ.
The MTG process, notes ExxonMobil, is relatively uncoupled—i.e., it can work with a variety of coal-to-methanol systems. DKRW Advanced Fuels (DKRW), for example, is using GE gasifier technology (earlier post) with MTG as part of its coal to liquids (CTL) project in Medicine Bow, WY. (Earlier post.) DKRW says it is planning a carbon capture system for the project.
An Alternative Route for Coal To Liquid Fuel: ExxonMobil Methanol to Gasoline (MTG) Process (ExxonMobil presentation, 2008)
A Low-Carbon Fuel Standard for California Part 1: Technical Analysis (UCD-ITS-RR-07-07)