This paper reports detailed process designs and cost assessments for production of clean liquid
fuels (methanol and dimethyl ether) by indirect coal liquefaction (ICL). Gasification of coal produces
a synthesis gas that can be converted to liquid fuel by synthesis over appropriate catalysts.
Recycling of unconverted synthesis gas back to the synthesis reactor enables a larger fraction of
the coal energy to be converted to liquid fuel. Passing synthesis gas once over the synthesis catalyst,
with unconverted synthesis gas used to generate electricity in a gas turbine combined cycle, leads
to less liquid fuel production, but provides for a significant second revenue stream from sale of
electricity. Recently-developed liquid-phase synthesis reactors are especially attractive for ‘‘oncethrough’’
processing. Both ‘‘recycle’’ and ‘‘once-through’’ plant configurations are evaluated in
this paper. Because synthesis catalysts are poisoned by sulfur, essentially all sulfur must be removed
upstream. Upstream removal of CO2 from the synthesis gas is also desirable to maximize
synthesis productivity, and it provides an opportunity for partial decarbonization of the process,
whereby the removed CO2 can be captured for underground storage. The analysis here suggests
that co-capture and co-storage of CO2 and H2S (if this is proven technically feasible) could have
important favorable impacts in some cases on liquid fuel production costs. Furthermore, the lifecycle
CO2 emissions from production and use of fuels made by ICL would be lower than with
production and use of petroleum-derived transportation fuels. If CO2 is not captured at ICL facilities,
lifecycle CO2 emissions to the atmosphere would be considerably higher than lifecycle
emissions with petroleum-derived fuels.