While coal to liquid diesel fuel is definitely an alternative fuel, it is most definitely definitely not renewable and absolutely not green. According to the EPA even if coal to liquid production is combined with carbon capture and storage, greenhouse gases will rise by four percent compared to petroleum. Since no one has done a commercial scale coal to liquid plant with carbon capture it is likely that at least early plants will not have it. Without carbon capture, coal to liquid could increase well to tank greenhouse gas emissions by 119% compared to petroleum.
It would appear that the only advantage of coal to liquid technology is the security issue since we have lots of coal. Beyond that it is even more of a boondoggle than corn ethanol.
Update: Hank the EcoGeek has more on this on this story as well.
[Source: New York Times via TreeHugger]