There's some confusion between UCG and CTL. I believe the USAF...

There's some confusion between UCG and CTL. I believe the USAF was looking at synthetic fuel made from above ground gasification - UCG specifically applies to underground gasification. Not that its a different substance just not the same process. UCG can be burnt like natural gas to produce electricity or converted to liquid fuel form (like natural gas).

Its currently illegal for the USAF to use coal to liquid , or gas to liquid fuel (CTL/GTL). The reason being the greenhouse emissions resulting from it are double that of standard oil derived fuels.