Our Air Force has a couple different sources of fuel for its jets, one of them being a blend derived from coal. Problem is, both the process used to turn coal into fuel and burning said fuel in flight results in a lot of carbon dioxide. So, what if it just didn't? Normally that'd come off as a stupid and naive question. To DARPA, it's a proposal.
The Defense Advanced Research Projects Agency is accepting proposals (due on the 24th of this month, if you happen to have one lying around) on how to turn coal into jet fuel with absolutely zero carbon dioxide emissions. The agency also wants to do it at half the cost. Sounds crazy, but DARPA's got $4.5 million to funnel into the research.