clarification to previous poster: the only fuel from syntroleum that is certified for flight on only USAF aircraft is based on coal or Fischer Tropsch fuels, which is well demonstrated to not be economic. Despite window dressing by FT proponents, the real cost appears quite high + the incredible water use by the FT process--which is a deal killer.

Syntroleum themselves are de-prioritizing fischer tropsch fuels developpment.

Any fuels from syntroleum using plant oils are not yet certifified for civil or USAF use--this owing to the FT and coal community deliberately trying to slow down the certification process for renewable and high quality plant oil based sources

If syntroleum want to play, they need to get full force behind the effort to certify plant oil based SPK fuels--which are chemically identical to fuels from Fischer Tropsch process, but are being discriminated against for entirely non-technical, rather commercial, reasons...