The ruling is strange. It basically says that the control technology for NOx and mercury has not been demonstrated on a commercial scale with lignite fuel, and that the TCEQ guidance document for "Best Available Control Technology" (BACT) says that such a demonstration is necessary.
It says TXU did not prove that these technologies would achieve the levels of reduction called for in the permit. (We should note that the permitted emissions for this plant are already far greater than any other proposed plant in the state). So, to a degree the ruling is against lignite as a fuel, because it causes so many problems for the pollution-control devices as compared to other types of coal.
It is unclear what TXU needs to do to remedy this situation. Should they propose other control methods that would not clean the emissions up as much? Should they dramatically weaken the BACT rate they must achieve so that the "preponderance of evidence" would show they could meet those weaker emission limits with the current controls?
In this case they would have to redo their modeling to show that property-line pollution at the higher rates would not exceed federal standards. Should they wait till these controls are demonstrated at a commercial level with lignite? If they do that, in the meantime, gasification will also likely become BACT, and TXU clearly doesn’t want to go the gasification route. We will just have to see.
Of course we would like to see them propose an IGCC coal-gasification plant which would emit a fraction of the pollution. The difficulties presented by lignite would be managed in the separate gasification process, not during combustion.
It is profoundly ironic that TXU’s response, when asked about gasification, is that it is experimental and unproven technology with lignite. What the Judges said was that their proposed control technology for Oak Grove was experimental and unproven with lignite. So, perhaps this will put IGCC on equal footing in TXU’s mind - don’t hold your breath.