Not a problem of the KFLL scenery: that power plant is part of the default FSX scenery. However, it shouldn't happen. Have you installed some kind of effect replacement addon ?
Hmm, maybe a REX contrails effect is the only thing I can think of; besides other 3rd party scenery add-ons that might have changed a few effects files without notice. I do agree, that it has to have something to do with an effects-file though, default or otherwise. If I figure it out someday, I'll drop a note back here in case anyone else notices the same.