Well I think it's established that Bobby does generate energy by sheer force of will now for his ice ability. Then again, Storm does generate bio electricity as well via her mutant metabolism as established by Claremont so I can see a basis for giving her some energy stats. Gotta love comic science. In the end it doesn't matter I guess. Storm's uber powerful whether she has a 6 or 7 or energy stats. That's why so many are pressed about her in this era.