Solarbabies

Solarbabies is a movie starring Richard Jordan, Jami Gertz, and Jason Patric. In a post-apocalyptic future ruled by the military, a group of renegade teenage orphans find a legendary orb, Bohdai, that can supposedly bring the rain...
In a future in which most water has disappeared from the Earth, we find a group of children, mostly teenagers, who are living at an orphanage, run by the despotic rulers of the new Earth. The group in question plays a hockey based game on roller skates and is quite good. It has given them a unity that transcends the attempts to bring them to heel by the government. Finding an orb of special power, they find it has unusual effects on them. They escape from the orphanage (on skates) and try to cross the wasteland looking for a place they can live free as the storm-troopers search for them and the orb.