Hiya!
Why does "repercussions" always have to be bad? ...
What if it was drawing in all the storms from the area...I guess that is already established. But now, blue skies, pleasant temperatures and warm, soothing breezes all around! Yay! The people in the area are *delighted* to have such a horrible device gone. Now they can live a normal life, without having to worry about "that crazy wizard up in Storm Keep playing with forces he can't control!". They thank the PC's for saving them from his madness and give them a heroes a feast and celebration in honor of their deed.
Of course, you could always mix in some bad stuff too... after all the partying and spotlight time is over... (this is an adventure game, after all...) ...so...
The apprentice is totally stunned by this. He always thought than he was doing the right thing...that this artifact 'helped protect the area'; that's what he was always told by his Master. But now... he had doubts about what he has done. He starts the long, slow process of trying the "heal the injustices and injuries" that he and his Master had inadvertently inflicted upon all the surrounding townships. To help in this endevour, he asks the PC's if they would carry out a task or two for him. Seems one of the things they (the master and the apprentice) did was keep an old and ornery griffin (or whatever beast you think is appropriate for their level) in check... with the help of air elementals and lightning quasielementals. Or maybe the apprentice needs the PC's to go down to the lowest dungeon level of the Dungeon of Horrendous Death; now that the master is gone the creatures there will be more willing to venture forth to harass and kill anything nearby.
In short, I wouldn't just "go for the bad". The PC's made a choice. A choice that wasn't "part of the expected script". By instantly slapping them with a wet newspaper as if they did something "wrong", encourage them with some "good-vibes". This will (A) make the players feel good about their choice, (B) encourage them to make their own choices, not just what they "think the adventure wants", and (C) set up everything for the next shoe to drop. In my example above, it also serves to give the players an emotional stake in what happens to the townsfolk. I mean, if you have some d-bag come up to you in the store and tell you to get the F outta the way when you are searching for that other $5 you need to pay for your stuff....you don't really want to "be nice" to him. However, if someone steps up and hands you $5 so you can finish paying for your stuff... you do want to "be nice" to him. Same thing with RPG's. By having everyone thank, help and generally praise the PC's (and thusly the players), you get the players emotionally invested in the NPC's and towns well-being. They will be more willing, and more "enthusiastic", about trying to protect it from whatever bad crap that's gonna hit the fan now that the storm-sucking-artifact and the Master of Storm Keep are no more.
^_^
Paul L. Ming