I've been keeping up with the developments of this via physics journals. There are already proto-type devices that are fairly efficient. Another few years, perhaps at most, they'll be commercial, maybe even consumer level. Of course, if the 'oilers' hadn't won over in the early 20th, stuff like this would've been around already. Or something just as good. Blame your forefathers, and wait for the day time travel is available to go back and give their nut sack a yank.
By the way, I think TG posted the same thing last year. Or someone did, because I remember seeing it here.