...And they say Science and Technology haven't had a earth-shattering break through since the atom.

I can't even begin to image the scale of the all encompassing impact something like this would have - economic (ofcourse), political, cultural, social, et all.

Just one thing though - I'm not sure if 50% efficient is good enough. That'll only call for more energy consumption - which is really not the road you want to go down, given the earth's pre-existing condition.