Shale Oil
I've heard before that shale oil was energy intensive. In fact, that's the most frequent criticism I've heard. But I had no idea it was this energy intensive:
Environmental groups such as the Natural Resources Defense Council have called oil shale one of the planet's dirtiest fuels. It can be converted into liquid petroleum, but only after being heated to 900 degrees Fahrenheit for five years or more, so production requires massive quantities of energy, the council says.
Wow. No wonder it's only worth pumping if oil is over $70 a barrel.