One possibility for future energy production involves harvesting the warmth of Earth’s tropical oceans, using the natural heat differentials in the water to drive turbines. It would be relatively simple if you didn’t need a ludicrously large piece of pipe, 33 feet in diameter and stretching a kilometer beneath the water. To put that in context, that’s a New York subway tunnel wide and two and a half Empire State Buildings high.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.