Wind turbines can be a radar operator's worst nightmare. By scrambling radar waves as blades spin faster or slower, large wind farms are sometimes capable of erasing airplanes from radar screens completely. But a Danish wind turbine company and a UK defense contractor may have found a solution by unveiling the first "stealth" wind-turbine blade last month.
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.