The magic of ocean currents is that they surround every continent on Earth and they run all day, every day. That’s what sets this energy source apart from wind, solar, tidal, or wave—all of which are cyclical, meaning that during certain periods they don’t produce power.

The ocean-current generator we’re planning to build would float 100 to 200 feet below the sea surface. The device is a 65-foot-diameter cylinder shaped to speed up water flow, with propeller blades attached to its frame. As water flows through, it strikes the blades and spins a rotor, which generates electricity. A 17-foot center opening would allow animals to pass through unharmed. We estimate that in the Gulf Stream, a few miles offshore from West Palm Beach, Florida, the five-knot current would turn the blades about eight times per minute, generating about a megawatt of power.