Recently the inventor bought two cast-aluminum molds to make the first few six-foot-diameter prototypes and has persuaded a plastic-molding company to produce them in segments. If he gets approval, he will have them spinning in inlets around the world this year. In a 10-knot current, each will generate five to seven kilowatts, enough to power four to six homes. Most important, he wants to show that his method of mass production is sound, so he can move on to the full-scale, 16-foot-diameter augers. "We already know it will work," he says. "Now it's just a matter of doing it."