In the quest for oil-free power, a handful of small companies are staking claims on the boundless energy of the rising and ebbing sea. The technology that would draw energy from ocean tides...is largely untested, but several newly-minted companies are reserving tracts of water from Alaska's Cook Inlet to Manhattan's East River in the belief that such sites could become profitable sources of electricity. The site that is furthest along in testing lies in New York's East River, between Manhattan and Queens, where Verdant Power plans to install two underwater turbines this month. If all goes well, New York-based Verdant could have up to 300 turbines in the river by 2008. The turbines would produce as much as 10 megawatts of power, or enough electricity for 8,000 homes. With 12,380 miles of coastline, the U.S. may seem like a wide-open frontier for the fledgling industry, but experts say interest will focus on only a few. Government and the private sector in Europe, Canada and Asia have moved faster than their U.S. counterparts to support tidal energy research. As of June 2006, there were small facilities in Russia, Nova Scotia and China, as well as a 30-year-old plant in France, according to a report by EPRI. Tidal power proponents liken the technology to little wind turbines on steroids. Water's greater density means fewer and smaller turbines are needed to produce the same amount of electricity as wind turbines. Wave energy technology is less advanced than tidal and will need more government subsidies...however, the number of good wave sites far exceeds that of tidal. But a few companies are working aggressively to usher wave power into the energy industry.