HERE'S ONE MORE reason to pray for surf: Wave energy from U.S. waters could someday meet 7 percent of the country's current electricity demand, according to the Electric Power Research Institute, a Palo Alto, Californiabased nonprofit. That's roughly the same amount produced by all of our hydroelectric dams. But unlike dams, wave-energy converters, which harness wave motion to generate electricity, are installed either on the seafloor or as floating buoys miles offshore, meaning that they generally can't be seen from land and don't disrupt the environment. While Europe has had wave systems online since 2003, they're just reaching the U.S., with projects slated for Hawaii, California, Washington, Rhode Island, and Oregon, where New Jerseybased Ocean Power Technologies has filed an application to install enough 50-ton buoys to power 50,000 homes. Too bad Vegas is so far from the ocean.