Lunar Power

I have to admit to having been unfamiliar with this technology, but Business Week has a nice article about Hydropower. It sounds promising: combined with Solar, Wind, and Ethanol, it is going to be tough for Nuclear to compete on costs:

... hydropower, the granddaddy of green energy, is making a comeback. Think Hoover Dam, but less visible and a whole lot easier on the environment. This born-again breed of clean energy isn't yet on the agenda for George W. Bush, who is out barnstorming the nation on behalf of renewable power. The President is pointing to the earth for plant-based ethanol, to the sky for wind power, and to the sun for photovoltaics. But he should also be pointing to the moon, say fans of the new hydropower, and to the seas that lie below it. Tugged by lunar gravity and stirred by wind and currents, the oceans' tides and waves offer vast reserves of untapped power, promising more oomph than wind and greater dependability than solar power.

The appeal of next-generation hydropower is hard to miss. "It's local, reliable, renewable, and clean. Plus, it's out of sight," says Trey Taylor, president of Verdant Power LLC, the Arlington (Va.) startup developing the East River site. Adds Roger Bedard, ocean energy leader at the Electric Power Research Institute (EPRI), the industry's research-and- development arm: "Offshore wave and tidal power are where wind was 20 years ago, but they'll come of age faster." By 2010, Bedard predicts, the U.S. will tap about 120 megawatts of offshore wave energy -- enough to power a small city -- up from virtually zero today.

... With its vast stretches of shoreline, the U.S. has some 2,300 terawatt-hours of potential near-shore wave power, estimates EPRI. That's more than eight times the yearly output of the nation's existing fleet of hydroelectric dams -- "a very significant resource," says Bedard. What's more, since water is heavier than air, marine systems pack a bigger punch than wind power. Because they work not by impounding rivers behind costly bulwarks but by tapping water's energy as it ebbs, flows, rises, or falls, upfront costs are lower than for dams. Maintenance to keep away barnacles and similar "biofouling" generally runs higher than for wind. Still, on balance, wave energy will evolve to be cheaper than wind was at similar levels of development, Bedard believes.

The power is more predictable, too. Unlike dam-based hydroelectric generators, which depend on rain or snowpack to keep current flowing and which shut down during droughts, newer "hydro- kinetic" systems exploit less capricious natural forces. "Lunar power" is the term offered by experts such as George Hagerman, a senior research associate at Virginia Tech and co-author of a recent EPRI marine-energy study. "You can't know if the wind will be up in an hour," he says, "but you can predict the tide 1,000 years from now."