For four months in 2008, the churning waters 3 miles off the north coast of Portugal were home to a test of the world's first commercial wave energy farm. To most observers, this marine power plant must have looked very odd. Each red device had four cylinders linked end to end, sausagelike and semisubmerged, with their noses pointed toward the incoming waves. The cylinders were connected by hinged joints that moved as the devices rode the waves—an action that pushed pressurized fluid through hydraulic motors, powering generators that sent a flow of electricity down to a single underwater cable.


Within the rapidly expanding renewable energy sector, wave energy farms like the one tested in Portugal are still a novelty. But not for long. As the push to develop clean alternatives to greenhouse gas-emitting, nonrenewable fossil fuels accelerates, most money, research, and development remain focused on wind and solar technologies. But marine power, particularly wave and tidal energy, might also eventually provide consumers with large amounts of affordable, renewable electricity. Essentially, the science, art, and costs of marine energy are where wind power was two or three decades ago. "It's not ready for prime time—it needs five to 10 years of technical development," says Dick K. P. Yue, a professor of ocean engineering at the Massachusetts Institute of Technology. "But it could have a huge impact in 20 years."

About 70 percent of the Earth is covered in water, and this water is the globe's biggest repository of solar energy. One need only watch waves crashing onto a rocky shore to appreciate the seas' might. If just 2 percent of the oceans' energy were converted to electricity, it would meet the world's entire power needs, according to the Northwest National Marine Renewable Energy Center in Oregon. Moreover—unlike wind and sunlight—waves, currents, and tides are highly predictable, which makes ocean power more grid friendly. With an increasing swath of the world's population living within 50 miles of the seas, marine power would not need to be transmitted great distances. The converters used to harness water power are generally environmentally benign and unlikely to harm marine life. Indeed, the environmental group Greenpeace has been lobbying heavily for ocean energy.

(U.S.News)

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