undersea turbines

The Big Picture: Wind power is all about location — getting turbines where the breeze blows steady and strong. One of the best places for that is far out at sea. And because one of the biggest obstacles to expanding wind power is overcoming the objections of residents who don't want wind farms blocking their views, deepwater wind, which is invisible from shore, has dual appeal.

The concept of harvesting the ocean as an energy source is nothing new, but in practice it's rarely utilized. That's beginning to change, though. This week, the first major underwater turbine was installed in Northern Ireland's Strangford Narrows—a body of water known for its fierce currents. SeaGen's twin blades measure 52 feet wide, and instead of intermittent winds, this green electricity generator will rely on the ever-changing tide to produce power for around 1,000 homes. Built by Marine Current Turbines, it will be operational this summer.