Hundreds of Miles of Wind Farms, Networked Under the Sea

On the Grid The Atlantic Wind Connection would link wind farms over hundreds of miles using undersea cables and voltage conversion stations. Kevin Hand

During the last ice age, glaciers a mile high pushed several dozen cubic miles of rock, sand and debris into the ocean off North America’s mid-Atlantic coast, creating a broad shelf that extends up to 40 miles offshore. This long, flat stretch of seabed and the shallow, windy waters that cover it make the ideal spot for dozens of offshore wind farms—and if all goes well, the network that would link those turbines together and back to the coast will soon be in place.

Offshore wind power has significant advantages over the onshore variety. Uninterrupted by changes in terrain, the wind at sea blows steadier and stronger. Installing turbines far enough from shore that they’re invisible except on the very clearest days lessens the possibility of not-in-my-backyard resistance. The challenge is getting the electricity back to land, to the people who will use it.

The Atlantic Wind Connection could provide an entirely new model for connecting seaborne energy with land users.The Maryland-based transmission-line company Trans-Elect proposes to do just that with a $5-billion undersea power grid that would stretch some 350 miles from northern New Jersey to southern Virginia. The Atlantic Wind Connection (AWC) would provide multiple transmission hubs for future wind farms, making the waters off the mid-Atlantic coast an attractive and economical place for developers to set up turbines. The AWC’s lines could transmit as much as six gigawatts of low-carbon power from turbines back to the coast—the equivalent capacity of 10 average coal-fired power plants.

So far, the project has attracted backing from Google, the clean-energy investment firm Good Energies, and the Japanese trading company Marubeni. Trans-Elect says it plans to begin construction on phase I—a $1.8 billion, 150-mile span from Delaware Bay to Atlantic City—in 2013, and that section could be operational by 2016.

To appreciate the novelty and potential of the Atlantic Wind Connection, it helps to understand the building blocks of an offshore wind system. At its simplest, offshore wind transmission involves connecting a group of wind turbines to an AC transmission cable, which will carry the electricity they generate back to land. (Nearly every wind turbine on the market today generates AC power, the standard for the terrestrial grid.) But AC cables are generally efficient only over short distances, particularly when they’re used underground or underwater.