The European Commission met last month to discuss linking all the European Union countries together in a continental supergrid. No, they're not planning to the spend millions (perhaps even billions) of Euros it would cost to install powerlines across land borders. Europeans are looking offshore--to connect their growing supply of offshore wind power with a grid spanning the Baltic Sea, North Sea and Mediterranean Sea. Europe is well on the way to its goal of drawing 20 percent of its total energy from renewable sources by 2020. Twenty-five offshore wind farms spread between Ireland, the U.K., Sweden, Denmark and the Netherlands , and more than 20 new projects have been approved in Germany.
While winds are stronger and more consistent at sea, they're still not foolproof. If a breeze fails, a local grid can turn to other energy sources to bridge the gap. That won't work if a country draws a large proportion of its power from renewables, says Frauke Thies of Greenpeace's European Unit. Linking wind farms along the coast could solve this problem by offering some insurance against the vagaries of Mother Nature: Odds are good that, if wind stops blowing in one region, it will be windy somewhere along Europe's ample coastlines.
On a small scale, this is already happening. An undersea transmission cable that cost nearly $800 million spans the 370-plus miles between Norway and the Netherlands, allowing the two countries to trade power. Thies's Greenpeace unit for a grid to link seven countries on the North Sea.
Such a project wouldn't be cheap or easy. The Greenpeace plan would cost $20 billion to $25 billion to build. And even small offshore wind farms are already complex. Generally, each row of turbines is attached to a cable buried 6 ft below the seabed that runs to a central hub. To bury it, builders use high-pressure blasts of water to "liquefy" the sandy sediment; after crews lay the cable, the sediment resolidifies around it. From the central hub, larger undersea cables carry the power to a substation on land, where its voltage is adjusted so it can enter the localized electrical grid.
In an offshore grid, wind power stations would link to each other rather than directly to the shore. In the few places where the system did connect to land, the electricity would tie directly into substations of the national electric grids. In Greenpeace's model for the North Sea, each country's grid would be connected to several others: The U.K., for example, would have connections to Norway, Germany and Belgium. Thies estimated that the project would require burying 10,000 miles or more of high-speed transmission cable in the North Sea, capable of carrying 69 gigawatts of electricity.
Despite the cost and hassle, Thies maintains that the benefit of an offshore grid--balancing inconsistent wind production with international consumption--will be well worth it. Allowing Norway and the Netherlands to share power when one has too much and the other not enough saves about $1 million every day, she says, enough to cover the cost of installing the line in a little more than two years. In other parts of Europe, wind farm operators have had to slow down their turbines because the existing grid can't accommodate the electricity, according to Jim Manwell of the University of Massachusetts Renewable Energy Research Laboratory. Plus, a European supergrid could link other renewable energy sources like Norwegian hydropower and Europe's planned , Thies says.
It would take years to plan and build an offshore grid, European Wind Energy Association CEO Christian Kjaer says, and "there are no timetables being discussed at the moment." According to Kjaer, half the problem is political: National monopolies both create and distribute power in most countries, and connecting to an international grid that contributes power from wind would lower energy prices, offering very little incentive for them to do it. The European Commission is working on legislation to change that situation, he says, because--besides benefitting renewable energy--such a grid would help even power distribution across the continent. "We need infrastructure," Kjaer says. "We need interconnectedness."
According to the Department of Energy, wind power by 2030--and that would include sources offshore. Cape Wind is racing to build the country's first offshore farm in Nantucket Sound off Cape Cod, and Bluewater Wind is navigating the same maze of permits to build offshore wind farms in Delaware and the Northeast. This summer, even New York City's mayor, Michael Bloomberg, proposed wind turbines off Long Island to provide renewable energy to the Big Apple. All of these projects would route power directly to a localized electrical grid--but if offshore wind begins to truly take off, the United States might look to a future European supergrid as an example of how to make the most of a finicky resource.