Europe Backs Supergrids

Recent efforts show hope for regional transmission planning for renewable power.

Tuesday, December 02, 2008

By Peter Fairley

Last month, the European Commission (EC) called for construction of regional electric transmission connections across the North Sea, around the Baltic region, and around the Mediterranean Sea, to distribute solar and wind power to and across Europe. It's all part of a plan to boost renewable energy from 8.5 percent of European energy consumption to 20 percent by 2020--and even more thereafter.

But the EC, the European Union's executive body, acknowledges that getting these so-called supergrids built will mean forging new agreements between European countries for transmission planning and investment--much as the United States needs more cooperation between states to, for example, move wind power from the Midwest to major cities. "The wind power which consumers demand cannot be delivered without new networks," the EC report says, and "there is little strategic planning" between nations to build the required connections.

However, several recent developments suggest that progress on transmission between European nations is possible. This summer, for example, a negotiator appointed by the EC convinced France to accept a new transmission connection with Spain, breaking a 15-year impasse over expanding power exchanges between the countries. Use of high-voltage DC (HVDC) technology will enable planners to bury the new line and thereby overcome local opposition to conventional overhead AC transmission lines.

The French-Spanish connection will help both countries balance power supply and consumption--especially Spain, which struggles at times to accommodate its installations of highly variable wind power, the largest in Europe. EC negotiator Mario Monti estimated that the link, called an interconnection, would reduce reliance on the countries' least efficient power plants, thus avoiding 1.5 million tons per year of carbon-dioxide emissions (roughly the annual emissions of 600,000 cars).

Christian Kjaer, CEO of the European Wind Energy Association, a Brussels-based trade group, calls it a "major breakthrough" that shows how Europe can overcome entrenched opposition to such interconnections. "It's a good example of why we need more than a national approach," says Kjaer.

Meanwhile, proposals for HVDC grids to deliver clean power from offshore wind farms to European consumers are getting more detailed. In September, for example, Brussels-based environmental consulting firm 3E mapped out a blueprint for what a North Sea offshore wind-power grid might look like. In 3E's design, 3,500 miles of underwater HVDC cables crisscross the North Sea, forming a network capable of hooking up 68,000 megawatts' worth of new offshore wind farms--enough generating capacity to meet 13 percent of the region's power consumption.

Still, political challenges remain. Kjaer points to a set of wind farms for Kriegers Flak, a shallow sandbar in the Baltic where the territorial waters of Denmark, Sweden, and Germany converge. Each country plans to build three of the world's largest offshore wind farms--up to 640 megawatts each, about the size of a medium-size coal plant--within a few miles of each other, yet without coordinated transmission. "They are talking about taking one grid into Sweden, and one into Germany, and then you have the Danes," says Kjaer. "It makes no sense."

A coordinated link, Kjaer says, would cost less to build than three separate lines, and would provide considerable extra value by linking Northern Germany's variable wind-power production with Sweden's hydropower riches. Germany could export excess wind power to Sweden via a Kriegers Flak interconnection when it has more than it can absorb, then import hydropower from Sweden when the wind dies down. The EC has appointed a mediator--as it did for the French-Spanish interconnection--to work on the issue.

Such efforts could pave the way to an entirely fossil-free power supply in Europe, much as Al Gore has proposed for the United States. Modeling by Gregor Czisch, an energy consultant in Kassel, Germany, shows that in theory, Europe and North Africa can source all of their electricity from renewable sources using a supergrid with conventional HVDC lines that can shift power thousands of miles with minimal losses. In this vision, wind power provides 70 percent of Europe and North Africa's energy needs, and Scandinavian hydropower serves as the backup battery, while African solar farms and distributed biomass-fueled power plants play supporting roles.

Notably missing from the supergrid vision? A role for the conventional power plants that provide most of today's power. "The utilities are thinking about the supergrid," says Czisch, "but not too fast." Czisch says that the utilities prefer a short-term approach to transmission planning that is more protective of their existing investments, whereas the public needs a bold new approach to planning at a European or at least regional level: "We really need an independent organization which can do the calculations necessary."

Copyright Technology Review 2008.