The next wave of renewable power is bigger, cheaper, and multi-megawatts stronger than ever before. And it's about to go online in the North Sea.
Windblown and chilly, the east coast of England isn't exactly the best place for sunbathing. But rather than fight reality, the seaside resort town of Skegness has long aimed to exploit it. That's why a vintage poster in the local tourism office is emblazoned with the slogan SKEGNESS IS SO BRACING. On it, a salty fisherman dances along a gusty stretch of beach in a fishing cap, sweater, and boots. The poster isn't terribly alluring to sun-starved British tourists, but it's just the ticket for someone like Bill Grainger. He's a wind farm engineer who recognizes the beauty in the incessant 15-knot wind that blows off the North Sea. "It's pretty much ideal," he says. "You couldn't ask for a nicer breeze."
It's not just the wind that's favorable. The sandy shoals about two miles off Skegness' beaches provide the ideal foundation for one of the world's first offshore wind farms, which will convert the strong air current into hundreds of megawatts of electricity. Due to begin construction late next year, the Skegness farm will consist of 60 steel towers, each standing in about 30 feet of water and jutting nearly 200 feet into the sky. The structures will be topped by powerful 2-plus megawatt turbines driven by massive rotor blades with wingspans wider than a Boeing 747. Strung across the water in long rows, the towers will be linked by an undersea cable that will send the electricity they produce to an onshore substation, then to about 150,000 homes near England's eastern seaboard.
"And that's just the beginning," says Grainger, who is a project manager for AMEC Wind, one of more than two dozen energy companies racing to construct offshore wind farms throughout Northern Europe's coastal regions. The Skegness site is one of 18 farms that will soon surround the British Isles, part of an aggressive scheme to wrest at least 12 percent of Europe's energy needs from wind and other renewable sources within the next eight years. Spurred by concerns over climate change and the United Nations Kyoto Protocol agreements to reduce fossil fuel emissions, the European Commission has called upon the nations of the European Union to increase their use of renewables. Member states, in turn, are obligating their public utilities to do the same.
Offshore wind farms are expected to supply a significant part of the increase, thanks largely to technological advances that have finally made the sea-based systems economically feasible. These include new high-output turbines, dynamic power controllers, and more efficient blades. The result is that wind has become the most economical of the clean energy sources - with a cost per kilowatt-hour that has fallen by 85 percent in the past 15 years.
Even so, it remains about a third more expensive than fossil fuels, so European governments are offering financial incentives to utilities and other energy companies that develop offshore wind farms. A combination of favorable electricity purchase contracts, low-cost leases, and tax breaks have helped persuade a variety of companies to get involved, among them power producers, offshore drilling suppliers, shipbuilders, and turbine manufacturers. 
Photo by Mads Eskesen
Large-scale projects in Denmark and the Netherlands are already up and running, including a 40-megawatt installation at Middelgrunden, just off the coast of Copenhagen. And new construction in Ireland, Germany, and Britain is due to put scores of farms in the water over the next five years. In the United States, Cape Wind Associates aims to build a 420-megawatt farm in Nantucket Sound by 2005.
For its part, the UK's Department of Trade and Industry has promoted a plan to install 6,000 or more high-output turbines off Britain's shore; if clustered together, they would fill an area of seabed roughly the size of London. Last year, the Crown Estate, a government-affiliated trust that oversees the coastal waters, inked agreements with 18 energy firms to lease the 18 sites. The government kicked in $100 million in capital grants - about 7 percent of the farms' total cost - and is finalizing regulations to require public utilities to purchase electricity from them.
The UK sites are now undergoing environmental and geologic studies to determine the best spots to position the towers. Construction is set to begin in the summer of 2003. When completed, the farms will generate about 1,600 megawatts, enough to replace two of Britain's nuclear power plants (several of which are slated for shutdown soon) and feed electricity to 1.1 million homes.
"We've got the windiest coastline in Europe," says John Doddrell, director of sustainable energy policy for the Department of Trade and Industry, "and we intend to take full advantage of it."
Renewable energy proponents have long eyed Northern Europe's vast coastal shallows in the hope of harvesting the region's wind resources. Devoid of obstacles to block or slow it, the North Sea region's wind energy is about 50 percent greater offshore than on land, according to the European Wind Energy Association. Offshore airstreams are also less turbulent than those onshore, improving turbine efficiency and reducing wear and tear on the machinery. Yet until recently, turning sea breezes into electricity just wasn't economical.
"When we started to investigate offshore wind energy in the late 1970s, the biggest turbines could generate only about 10 kilowatts each," recalls Nick Goodall, executive director of the British Wind Energy Association, a nonprofit trade group. "To meet the demand for electricity, we would have had to install hundreds of thousands of towers, which was completely unreasonable."
Since construction costs on land were lower, the economics were more favorable to terrestrial systems. So wind farm developers in Britain focused on building in the country's gusty highlands. Trouble was, in densely populated areas where available real estate is in painfully short supply, their projects often butted up against private landowners: Neighbors objected to the windmills' noisy operations and tried to put the kibosh on any new ones.
But the largest hurdles were the limitations of the technology itself. Early systems were plagued with design problems that kept most from generating electricity more than half the time. Poor aerodynamics caused the towers to shake under severe wind loads. Inflexible rotor blades cracked and fell off. Generators burned out. "[The old turbines] required a lot of maintenance and suffered a lot of downtime," says Sandy Butterfield, chief wind engineer for the US Energy Department's National Renewable Energy Laboratory in Golden, Colorado. "That didn't exactly make them economical."
First developed in the United States during the 1970s, and fueled by government subsidies and tax credits as a result of the energy crisis, wind farms enjoyed a short-lived boom in the US and Northern Europe. But as energy prices stabilized and governments withdrew funding, the fledgling industry went all but bust. An exception was Denmark, which continued to subsidize the industry and eventually established a long-term target of generating 50 percent of the country's electricity supply with wind-based systems. Turbine manufacturers there continued to advance the technology. And when demand finally returned in the 1990s amid higher oil prices and growing environmental concerns, the Danes found themselves in a position to dominate the market.
Today, Denmark is the world's leading supplier of wind energy systems - and one of its most dedicated consumers. It generates more than 2,500 megawatts from wind, about 13 percent of its total electricity usage. Four of the five largest manufacturers are Danish, among them Nordex A/S, maker of a 2.5-megawatt system, the world's biggest. Last year, Nordex announced plans to build a 5-megawatt generator for offshore applications - more than twice as powerful as the ones off Skegness.
The newest turbines aren't just more powerful than their predecessors, they're more efficient and reliable. With the help of design software, engineers can devise towers and components that match the wind loads they must withstand. New manufacturing methods have also yielded rotor blades that are lighter and more flexible. This reduces the dynamic loads on the supporting tower, drivetrain, and generator housing, lowering construction costs and easing the stress on the components.
"The quality of the engineering has taken major leaps," says NREL's Butterfield. "It used to be that two mechanics would be able to keep 10 machines running. Now those same two guys can look after 100 machines, and much bigger ones at that."
Meanwhile, advances in microprocessors and power electronics - which employ semiconductors to convert electricity from direct to alternating current - have helped ease the integration of wind farms into power grids. The new line of wind systems incorporates two microprocessor-driven controllers to ensure that variable wind speeds yield a stable electrical output.
Such improvements have lowered the cost of delivering wind-based electricity by about 25 percent in the past five years, while also decreasing the turbines' downtime. "We're approaching 98 percent availability, which means we can produce electricity pretty much whenever the wind is blowing," says AMEC's Grainger. "That's exactly what we needed to make offshore wind farms feasible."
With the technology finally at a tipping point, wind farm proponents are set to construct large sea-based systems capable of delivering hundreds, even thousands, of megawatts. The decision to go big is an economic one. While the size of onshore farms is limited by the availability of open land and tolerant neighbors, offshore systems have no such constraints. Nor do their builders need worry about transporting huge towers and rotor assemblies along highways or under bridges. In fact, because the cost of the tower structures remains relatively fixed regardless of turbine size, offshore developers can realize substantial economies of scale by incorporating the largest turbines possible. That has triggered a race among manufacturers to design supersized wind systems.
"The jury is still out on the optimal size for offshore, but it's entirely conceivable that you could see a 10-megawatt turbine on the market within the next few years," says Bob Gates, senior vice president at Enron Wind, an independent Enron subsidiary that's being acquired by General Electric. The company recently introduced a 3.6-megawatt turbine for use off the coast of England in an area known as Gunfleet Sands. "These things are going to get very big."
That's just the size the offshore construction industry is used to handling. Adapting the skills and equipment that have been employed for decades to create deep-sea oil and gas rigs, at least two firms plan to enter the market this year. England's Mayflower Energy, for example, will soon complete a 400-foot vessel that will be the first specifically designed to construct offshore wind farms. Equipped with six submersible "jack-up" legs to stabilize the ship and a massive crane to position the towers, the vessel can hold up to 10 turbine assemblies on what amounts to a floating factory. "We expect to be installing about one turbine a day by year's end," says Paul Gibson, business development director for Mayflower. The company, which is considering putting up its own farm, plans to produce as many as six additional ships to meet the growing demand throughout Northern Europe. "We've surveyed the market and it seems that things are just ready to take off. This is clearly the wave of the future."
And you can't build a big wave without a strong gust.
