It will come as no news to IEEE Spectrum readers that wind energy has been the fastest-growing part of power generation in recent years. Two recent developments, however, put the outlook for wind in a whole new perspective. On 18 December, British authorities issued contracts to build 15 huge offshore wind farms, to provide most of the added electricity England will need in the coming two decades. And almost simultaneously, New York City officials unveiled a concept for putting an array of wind turbines atop the Freedom Tower, the main new building to be erected later this year on the World Trade Center site.

The idea for the Freedom Tower is to put about 25 turbines into a cagelike structure at the top of the building, between the main body of the structure and its TV and radio antenna, a combination intended to vaguely echo the Statue of Liberty [see artist's conception, "Turbine Tower"]. There also is some notion, inspired by Tibetan Buddhism, of incorporating cylinders containing mantras or prayers written on thin paper into the turbine systems. Perhaps this could be of some comfort to September 11 survivors, who have complained that designs for the site have been impersonal and have not included relics from the downed towers.

The overall design for redevelopment of the Trade Center site reflects a compromise between the principal architect, Daniel Libeskind, best known for the Berlin Holocaust Memorial, and David Childs of Skidmore, Owings, Merrill. Childs was brought in at the property owner's insistence to see that practical considerations would not be neglected in fleshing out the details of Libeskind's Freedom Tower, resulting in some acrimony between the two architects and, some would say, a compromised final design. But it evidently was Childs's idea to cap the Freedom Tower with an array of windmills.

If that concept is adopted and actually built, it will be a world first and, to many, more than a little startling. But the idea of capping skyscrapers with windmills to produce some of the buildings' electricity has been under development for more than a decade by

Photo: Amec Border Wind

The British seem to be stealing a march on the Germans and Danes, who so far have led the way in promoting large-scale wind generation

academic groups like the Stuttgart School of Architecture and City Planning in Germany and by firms like the Richard Rogers Partnership in London.

In the early 1990s, the Rogers partnership developed detailed designs for tall buildings to be built in Tokyo that were configured to concentrate and accelerate wind both to ventilate the structures and to drive propellers. Though never built, those designs got wide notice, since they came from a top-name architectural firm. The senior partner, Sir Richard Rogers, was a student of the London architect Norman Foster—also a pioneer in thinking about how to integrate windmills into high-rise designs—who codesigned the Pompidou Center in Paris with Renzo Piano.

The initial design work for the Freedom Tower turbines was done by Guy Battle, of Battle McCarthy Consulting Engineers in London, which has worked closely on projects with Foster and the Rogers partnership, among others. It was Battle's idea to include prayer wheels in the turbine systems.

With the latest developments in wind, the British seem to be stealing a march on the Germans and Danes, who so far have led the way in promoting large-scale wind generation. About the same time New York authorities were publicizing the idea of topping the Freedom Tower with wind turbine technology largely developed in London, the British government announced an enormously expanded program of offshore wind farm construction. On 18 December, Britain's Crown Estate—the organization that manages a large chunk of the monarchy's far-flung holdings, including its offshore continental shelf—announced the winners of contracts to build 15 wind farms at three locations off Great Britain's coasts.

The wind farms, with hundreds of turbines each, will have a total generating capacity of 5.4-7.2 GW and cost, in all, upwards of 7 billion British pounds (about US $13 billion). The project, said the UK's energy minister, Stephen Timms, puts Great Britain on course to be producing 10 percent of its electricity from renewables by 2010 and 20 percent by 2020, compared with 3 percent now. It represents the second round of windmill construction spearheaded by British energy authorities.

The new turbine towers, which will be about 80 meters tall, are to be installed in three main areas: the river Thames estuary; the Greater Wash, 30-40 kilometers off the Lincolnshire coast; and the North West, extending from the north Wales coast to the Solway Firth and out into the Irish Sea. Developers, which had until 20 January to accept offers from Crown Estate, will be granted leases of 40-50 years. They include Warwick Energy Ltd., Airtricity (an Irish renewables company), the construction group Amec, Powergen (owned by Germany's E.ON AG), RWE Innogy (owned by the German utility RWE), and the oil companies Total and Royal Dutch/Shell. GE Wind Energy, a growing presence in Europe and worldwide, already is building a big farm at Gunfleet Sands off the Essex coast, as part of the first round.

Of course, anything as large-scale and visionary as England's wind program does not go without critical comment. The Royal Society for the Preservation of Birds has worried about the impact of the farms on species that feed at the sites. Onshore wind farms already have come under heavy fire in parts of England, with residents complaining about their noise, unsightliness, and even light effects. Janet Wadham, a resident living near one of the first wind farms, complained to the Dallas Morning News that as a result of sunlight reflecting off turbine blades, her living room "lit up like a discothèque."

Papers like the Financial Times have been inundated with letters from taxpayers worrying about the added cost of producing electricity from wind. The price of electricity generated by offshore wind turbines is still higher than market prices for electricity from fossil fuels, which means that one way or another British citizens and businesses will be paying significantly more for electricity in the next two decades.

For now, though, the British consensus seems to be that the price is worth paying to obtain an adequate future energy supply while reducing greenhouse gas emissions without resorting to new nuclear power.