The Netherlands experiments with urban windmills

Jan 26, 2003 01:00 AM

In this small town whose old wooden mill generates more tourism than energy, a shiny new stainless steel windmill on the roof of a technical school barely whispers as its blades spin in a brisk winter breeze. Such high-tech turbines, which feed kW to local power grids, are now poised to conquer a new frontier -- the modern city centre, often fused into building designs and barely noticeable from a distance.
They are lighter, quieter and often more efficient than their lumbering rural counterparts, and built to take advantage of the extreme turbulence and rapid shifts in direction that characterize urban wind patterns. Germany, Finland and Denmark have also been experimenting with the technology, but the ever-practical Dutch are natural pioneers in urban wind power "mainly because of the lack of space here," said Sander Mertens, a wind energy researcher at the Delft University of Technology.

Dutch cities including Amsterdam, The Hague, Tilburg and Twente plan to install urban windmills in 2003, mostly small-scale projects with fewer than a dozen turbines each. The prospect of a new, environmentally correct energy source has attracted Dutch energy companies. Cor De Ruiter, a spokesman for one company, Eneco, said research has indicated there are 50,000 locations in The Netherlands where small urban turbines could be installed.
The new windmills pay for themselves in about five years, according to the Dutch manufacturer Prowin. And as the technology improves, prices will drop further. The smallest models weigh roughly 440 pounds and can be installed on a roof in a few hours. "All the technical problems are behind us now," says Dick Sidler, an engineer at Core International, another company that builds the latest-generation turbines. Current models cost $ 5,000 to $ 12,000.

The windmill on the roof of the technical school in Ede can generate about 5,000 kWh of energy per year, which would cost $ 900 if taken from the fossil-fuel-powered grid. That's more than enough for the average Dutch household, which consumes roughly 3,500 kWh per year -- the average American family uses 10,000 -- although most new windmills are designed more for public or commercial buildings than for private homes.
The Netherlands, with 16 mm people crowded into a country twice the size of New Jersey, is the most densely populated in Europe. It generates less than 1 % of its electricity from wind. In Denmark, that figure is 18 %; Germany, 4 %.
In the United States, it's a fraction of 1 %. But Holland has on average 245 days per year with wind speeds of 13 to 19 mph, which can power even the biggest turbines. Many of the new urban turbines can begin spinning with wind speeds as low as 5 mph.

With fewer moving parts than their rural kin, urban turbines generally require less maintenance. And because the energy they generate is close to where it is consumed, less electricity dissipates while crossing transmission lines. Problems remain, however: notably public safety concerns.
"Just one accident would be enough" to quash enthusiasm for the idea, said Mertens, the researcher. One theoretical danger, runaway windmill blades, could be averted by covering the turbines with gratings, he said, but the effect of vibrations on local buildings and inhabitants is still unknown.

Source: Milwaukee Journal Sentinel
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