Wind technology development is now raising a new issue, re-cycling and re-using wind plants. In the Netherlands two wind power stations are now looking for a new lease of life.

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Over the past decade wind energy has developed into a fully fledged industry with all the responsibilities that adulthood entails. Finding a use for old or discarded components is just one of those responsibilities now being tackled in the wind business. Re-using or re-cycling wind plants is becoming a new specialisation -- and there is more to it than simply off-loading tired old turbines at the breaker's yard. There is also the question of what to do with the site and possibly the permits that go with it, too.

In the Netherlands two wind power stations are now looking for a new lease of life. One is the infamous test wind farm of Holec machines at Oosterbierum, belonging to SEP, the Dutch Electricity Generating Board. The wind farm, which never lived up to expectations and has been idle for some time, was recently sold to electricity distribution company, NUON. The other wind station is in the village of Anna Paulowna in the province of North Holland. It has been handed over by local electricity distributor, PEN, to a private consortium led by wind turbine manufacturer Lagerwey. The Anna Paulowna project was one of the best known in the Netherlands. Built in 1988, it consists of 16 turbines arranged in a spectacularly neat line alongside the North Holland Canal. The canal, once a lifeline for Amsterdam Harbour, is too narrow for modern vessels and is now obsolete. So, too, are the 16 wind turbines.

The machines, each with an installed capacity of 160 kW and a rotor diameter of 20 meters, were originally built by Bouma -- a company long since extinct having been partially taken over by NedWind. Before it disappeared, though, Bouma had to carry out major blade repairs on the machines in 1989. Blade problems cropped up again several months ago when the turbines were stopped after the discovery of blade fatigue. It was felt this could lead to cracks and the loss of a blade. "After that discovery we had a few options," says Jos Kouwenhoven from PEN. "We could either try to repair the turbines, put up new turbines on the same spot or sell the site for some other use."

In the end it was decided to re-use the site for another wind farm, but not with PEN as the developer. The utility is moving away from building and operating its own wind turbines. "Power purchase contracts" are the current buzz words at PEN -- the utility wants to buy electricity, not produce it. Practising what it preaches, PEN handed over the site to a third party which intends to use both the electric infrastructure and the existing wind turbine foundations.

The Lagerwey consortium, operating under the name Windpark Anna Paulowna BV, was chosen from a number of potential developers. Lagerwey has a 50% stake in the consortium, amounting to eight of the 16 new turbines proposed for the site. The other half is owned partly by a wind co-operative, De Eendracht, and partly by private citizens, mainly dairy farmers in the area. The existing 160 kW Bouma turbines will be replaced by considerably smaller Lagerwey 18/80 turbines. According to David Mol from Lagerwey, the choice of a smaller turbine was inspired by PEN's desire to have the Boumas replaced as soon as possible. By using the 80 kW turbine, complex legal procedures could be skirted and problems with the existing electric infrastructure avoided. Mol expects the 16 turbines to each produce 200,000 kWh a year, only a little less than the maximum 250,000 annual output of the Bouma machines.

The Lagerweys can also be mounted on the original, 30 metre Bouma towers. These will be elongated by three metres using a new section with a flange fitting. The turbine top will be fixed to the added section. Mol does not anticipate difficulties in obtaining a certificate of technical approval for his Bouma/Lagerwey hybrid. If all goes well the turbines will be up and running by the beginning of April, he says. What PEN is to pay for the power produced by Anna Paulowna has not been disclosed, but it is probably a lot less than the NLG 0.15/kWh the utility normally purchases its wind energy for. PEN's eagerness to get rid of its Bouma machines is unlikely to have extended to giving away the site, foundations, infrastructure and towers.

New beginning for troublesome SEP

The second wind farm up for recycling, the troublesome SEP station in Oosterbierum, came to life in 1988 with 18, 300 kW turbines built by Dutch manufacturer Holec. It took Holec, now also up for sale, almost six years to make the 18 turbines which, unusually, were equipped with blades of steel. Oosterbierum was an experimental project and one of its remits was to investigate the effect of a whimsical supply of wind on the national grid. Another research topic was wake-effects and more recently the impact of the wind farm on birds has also been studied.

The SEP wind farm was plagued with problems from the outset, starting with gearbox failure. When the project did start operating as intended, blade failure struck and two wind turbines threw a blade each in two different storms. Since last April all the SEP machines have stood still, much to the consternation of the Dutch wind community -- who feel the sight of stationary turbines does no good for wind's image -- and the local population, who regard the defunct power station as no more than an eye-sore. A risk analysis of the blade failures, published this month, shows the blade loss was due to extreme wind force coupled with a violent change in wind direction.

But the blade failures had nothing to do with the decision to sell the wind farm to NUON, says Irene Carsouw of SEP. "From the beginning it was clear this park would be closed. It was meant for research and it has now fulfilled its task," she says. According to Carsouw, SEP has no plans to become involved in the production of wind electricity. "Our business is large scale production of electricity. I wouldn't call a wind park large scale," she comments.

The results of the research at Oosterbierum will be made public in the near future. One of these is that a wind farm produces no more victims among birds than a power line or a highway. Another result, according to the study of this misbegotten wind farm of relatively old technology, is that 1000 megawatt of wind capacity is needed to replace 165 MW of conventional power. That makes wind energy very expensive, according to SEP. Too expensive, at least, to use wind as a main source of electricity on the national grid.

The exact sum NUON has paid for the Oosterbierum project is a well kept secret. Neither Carsouw nor Kouwenhoven will be more specific than "a few million Dutch guilders." Compared with the original investment of NLG 60 million in 1988, it does not sound like much. The wind farm is being handed over to NUON this month, by which time the distribution utility might have found a use for it. Deliberations over the future of the project started at NUON in early December. The existing turbines -- recognised as outdated technology -- will definitely be dismantled, probably to be replaced by either 12, 500 kW turbines or 24, 250 kW machines. Total investment in the recycled wind power station will amount to somewhere in the region of NLG 12-15 million. NUON is now studying whether any more of the project can be re-used, aside from the foundations and electrical infrastructure.

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