Uprooting larger numbers of small and ageing wind turbines installed in the first years of Germany's wind energy boom and replacing them with fewer, larger turbines is to become big business in the north of the country in the next three to four years. Many operators in the states of Schleswig-Holstein and Lower Saxony, where wind development began ten years ago, will replace their 150-250 kW machines with turbines of around 2 MW, says the German wind energy association, Bundesverband Windenergie (BWE). "Wind stations can halve their turbine number but double or even treble their output after repowering," states the organisation.
"Repowering can double not only protection of the environment and regional wealth creation, but also the contribution of renewables to electricity generation, and simultaneously reduce the number of turbines and increase public acceptance," says BWE vice president Hans Albers. "The new large turbines' rotor speeds of 10 to 20 rotations per minute, compared with 50 to 70 per minute of the old machines, is visually more acceptable, and noise levels fall."
Estimates of the number of turbines that could be repowered over the next four years are vague because of planning uncertainties, but the statistics give an inkling of what lies ahead. At the end of 1991 there were 806 turbines in Germany, most of them smaller than 200 kW, amounting to 110 MW and almost all in Schleswig-Holstein and Lower Saxony, according to the Deutsches Windenergie-Institut (DEWI). If all these were repowered, the number of turbines could be halved if BWE's suggestion is followed, while generating capacity could increase to 330 MW.
Four hundred a year
According to DEWI, all 2617 turbines (643 MW) installed by 1994 are theoretically eligible for repowering by the end of 2004, implying a market for 1300 state-of-the-art turbines, or 400 a year, to raise the capacity of those they replace to about 1900 MW.
What role this repowering will play in the German wind market is not clear. Wind developers had 2300 MW of new wind capacity in the pipeline in 2001, and will have 2500 MW in 2002 and 2500 MW in 2003, according to a survey by Övermühle Consult & Marketing. So far developers have not published news of repowering projects, implying that the figures reported to Övermühle are for new wind projects. The repowering would then be an additional market.
But repowering is not entirely straightforward and not "a chance for everyone," as the BWE claims, points out Olaf Hohmeyer, professor of energy and resources economics at Flensburg University. In areas officially designated as wind development zones, repowering will be easier. "The question is, how many turbines can you get licensed?" he asks. "It's a matter of negotiation with the local authority," he says. "They want fewer turbines but don't want a cut in their fiscal income from the wind station operator companies. Some want larger turbines, but don't want higher hub height or larger rotor diameter, a contradiction in terms. Operators will have to convince local politicians that visually, big turbines are scarcely distinguishable from smaller ones." Insufficient grid connection capacity for larger turbine output may also "put a brake on repowering," he adds. Operators of turbines installed outside the wind zones subsequently introduced are unlikely to be allowed to repower. "Everything is negotiable but the legal situation is clear. A licence to install and operate is granted for only the one existing turbine, not for a new machine," says Hohmeyer.
Pioneers in trouble
"Something must be done here," says Manfred Luehrs, wind energy engineering consultant in Süderdeich. "We're talking about the pioneers who risked everything in the early days and were unlucky when planning finally got going." Hohmeyer points out that some of these "may have to be taken on board somehow" because ill-feeling against those with turbines in authorised wind areas could impact on licensing procedures for their repowering projects. But Schleswig-Holstein energy minister Claus Möller has already said he is not minded to extend the priority areas for wind.
Operators with turbines outside the privileged wind areas "may seek to run their plant for as long as possible, 20 years and more, by replacing components," surmises Hohmeyer. "Already, turbine manufacturers are discussing how they can ensure spare parts are available for these veteran machines," he points out. "Customer care is important. The small turbines taken down in official wind areas could be plundered for parts for those that continue to operate," he suggests.
The money is there
Thanks to the payment system for wind energy written into Germany's renewable energy law, the Erneuerbare Energien Gesetz (EEG), from April 2000, investment in repowering should run smoothly. "Repowering will take place for machines that are so old that they are written off and where payments under the EEG have fallen to a minimum. The new, more efficient plant that replace them will be eligible for the highest payment rate under the EEG," according to Möller.
Under the EEG, wind turbines in operation before the law took effect receive DEM 0.178/kWh for at least four years to April 2004. Beyond that, depending on the performance of the plant compared with a "standard turbine" of the same type, it drops to DEM 0.121/kWh.
"Financing is not a problem, the money is there," says Hohmeyer. Klaus Isele, marketing co-ordinator at wind financing company Grüne Emmissionhaus in Freiburg agrees. He says low risk, closed-end wind funds will be used to raise capital. Each fund is launched for a specific project, structured as a limited liability company, with private investors participating as limited partners. They supply the capital to secure the soft bank loans. "The wind conditions are well known. Turbines have been improved. The risk is lower than for the original project," he says.