Designed and built with the support of the European Commission, the gigantic Tjaereborg wind turbine is a fully-fledged local electric power station, generating some 3,500 MWh per year. A fine example of the tremendous potential of this renewable energy source.
Up north in the windswept land of Denmark,
the Danes have long believed in the possibilities of wind power.
The first windmill capable of generating electricity was built in
1890 and the energy which it provided was stored in batteries. Almost
a century later, the emergence of energy as one of the major issues
of our time, thanks to the first oil crises, was to generate growing
interest in renewable energy sources. Denmark took the development
of small wind-powered stations capable of meeting local electricity
needs very seriously: two research turbines, each producing 630
kW, were built in Nibe. In 1981, the Danish Minister for Energy
decided to extend the experiment, with the aim of designing a wind
turbine capable of attaining 2MW.
Although Denmark possessed the necessary scientific and technical resources to tackle the job on its own, it appealed to the European Commission to help fund this ambitious project. The latter agreed to bear 25% (ECU 2.5 million) of the total cost of building and testing Denmark's biggest wind turbine.
Eco-friendly energy, large-scale facilities
The feasibility studies lasted until 1984 - and with good reason. They involved installing a 100m2 nacelle (6 metres high) supporting a 7.8 tonne electric generator and a propeller consisting of 3x30m blades on a 56m high concrete tower. The nacelle weighed nearly 200 tonnes and the entire edifice just under 3,000 tonnes. Environmentally friendly energy had joined the engineering big league.
In 1985, the "Tjaereborg Wind Turbine" project took shape on the west coast of Denmark, not far from the town of Esbjerg. The process of assembling the turbine plus all its computer equipment, and building the tower, took place during 1986. On 10 October 1987, the nacelle was hoisted on to the top. The first tests commenced on 23 March 1988 and once the rotor attained its cruising speed (approximately 22 rpm), the exciting business of large-scale windpower generation could get under way.
The European Commission nevertheless insisted on a demonstration of the durability and technical viability of the project. In June 1988, engineers began carrying out the validation tests and the wind turbine was able to be connected up to the national grid a few months later.
Up until 1992, when the contract with the European Commission ended, the engineers measured numerous parameters (speed, orientation, turbulence and wind frequency, etc.), refined the computer programs which control the machine, monitored the electric current output, ensured that the installation was safe, analysed the amount of power generated, and so on.
Power and productivity
The Tjaereborg wind turbine is designed to operate in winds from 18 to 90km/h. In 1988, it delivered 187 MWh. Three years later, the figure had increased to 3,152 MWh, using 76% of the available wind. Between 1991 and 1994, it generated on average 3,500 MWh per year, i.e. enough to meet the electricity needs of over 700 families. By March 1995, the turbine was approaching 23,500 hours of regular service, whereas the contract with the Commission had put the minimum amount of time needed to declare the experiment viable at just 8,760 hours.
This gigantic machine also explodes the myth that wind turbines create noise pollution. In winds of 36 km/h, it produces a noise level of 64 decibels at a distance of 90 metres, i.e. roughly the same volume as a lively conversation.
Thanks to the Tjaereborg project, similar wind turbines can be built today for a quarter of the cost. European engineers now have access to all the data relating to this ambitious experiment.
"By proving that large-scale power generation using wind is technically feasible, this project has helped speed up the development of large, industrially-produced turbines. A process which would otherwise have taken many years," maintains Peter Christiansen, project coordinator.