Upwind power plants as environmentally friendly electricity generators

A landmark for the Expo?

Expo 2000 in Hanover is getting closer and closer. You can find out exactly how many days are left on the official homepage every day. The hope of an entire region hangs on this event. The city of Hanover and the surrounding area are to be in the public eye for at least three months, demonstrating how far progress has come.

If you want to live up to such expectations, you have to make do and not spill the beans. Started a few years ago with high goals, Expo GmbH is now suffering one setback after another. Financing is on shaky ground and several planned projects are failing due to lack of money. Even the theme park, in which among other things the energy supply of the future is to be presented, is affected by this.

For the energy industry, this poses three forward-looking challenges. The energy supply must firstly be secured for the long term, secondly affordable and thirdly environmentally compatible.

As "Landmark" of the Expo was planned to build a model of the so-called updraft power plant. The tower, with a height of 180 meters, should tower over the other buildings of the event, which expects visitors from all over the world.

Wind turbines as environmentally friendly power generators

Model of the solar chimney power plant for the Expo

But also this project seems to fail because of the financing. According to Prof. Schlaich, the father of this power plant, this tower in Hanover could only be realized if sponsors were found for the construction costs. In spite of these problems, the enthusiasm with which Prof. Schlaich has been calling for this plant for two decades now. "The environment will be relieved, natural resources will be saved and jobs will be created."

The principle is relatively simple: a round glass roof with a diameter of about 3,600 meters, rising slightly toward the center, serves as a collector. The rising warm air is sucked up into a chimney and rises with a speed of about 15.8 m/s (updraft).

Solar chimney power plants as environmentally friendly electricity generators

View into the chimney of the power plant

The resulting air suction is used to drive turbines in the tower and to produce electricity via generators.

Several such plants are currently under discussion for the state of Rajasthan in India and for Ghana. The height of these upwind power plants should be around 1000 meters. Problems with the statics, according to Prof. Schlaich none. With an internal diameter of 115 meters, spoke wheels are to be installed at certain intervals to stabilize the tower and give the chimney the necessary strength over its entire height. At the beginning of the eighties, a prototype of such a power plant was built in Spain. Planned as a test site, the tower’s stability and power generation capacity were to be tested, among other things. The project, which reached a peak output of 50 kW, was subsidized by the German government.

updraft power plants as environmentally friendly electricity generators

Prototype in Manzanares

The prerequisites for the operation of such a project are sufficient surface area and solar radiation. These conditions are available in abundance, especially in countries with desert regions. Even the necessary building materials of glass and concrete pose no problem. These energy towers are especially interesting for developing countries. Since the operation does not make high demands on the personnel, jobs could also be created in structurally weak areas. The demand for environmental compatibility is self-evident for such a plant. The energy can be produced without the consumption of fossil or radioactive fuels and there are no harmful waste products such as carbon dioxide. In addition, the operating costs of a solar chimney power plant were negligible compared to other power plants. The challenges of energy supply could thus be impressively illustrated by such a power plant.

As already mentioned, there is also interest in the towers – but the demand on the part of the Federal Ministry of Research was stopped. The opportunity to be a trendsetter in new technologies seems to have passed Germany by once again. The projects were "uneconomical", is the succinct reasoning of the ministry. Of course, the construction of such a large-scale facility would not be without risk, especially since experience has only been gained with the comparatively small test facility. But if you don’t take a risk, you can’t get anywhere. Prof. Schlaich is sure, "that the technology could offer enormous opportunities if the principle was demonstrated on the basis of a rough installation." If you don’t give new technologies a chance, you can’t be the first to arrive at your destination. The Expo faces a similar problem. It is supposed to be trendy, but there won’t be much left of it if nothing is risked. And of course nothing can be risked if no money is available.

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