Solar Power from the Desert

SCHOTT North America

SCHOTT solutions no. 2/2009 > Solar Initiative

Andasol 1 (at the back) and 2, Europe’s first parabolic trough power plants in southern Spain, generate two times 50 megawatts of electrical power and are the role model for the megaproject Desertec.
Photo: Paul-Langrock.de/Solar Millennium

The Desertec project calls for large solar power plants to be built in the desert regions of Africa and Arabia that will supply Europe with energy. Receivers from SCHOTT are a crucial component.

Christoph Hadnagy

Per year 360 days of sunshine. Up to 4,300 hours of sun. The largest source of energy on earth. Until now, it seems that the sun has been shining on the sand dunes of the Sahara without actually serving any real purpose. This is now due to change, however. Twelve well-known international companies are convinced that Europe’s energy future lies in the deserts of North Africa and the Middle East (the MENA Region). Representatives of these companies met in Munich in mid-July of 2009 to sign a “Memorandum of Understanding” on founding a Desertec Industrial Initiative Planning Company (DII). SCHOTT AG is part of this initiative with its subsidiary SCHOTT Solar, a company that manufactures an important technological prerequisite for the efficient use of solar energy: receivers for Concentrated Solar Power plants.

With this memorandum, an abstract vision has actually become a real project for the future. The consortium is seeking to generate approximately 15 percent of the electricity that Europe needs and cover a large share of the power demands of the producing countries with the help of a network of large solar power plants that are distributed all over the MENA region by the year 2050. This will not only allow for much higher energy security for European Union countries, but also holds immense development opportunities for the nations of North Africa and Arabia. The project is moving along at a fast pace, thanks in part to the huge echo in the international media. The planning company that will be attending to the analysis and development of the technical, economic, political, legal and ecological parameters and developing pragmatic plans for this ambitious project was founded in the fall of 2009.

The receiver tubes that are situated in the focal line of the trough-shaped parabolic mirrors represent the heart of solar power plants.
Photo: Paul-Langrock.de / Solar Millennium

Technically speaking, nothing more stands in the way of realizing Desertec. The energy generated can be transported from the desert belt to the industrial centers of Europe with only very low losses due to high-voltage direct-current transmission technology. During transmission over a distance of 3,000 kilometers, only around 10 percent of the energy is lost. This technology has already been in use in larger countries like China, the United States and India, as well as submarine cables, for decades. In fact, this technology is already suited for industrial applications in yet another important area. For more than two decades, Concentrated Solar Power plants of the first generation in the United States have been generating energy from sunlight. The latest installation, Andasol 2 in the south of Spain, now supplies around 200,000 households with clean power all year long.

The receiver represents the heart of a solar power plant. It is located in the focal line of a trough-shaped parabolic mirror and consists of a specially coated absorber tube made of metal that is embedded inside a vacuum-sealed glass tube. Both the glass tube and the absorber tube are exposed to severe thermal and mechanical stress. Especially the coating on the absorber tube that is only a few hundred nanometers thick must be able to stand up to severe shifts in temperature. Whereas temperatures inside the receiver climb to as high as 400 degrees Celsius, the thermometer drops to zero degrees and below at night in the desert. In order to be able to work efficiently, these conditions are not allowed to have any effect on the receivers for a period of at least twenty years. The latest receiver generation from SCHOTT Solar is designed to be able to handle the extreme operating conditions of solar thermal parabolic trough power plants. The mechanical and optical properties allow for the highest possible efficiency and durability.

“The Initiative represents a collective commitment to renewable energy sources and the will to take sustained responsibility for the future of our planet,” emphasized Prof. Udo Ungeheuer (left), Chairman of the Board of Management of SCHOTT AG, during the signing of the Desertec Memorandum in Munich in July 2009.
Photo: SCHOTT/J. Meyer

In the meantime, the question is not whether, but rather how this idea that was considered to be a utopian line of thinking or an energy policy mirage only a few years ago can actually be realized. Nobody has any doubts today on the basic feasibility, due in part to the considerable expertise that the founding companies have in the areas of financing and technology. The total investment amount is estimated to be about 400 billion euros by the year 2050; an enormous sum that needs to be divided across many different areas of development and project phases, however. Even and especially the producing countries stand to benefit from Desertec. A large share of the electricity generated is to be fed into the local power grids. In addition to private and commercial consumers, seawater desalination plants for producing drinking water can also be supplied with thermal or electrical energy. This means the project will also contribute towards improving the infrastructure and standard of living in the MENA region and thus result in greater political stability. <|

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