Bright Prospects for Solar Energy

Essen, (PresseBox) - In Karlsruhe, Germany, the streetcar drivers are said to have an especially sunny disposition - and in the truest sense of the word. It's not surprising: Their streetcars are powered with help from the sun. As part of a project sponsored by the European Commission, energy suppliers in this city in Baden-Württemberg intend to show the world that a photovoltaics plant can work in connection with the direct-current system of the municipal transport services. Now that the lengthy project is complete, management of the public utility is excited because the conversion to alternating current otherwise needed to generate power from sun energy is unnecessary here. A cost-effective mobility concept has been born, and the CO2 savings is just icing on the cake. All the same, the savings here is 36 metric tons!

The South-facing roof of the Center for Art and Media Technology is used for the photovoltaics unit. The module on the 1,000-square-meter area supplies about 90,000 kilowatt hours of continuous current per year and also powers the Karlsruhe light rail system. The city is also entering unknown territory architecturally, as the solar power unit was integrated into a building protected as an historic monument.

A more international mindset

Whether you are powering a national monument or a light rail system, solar energy is in. Twenty years ago, solar energy users were dismissed as visionaries of an alternative lifestyle. Today they are seen as smart trendsetters. Residents who have solar collectors on their roofs can bask in the silent envy of their neighbors, not least when the electricity bill arrives. A number of industrial enterprises have already discovered the solar energy business. Evonik Industries has been closely monitoring this growth market for some time, too, because solar power technology is becoming more prevalent, and not only in Germany. Of particular interest here is that Spain, Italy, Greece, and France now have legislation modeled after Germany's Renewable Energies Law. The feed-in rate for solar power in these countries lies between 30 and 55 eurocents per kilowatt-hour, providing added incentive to invest in renewable energies.

Collaboration to ease bottlenecks

Interest generally focuses on solar modules. At Evonik, we expect more than 90 percent of these modules are based on solar silicon wafers, a starting material that is slowly becoming scarcer because of heavy demand worldwide. In collaboration with SolarWorld AG and Joint Solar Silicon (JSSi), Freiberg, the joint venture established by the two partners, Evonik has developed a new process for the production of this globally prized component. For this achievement, the Inorganic Materials Business Unit won the company's Innovation Award for 2007 in the New Processes category. A promising feature of the development is that it will reduce the cost factor and the supply bottleneck. Moreover, the solar silicon obtained is pure enough to use in the manufacture of solar cells.

In Evonik's new process, raw silicon metal is used to produce trichlorosilane. This is converted to gaseous monosilane, which is decomposed into its constituent elements, silicon and hydrogen, at temperatures above 600°C. "This step requires 90 percent less energy than in the previously used Siemens process. The conversion of trichlorosilane to monosilane consumes energy, too, but the overall energy savings is more than 60 percent. By comparison, the Siemens technology requires up to 160 kilowatt-hours per kilogram of silicon," explains Dr. Raymund Sonnenschein, (Head of the Solar Silicon project at Evonik and President of JSSi) "In our partnership with Joint Solar Silicon (JSSi), responsibilities are clearly delineated: Evonik produces the monosilane and JSSi produces solar silicon.

This makes sense, because Evonik has many years of experience in silane chemistry." At the Rheinfelden site, where Evonik already operates a facility, JSSI is currently putting a plant on stream that will produce solar silicon through a novel production pathway. It is scheduled to open this summer and will have an annual capacity of about 850 metric tons of the sought-after material. Evonik is also collaborating on photovoltaics with other partners such as Erfurt-based PV Silicon, which is currently building a production facility in Bitterfeld with an initial capacity of 1850 metric tons of solar silicon. Evonik contributes the required chlorosilanes in what is clearly a win-win venture for both companies. Other partnerships exist with the Dutch company The Silicon Mine (TSM) and the French company Silicium de Provence (Silpro).

The end of the solar boom is nowhere in sight. According to information from BSW, the German Solar Industry Association, an international study has estimated that the world market grew last year to 2,179 megawatt peak (MWp), an increase of nearly 35 percent over the previous year. Industry experts and market researchers predict an annual market growth rate of 20 percent for the industry up to 2020. In concrete figures, technological advances and cost-effective systems are expected to increase sales to more than US$16 billion within the next five years (source: Frost & Sullivan). With its energy-saving production process, Evonik is now even better placed to profit from this growth market, for which scarcity of solar silicon could be a stumbling block. For the streetcar drivers of Karlsruhe, this will mean lots of room to maneuver.

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