The Sun Rises on a Pilot Power Project

01.05.1997

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Pilot solar plat design


A unique pilot solar power plant is about to be set up at the Weizmann Institute. Its construction is the first step in a large-scale U.S.-Israel project whose ultimate goal is to build commercial solar power stations throughout the world.

The project's participants are America's McDonnell Douglas and Israel's Ormat Industries Ltd., Rotem Industries Ltd. and the Weizmann Institute -- through its commercial arm, Yeda Research and Development Co. They have been awarded $5.3 million by the U.S.-Israel Science and Technology Commission to jointly demonstrate the commercial feasibility of an advanced solar power plant capable of generating anything from hundreds of kilowatts to tens of megawatts of power. The signing of the collaboration agreement was announced on March 10 at the U.S. Space and Rocket Center in Huntsville, Alabama.

The U.S.-Israel Science and Technology Commission was set up in 1994 by President Clinton and the late Prime Minister Rabin to enhance cooperation and create technology-based jobs for the 21st century. It was within this framework that the McDonnell Douglas-Rotem-Ormat collaboration was initiated.

The novel American-Israeli system uses special optics and an innovative air receiver developed by the Weizmann Institute. These reflect, concentrate and convert sunlight to provide the high temperatures necessary to directly power gas and steam turbines in a combined cycle and thus generate electricity.

The ability to operate on either solar power, gas, or a combination of solar power and gas, will provide operational flexibility and guarantee electricity even during inclement weather. The application of combined cycles ensures very high efficiency in all modes of operation. Recent market assessments indicate that this new technology has the potential for wide international applications.

In less than three years, the American-Israeli team will develop an operational 200-300-kilowatt system to be located at the Weizmann Institute's solar research facility, known as the Canadian Institute for the Energies and Applied Research. This pilot system will use some of the facility's highly reflective mirrors, or heliostats, which track the sun. These heliostats will reflect sunlight up to a new reflector to be installed atop the Institute's solar tower. This reflector will then redirect the sunlight back down to a matrix of optical concentrators, capable of concentrating the light 5,000 to 10,000 times, as compared to natural sunlight reaching the earth. The concentrated radiation will then enter a group of solar receivers, located on the ground, which will heat up compressed air to be used for driving the turbogenerator that produces electricity.

The pilot system's advantages stem from a unique combination of technologies. First, the production facilities, including the concentrators, receivers and turbogenerator, are located on the ground rather than at the top of the tower, making construction of the tower significantly simpler and cheaper.

Second, the sophisticated design of the concentrators, based on pioneering research at the Weizmann Institute, will make it possible to concentrate sunlight sufficiently to heat the air to the temperature needed for driving advanced gas turbines.

A third innovation is the use of the Weizmann Institute-designed solar receiver (nicknamed "Porcupine") which contains hundreds of ceramic pins arranged in a geometric pattern that maximizes the collection and use of sunlight. Compressed air that flows across the pins is heated and channeled to the gas turbines. Sunlight enters the device through a special cone-shaped quartz window that can withstand higher pressure than can a similarly designed steel cone.

Many of the new technologies originated at the Institute. Following the initial stages of the research, the Institute scientists were joined by experts from Rotem Industries, who collaborated with Weizmann on the design and construction of the first prototype of the "Porcupine" receiver, as well as on consolidating the design of its optical components. Most of the research conducted up to this stage was supported by the Chief Scientist of Israel's Ministry of Energy (now the Ministry of National Infrastructures).

When the research reached a relatively advanced stage, Consolar Ltd. -- a consortium of Israeli companies and academic institutions -- was established comprising Rotem Industries, Ormat Industries, Silver Arrow, the Israel Aircraft Industries, the Weizmann Institute of Science, Tel Aviv University and Ben-Gurion University of the Negev. It is supported by the Chief Scientist of Israel's Ministry of Industry and Trade, under the Ministry's Magnet program, whose aim is to promote the application of new and emerging technologies.

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