Receivers represent the heart of solar thermal power plants

Receivers Represent the Heart of Solar Thermal Power Plants

September 26, 2006 (MITTERTEICH, GERMANY) - Executives with SCHOTT gathered today in Mitterteich, Germany to celebrate the official opening of SCHOTT's new solar receiver production facility.

"Receivers are a key component of the solar thermal parabolic trough power plants, which will become an important source of power in the future." said Professor Dr.-Ing. Udo Ungeheuer, Chairman of the Board of Management of SCHOTT. "We are the technology leader with our receiver and are now shifting from pilot production of small quantities to industrial serial manufacturing,"

"Solar is an important strategic venture for the future of SCHOTT. Entering into mass production of receivers represents yet another important milestone in the expansion of our solar activities," Ungeheuer said.

The plant manufactures SCHOTT's PTR 70 solar receiver, which is currently used at the APS Saguaro Solar Generating Station in Arizona, the nation's first solar thermal parabolic trough power plant built specifically to produce electricity since 1988.

SCHOTT has received orders to supply PTR 70 receivers to several solar thermal power plants currently under construction, including the 64MW Nevada Solar One power plant being built near Las Vegas and a 50MW project in the south of Spain.

Nevada Solar One is the largest solar thermal power plant to be built In U.S. since 1988. The Spanish power plant will one of the first commercially operated solar thermal power plants in Europe.

How Parabolic Trough Power Plants Work

Solar thermal power plants use solar energy to generate heat, which is then converted into electricity. Parabolic trough power plants consist of numerous trough-shaped parabolic mirrors that concentrate sunlight onto receivers (absorber tubes) [Figure 1]. Inside these specially coated receivers, concentrated solar radiation is converted into heat which is transferred to a special heat resistant transfer fluid reaching temperatures of up to 752 °F (400° C).

This fluid is then pumped to a central generating unit. It passes through several downstream heat exchangers and, as in conventional power plants, generates the steam that is required to drive the turbines that produce electricity. [Figure 2]

Since they require direct sunlight, solar thermal power plants are best suited for sunbelt areas of the world, like the southwestern United States, Spain, and North Africa.

"Because they offer the highest level of efficiency and incur the lowest costs for generating power of all solar technologies, parabolic trough power plants will soon offer the potential to generate solar electricity in the world's Sunbelt at competitive prices," said Chairman of the Management Board Ungeheuer.

The PTR 70 Lower Costs, Improves Efficiency

SCHOTT PTR 70 receivers incorporate several features that make solar thermal power more dependable and affordable, including:

• Anti-reflective glass coatings: Previous glass coatings failed to adhere to solar receivers' borosilicate glass outer envelope tubes over time. SCHOTT has developed a new anti-reflective glass coating for its receivers that resists abrasion for years, while still allowing more than 96 percent of solar radiation to penetrate the receiver and heat the heat transfer fluid within.

• Absorptive steel coatings: In order to achieve peak efficiency the steel absorber tube located inside the outer glass envelope tube needs to absorb as much solar radiation as possible while releasing as little heat as possible. SCHOTT's new absorptive steel coating improves radiation absorption rates to 95 percent, while helping ensure that no more than 14 percent of the heat from the steel tube is released.

• Improved glass-to-metal seals: In other solar thermal receivers, differences in the thermal expansion of the inner steel tube and the outer glass envelope tube resulted in tube failure when there were severe shifts in temperature. The new PTR 70 receiver uses a new borosilicate glass with the same thermal expansion coefficient as steel. The result is a receiver that can handle the changes in temperature that occur as cool nights quickly become hot days. This improvement was designed to reduce both maintenance time and the need for replacement parts.

High Resolution pictures of the new production facility, solar receivers, and solar thermal power plants can be downloaded from www.schott-pictures.net

About SCHOTT:

SCHOTT is a technology-driven, international group that sees its core purpose as the lasting improvement of living and working conditions through special materials and high-tech solutions. Its main areas of focus are the household appliance industry, pharmaceutical packaging, optics and opto-electronics, information technology, consumer electronics, lighting, automotive engineering and solar energy.

SCHOTT has a presence in close proximity to its customers through highly efficient production and sales companies in all of its major markets. It has more than 17,000 employees producing worldwide sales of approximately $2 billion. In North America, SCHOTT's holding companies SCHOTT Corporation and its subsidiary SCHOTT North America, Inc. employ about 2,500 people in 16 operations.

The company's technological and economic expertise is closely linked with its social and ecological responsibilities.

SCHOTT is one of the leading solar industry companies worldwide. The international technology group supplies components for almost all photovoltaic and solar thermal applications. PV solar electricity modules with various performance ratings are used for decentralized power generation. Receivers are the key components in solar thermal parabolic trough power plants, a future technology for centralized power generation along the Earth's sunbelt.