Stretched-membrane heliostats for solar central-receiver power plants
For more than 10 years, the US Department of Energy's Solar Thermal Program has pioneered the developed of heliostats, mirrors that track the sun, for solar central-receiver power plants. The field of heliostats is the single most expensive part of such plants, so their cost must be as low as possible for the technology to be commercially successful. Recent efforts have focused on the development of heliostats that use stretched-membrane reflectors in place of the more familiar glass mirrors. In a stretched-membrane heliostat, metal foils are stretched over both sides of a large-diameter metal ring. The reflective surface is a silvered-polymer film glued to the front membrane. A slight vacuum in the space between the two membranes is actively controlled to provide a concave, focused contour to the mirror, and in an emergency this space can be rapidly pressurized to defocus it. Because of their simplicity and lighter weight, stretched-membrane heliostats have the potential to cost significantly less than current glass-mirror designs. The first 50-m/sup 2/ mirror modules, built under contract to Sandia in 1986, demonstrates that the optical performance of membrane heliostats would be at least as good as heliostats using glass mirrors. Insights gained from Sandia's testing and evaluation of the first-generation units were incorporated into the designs of two improved 50-m/sup 2/ mirror modules that were recently completed. Preliminary measurements show significant improvement in optical performance over the first-generation designs, especially in windy conditions. 19 refs., 7 figs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5785277
- Report Number(s):
- SAND-89-0839C; CONF-890836-8; ON: DE89016034
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140702 -- Solar Thermal Power Systems-- Central Receiver
141000* -- Solar Collectors & Concentrators
CENTRAL RECEIVERS
COST
ENERGY
ENERGY SOURCES
EQUIPMENT
HELIOSTATS
MEMBRANES
OPTICAL PROPERTIES
PERFORMANCE
PHYSICAL PROPERTIES
REFLECTIVITY
RENEWABLE ENERGY SOURCES
SOLAR ENERGY
SOLAR EQUIPMENT
SOLAR RECEIVERS
SURFACE PROPERTIES