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Parabolic Dish systems use satellite-like mirror dish(es) to focus the light onto a singlecentral receiver in front of the mirror. They so far have the highest heat-electricity conversion efficiencies among all CSP designs (up to 30 %). The size of the concentrator is determined by its engine. A dish/Stirling system’s concentrator with a nominal maximum direct normal solar insolation of 1000 W/m2 and a 25-kW capacity has a diameter of approximately 10 meters. It could also run on a single Brayton cycle, where air, helium or other gas is compressed, heated and expanded into a turbine. Parabolic dish could be applied individually in remote locations, or grouped together for small-grid (village power, 10 KW) or end-of-line utility (100 MW) applications. The electricity has to be used immediately or transmitted to the gird as the system has no storage device. Intermittent cloud cover can cause weakening of highly concentrated receiver source flux. Sensible energy storage in single-phase materials was proposed to allow a cylindricalabsorber element not only absorb the energy but also store it in its mass, thus reducing the amplitude of cloud cover transients. Although this design only allows short period energy storage, potential longer time storage technology would make parabolic dish more appealing.

Dish/engine system schematic. The dish that follows the sun on two axes focuses the sunlight onto one single point on a receiver posed right in front of the mirror. (C) SES

 


Stirling Energy System Inc.’s 300 MW commercial solar thermal power plant in California.(c)International Rivers

Following is a video clip about this plant:

 

 



The Stirling Engine used in the aboved parabolic dish:it produces grid-quality electricity using the heat gathered by the receiver directly.It is a 4 cylinder, each with a 95cc displacemen engine (4-95 engine) that evolved from the Philips engines of the 1960's.(C) SES

 

 

Click here for an animation on how it works: http://www.keveney.com/Vstirling.html


Costs and Rates One dish costs around $250,000 averagely, depending on the capacity of it. Once production rates rise, they could cost less than $150,000. Southern California Edison Electric Company cannot give away the actual price per kWh, but they say it is well below the 11.33 cents seen currently.

 


More Designs

Dish/engine system with stretched-membrane mirrors: this design allows wind to pass through to minimize the destructive force of wind. These dish systems were designed progressively by Jeffrey Sandubrae, P.E., a senior SAIC engineer at Science Applications International Corporation (SAIC) with funding from D.O.E ( Picture from Algor.com, Sunlab and Department of Energy )

 

infinia.jpgInfinia Inc. ’s Modular Solar Thermal Dish

  • $50 million investment in total
  • 20-30% cheaper energy production than PV cells
  • 334 dishes per 1MW of power
  • designed to be assembled with mass produced parts that an auto parts supplier could manufacture
  • each dish costs approximately  $20,000

 

 

 

The History Of Solar Dishes

  • Solar dishes have been in use since ancient Mesopotamian times
  • Polished gold dishes were used to concentrate the sun and light altar fires
  • In the 17th century glass lenses were used to smelt iron, copper, and mercury
  • In the 18th century, concentrated solar power was used to heat ovens and furnaces
  • Supposedly the Greek scientist Archimedes used reflective bronze shields to focus sunlight at wooden Roman ships to set fire to them

Bibliography

*the page is contributed by Molly Baker Mercer '12,Hampshire College

Lund, K. O.A., Direct-Heating Energy-Storage Receiver for Dish-Stirling Solar Energy Systems, J. Sol. Energy Eng. Feb1996 Volume 118, Issue 1, 15

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x158332

http://www.starpointsolar.biz/

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Copyright Yiting Wang 2008