[Editors] MIT prototype solar dish passes first tests

[Elizabeth Thomson]

http://web.mit.edu/newsoffice/2008/solar-dish-0618.html



For Immediate Release
THURSDAY, JUN. 19, 2008

Contact: Elizabeth A. Thomson, MIT News Office
T. 617-258-5402E.: thomson at mit.edu

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MIT prototype solar dish passes first tests
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CAMBRIDGE, Mass.—A team led by MIT students this week successfully  
tested a prototype of what may be the most cost-efficient solar power  
system in the world—one the team believes has the potential to  
revolutionize global energy production.

The system consists of a 12-foot-wide mirrored dish that team members  
have spent the last several weeks assembling. The dish, made from a  
lightweight frame of thin, inexpensive aluminum tubing and strips of  
mirror, concentrates sunlight by a factor of 1,000—creating heat so  
intense it could melt a bar of steel.

To demonstrate the system’s power, Spencer Ahrens, who just received  
his master’s in mechanical engineering from MIT, stood in a grassy  
field on the edge of the campus this week holding a long plank.  
Slowly, he eased it into position in front of the dish. Almost  
instantly there was a big puff of smoke, and flames erupted from the  
wood. Success!

Burning sticks is not what this dish is really for, of course.  
Attached to the end of a 12-foot-long aluminum tube rising from the  
center of the dish is a black-painted coil of tubing that has water  
running through it. When the dish is pointing directly at the sun,  
the water in the coil flashes immediately into steam.

Someday soon, Ahrens hopes, the company he and his teammates have  
founded, called Raw Solar, will produce such dishes by the thousands.  
They could be set up in huge arrays to provide steam for industrial  
processing, or for heating or cooling buildings, as well as to hook  
up to steam turbines and generate electricity. Once in mass  
production, such arrays should pay for themselves within a couple of  
years with the energy they produce.

“This is actually the most efficient solar collector in existence,  
and it was just completed,” says Doug Wood, an inventor based in  
Washington state who patented key parts of the dish’s design—the  
rights to which he has signed over to the student team.

Wood credits the students who built this dish, as an independent  
project that started in January, with making significant improvements  
to his original design to make it a practical and competitive energy  
producer. “They really have simplified this and made it user- 
friendly, so anybody can build it,” he says.

One of the keys to making an inexpensive design was something Wood  
discovered by accident as he built a variety of solar dishes over the  
years: Smaller really is better. Unlike many technologies where  
economies of scale dictate large sizes, a smaller dish requires so  
much less support structure that it ends up costing only a third as  
much, for a given collecting area.

MIT Sloan School of Management lecturer David Pelly, in whose class  
this project first took shape last fall, says that, “I’ve looked for  
years at a variety of solar approaches, and this is the cheapest I’ve  
seen. And the key thing in scaling it globally is that all of the  
materials are inexpensive and accessible anywhere in the world.”

Pelly adds that “I’ve looked all over for solar technology that could  
scale without subsidies. Almost nothing I’ve looked at has that  
potential. This does.”

The team, led by Ahrens, also includes Micah Sze (Sloan MBA ’08), UC  
Berkeley graduate and Broad Institute engineer Eva Markiewicz, Olin  
College student Matt Ritter and MIT materials science student Anna  
Bershteyn. Various other students also helped out over the course of  
the semester.

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Written by David Chandler, MIT News Office