Practical Solar heliostat
2 of 15 from Photo quiz: Gear for green buildings
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The answer to the previous question is B, a vertical-axis wind turbine capable of generating 1 kilowatt of electricity. A larger version of the same design is installed on Esther's Island near Nantucket.
Next question: This heliostat from Practical Solar is used to:
A. bring sunlight into buildings to cut lighting costs.
B. convert sunlight into electricity.
Answer and new question on next page.
March 16, 2009 4:00 AM PDT
Photo by: Martin LaMonica/CNET
