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Direct Conversion of Light into Work

Lawrence Berkeley National Laboratory

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Technology Marketing SummaryAlex Zettl, Jean M. J. Fréchet, and a team of Berkeley Lab researchers have discovered a mechanism for converting solar energy directly into mechanical work, thus eliminating the need for capital-intensive energy storage and distribution facilities. DescriptionIn the Berkeley Lab approach, concentrated sunlight or laser light focused on a highly absorptive material capable of converting light energy into heat generates thermal surface tension gradients that move objects across a liquid surface. The technology can generate controlled linear motion by focusing light on different, selected regions of the absorber. The light absorbing material can also be incorporated into specific locations and orientations in a device, such as on the faces of rotor fins, to generate rotational motion.

Although carbon black and multiwall carbon nanotubes can be used in this technology, the Berkeley Lab researchers focused on VANTs (vertically aligned carbon nanotube forests) for their reported ability to absorb greater than 99.9% of incident visible light. VANTs were embedded in a supporting polymer to maximize structural integrity without interfering in heat exchange properties. The VANT-polymer composites were floated on liquids, and sunlight or laser light focused on the light-absorbing material directly resulted in linear propulsion without boiling the liquid.
  • Eliminates the need for energy storage and distribution facilities
  • Combines energy collection and utilization in one material
  • Operates independently of scale
  • Works with simple materials and manufacturing processes
  • Allows for controlled linear and rotational motion
Applications and Industries
  • Solar powered devices such as water pumps
  • Optically controlled microfluidics
  • Renewable energy production research
More InformationPUBLICATIONS:
Okawa, David; Pastine, Stefan J.; Zettl, Alex; and Fréchet, Jean M. J. "Surface Tension Mediated Conversion of Light to Work," Journal of the American Chemical Society, 2009, 131 (15), 5396-5398.

Okawa, David; Pastine, Stefan J.; Zettl, Alex; and Fréchet, Jean M. J. "Direct Conversion of Light into Work," Research Highlights, Zettl Research Group Website, Department of Physics, University of California at Berkeley.
Technology Status
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