Renewable Energy Hornet

Rather startling and alsoapparently unique, the oriental hornet uses it yellow and orange banding to tapsolar energy during peak times allowing it to prosper at a time period when thesame conditions suppress the competition.

We may or may not be able to usethe method ourselves but the surprise is that the solar process produceselectricity rather than chemical reagents. Who would have thought that at all?

This particular insect promisesto be a trove of curious phenomena well worth the effort.

Is the hornet our key to renewable energy?

Jan 7, 2011

As every middle-school child knows, in the process of photosynthesis,plants take the sun's energy and convert it to electrical energy. Now a TelAviv University team has demonstrated how a member of the animal kingdom, theOriental hornet, takes the sun's energy and converts it into electric power —in the brown and yellow parts of its body — as well.

"The interesting thing here is that a living biological creaturedoes a thing like that," says physicist Prof. David Bergman of Tel AvivUniversity's School of Physics and Astronomy, who was part of the team thatmade discovery. "The hornet may have discovered things we do not yetknow." In partnership with the late Prof. Jacob Ishay of the university'sSackler Faculty of Medicine, Prof. Bergman and his doctoral candidate MarianPlotkin engaged in a truly interdisciplinary research project to explain thebiological processes that turn a hornet's abdomen into solar cells.

The research team made the discovery several years ago, and recentlytried to mimic it.

 The results show that thehornet's body shell, or exoskeleton, is able to harvest solar energy. They wererecently published in the German journal Naturwissenschaften.

Discovering a new system for renewable energy?

Previously, entomologists noted that Oriental wasps, unlike other waspsand bees, are active in the afternoon rather than the morning when the sun isjust rising. They also noticed that the hornet digs more intensely as the sun'sintensity increases.

Taking this information to the lab, the Tel Aviv University team studied weatherconditions like temperature, humidity and solar radiation to determine if andhow these factors also affected the hornet's behavior, but found that UVBradiation alone dictated the change.

In the course of their research, the Tel Aviv University team also found that theyellow and brown stripes on the hornet abdomen enable a photo-voltaic effect:the brown and yellow stripes on the hornet abdomen can absorb solar radiation,and the yellow pigment transforms that into electric power.

The team determined that the brown shell of the hornet was made fromgrooves that split light into diverging beams. The yellow stripe on the abdomenis made from pinhole depressions, and contains a pigment called xanthopterin.Together, the light diverging grooves, pinhole depressions and xanthopterinchange light into electrical energy. The shell traps the light and the pigmentdoes the conversion.

A biological heat pump

The researchers also found a number of energy processes unique to theinsect. Like air conditioners and refrigerators, the hornet has awell-developed heat pump system in its body which keeps it cooler than theoutside temperature while it forages in the sun. This is something that's noteasy to do, says Prof. Bergman.

To see if the solar collecting prowess of the hornet could beduplicated, the team imitated the structure of the hornet's body but had poorresults in achieving the same high efficiency rates of energy collection. Inthe future, they plan to refine the model to see if this"bio-mimicry" can give clues to novel renewable energy solutions.

The research team also discovered that hornets use finely honedacoustic signals to guide them so they can build their combs with extraordinaryprecision in total darkness. Bees can at least see what they are doing,explains Prof. Bergman, but hornets cannot — it's totally dark inside a hornetnest.

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