There is always someone who will believe an incredible science or technology story, especially when the technology could save the planet, or is invented by a teen-ager, or comes from the third world. When the story has all three elements, the suckers get in line.
Today, the Daily Mail reports that an Indian teen-ager has created an inexpensive solar cell from human hair. It is an inspiring story about a plucky teen who will one day change the world. The only way for it to be a better story would be for it to be true. I’d be happy if it just were not jibberish.
As with many hoaxes, there is an element of truth. Melanin, a component of dark human hair, is a semiconductor and is photo-reactive, and you can use it to create a solar cell. However, these cells, like most solar cells made from organic semiconductors, are not very efficient, about 2.7%. Unless the cell is virtually free, 2.7% is not going to change the world.
So, it is possible to do, and it has been know to be possible for about 40 years, but it isn’t economically feasible. Also, it isn’t very easy to do. You have to extract the melanin from the hair (pdf) into a solution or a substrate, and one of the electrodes is copper wire coated with silicon.
What is certain not to work is to string the hair along thumbtacks on a board, which is what it appears the intrepid teenager did. The probable problems with this arrangement are numerous:
- Hair is not a conductor.
- The melanin in the hair is likely to be too diffuse to be useful.
- The melanin in the hair is not in contact with any electrode.
- The hair has far too small of a cross section to collect any energy.
Don’t forget the simple economist’s argument: The photoelectrochemical properties of melanin have been known to science for 40 years, so if it was a reasonable way to build a solar cell, they would already be doing it. There is too much money going into green tech to leave an option like this unexplored.
It is instructive to read the comments to the Daily Mail article. The ones that praise the kid for his accomplishment are rated very highly, and the ones that call Bullshit are rated very low. I suppose it is natural to prefer a fantasy, but it doesn’t help to save the world.
Edward Criag Hyatt has a much more detailed explanation of the problems with the hair solar cell. Basically, the student made a cupric oxide solar cell, and the hair, which was soaked in salt water, is simply an electrode.
BTW, I think the story-behind-the story is very inspiring. Way to go Milan Karki! You punked the Daily Mail! The kid is clearly very intelligent, because the science is plausible, and he got his mug spread worldwide while spraying the Brits with rotten veg. That is an accomplishment worthy of respect, although not as much as hoaxing the BBC. ( Although, as Hyatt explains in his article, this is likely to be a case of poorly understood science, not an intentional hoax. )
Note: I’d made an error in the original article, writing “BBC” where it should have been “Daily Mail.” I caught the error immediately after posting, but Google picked it up within minutes and still has the wrong title in the cache.