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MIT Envisions DIY Solar Cells Made From Grass Clippings
Zothecula writes "Research scientist Andreas Mershin has a dream to bring inexpensive solar power to the masses, especially those in developing countries. After years of research, he and his team at MIT's Center for Bits and Atoms, along with University of Tennessee biochemist Barry Bruce, have worked out a process that extracts functional photosynthetic molecules from common yard and agricultural waste. If all goes well, in a few years it should be possible to gather up a pile of grass clippings, mix it with a blend of cheap chemicals, paint it on your roof and begin producing electricity. Talk about redefining green power plants!"
Let's see what XKCD says about it...
And yet another 10 years later they find that those "cheap chemicals" cause cancer...
From the fine article they're getting 0.1% efficiency right now. In other words, about a thousandth. Conveniently, you get about a KW of light per sq meter. So, you get about one watt per square meter. So I could get about 40 watts at noon off my roof, well, other than that tree being in the way which shades me from the summer sun. That is somewhat more than the naysayers claim (barely enough to run a watch, etc) but is not enough to be useful.
Its unlikely they'll exceed the best plants which have had hundreds of millions of years to optimize their design... so figure 5% or so would be quite an achievement. So in Star Trek miracle land, a KW or two is quite possible off a typical roof. Of course in Star Trek miracle land, you'd have 47% efficient cells thus generating about 40 KW. I donno what I'd do with 40 KW laying around, I guess air condition my entire open air backyard, replace my beer fridge with a supermarket open display case so I don't have to waste time opening the door?
The crack about painting it on is laughable. conductive acid rain and bird poop will short it out. You're still going to need glass/plastic/etc and the cost of that will probably make high efficiency silicon more economical.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Yes, it takes grass clippings. Also "zinc oxide nanowires interspersed with titanium dioxide sponges".
Claiming that this is a solar cell made from grass clippings is like the Rubik's cube solver built from Lego (one component of which was a computer; the computer's not built from Lego). If you want a car analogy, it's like claiming your car is made from glass (since it has glass in the windows).
Yes, and we would have needed an airport every 50 meters if the plane built by the Wright Bros was really the best that could ever be built.
The first step is rarely the last one.
A modified type of dye sensitized solar cell, nothing new.
https://en.wikipedia.org/wiki/Dye-sensitized_solar_cell
You can easily make those at home: Take a piece of conductive glass, coat it with titanium dioxide (yes, exactly the pigment used for white paint, I tried the commercial pigments myself), dip it into a dye (yes, I tried chlorophyll, these things were known at least 15 years ago, this is when I did it), put on a second piece of glass and fill with electrolyte.
I have made hundreds of those, you can do it at home it a toaster oven, google for "graetzel cell video".
This type of cell has several very serious issues:
1) The efficiency is very low
2) The cell uses a liquid organic electrolyte. Of course there are tons of problems with leakage, toxic solvents etc.
The electrolyte often breaks down from the light, you'll always have oxygen diffusion into the system and react with all the chemicals. It is extremely difficult to make anything organic that can withstand light. Have a look at your painted garden chairs after a few years in the sun.
3) The dye breaks down quickly. Make a simple test. Take a few grass clippings and put them into the sun. You'll notice that they change color from green to brown.
The reason is that the chlorophyll degrades very rapidly in the sun. Grass makes new chlorophyll all of the time.
4) Titanium dioxide (and zinc oxide as well) are highly reactive materials under illumination. This is why you use them as white pigments. The sunlight creates free electrons, and those decompose a lot of the dirt in contact with the stuff. A white wall in the suns cleans itself to a large part.
Of course, you'll have the same effect in the solar cell, the TiO2 will act as a catalyst and degrade dye and electrolyte.
Make a simple test at home: Take a wall painted with titanium or zinc white. Dissolve some grass clippings in alcohol and spray the green stuff on the wall. Expose to sunlight and see how quickly it bleaches.
As a scientist myself, I find it very sad and unprofessional, how MIT is lying to the public.
A statement like
"If all goes well, in a few years it should be possible to gather up a pile of grass clippings, mix it with a blend of cheap chemicals, paint it on your roof and begin producing electricity. Talk about redefining green power plants!"
is very misleading, unethical and close to being a scientific fraud. Of course, you could never paint it on, how are you going to put on the electrodes?
what is useless is to denigrate basic research
to do that, as an engineer, you should be ashamed of yourself
the common joe might bloviate ignorantly about how silly basic research is, and confuse basic research claims and evidence with the end-all be-all of claims and evidence, but you really should know better
yet, looking at other comments here on slashdot, it seems the intelligence to appreciate basic research has indeed been replaced by this kind of ignorant jump to judgment
you know what? paint on grass clippings does sound silly. but i thought we had a scientific bent here, and this would be EXCITING
imagine that
so shame on you slashdot
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it