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Carbon Nanotube Towers Could Increase Solar Power
Vict0r writes "Researchers at the Georgia Tech Research Institute have recently demonstrated a way to grow carbon nanotubes in towers. The article also discusses applications for solar cells." From the article: "Reflections off the Gothamesque towers would provide more opportunity for each photon of sunlight to interact with the p/n junction of the cell. That would increase the power output from PV cells of a given size, or allow cells to be made smaller while producing the same amount of power."
But that's only because we emphasize military spending, and military might. Personally, I'm of the belief that education and educational applications - such as invention, or innovative teaching and learning - in addition to practical humanitarian applications should drive technological innovation.
If we maintain the mindset that military applications drive innovation, then that's all we'll receive. On the other hand, if we start applying for grants, and applying our funding in new directions, it's forseeable that the locus of innocation could change. I, for one, strive for such.
No, all the heat energy in the PV should be going into accelerating electrons to the cathode instead. Any heat is waste, inefficiency, and powering a cooler just consumes more energy from the net. Besides, silicon solar cells get more efficient per incident watt as they heat up - a catch-22 that should be broken by making cells with a different nanoarchitecture which captures more of the incident power.
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make install -not war
Generally, increasing surface area on solar cells is detrimental to producing electricity, particularly if the semiconductor material is very thin. (Yes, I am well aware that it is more than counteracted by the additional light coupled into the cell, but the writer makes it sound as though increasing surface area is a magical formula for making more power. And the increase in surface area, by itself, is still detrimental.) I would very much like to know what are the "special" semiconductor materials they plan to coat the towers with.
I don't think this is so much a breakthrough as it is just another in a long line of textured substrates for thin-film solar cells that don't even work yet and won't be hitting the market for another 10 years.
Because their cells will be more efficient, Ready believes they can use older and more mature p/n-type material technologies and less costly silicon wafers to hold down costs and rapidly advance the project into products that can be used in the field.
If he is going to use silicon wafers as simple substrates then his cells had better be substantially more efficient than standard crystalline silicon solar cells -- otherwise, he is guaranteed to be priced out of the market. Silicon wafers make up half the cost of a solar module, and the module materials and assembly make up another 30-35%. Assuming he can actually deposit these nanotowers and their semiconductor coatings at a cost similar to that of converting a silicon wafer to a silicon solar cell, it doesn't give him much choice but to leverage efficiency to get a lower cost per watt.
Powering mobile computing systems for rural schools in India isn't mentioned because the rural school system of India isn't paying for the research - the DoD is.
Why is this?
Firstly, because military problems attract money. Privates bitch to Sergeants, Sergeants bitch to Captains, Captains bitch to Colonels, Colonels bitch to Generals, Generals bitch to Congress, who has the people's money. If a private is too hot, too cold, too vulnerable, lacking ammo, too slow, too visible, etc, it becomes a problem that the Generals will address in order that the solution will be a military advantage.
Secondly, because the military will accept a sub-optimal solution if it addresses the primary problem really well, or if it addresses a previously unaddressed problem. Consider the WWII company radio. It was expensive, heavy, bulky, the range wasn't very good, the transmission quality was horrible and it was fairly fragile. There was probably a very high failure rate in the manyfacturing process. It required a dedicated soldier to bear and operate it, to the exclusion of food and ammo, which reduced his combat effectiveness and survivability. It was recognizable from a distance, which made him target number one for snipers.
All that being true, a company with a radio was part of an army. A company without a radio was a isolated group of men without support or supply that would surely only last a single firefight, if that. As technology developed, the radio got lighter, cheaper, more reliable, and encrypted. Soon it was affordable to equip a platoon with a radio, then individual squads. At a certain point along this progression, the technology really took off to the civilian market once it was cheap, reliable and small enough for, say, an important business person to have a brick-size device. With the new influx of money from a consumer market, the radios became smaller and cheaper until just about every one of us has a personal radio: the cell phone.
So, while you beat your breast and cry out to the cosmos, "Why does all the technology has to have military purposes first," remember that the military purposes will wring bugs out of the technology, establish an industrial base from which to launch into the civilian market, and provides a "reference" that business can rely on. If you try to jump straight into the civilian market with a buggy technology, no problems-solved stories and no industrial base, you'll be out of business like a dot-COM unless you have VERY deep pockets, or very stupid/very far-sighted (HA!) venture capitalists.