効率６０％のPV？？

ソース：http://science.slashdot.org/article.pl?sid=08/01/09/2310232&from=rss
Super Soaker Inventor Hopes to Double Solar Efficiency
Posted by timothy on Wednesday January 09, @06:32PM
from the if-they-get-too-hot-we-can-super-soak-them dept.
mattnyc99 writes
"With top geeks saying photovoltaic cells are still four years away from costing as much as the grid, and the first U.S. thermal power plant just getting into production, there's plenty of solar hype without any practical solution that's efficient enough. Until Lonnie Johnson came along. The man who invented the Super Soaker water gun turns out to be a nuclear engineer who's developed a solid-state heat engine that converts the sun's heat to electricity at 60-percent efficiency—double the rate of the next most successful solar process. And his innovation, called the Johnson Thermoelectric Energy Conversion (JTEC) system, is getting funding from the National Science Foundation, so this is no toy. From the article: 'If it proves feasible, drastically reducing the cost of solar power would only be a start. JTEC could potentially harvest waste heat from internal combustion engines and combustion turbines, perhaps even the human body. And no moving parts means no friction and fewer mechanical failures.'"
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Cheaper Solar, Battery-Free Devices and Nano-Energy Coming Soon, Top Geeks Say
http://www.popularmechanics.com/blogs/science_news/4236627.html

WASHINGTON — A big focus here at the IEEE’s IEDM conference has been on devices for energy harvesting—sometimes called energy scavenging. Essentially, they can produce their own electricity from ambient sources. This “free energy” comes from solar, vibration, pressure and temperature gradients, as well as human power (solar obviously being the most well known and technologically developed of the bunch).

Richard Swanson of SunPower Corporation spoke today to give an update on solar photovoltaic technology, predicting that panels should reach $1.50 per watt—what he called the “magic number,” because it represents price parity with the electrical grid—by 2012. For the record, that’s three years earlier than many in the industry have predicted. According to Swanson, two of the main challenges confronting photovoltaics are a shortage of silicon and a lack of efficiency as scientists try to push toward the theoretical limit of 29 percent.

After Swanson, the University of California at Berkeley’s Jan Rabaey discussed the state of “Disappearing Electronics,” super low-power devices that need no batteries or outside power supply, instead relying upon microgenerators. These generators could be used in implantable medical devices such as pacemakers (because having extra surgeries for battery replacement is uncomfortable, to say the least) as well as low power sensors for industrial use.

The repurposing of motion energy for devices is hardly new—self-winding watches have been using human movement for years, and several companies, such as Lightning Switch and Ad Hoc electronics, sell battery-free wireless light switches that convert the energy of a button push into a wireless signal. Rabaey showed some of his own work on battery-free tire pressure sensors, and he’s currently developing a next-generation “intelligent tire” with cymbal transducers that convert impact acceleration into power for sensors. Such tires could measure all aspects of tire performance in real time.

The real heady stuff came in the form of nanogenerators. Two types were discussed at the conference, and required putting on your physics thinking cap for full impact. The first was a DARPA-sponsored project for nanoscale thermoelectric energy harvesting. Basically the idea is to create a thin-film, solid-state heat pump that turns temperature variance directly into electricity—taking advantage of a phenomenon called the Seebeck effect. As with much of this research, the scientists behind it saw an application in implantable biomedical devices, but they also offered an innovative potential use as a layer on top of computer chips. As the chip heats up, it could produce enough power to run a fan on the heat sink that would cool it down. Since heat from computer chips is entirely the product of energy waste, the solution seemed particularly elegant.

The award for craziest idea that just might work goes to Zhong Lin Wang of the Georgia Institute of Technology. He’s experimenting with a piezoelectric nanogenerator, though Wang uses the term Nano-Piezotronics (he’s even trademarked it). What the hell does that mean? Well essentially Wang has created nano-wires out of zinc oxide (pictured above) that create an electric charge when bent. Suspended over these tiny wires is a zigzagging series of electrodes. When vibrations shake the whole setup, the wires act like a brush over the electrodes, sending a stream of electricity. What do they want to use it for? Yes, yes, implantable biomedical devices and sensors for industrial use. I hope that there’s another room full of scientists putting as much thought into how to make those sensors do the job of sensing, because there are a lot of tiny generators coming down the pike that need a home. —Glenn Derene

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