Slashdot Mirror
Stanford's New Solar Tech Harnesses Heat, Light
An anonymous reader writes with this excerpt from a Stanford news release:
"Stanford engineers have figured out how to simultaneously use the light and heat of the sun to generate electricity in a way that could make solar power production more than twice as efficient as existing methods and potentially cheap enough to compete with oil. Unlike photovoltaic technology currently used in solar panels — which becomes less efficient as the temperature rises — the new process excels at higher temperatures. ... 'This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak,' said Nick Melosh, an assistant professor of materials science and engineering, who led the research group. 'It is actually something fundamentally different about how you can harvest energy.' And the materials needed to build a device to make the process work are cheap and easily available, meaning the power that comes from it will be affordable."
The abstract for the researchers' paper is available at Nature.
What I want to know is what mechanisms are causing their Gallium-Nitride junction to conduct more reverse current above 227 C.
They are currently projecting operating at 200 C for max efficiency but if it's as I suspect -- increased current flow with higher temperature -- then they can modify the doping mixture to get even higher temps and therefore higher efficiencies.
This would also boost the Carnot Cycle efficiency limit for the secondary heat exchanger that operates after the GaN primary power generation.
I'm reading from the slides.
Roof top glass enclosures (solar hot water) nearly achieve this all by themselves in some sunny locations. http://en.wikipedia.org/wiki/Solar_thermal_collector
Its contained in the collector. Its so hot you generally have to mix with cold water for household use.
Sig Battery depleted. Reverting to safe mode.
CSPV cells are one of the tech items that do in fact come to market. EMCOR and Spectrolab and others like Ammonix routinely bump their efficiency with new processes -- not just the efficiency of their "champion cells" but of their normal end product. In fact there have been upgrades done to concentrating PV plants whereby just by replacing the cells/heatsink, leaving all the dishes or whatnot untouched, they have increased output of the plant.
I feel like someone let my jet-pack fall out the back of the UPS truck, too, but not in this particular sub-area of solar PV.
Someone had to do it.
So if you could reflect the heat to generate power and use photovoltaics to generate power, could you also create them translucent to some spectrum of light? Then you could grow crops under the solar array, use the array for water capture so the irrigation would hold water better and provide power and temperature maintenance. This idea only works if photovoltaics and plants uses different spectrum to generate power/photosynthesize.
This seems to be the new scam for this decade. Your company/university/research-lab accounces a "breakthrough" using commonly available, cheap materials that "somehow" provide energy because the arrangement of these materials is the part no one has thought of before.
We've got: EEstor with their "ultracapacitor", Bloom Energy with the "Bloombox", Stanford's now got their Solar Gen whatever it is, there's the Science Fair Kid that made a 30% increase in PV efficiency, yadda yadda... Hell, a few weeks back even the Chinese announced a "new solar product" that was supposed to be more efficient...
Someone should go through the last 5 years of Slashdot and pull up all the articles about new energy technology and where they announce it will be available in stores in 5 years time, and let's see what the claims are versus what reality has brought us.
Because so far, all I ever see in stores or online is the same old crap that's been available since forever, plain old 12% efficient silicon-based PV panels, where you still need $2000 worth of them to run a fridge.
If telephones are outlawed, then only outlaws will have telephones.
Even if the tech gets to a point where Joe-Bob can buy a 5,000 watt solar array at Wal-Mart for $999, he won't be able to install it permanently in a safe manner, because you're still dealing with 5,000 watts. It becomes nothing more than a fuel-less generator. Mounting it permanently on his roof, tying it in to his household wiring and setting up a grid-tie net-metering arrangement will still take the work of professionals.
Of course, we may someday get to a point where the process is simplified and routine enough that installation costs might approach something like putting in a tankless water heater, gas lines or satellite dish.