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'We've all been taught that this doesn't happen'
April 17, 2011 4:48 PM   Subscribe

A dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.
posted by Confess, Fletch (19 comments total) 19 users marked this as a favorite

 
Huh, I thought it was Michigan State that was going to save the world. This is one helluva rivalry!
posted by NoMich at 5:00 PM on April 17, 2011 [3 favorites]


Can I just say.....GO BLUE

(man I miss that place)

Also, this would a beautiful way to catapult organic solar cells forward in efficiency.
posted by Existential Dread at 5:12 PM on April 17, 2011 [2 favorites]


Holy cow, this could be big.
posted by Strange Interlude at 5:13 PM on April 17, 2011


There is also a research program led by Daniel Nocera to create "artifical leafs". It is really interestin
posted by juanillogg at 5:25 PM on April 17, 2011


This looks pretty cool, but this looks kind of like a choke point

it must be focused to an intensity of 10 million watts per square centimeter.
posted by RustyBrooks at 5:28 PM on April 17, 2011 [2 favorites]


"it must be focused to an intensity of 10 million watts per square centimeter."

Totally doable if there is a good enough reason
posted by Blasdelb at 5:44 PM on April 17, 2011


GO GREEN!

(Actually, this sounds like it could be pretty amazing. It's really heartbreaking that the realities of the economy are probably going to have suck a negative effect on both universities' ability to do amazing work like this.)
posted by graphnerd at 5:48 PM on April 17, 2011


This new technique could make solar power cheaper, the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to useable energy. That's equivalent to today's commercial-grade solar cells.

Today's best "commercial-grade solar cells" are already at 24.2%. There are solar modules from First Solar that cost $0.75/Watt (heading towards $0.50/Watt) to make that are about 11% efficient, and they have more than 1.5GW of production capacity.

So nice press release guys, good luck with the grant application, but you've got a long way to catch up. Perhaps next time your university press office might pitch this as just some very interesting physics rather than the next great solar technology. But's that probably asking too much.
posted by Long Way To Go at 6:15 PM on April 17, 2011 [5 favorites]


it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this intense on its own

Are you sure? Our sunlight isn't making the grade of 100 gigawatts/m^2?
But I could have sworn everything on earth was instantly and properly vaporized when the sun came up this morning!

What? That was just a hangover? Oh.
posted by -harlequin- at 6:59 PM on April 17, 2011 [1 favorite]


The paper:
Optically-induced charge separation and terahertz emission in unbiased dielectrics [PDF]
posted by ryanrs at 8:28 PM on April 17, 2011


...light at intensities as low as 107 W/cm2

That's a pretty sunny day.
posted by ryanrs at 8:35 PM on April 17, 2011


Too much handwaving We're gonna save the world!!!, too much You could stare at the equations of motion all day and you will not see this possibility!!!, and not nearly enough Here's WTF they actually do.

My money: this pop science hysteria is over a bullshit discovery.

Extra gag: We've all been taught that this doesn't happen. WHAT doesn't happen? The magnetic field is coupled to the electric field? At gigahigh field strengths, even magnetic fields have interesting interactions? Weed is now legal AND free?
posted by IAmBroom at 8:38 PM on April 17, 2011 [1 favorite]


Here is another interesting new manipulation of light, resulting in an optical transistor. This could lead to faster computers.
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 8:47 PM on April 17, 2011


My default take on any mainstream article about a new scientific discovery these days is that it's probably overhyped bullshit. This goes double for 'cure for hiv/cancer' and triple for 'green energy'.
posted by empath at 8:51 PM on April 17, 2011 [4 favorites]


Peak insolation on Earth's surface = 1.3 kW/m2
Brightness required to see this effect = 10 MW/cm2
Brightness ratio = 10M / 1.3k = 7.7e7 times

We can achieve this magnification by moving closer to the sun by a factor of sqrt(ratio). Inverse square law, yada, yada.

Earth—Sun distance = 1.5e8 km
Target power plant distance = 1.5e8 / sqrt(7.7e7) = 1.7e4 km
Mean diameter of Sun = 1.4e6 km

Huh. I guess the Sun is not bright enough for this to work. Even if you were on the surface of the Sun, it's still not anywhere near bright enough. (So I don't expect mirrors in the desert to work either.)
posted by ryanrs at 9:02 PM on April 17, 2011


Bleh. The published paper in question doesn't try to make an actual device. It just models it theoretically. They say they're going to try actual experiments this summer, so let's see how they do then.
posted by beepbeepboopboop at 9:24 PM on April 17, 2011


It has just now occured to me that I read GW as "jigga" still, but G for any other unit is "gig-a."
posted by Threeway Handshake at 9:44 PM on April 17, 2011 [4 favorites]


Long Way To Go, the key phrase here is "...without traditional semiconductor-based solar cells." The commercial-grade solar cells you reference are Si-based cells; if the technology described in the main article can be successfully applied to organic solar cells, then the cost per watt has the potential to be much lower than $0.75 (potentially $0.10/watt, but take that with a grain of salt, like any press release). The target of 10% photon conversion efficiency is the point at which these organic photovoltaics (OPVs) become economically viable.

Potential advantages offered by organic photovoltaics include roll-to-roll printing and drastically decreased materials costs (some OPVs make use of dyes similar to those used to make denim blue). If this research could be applied to a flexible dielectric material, rather than glass, then you've got a solar cell that could be printed on a kilometer scale. Hell, even if they use glass....that's a hell of a lot cheaper even than amorphous Si.

The published paper in question doesn't try to make an actual device. It just models it theoretically.

I've only scanned the manuscript, but the citations in the introduction state that this phenomenon has been observed and reported in prior publications. This paper focuses on the potential to enable charge separation, one of the challenges for OPVs.

Also, on rereading: they don't even mention OPVs, which makes me think that they might be thinking about doing charge separation directly on glass, which would be even cheaper! I'll have to read more about this.
posted by Existential Dread at 9:45 PM on April 17, 2011


OPV has a very long way to go, with a great deal of effort this draft NREL road map forecasts it to hit 12% efficiency by 2020 with a degradation rate of just 2%/1000h. To put that in context, there is roughly 3000h of sunlight in a year. So using round numbers that suggests a super OPV cell will degrade about 5% a year, so by year 4 you're at around 80% of initial output. Inorganic cells today are warrantied at 80% initial output for 20 years and in practice can do far better than this (4% in 22 years).

I'm not knocking OPV, it will have it's place in lots of diverse places where relatively shortlived flexible power generation is needed, think things like tents or clothes that generate a little power. But hundreds of square kilometers of OPV are never going to stretch across the desert.

People are already printing solar cells roll to roll (Nanosolar for example, see it before its gone!), it remains to be seen if they can really reach the cost and efficiency of the existing processes. Roll to roll sounds like it should be cheaper, but in practice at these manufacturing scales the deposition of the cell is a smaller part of the total cost and you find that overall costs are not that much different. Simply put there is no technological short cut to ultra low costs. Lastly solar has already reached the point where the actual solar modules are less than half of the costs to install solar systems. Balance of system costs such as the concrete, steel an electricians are starting to dominate.
posted by Long Way To Go at 9:53 AM on April 18, 2011


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