They need to make a longer-wavelength version which can operate on engine exhaust heat.

Actually, I believe the A/C in the hybrid Camry runs of electric power.

If Toyota is partly funding this, you can bet they have a real interest in this technology, so expect to see it show up in some form on production vehicles.

There is potential for using this for co-generation in a lot of different places - from wood stoves to nuclear reactors.

Fantastic if it scales and is not too expensive.
I assume you could burn the fuel in a very clean way and so get a cleaner electric car running on Gasoline !
(or diesel) or any biofuel.
No hydrogen required !

LochDhu, Engineer-Poet:
You are correct, the US will need an additional 50% increase in electrical power in the next 20 years. Thermoelectrics can provide a very large contribution (80-95% of projected demand increase) without increasing emmisions of GHGs. Further implementation/improvements of thermoelectrics/votaics will improve the efficiencies of heat engines like automobiles, ships, Strerling engines, etc. Add in technologies like plants with co-generation, coal gasification (also eliminates Sulfur oxides and heavy metals), sequestation, algae oil/biomass production, you can start moving away from fossil energy and towards susutainable energy.
_
http://www.unh.edu/p2/biodiesel/article_alge.html
http://en.wikipedia.org/wiki/Biodiesel

You have to pick the materials you use to build the P-N junction, this determines the band gap

To tune it for a longer wavelength (lower energy photon) you need a lower band gap.

This is all fine and good however we are limited in the materials we have, and a photon with more energy than the band gap energy does not produce more power it just produces more heat.

"Why can't we choose a material with a really low band gap, so we can use more of the photons? Unfortunately, our band gap also determines the strength (voltage) of our electric field, and if it's too low, then what we make up in extra current (by absorbing more photons), we lose by having a small voltage."

http://www.howstuffworks.com/solar-cell1.htm

http://www.lbl.gov/Science-Articles/Archive/MSD-full-spectrum-solar-cell.html

http://www.lbl.gov/msd/PIs/Walukiewicz/02/02_8_Full_Solar_Spectrum.html

nothing is ever easy

Allen Zheng, I like your thinking. Even better would be to choose to target a 25% reduction in consumption in the next 20 years. Can you imagine that?

This looks like a candidate for use with reflective solar concentrators as the energy source. Interesting!

How does this technology compare to the technology behind the old vacuum tubes?

The Vehicle Research Institute at Western Washington University did some work with a thermophotovoltaic powered electric car starting in the mid 90s. It used a 10 kWhr battery as a buffer between the thermophotovoltaic power plant and the electric motor.

They only claimed 7% efficiency for the thermophotovoltaic power plant, though. Not 40-50%.

http://vri.etec.wwu.edu/tpv.htm

http://vri.etec.wwu.edu/viking_29_paper.htm

Layman's comment; A similar technology is currently being marketed and run in diesel long haul rigs to eliminate the alternator for fuel efficiency. It replaces the muffler on the exhaust stacks. Probably not nearly as efficient, of course

There was a story on here about engine heat and thermoelectric semiconductors a while back. The impression I got was that the efficiency was in the single digits. Even though most of the energy used in an ICE goes out as heat, until the conversion efficiency goes up, it may not be very cost effective.
http://www.greencarcongress.com/thermoelectrics/index.html

Re: Layman's comment;

Where can I read about this similar technology that is currently being used on long haul stacks?
TG

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It seems they MAY use it in their automobiles. I live in Tokyo and I will attend a press conference at Toyota Head Office on the 16th of June (2006) to discuss it. I will do more research to be sure. If anyone is interested or can give me additional information please feel free to contact me ;)

My address is lfrohling zero one at yahoo dot com dot au

Luke Frohling

Interesting, where can I learn more? I would like to study pv concepts. I'm currently an engineering student with a devoping fondness of physics.