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An Alternative to your Alternator

Continued from page 1

By Kevin Bullis

Thursday, June 1, 2006
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Indeed, if the new materials do make more efficient thermophotovoltaics, there will be no shortage of potential uses. Kassakian says a particularly good application, when combined with the a new air-conditioning system, could be for use in trucks with sleeper cabs to cool the cabs and provide electricity for televisions and other equipment. And, says Donald Chubb, a researcher at the NASA Glenn Research Center, "The military has had a lot of interest in it for portable power supplies in the field. Because there are no moving parts, there wouldn't be any noise, so you couldn't detect it."

It will be several years before the technology can used in vehicles, though. Challenges include scaling up the fabrication process, developing effective insulation and cooling systems to manage the heat generated, and ensuring that the system remains efficient on a larger scale. The MIT research is funded in part by Toyota, but the automaker has not committed to implementing the technology.

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Comments
  • thermophotovoltaic technology
    Wouldn't this technology be useful in aircraft as well,or would the weight to power ratio be too high?
    Rate this comment: 12345
    Guest (C.N.Guerriere,M.D.)
    06/01/2006
    Posts:1
    • thermophotovoltaic tech
      Wellwellwell, why don't they just put a second one of those things next to the exhaust.. that way they get heat for free.
      Rate this comment: 12345
      Guest (Patrik)
      06/30/2006
      Posts:1
  • Isnt there already so much heat
    Cant the heat thats wasted in enormous amount in the engine be used for something useful ?
    Rate this comment: 12345
    Guest (Sam Tuole)
    06/01/2006
    Posts:1
    • re: isn't there already so much heat..
      I'm no expert but I would think that the heat now wasted could be utilized as the driver for a device
      similar to that described in the article. A typical alternator puts out something like 1 kw. Not sure
      how much heat a typical engine puts
      out(radiated plut the exhaust heat) but it has to be in the range of at least 10 times that much so the device would not have to be very efficient. However, it would have
      to operate in the presence of pretty high temperatures.
      Rate this comment: 12345
      Guest (Bob Downs)
      06/01/2006
      Posts:1
      • Energy in a car engine
        A car engine is assumed to be 30% efficient. Assuming a car engine to have a average power rating of 80 kW that would mean an excess of heat in the order of 56 kW. There was an article before on TR about advance in thermoelectric materials which convert heat directly into electricity. These have been used before in space systems but have a rather poor efficiency which was improved upon.
        Rate this comment: 12345
        Guest (Jonas Norrby)
        06/01/2006
        Posts:1
        • --
          This means that You put 280 potential Kw in an engine as fuel obtaining 80 Kw. There are 200 Kw in heat.
          Rate this comment: 12345
          Guest (L)
          06/01/2006
          Posts:1
    • engine has heat, just can't convert it
      There's plenty of heat from the engine. But it's at too low a temperature to give off photons that a TPV device like MIT's could use. And using a Peltier wouldn't work much better because there's too small a delta-T. Low grade heat is tough to turn into electricity.
      Rate this comment: 12345
      Guest (CKE)
      06/01/2006
      Posts:1
      • Engine heat to supplement only
        They can use the engine heat to bring the thermophotovoltaic alternator to operating temperature(maybe half way) and the unit can raise the temperature to power generating point.  The battery and supply the necessary power until the engine reach operating temperature.  A penny save is a penny earned.  A few degree save in heating fuel is a few degree earned.
        Rate this comment: 12345
        Guest (Techno)
        06/01/2006
        Posts:1
      • engine has heat, just can't convert it
        Heat basically is infrared radiation isn't it? there is another group of scientist who are using quantum Microdotting to create full spectrum solar pannels.
        I wonder if their reseach could aide the MIT crew?
        lbl.gov/Science-Articles/Archive/MSD-full-spectrum-solar-cell.html
        I also think they overlook something simple as well the thermal imager the technology behind that turns heat into visible light as well.
        Of course this is just a thought.
        If enough of scientist come together they can make the difference.
        N~K
        Rate this comment: 12345
        Guest (Nick Kearney)
        06/10/2006
        Posts:1
    • thermoelectric
      Yes, there are thermoelectric or TCs that are used to produce electricity from heat, a CO in AZ
      makes and markets them,, LFM
      Rate this comment: 12345
      Guest (lee mcclune)
      06/07/2006
      Posts:1
  • Tungsten
    I'm intrested in how much tungsten they use and how much tungsten is available? Basically the kW/kg tungsten compared to kg tungsten/Tons tungsten available. The problem with materials which are not common is that the demand can kill any advantage due to increases in the price. For example PV cells based on silicon where the material is now becoming the bottleneck due to possible greater demand than availability.
    Rate this comment: 12345
    Guest (Jonas Norrby)
    06/01/2006
    Posts:1
    • Tungsten
      They're only using tungsten now--it might not be the final material. Besides, they can use microns thick layer.
      Rate this comment: 12345
      Guest (KB)
      06/02/2006
      Posts:1
  • don't too get excited yet
    To sustain combustion, a good amount of heat will go up the flue with waste gases via convection. As for undetectable in the field - ever heard of infrared cameras? There will be a heat plume visable from far away. Past TPV (thermovoltaic) efforts have fooled with light filters, special emmitters, etc. As I understand, they have not cracked 30% efficiency either. I wonder if at the end of the day, system efficiency is not much better than the common ICE/alternator.
    Rate this comment: 12345
    Guest (CKE)
    06/01/2006
    Posts:1
    • Higher efficiency engine
      There is a new engine design call toroidal engine that is much more efficient that the existing inline IC engine.  You can check it out at http://www.rotoblock.com/
      Rate this comment: 12345
      Guest (Techno)
      06/01/2006
      Posts:1
      • Another ICE?
        designs claiming to be more efficient internal combustion engines have been around since it was invented, but unfortunately, most are dead ended. This one is very complicated and the frictional losses of 8 pistons probably will be its downfall. ICEs are simply inefficient by nature. Some ways to improve efficiency are to run at higher temperatures like a F1 engine which runs at about 140-150 deg C and has minimal surface area. (How about 750 HP from a 100kg engine.) Ceramic coatings on cylinders and exhausts combined with turbochargers allow  higher specific output from smaller engines and better efficiency, but not enough.
        Rate this comment: 12345
        Guest (Jim)
        06/01/2006
        Posts:1
  • How efficient can these devices get?
    I'm imagining a vehicle entirely powered by these devices. Fuel -> light -> electricity -> motion might become competitive with the ICE.  And I think you could control emissions more easily in a system designed solely to extract heat from the combustion of fuel.
    Rate this comment: 12345
    Guest (JimD)
    06/01/2006
    Posts:1
  • ICE
    With all this nanotech why can't we design a filter that traps all the combustion products and produces some kind of useful byproduct?

    jemd@wcvt.com
    Rate this comment: 12345
    Guest (Jim Dodds)
    06/01/2006
    Posts:1
  • Another great idea that you'll that will never be put to practical use.
    "It will be several years before the technology can used in vehicles, though."

    I've lost count of the number of times I've read about some great new idea only to see that sentence or a variation of it at the end of the story.  Another tease! 

    Here's some ideas: stop having so many babies and ride a bicycle.
    Rate this comment: 12345
    Guest (Ben)
    06/02/2006
    Posts:1
    • another popular tagline
      I must have seen this tagline at the end of dozens of these R&D articles: "The authors feel this technology will be ready for commercial introduction in 2 years"
      Rate this comment: 12345
      Guest (CKE)
      06/06/2006
      Posts:1
  • How much power vs size
    Using PV cells, in order to say get 14vdc@60 amps, minumal for todays cars, your talking more square footage of PV cells than your avererage 40' semi has. Unless they have come up with something new, I don't see the application being viable. Maybe they should just put it over the fireplace as a cute lightbulb
    Rate this comment: 12345
    Guest (Jeff)
    06/02/2006
    Posts:1
    • don't need much power
      they're only talking about running the lights, not moving the vehicle.
      Rate this comment: 12345
      Guest (mARK)
      06/07/2006
      Posts:1
      • yes, you do
        Yes, you do need the amount of power that Jeff mentioned (60A).  Your electrical system is far more than just lights - blower motors, stereos, gages/displays, computers, valves, etc.  Even the smallest cars have 80-90A alternators.  Do a little check - add up the amps of all the fuses in your fuse box.
        Rate this comment: 12345
        Guest (Steve)
        06/15/2006
        Posts:1
  • I'd rather go from heat straight to electricity
    More research needs to go into thermoelectric(Seebeck) effect.  Reference http://en.wikipedia.org/wiki/Peltier-Seebeck_effect

    I would think you'd get better efficiences by skipping the light conversion.  Great research though.  Any improvement is good improvement.
    Rate this comment: 12345
    Guest (Simon)
    06/02/2006
    Posts:1
    • How could you get better efficiency?
      How would you do it? I am more interested in home and industry based systems using biomass and waste heat, and solar heat.
      Rate this comment: 12345
      Guest (Ron Wagner)
      06/06/2006
      Posts:1
    • Seebeck
      This is a very weak effect. In addition to a strong source of heat (we have this), it also needs a capacious source of cold - a large capacity heat sink. This is what's missing.
      Rate this comment: 12345
      Guest (CKE)
      06/06/2006
      Posts:1
      • Re: Seebeck
        Cars use the Delta T of the radiator and the air to cool the motor. Isn't this a heat sink

        Gr.
        Rate this comment: 12345

        Ixe
        08/20/2006
        Posts:1
  • how about a sterling engine
    you bastard
    Rate this comment: 12345
    Guest (sterling)
    06/02/2006
    Posts:1
  • English
    Thermophotovoltaic is one of the coolest words I have ever seen, regardless of how well this technology works currently.
    Rate this comment: 12345
    Guest (Jonathan)
    06/05/2006
    Posts:1
  • Home heat and electricity from biomass
    Clean burning biomass might be able to supply electicity for hybrid vehicles and homes with this or other technologies. Industries also could produce their own electricity with waste heat. Simple solar devices could build enough heat to fuel these systems in hot climates.
    Rate this comment: 12345
    Guest (Ron Wagner)
    06/06/2006
    Posts:1
    • re: biomass
      These alternative energy schemes all work better when they are stationary, and can take up a lot of space and weight. Hence, they should be used to create electricity as power plants. And another scheme on how to get the electricity into the cars (charging batteries, or making fuel) should be found.
      Rate this comment: 12345
      Guest (CKE)
      06/06/2006
      Posts:1
  • Thermoelectirc - No photocell
    Couldn't you just use the Seebeck Effect and convert the heat directly to electricity. You would get 1 volt per degree difference from every 2 million pieces of nano-metal. You could pack a lot of them on anything of macroscopic size so this should work right?
    Rate this comment: 12345
    Guest (Brandon B)
    08/04/2006
    Posts:1
    • Power Density
      Going by those figures you should be able to get 5 volts of electricity per degree difference for every square centimeter of surface area.
      Rate this comment: 12345
      Guest (Brandon B)
      08/04/2006
      Posts:1
  • Uni-directional gear box
    To turn oscillations in to unidirectional rotations easily fabricated design available at http;/ww.ljsite.com/unigear.htm
    Rate this comment: 12345

    leel6391
    10/28/2007
    Posts:1
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