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Power Transportation Science

MIT's Nano Storage Could Replace Hybrid Batteries 191

Posted by Zonk
from the replace-the-darn-bunny dept.
mattnyc99 writes "Last week we discussed Popular Mechanics' reporting from MIT, but missed one of the coolest breakthrough of all, something scientists have been working on quietly as Detroit spends money elsewhere. The Lab for Electromagnetic and Electronic Systems has been doing some mega-efficient work with ultracapacitors, which store drastically less energy than a battery but have essentially none of the drawbacks — especially via carbon nanotube arrays. Automotive experts say the new research is enough to start replacing batteries in hybrid cars, and plug-in vehicles might not be far behind. From the scientist who thinks ultracapacitors are potential competitors for the pack in his Toyota Prius: 'I try to contain myself, because it hasn't been proven yet, but it could be a real paradigm change.'"
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MIT's Nano Storage Could Replace Hybrid Batteries

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  • Better capacitors (Score:4, Interesting)

    by QuantumG (50515) * <qg@biodome.org> on Monday March 03, 2008 @06:13PM (#22628644) Homepage Journal
    Implications for Focus Fusion? [lawrencevi...hysics.com]

  • by JohnnyGTO (102952) on Monday March 03, 2008 @06:16PM (#22628684) Homepage
    leave charged capacitors on the parts shelf to reinforce the "Don't Touch" rule? I bet one of these would reallllly hurt :-)
  • by mikeee (137160) on Monday March 03, 2008 @06:49PM (#22629096)
    A capacitor has to hold the positively and negative charged portions of itself nearby, but electrically isolated; to keep the insulation from being crushed (opposite charges attract, remember) requires a certain physical strength proportinal the the charge stored that will put at least a top-end limit on capacitor capacity.

    Interestingly, this is dependent (duh) on the strength (energy) of chemical bonds, so IIRC, the theoretical limit for capacitors is actually pretty much the same as for chemical fuels or batteries. (Now, small electric motors are more efficient than small engines, so electric systems can be a huge win, although the fuel system don't have to carry their own oxidizer...blah blah blah.)

    Pretty much anything non-nuclear (you can throw flywheels, nanotech windup springs, and what have you in, too), should in a perfect world max out at roughly the same magnitude because they're all fundamenentally dependent on that chemical bond strength.
  • by Anonymous Coward on Monday March 03, 2008 @06:56PM (#22629176)
    Let me get this straight. You don't think that the scientists at MIT have thought of this? To read your post, it's a deal breaker and the MIT guys are a bunch of Cold Fusion Clowns.
  • by Ixlr8 (63315) <L.MolNO@SPAMewi.tudelft.nl> on Monday March 03, 2008 @07:15PM (#22629392) Homepage
    Although your point is valid to a certain extent, I think you're exagarating the 'problem' of charge and voltage being proportional. Modern switched mode power converters can do a good job.

    Additionally I could see a solution in which not all capacitors are use at the same time. By activating them in a proper order/way, one could make a more constant source that can then be the input for a SMPS.
  • Electricity (Score:4, Interesting)

    by Archangel Michael (180766) on Monday March 03, 2008 @07:23PM (#22629472) Journal
    So, how is all the new demands for electricity going to be satisfied.

    I know everyone likes Electricity and such, but current demands are taxing the existing power grid / infrastructure.

    And with all the NIMBYs out there, nobody is willing to build new and needed Hydro Electric, Nuclear, Coal powered plants anytime soon. So, the result is "cool, electric cars, but I can't use them because of the blackouts". And I don't assume that somehow people will give up the NIMBY attitudes for an electric car.

    Its easy to be an environmentalist, you don't have to think of the requirements to achieve whatever goals you might have. It just has to sound good.
  • by blanchae (965013) on Monday March 03, 2008 @07:59PM (#22629868) Homepage
    In the early 2000s, I researched the design of a capacitor that would be able to power a 2000 lb car (CRX) at 70 mph for 180 miles then recharge and drive back. The best capacitor technology at the time required an electrolytic cap the size of one of those old wooden oak office desks with each layer being in the order of 0.001" thick. It would of required some major thin film technology. On top of that it would weigh more than the car it was supposed to power!

    An alternative was to purchase existing 1 farad supercaps and build the required capacitance through series and parallel circuits to get the voltage and capacitance up. The cost was over $250,000 at the time. The last issue was building a charging circuit that could quickly charge the cap up within 30 minutes.

    I also explored the design of making a 200 mph electric dragster. The issue was the megawatts of electrical energy that needs to be transferred within 6 seconds to the electric motors. It was the equivalent of a large electrical explosion. Here's the latest world record electric dragster at 160 mph: Dennis "Kilowatt" Berube [teva2.com]

  • by Anonymous Coward on Monday March 03, 2008 @08:02PM (#22629900)
    Umm, what happens when the charged ultracapacitor is crushed in a collision?

    Is all the energy released in a few milliseconds, as an explosion, or a cool lightning bolt that burns up the car's sheet metal parts, like what happens to a CD in the microwave?

    Will I be able to get an automotive ultracap from the junkyard in a few years, charge it, and cross its terminals with a bolt (from a distance), for 4th of July?

    Anybody think that will be illegal in California?
  • Re:rtfa (Score:-1, Interesting)

    by Anonymous Coward on Monday March 03, 2008 @08:11PM (#22629994)
    One advantage to capacitors that I haven't seen mentioned yet is they tend to be have much higher charge/discharge efficiency then batteries. NiMh batteries, in a Prius, are roughly only 60% efficient over a charge/discharge cycle where as capacitors can often be 95+% efficient. While this doesn't help a plug-in hybrid that much (where overall capacity is most important) it might be compelling on a normal hybrid where there is frequent charging/discharging of the battery (regenerative breaking, smoothing out the engine etc.). Might get a couple extra MPG out of that effect alone.
  • Re:Ka Booooooom!!! (Score:3, Interesting)

    by clonan (64380) on Monday March 03, 2008 @08:17PM (#22630050)
    Unless of course you created a bank of super capacitors...This picture in the article suggested they were only maybe 1 cm across.

    Lets take your 400 miles of charge (100 kw/h) and break it into 1000+ watch battery sized devices.

    Sure if one gets pierced it is bad, but a well grounded system will prevent the others from melting while the one goes Ka BOOOOOOM.

    Not only that, but I bet it will be cheaper to manufacture them in mass when they are small.
  • Re:Ka Booooooom!!! (Score:2, Interesting)

    by Powerbear (1227122) * on Monday March 03, 2008 @08:18PM (#22630064)
    Sorry link wrong.. http://www.youtube.com/watch?v=B8gFgIQl2HI [youtube.com]
  • by hardburn (141468) <hardburn@wumpu[ ]ave.net ['s-c' in gap]> on Monday March 03, 2008 @09:38PM (#22630764)

    Regenerative braking plays a big role there. Right now, a lot of energy from the brakes on electrics/hybrids is lost to heat because the battery can't absorb the charge fast enough. Adding a supercap (even if it's just a few) would greatly increase overall efficiency.

    But in general, supercaps are dumb if they're used alone. Caps are good for storing and releasing a lot of charge very quickly, not letting it bleed out slowly.

  • Re:Ka Booooooom!!! (Score:3, Interesting)

    by Agripa (139780) on Tuesday March 04, 2008 @01:58AM (#22632444)
    Sealed electrolytic capacitors fail through bursting when the pressure inside becomes too great which is usually caused by too high a voltage. That does not have the characteristics of a dialectic failure in a high energy capacitor which happens much more quickly and is limited only by inductance. I have seen 1 x 1/2 inch aluminum bus bars used for connecting capacitor banks in high energy physics experiments with holes punched through them from when the capacitor bank shorted out. I have had my own glass plate capacitors short out and 0.1 microfarads at 15000 volts makes quite a bang.

    Ultimately for car applications what is going to matter is discharge rate and recovery. If the capacitor bank completely discharges in an event then figure anything in current path is now molten. Any electrolyte will become a vapor. Don't the double layer carbon capacitors use sulphuric acid as an electrolyte?
  • by TheRaven64 (641858) on Tuesday March 04, 2008 @07:40AM (#22633992) Journal
    All the systems of this nature I've seen only work while the vehicle is resting and contain an RF tag that handshakes with the vehicle and turns off the coil while it's not in use. In China, they're used at bus stops, so the bus can charge while people are getting on and off. They could also be embedded at traffic lights, so if you stop when the lights are red you can recharge your car a bit. If they can get the switching to happen fast enough then it might be feasible to use them while in motion, but I suspect not for a long time.

Some programming languages manage to absorb change, but withstand progress. -- Epigrams in Programming, ACM SIGPLAN Sept. 1982

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