• Mar 8th 2008 at 1:04PM
  • 5

In a recent article in Popular Mechanics, editor Mike Allen declared himself a fan of ultracapacitors for hybrid cars. He explains how he visited Honda's development facilities 15 years ago and found himself testing a mild hybrid that used an ultracapacitor to store energy. However, we all know that current hybrids don't use ultracapacitors. Instead, they have powerful batteries, which have a higher power density and a price that is going down.

Nevertheless, Allen predicts that once ultracapacitors can be made successfully at a competitive price point, conventional hybrids will use them because of the "capacitor's longer life span and lower internal resistance, as well as its deep-discharge tolerance. While a battery pack can be damaged by being discharged completely, capacitors simply don't care." On the other hand, he foresees that plug-in hybrids will always need batteries for their main battery pack, while using capacitors to reclaim energy while slowing down and to provide high-current acceleration. EESTOR must be happy.

[Source: Popular Mechanics]




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  • 5 Comments
      • 8 Months Ago
      A more efficient and cost effective renewable energy system is needed.
      A more efficient and cost effective renewable energy system is needed.
      To accelerate the implementation of renewable electric generation with added incentives and a FASTER PAYBACK - ROI. (A method of storing energy, would accelerate the use of renewable energy) A greater tax credit, accelerated depreciation, funding scientific research and pay as you save utility billing. (Reduce and or eliminates the tax on implementing energy efficiency, eliminate increase in Real estate Taxes for energy efficiency improvement).
      In California, you also have the impediment, that when there are an interruption of power supply by the Utility you the consumer cannot use your renewable energy system to provide power.
      In today's technology there is automatic switching equipment that would disconnect the consumer from the grid, which would permit renewable generation for the consumer even during power interruption. Energy storage technology must advance substantially. “Energy conservation through energy storage”.
      New competition for the world's limited oil and natural gas supplies is increasing global demand like never before. Reserves are dwindling. These and other factors are forcing energy prices to skyrocket here at home. It's affecting not just the fuel for our cars and homes, but it's driving up electricity costs, too. A new world is emerging. The energy decisions our nation makes today will have huge implications into the next century.
      A synchronous system with batteries allows the blending of a PV with grid power, but also offers the advantage of “islanding” in case of a power failure. A synchronous system automatically disconnects the utility power from the house and operates like an off-grid home during power failures. This system, however, is more costly and loses some of the efficiency advantages of a battery-less system.
      We’re surrounded by energy — sun, wind, water. The problem is harnessing it in an economical way.
      Jay Draiman, Northridge, CA
      May 29, 2008
      • 8 Months Ago
      Presently, ultracaps have only a tiny fraction of the energy density (W-H/Kg) of batteries. While I expect substantial improvement in that, I also expect substantial improvement in battery technology, including one or more satisfactory solutions to the discharge cycle problem (Altairnano claims to have a solution, but I haven't actually seen it yet).

      That said, there are probably several ways to combine both battery and ultracap technologies to combine the advantages of both.

      W-H/Kg isn't the only important measure. It might be that W-H/$ might be more important, especially when lithium becomes scarce. (Na-ion, anybody?)
      • 8 Months Ago
      Ultracaps have remained the ugly stepchild of the electricity storage industry largely because California's ZEV legislation was severely biased in favor of high all-electric range (i.e. zero toxic tailpipe emissions) rather than fuel economy.

      Fortunately, someone was wise enough to at least write phase-out clauses into the legislation so at least the bias is weakening. Ultracaps make a lot of sense for beefed-up stop-start systems, especially for diesels and large displacement gasoline engines (cp. Valeo Stars-X system). They also do a better job of recuperative braking and acceleration boost, simply because there are no chemical reactions involved.

      Given that all OECD countries except Germany have general speed limits, high engine power is only required for high torque during acceleration at low speeds. Ergo, even a modest ultracap banks permits the use of a substantially weaker - but more frugal - engine.
      • 8 Months Ago
      "Instead, they have powerful batteries, which have a higher power density and a price that is going down."

      It's about time you guys learned the difference between energy and power. Power is the rate of energy delivery.

      Generally speaking, batteries have far higher energy density than caps ie. they can store more energy per weight, but they can deliver far less power per weight.
      • 8 Months Ago
      Confusing Power (Kilowatts) with Energy (Kilowatt-hours) is like confusing distance (miles) with speed (miles per hour).

      Ultracaps have very high power density, but low energy density. While the power density of batteries isn't as high, it is still sufficient for hybrid and EV use, and batteries have much better energy storage capability.

      The only remaining advantage to using ultracaps for hybrids is an almost unlimited charge cycle count. By handling most of the minor charge/discharge cycles, the lifespan of the main storage battery could be increased.
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