After Gutenberg

Subtitle: When Ultra capacitors ruled the Circuit

A converted Toyota Supra GT won a 24-hour endurance race in Japan. Some automotive writers have gone so far as to state that a new era had dawned when the specially modified Toyota Supra HV-R hybrid race car won the Tokashi. The ultracapacitor-equipped Toyota Supra HV-R coupe became the first hybrid to win the 24-hour endurance car race held at Japan’s Tokachi International Speedway. The hybrid Supra finished 616 laps of the 5.1-kilometer (roughly three-mile) course—19 more laps than the second-place, non-hybrid, Nissan Fairlady Z.

This blog previously expressed the hope that, with mass production, an ultra capacitor module could become a cost effective, energy storage component in the design of regenerative systems that capture and re-use kinetic energy.

The author of a recent SciAm (Scientific American) article sees the ultra capacitor as the current “dark horse” in electric drive development, yet entertains the possibility that

Toyota and its Earth-loving ilk may yet have the last laugh as they cultivate encouraging new advances in ultracapacitor technology that promise to one day put hybrids in the driver’s seat.

With regenerative braking / suspension systems, the kinetic energy must be quickly recovered. The SciAm author, Larry Greenemeier, is aware of the debate as to whether super capacitors or fast charging batteries will be the preferred electric drive component to provide sufficient specific power for kinetic energy capture. The quick discharge ability of capacitors makes them suitable for release of high current to boost vehicle acceleration.

Despite Toyota’s success with ultracapacitors, most automakers in recent years have been focused on new developments in the lighter, more stable lithium ion batteries, says Brett Smith, an alternative-fuel analyst at the Center for Automotive Research in Ann Arbor, Mich.

“Moving from the type of lithium battery used in laptops to a nanophosphate lithium ion battery may have been the invention or the paradigm shift that the industry was requiring,” Smith says. “Now the challenge is can they get the cost down.” That’s the pivotal question that is likely to ultimately determine the fate of ultracapacitors used in hybrid cars.

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“The Toyota that won was able to deliver energy more quickly, accelerate faster, and use braking generation more efficiently,” says Kevin Mak, an analyst with research and consulting firm Strategy Analytics and author of a recent study that explores the potential for ultracapacitors to complement and possibly even replace batteries in hybrid vehicles. “The days of the large hybrid vehicle battery pack may be numbered,” he adds.

Ultra capacitors have demonstrated quicker storage of electricity. On the other hand, deep cycle batteries have demonstrated greater capacity.

Greenemeier, also would seem aware of testing of hybrid systems. “The Tokachi race” he writes, “proved that ultracapacitors could be more widely used in conjunction with smaller batteries to power hybrid cars.” He certainly is aware of DESDs (Digitized Energy Storage Devices).

Capacitors haven’t been competitive with batteries in the past, because they have not offered a higher energy density, says Olgierd Palusinski, a University of Arizona professor of electrical and computer engineering. Palusinski argues that energy density is an even better measure than storage capacity of how effective a power source can be. “You could have a very high storage of charge but at a very low voltage,” he notes.

Noting the idea that ultra capacitors could mean the need for smaller battery packs in hybrids Paul Kuehnel observes:

Capacitors haven’t been competitive with batteries, because they cannot pack the energy density needed to propel a vehicle for more than short bursts although surges of power needed by hybrids during short periods of heavy acceleration or braking require nearly instant access to large energy pulses. A combination of both would create the best of both worlds.

Well, maybe, integration of these two types of energy storage with proper power electronics to make the combination work is the way to go. Argonne National Laboratory is testing the idea. It will be a question of which could be made sooner and more cheaply, fast charging lithium ion batteries or ultra capacitors?