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Ultracaps Not Ready to "Supersede" Batteries, Despite What Tesla's Elon Musk Says

Tesla Motors' CEO, Elon Musk, is a game changer, but he's not necessarily the Oracle at Delphi. His recent pronouncement at a Cleantech Forum that batteries could be "superseded" by ultracapacitors, a technology only now emerging in car applications, could turn out to be wrong -- and some key ultracap executives, who would certainly benefit if he was right, are instead very skeptical.

A high batting average
Musk has a pretty good track record. When most people thought that electric cars were slow, boring sedans, his sexy Tesla Roadster proved otherwise. And his private rocket company, Space X, is turning doubters into believers as it grabs government contracts and (unlike Tesla so far) makes profits.

Musk was prescient in an early investment in the rapidly expanding SolarCity, his cousin's company. But when Musk was asked at a Cleantech Forum about game-changing technology, he said, "If I were to make a prediction, I'd think there's a good chance that it is not batteries, but capacitors."

Yikes! Musk thinks the multi-billion-dollar investment in advanced-generation batteries may end up as stranded assets as a left-field technology ascends to Mount Olympus! That angle led a lot of blog posts, some of which noted that Musk had gone to Stanford intending to study ultracaps. Yes, but he left that program after only two days.

What are ultracaps, anyway?
Ultracapacitors are a mystery technology for most people. They still have a very low profile in the U.S., though applications in Europe make them better known there. What are ultracaps (sometimes called "supercapacitors") exactly? Cousins to batteries, they're long-lived (a million or more charges) electronic devices that are adept at taking a fast electric charge (in less than a second, compared to hours for batteries), and discharging it just as quickly.

But their weak point when compared to batteries is low energy density. They can't hold a charge over the long haul, and as a result are so far mostly used in cars to complement batteries, not replace them. The one company that promised incredible performance from capacitor-powered cars, EEStor, lost a lot of credibility when it couldn't deliver. That one incident was a big setback for ultracaps' reputation, to the extent this sleeper technology had one.

The French auto giant PSA is using an ultracap/lead-acid battery combination to power millions of "micro hybrids," regular gas cars that borrow shutoff-at-stoplight technology from cars like the Prius for a 10 to 15 percent fuel savings. Both Ford and General Motors are likely to bring micro hybrids to the U.S. in a big way over the next two years, though few are available now. The Big Three are investigating ultracaps, which can save money by downsizing the size of the required battery, but none have made a commitment yet.

Ultracap makers get down on their own tech
Those PSA ultracaps are made by U.S. market leader Maxwell Technologies, whose CEO, Dave Schramm, says they reduce battery size by 30 percent. But he doesn't see ultracap cars on the horizon:

Ultracaps in today's configuration can't replace batteries. They're very different -- the battery is an energy device, and the ultracap is a power device. Batteries have 10 times the power of an ultracap, and ultracaps have 10 times the power. I wouldn't say ultracaps can "supercede" batteries, I'd say "complement."
Harvey Wilkinson, the vice president of business development at another major ultracap company, Ioxus, thinks that Musk's dream could come true -- but not now, maybe 10 years down the road:
There's a lot of work being done on increasing the energy density of ultracaps. In a decade, they could be storing six times the energy that you're seeing now. By then they could have the energy density lead-acid batteries have today.
But, of course, lead-acid has a lot less density than the lithium-ion batteries that are the standard power for electric cars today. Energy density is their big selling point, and there's nothing on the immediate horizon to replace them.

Major battery supplier A123 Systems has just announced a lithium-ion battery that is going into production in an unnamed German automaker's micro hybrid sedan in 2013. But he says simply:

Ultracaps are good for short bursts of power. We don't need to use ultracaps in our application because our li-ion batteries have enough power without them.
File the ultracap as useful technology that doesn't have stand-alone uses in cars yet. A decade down the road, we may have a different conversation, and Elon Musk will be vindicated.

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Photo: Jim Motavalli