They're called "battery cars" for a reason--The EVs that are to start appearing next year will have large onboard packs that they'll rely on for most of their motive power. But as noted in our earlier story on Maxwell Technologies, ultracapacitors will also play a so-far behind-the-scenes role. And one of the emerging players in ultracaps is Ioxus, a small venture capital-funded startup based in Oneonta, New York. It has just 21 employees right now, but in addition to venture capital it has "millions of dollars in grant funding from federal, state and local resources."
According to Global Markets Direct, electric car and hybrid deployments will cause global ultracapacitor sales in the auto sector to grow 50 percent annually starting next year. The current big player in ultracaps is the Panasonic Corporation, which had an almost 20 percent revenue share last year.
Chad Hall, the chief operating officer of Ioxus, said the company was founded in 2006, but began making ultra-capacitors of 100 to 2,000 farad size in July. By supplying power for fast acceleration, he said that ultracaps of approximately 3,000 farads can dramatically extend battery pack life in EV applications, and that's why the company is in talks with four potential automaker partners (both foreign and domestic). "We hope to have our ultracaps in cars by 2011," he said.
According to Hall, ultracaps play a small role in current cars, and are in thousands of hybrid buses. In the Toyota Prius, wheel-based ultracaps provide backup power for braking, and in three BMW models they'll serve as backup for power assist (and make sure the windows can go down when a car plunges into water--a Bugatti Veyron did exactly that recently).
In hybrid buses, large ultracapacitors can reduce the size of diesel engines, cut nitrous oxide emissions by 75 percent, and increase fuel efficiency 50 percent. The big obstacle is cost, since a hybrid bus ultracaps for hybrid buses can run $15,000 to $20,000. If customers are going to lease lithium-ion battery packs going forward, one solution could be leasing the ultracap as part of that package.
Ultracaps are in some ways batteries' polar opposities. Instead of providing measured amounts of power over a long period of charge, they can release large amounts in short bursts. Ultracapacitors have 10 times the power density of batteries, and discharge in seconds rather than hours. They're temperature-stable, too.
Another benefit is long life, with from 500,000 to a million charge-discharge cycles (compared to a battery pack's 10,000). One practical use will be to reduce auto battery pack size by 20 percent. Ultracap maker Maxwell Technologies signed a memorandum of understanding last June with San Diego-based ISE Corporation for a strategic alliance on supplying technology for hybrid-electric buses and trucks. Maxwell has been supplying its BoostCap units to ISE (for recapturing braking energy and acceleration assistance) since 2002.
Another potential use for large ultracaps is to brace utilities for fast-charging of EVs, Hall said. An ultracap "bank" could store power to be released at peak charging periods. Southern California Edison, in conjunction with A123 Systems, is building a 31-megawatt-hour battery farm for that purpose, using power from wind turbines.