Maxwell Ultracapacitors to Capture Subway Braking Power

Maxwell Ultracapacitors to Capture Subway Braking Power
The South Korean government is testing Maxwell Technologies' ultracapacitors for subway regenerative braking systems. .Maxwell Technologies' ultracapacitors are hitting the brakes on South Korean subways - a test of the technology's promise to outperform batteries in capturing and discharging electricity.

The San Diego-based company announced late Wednesday that its ultracapacitors would be used in a regenerative braking project being done by the Korean Railroad Research Institute in a Korean subway system.

That's a new market for Maxwell (NASDAQ: MXWL), one of the more established companies in the field of ultracapacitors. Maxwell and its competitors – including APowerCap Technologies, EnerG2 Inc. and EEstor – say their products can beat batteries on power storage and lifespan measures (see Is This the Way to Build Electric Cars?).

One application for ultracapacitors that's been getting a lot of attention lately is regenerative braking, which captures the kinetic energy from brakes. Regenerative braking is used on some hybrid cars, such as the Toyota Prius and Honda Insight, to help charge their batteries. Subway systems, including the world's largest in New York, have also experimented with the technology.

To supply the Korean subway test, Maxwell shipped 72 of its 48-volt ultracapacitor modules to contractor Woojin Industrial Systems earlier this year, where they were used to test a 740-volt regenerative braking system on the Gyengsan light rail transit track. In October, Maxwell shipped another 220 modules to be part of a 1500-volt DC system to be installed by the second quarter of 2009.

That system is scheduled to be demonstrated in mid-2009. But Maxwell said preliminary tests showed that the regenerative braking systems using its modules could reduce grid power consumption by more than 20 percent, or enough to pay back the system's cost in four years.

Capacitors store energy as an electrical field, rather than chemically as batteries do. That means they can charge and discharge faster, and over more life cycles, than batteries, at the expense of "energy density," or amount of power stored per unit of weight. Ultracapacitors promise to solve that problem through improved energy density, using a variety of methods.

Maxwell has sold its ultracapacitors to other customers, for uses including regenerative braking systems for bus companies in China and Europe, and to provide backup power for wind turbine blade pitch control systems built by Germany's LTi REEnergy.

The Economist magazine has pointed to ultracapacitors as a potential replacement for batteries as the energy storage technology of choice - if the technology can prove to work as well as its backers say it can. Investors seem willing to place bets on that question.

EnerG2 Inc. raised $8.5 million for its first round to develop an ultracapacitor for storing energy in electric cars and electronic devices. The Seattle company, founded in 2003, raised the money from OVP Venture Partners, Firelake Capital Management, WRF Capital, and Northwest Energy Angels.

APowerCap, a Ukraine-based company that said it has received funding in 2006 from Ukrainian venture capital firm TechInvest, recently received a funding commitment for between $5 and $20 million from an investment firm called EastOne Group, according to Dow Jones' Clean Technology Investor (via VentureBeat).

AS for EEStor, the Cedar Park, Texas-based company has announced deals with Toronto-based Zenn Motors and Eugene, Ore.-based Light Electric Vehicle Co. to provide ultracapacitors that it said could replace batteries in electric cars.

But EEStor has seen continual delays in launching its product, which it first promised to deliver by the end of 2007. Recently, EEStor CEO said in a blog post that the company would not deliver its ultracapacitors to market by the end of 2008 because of a lack of funding (see Sounds Like EEStor Has Delayed Again).