Start-up redesigns fuel cells
Published: 11 Feb 2003 09:29 GMT
A start-up company says it has developed a way to make fuel cells out of silicon, a change that potentially could increase the performance of cells and make them easier to manufacture.
As far-fetched as it might sound, fuel cells for cell phones or notebooks are likely to emerge in the market next year and grow in popularity. Unlike microprocessors, hard drives or memory, batteries are not continuing to improve at a rapid, predictable rate. This is forcing tech companies to seek alternatives or products that will complement batteries.
The twist developed by Neah Power Systems essentially replaces the polymer membrane inside fuel cells with layers of porous silicon, said David Dorheim, chief executive of Neah.
Current fuel cells produce energy by creating a chemical reaction between methanol and oxygen. Electrodes draw those substances toward a plastic membrane, and when they come in contact with the membrane, the methanol breaks down and releases electrons, which are then funneled to power the host device. The byproducts of the reaction eventually recombine with the electrons to form water and carbon dioxide.
However, the amount of electrons produced is directly related to the surface area of the membrane. Increasing the power means expanding the physical size of the fuel system. Polymer membranes can also tear and leak.
To boost surface area, Neah's fuel cell uses layers of silicon chips, each shot through with pores, to serve as the surface area for the chemical reaction. Just as Greece -- with its islands and rocky coastline -- has almost as much coastline as all of North America, Neah said the collective surface area from pores in its chips will far exceed the surface area of most polymer membranes.
As a result, more energy can be produced at once, even though the external dimensions of the polymer membrane and silicon chip are the same. The Bothell, Washington-based company, which started in 1999, asserts that it can make a fuel cell with eight porous chips that will be adequate to run a standard notebook and will be no bigger than today's standard laptop battery pack.
"The location where you can have the reaction is increased dramatically," Dorheim said. "We've been talking to notebook makers for six months."
The use of silicon also lets Neah use hydrogen peroxide, rather than the ambient atmosphere, as the source of oxygen. This leads to a greater concentration of oxygen, which boosts power.
Just as important, silicon is a known quantity. The company's chips can be produced with the chipmaking machinery developed for the semiconductor industry. Neah's chips are far from standard -- most of Neah's patents revolve around the techniques involved in creating the pores in the silicon -- but the tools work.
"There is 40 years of science around dealing with silicon," he said.
One of the company's fuel cells should be capable of running a notebook for six to eight hours, Dorheim said. Neah, like other fuel cell manufacturers, is also tinkering with ways that will let customers refill fuel cell cases with methanol.
In addition, trade associations such as the US Fuel Cell Council are working with respective agencies, such as Underwriters Laboratories, to gain regulatory approval and set product standards.
Although the concept is intriguing, the company acknowledges that it is still in the first stages. It has demonstrated the concept in the lab and hopes to have a working demo model by the end of the year. Products aren't set to start shipping to customers until 2005.
Fuel cell materials aren't cheap. Like all fuel cells, the reactive surface area on Neah's cell is coated with platinum and ruthenium, two relatively expensive elements.
Investors in the company include Alta Partners, Frazier Technology Ventures and Intel Capital. So far, the 28-employee company has raised between $7m and $10m, or £4.3m and £6m Dorheim said.
Neah's approach has analysts intrigued.
"Obviously, they are way ahead of having a tangible product, but it is an interesting approach," said Dean McCarron, principal analyst at research firm Mercury Research. "They are addressing a lot of the problematic issues with fuel cells... It looks at this stage like a fairly interesting approach."
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