A new generation of cheaper and more efficient hydrogen fuel cells may bring the environmentalists’ dream of affordable, green cars one step closer to reality.
The cells are being developed by PolyFuel in Mountain View, California, US, using a type of membrane made from a hydrocarbon polymer instead of the traditional Teflon-based perfluorinated membrane.
The membrane is crucial in fuel cells as it serves the dual role of splitting hydrogen into protons and electrons, and then only allowing the protons to cross the membrane. The electrons are then sent through a wire to combust with oxygen and the newly separated protons, creating power and a single by-product: water.
“The membrane is the heart of the fuel cell,” says Jim Balcom, CEO of PolyFuel, and accounts for a large proportion of its cost.
The cost of traditional membranes has been a major obstacle in reducing the price of fuel cells to a commercially viable level for cars. “Ideally, you would hope for a solution that yielded vehicles with costs, capabilities and performance similar to those on the road today,” says Atakan Ozbek from ABI Research, Oyster Bay, New York.
The hydrocarbon membrane seems to edge the fuel cell closer to meeting these criteria and there is competition to produce them – Honda is also developing its own fuel cell with a hydrocarbon-based membrane.
Balcom says it is more efficient. Where the perfluorinated membrane is a jumble of fibres through which the protons have to travel, the hydrocarbon polymer offers a direct path through the membrane.
The PolyFuel membrane is expected to cost significantly less than traditional perfluorinated membranes and carries other practical benefits.
Stronger and stiffer
Balcom claims the new cell produces 10% to 15% more power, and is stronger and stiffer, adding to its durability. It can also operate over a wider range of temperatures, he says, having been tested from 2°C to 95°C.
But not everyone believes that being able to run at such high temperatures is necessarily a benefit. Scott Ehrenberg, of Dais-Analytic, Florida, told the New York Times that operating the membranes too close to water’s boiling point risked turning it to steam, which could tear holes in the membrane.
And there are still large barriers to making fuel cells commercially viable. For example, hydrogen fuelling-points must be created. And the technology to allow safe storage of hydrogen in vehicles also needs improvement.
As more pressure to reduce emissions is placed on the transport industry, the potential for fuel cells is huge if these remaining barriers can be overcome. “We have been engaging with automotive manufacturers over the past few months,” says Balcom. “They’ve all been very excited to see the data.”
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