Anode for efficiency

Aberdeen University researchers are developing a new type of low-temperature fuel cell that overcomes the high cost of components and low tolerance to carbon.

The technology will hopefully make low-temperature fuel cells a viable replacement for internal combustion engines in vehicles or lithium batteries in portable devices.

The Aberdeen team is redesigning the fuel cell's anode, one of two electrodes used to combine hydrogen and oxygen. This process releases electrons that can, for example, drive an electric motor in a fuel cell vehicle.

The electrochemical reaction works efficiently in principle and produces no emissions, but it relies on a fuel source that is less dependable.

Approximately 90 per cent of hydrogen is produced from fossil fuels and it can therefore carry carbon-containing impurities. Over time, these impurities build up on the fuel cell's anode, creating a film that can eventually prevent the chemical reactions needed to release electrons.

The Aberdeen researchers, led by Dr Angela Kruth, hope their new anode design will cope with these impurities.

Dr Kruth said that the most troublesome impurity found in hydrogen is carbon monoxide. The CO originates from the process used to reform fossil fuel into hydrogen.

The goal of this process is to oxidise all the carbon in the fuel into carbon dioxide, which can be captured. However, a small percentage of the carbon does not fully oxidise and forms CO. Dr Kruth added that CO is particularly harmful to low-temperature fuel cells. 'It's an electrode poison,' she said.

The Aberdeen research team is testing a new design and material for the anode, which is usually made of platinum.

Dr Kruth said they will still use platinum in their electrode, but less of it. In its place they will introduce a metal oxide material that is much less expensive than platinum and has better oxidation properties for carbon monoxide.

The new electrode will allow low-temperature fuel cells to use either carbon-contaminated hydrogen or hydrocarbon fuels such as methanol, biofuels or natural gas without the need for upstream reforming, which is a costly and cumbersome process for cleaning hydrogen fuel prior to use.

While it is hoped that fuel cell cars will one day run on ultra-pure hydrogen made from electrolysis processes powered by renewable sources such as wind, solar or tidal energy, Dr Kruth said those methods are still too expensive.

In the meantime she expects her team's newly designed electrode will shrink the cost of low-temperature fuel cells and drastically accelerate the technology into the market.

The Aberdeen University researchers were recently awarded £288,000 of funding from Scottish Enterprise's Proof of Concept Programme.

The team hopes to have a 300W prototype of a demonstration fuel cell within three years.

'We will then look for further funding to take the device to the market, which we hope to achieve in five years,' said Dr Kruth.

Siobhan Wagner