Running the hydrogen economy on alcohol

Ethanol reactor offers green energy solution.

A team of US and Greek chemical engineers has developed a reactor that can efficiently convert ethanol into hydrogen. This research could help bring the much-heralded hydrogen economy a step closer.

Currently, hydrogen is produced from fossil fuels in large-scale steam reformers. This manufacturing process is hardly ideal, because it is polluting and unsustainable. Another way to produce hydrogen involves oxidising biomass-derived material, such as ethanol. This is more sustainable but the reaction is highly flammable and not very efficient at producing H₂.

The researchers at the University of Minnesota, Minneapolis, US, and the University of Patras, Greece, tried to overcome many of these problems by combining the steam reforming and biomass oxidation reactions. To do this, they devised a reactor in which a fuel injector sprays a mixture of ethanol and water into a tube. This mixture is then heated in the presence of air and finally passes through a ceramic foam that contains a novel rhodium-ceria catalyst.

The reactor proved to be very effective, producing an output stream that contained around 50 per cent hydrogen, which was generated from both the ethanol and the water.This output stream could then be fed straight into a fuel cell, although it is possible that some of the other reaction products, such as carbon monoxide, will have to be removed first.

The reactor appears to offer a highly efficient way of using ethanol as a fuel, rather than simply burning it. ’Ethanol in car engines is burned with 20 per cent efficiency,’ says lead researcher Lanny Schmidt, professor of chemical engineering at the University of Minnesota, ’but if you used ethanol to make hydrogen for a fuel cell, you would get 60 per cent efficiency.’

Anthony Kucernak, an expert on the hydrogen economy at Imperial College London, says that the reactor is ’sound science, but only represents an incremental improvement’. He also questions whether such a fuel reformer could practically be used in a car, arguing that it’s only really suitable for large-scale systems.

Jon Evans