‘Dirty’ oil to fuel homes of future

Cheap vegetable oil and even oil from household waste could soon be used to produce hydrogen to power fuel cells for cars and homes, following work at Leeds University.

Researchers at the university are testing a system based on catalysts that convert sunflower oil into hydrogen without producing harmful emissions.

Once they are successful, they hope to develop the process further to allow it to use cheaper vegetable oil or even oil produced from household waste, said Dr Valerie Dupont, senior lecturer in energy and fuel.

Cleaner process

‘Sunflower oil is clean, so the real challenge will be to develop the system to run on dirty oils, which are cheap and can be easily obtained,’ said Dupont.

Plastic and rubber waste converted into oil through pyrolysis – or decomposition caused by heat alone — is already burnt as fuel. But this process can cause pollution, as the waste can contain carcinogenic substances such as benzene, she said.

‘Our system would still make use of its energy potential, while allowing the often noxious chemicals in the oil to be more easily controlled.’

The method is based on a fixed-bed reactor, which contains two catalysts. Air is fed into the reactor, and the first of the two catalysts absorbs the oxygen from the air in a process that produces heat.

Water vapour combined with oil is then fed into the reactor, and the heat produced from the earlier reaction is used to generate hydrogen from the mixture.

Meanwhile, the second catalyst absorbs carbon dioxide, also causing it to heat up and allowing more hydrogen to be produced. Once the carbon dioxide has been absorbed by the catalyst, it is released for storage or use in other chemical processes, ensuring damaging levels of the substance are not put back into the atmosphere, said Dupont.

The process produces hydrogen only 50 per cent of the time, so two reactors would be built next to each other, operating out of phase, to ensure a constant stream, said Dupont.

The size of the two reactors would be directly linked to the amount of hydrogen needed to be produced, as the more catalysts the plant contains, the longer the reaction cycle, she said.

The basic catalytic process was first developed by researchers in the US in the late 1990s, to convert substances such as methane into hydrogen. But the Leeds team is modifying this technology to allow it to handle oils, which can be more difficult to use.

Suitable catalysts

The research team, which has received funding from the Engineering and Physical Sciences Research Council for a three-year project, is working with industrial partners to identify the best catalysts to use in the system.

The first catalyst is likely to be nickel based, and the second will probably be a mixture of magnesium and calcium oxides.

On the web