On-board reformer turns exhaust fumes into fuel

The fuel efficiency of modern cars has improved by 20 per cent since 2010, as a result of improvements to engine design, weight reductions, and the use of hybrid technologies.

But while these improvements have enabled manufacturers to meet their 2015 targets for reducing carbon dioxide emissions, car makers are still 15-30 per cent short of their 2020/21 target of 95g/km, according to Dr Athanasios Tsolakis at Birmingham University.

To help meet this target, Tsolakis and his colleagues are developing a catalyst-based reformer capable of improving the fuel economy and therefore greenhouse gas emissions of petrol engines.

“The system uses the engine exhaust gas, consisting of heat, water, CO₂ and in some cases O₂, and fuel to produce a hydrogen-rich gas that is then used for combustion in the engine,” he said.

The on-going EPSRC-funded project, which also includes researchers at Brunel University, as well as Ford and Johnson Matthey, will use platinum/rhodium (Pt-Rh)-based catalysts to produce the hydrogen-rich gas, which can then be used for combustion.

“This means that the engine fuel - gasoline and hydrogen–rich gas - has a higher energy content,” he said.

It should also reduce engine pumping losses by allowing for a more favourable throttle position, said Tsolakis.

The technology can also be designed to reduce emissions from diesel engines, he said.

It can also indirectly improve diesel engine fuel efficiency by improving the performance of after-treatment systems. Existing after-treatment systems can use large quantities of fuel to remove pollutants from the exhaust, but the new reformer would need only a few parts per million of hydrogen to operate, said Tsolakis.

In the first stage of the project, the fuel reformer will be integrated into the exhaust, to provide small quantities of hydrogen-rich gas to the engine’s after-treatment system, when needed.

Later, the researchers plan to develop a compact catalyst brick, designed using additive manufacturing techniques, which can be integrated into the after-treatment system itself in both diesel and lean combustion petrol engines.

This should help to improve the speed of the system’s response to engine or emissions changes.