UNSW engineers convert diesel engine to hybrid hydrogen

Engineers from UNSW Sydney have successfully converted a diesel engine to run as a hydrogen-diesel hybrid engine – reducing CO2 emissions by more than 85 per cent.

The team, led by Professor Shawn Kook from the School of Mechanical and Manufacturing Engineering, spent around 18 months developing the Hydrogen-Diesel Direct Injection Dual-Fuel System, which means existing diesel engines can run using 90 per cent hydrogen as fuel.

The researches say that any diesel engine used in trucks and power equipment within the transportation, agriculture and mining industries could ultimately be retrofitted to the new hybrid system in just a couple of months.

“This new technology significantly reduces CO2 emissions from existing diesel engines, so it could play a big part in making our carbon footprint much smaller, especially in Australia with all our mining, agriculture and other heavy industries where diesel engines are widely used,” Kook said.

“We have shown that we can take those existing diesel engines and convert them into cleaner engines that burn hydrogen fuel.”

In a paper published in the International Journal of Hydrogen Energy, Kook’s team showed that using their patented hydrogen injection system reduces CO2 emissions to just 90 g/kWh – 85.9 per cent below the amount produced by the diesel powered engine.

“Being able to retrofit diesel engines that are already out there is much quicker than waiting for the development of completely new fuel cell systems that might not be commercially available at a larger scale for at least a decade,” Kook said.

“With the problem of carbon emissions and climate change, we need some more immediate solutions to deal with the issue of these many diesel engines currently in use.”

The UNSW team’s solution to the problem maintains the original diesel injection into the engine, but adds a hydrogen fuel injection directly into the cylinder.

The research found that specifically timed hydrogen direct injection controls the mixture condition inside the engine cylinder, which resolves the problem of harmful nitrogen oxide emissions which have been a major hurdle for commercialisation of hydrogen engines.

“If you just put hydrogen into the engine and let it all mix together you will get a lot of nitrogen oxide (NOx) emissions, which is a significant cause of air pollution and acid rain,” Kook said.

“But we have shown in our system if you make it stratified – that is in some areas there is more hydrogen and in others there is less hydrogen – then we can reduce the NOx emissions below that of a purely diesel engine.”

The diesel-hydrogen hybrid has shown an efficiency improvement of more than 26 per cent compared to existing diesel engines, and the research team hopes to commercialise it within the next 12 to 24 months.

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