Engineers from the University of New South Wales (UNSW) have developed a dual-fuel injection system that allows a diesel engine to run on a Hydrogen-Diesel hybrid fuel with 90% hydrogen in the mixture.

The engineering team found that the new H2DDI hybrid system can be retrofitted to any diesel engine — used in lorries and power equipment in the transportation, agriculture, and mining industries – within a few months.

The team led by Professor Shawn Kook claimed that the new system reduces carbon emissions by over 85%. The patented H2 injection system developed by the UNSW engineers reduced carbon emissions to just 90 grams/kWh, which the team observed is 85.9% below the amount produced by a diesel-fuelled engine.

Professor Kook observed, “We have shown that we can take those existing diesel engines and convert them into cleaner engines that burn H2 fuel. If you just put H2 into the engine and let it all mix, you will get a lot of nitrogen oxide (NOx) emissions, which is a significant cause of air pollution and acid rain. 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 H2— then we can reduce the NOx emissions below that of a pure diesel engine.”

The paper published in the International Journal of Hydrogen Energy said that the new H2DDI system does not need high-purity H2, which has to be used in alternative H2-fuel cell systems and is more expensive to produce. The engineers found an efficiency improvement of over 26% in the diesel-H2 hybrid engine compared to the existing diesel engines.

To begin with, the engineers at UNSW’s Engine Research Laboratory installed an H2 direct injector after modifying an automotive-size inline single-cylinder diesel engine.

Further, the team’s timing of H2 direct injection was independently controlled by maintaining the time for diesel injection, enabling complete control of combustion modes. The injection timing control resolves harmful nitrogen oxide emissions, a major hurdle for commercializing hydrogen engines.

The hybrid dual-fuel system-powered engine was operated at a constant speed of 2,000 revolutions per minute and fixed combustion phasing of −10 crank angle degrees before top dead center (°CA bTDC) while evaluating the power output, efficiency, combustion, and engine-out emissions.

The engineers studied the high indicated mean effective pressure (IMEP), which reached up to 943 kPa, and 57.2% indicated efficiency was achieved at 90% hydrogen energy fraction at the expense of NOx emissions.

Earlier this year, a group of Indian scientists from CSIR-Indian Institute of Chemical Technology designed a hybrid material to simulate capturing carbon dioxide onsite and converting it into clean H2 from non-fuel grade bioethanol.

Significant investments are being made in hydrogen production globally to explore advanced ways to use green H2 as biofuel and as the means to produce power. Last month, the U.S. Department of Energy announced a $7 billion funding opportunity to create regional clean H2 hubs (H2Hubs) across the country.