The team, led by Professor Sean Cook of the School of Mechanical Engineering and Mechanical Engineering, spent about 18 months developing a dual fuel system with direct injection of hydrogen and diesel, which means existing diesel engines can run on 90% hydrogen as fuel.
The researchers say that any diesel engine used in trucks and electrical equipment in the transportation, agricultural and mining industries could eventually be adapted to the new hybrid system in just a couple of months.
Green hydrogen, which is produced using clean and renewable energy sources such as wind and solar, is much more environmentally friendly than diesel.
And in an article published in the International Journal of Hydrogen Energy, Professor Cook’s team shows that using their patented hydrogen injection system reduces CO2 emissions to just 90 g/kWh, 85.9% below the amount produced by a diesel engine.
“This new technology significantly reduces CO2 emissions from existing diesel engines, so it can play a big role in reducing our carbon footprint, especially in Australia with all of our mining, agriculture and other heavy industries where diesel engines are widely used.” He says. Prof. Cook.
“We have shown that we can turn existing diesel engines into cleaner hydrogen engines.
“The ability to upgrade existing diesel engines is much faster than waiting for the development of completely new fuel cell systems, which may not be available on a large scale for at least a decade.
“On the issue of carbon emissions and climate change, we need more immediate solutions to deal with the large number of diesel engines currently in use.”
Direct high pressure hydrogen injection
The UNSW team solved the problem by keeping the original diesel fuel injection in the engine, but adding hydrogen fuel injection directly to the cylinder.
“If you just fill the engine with hydrogen and let it mix, you’ll get a lot of nitrogen oxide (NOx) emissions, which are the main cause of air pollution and acid rain,” says Professor Cook.
“But we’ve shown in our system that if you make it stratified, meaning some areas have more hydrogen and some have less, then we can get lower NOx levels than with a clean diesel engine.”
It is important to note that the new direct injection hydrogen-diesel dual fuel system does not require the extremely high purity hydrogen that must be used in alternative hydrogen fuel cell systems and is more expensive to manufacture.
And compared to existing diesel engines, the diesel-hydrogen hybrid has been shown to increase efficiency by more than 26%.
This increased efficiency is achieved through independent control of direct hydrogen injection timing, as well as diesel fuel injection timing, allowing full control of combustion modes: blended or controlled premixed hydrogen combustion .
The research team hopes to be able to commercialize the new system within the next 12 to 24 months and wants to consult with potential investors.
They say the most immediate potential application of the new technology is in industrial facilities where permanent hydrogen fuel lines already exist.
This includes mining operations, where studies have shown that around 30% of greenhouse gas emissions are caused by the use of diesel engines, primarily in mining vehicles and power generators.
And the Australian market for diesel power generators is currently valued at around $765 million.
“In hydrogen-powered mines, we can retrofit existing diesel engines that are used to generate electricity,” says Professor Cook.
“In terms of applications where hydrogen fuel needs to be stored and moved, such as in a truck engine that currently runs exclusively on diesel fuel, we will also need to implement a hydrogen storage system to integrate it into our injection system.
“I think mobile hydrogen storage technology in general needs to be further developed because it’s a big challenge right now.”