Automotive

Retrofit system converts existing diesel engines to run on 90% hydrogen

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Retrofitting existing diesel engines to run mainly on hydrogen may be a fast way for large fleets to rapidly reduce their carbon footprint without junking existing assets
Prof Shawn Kook / UNSW
Retrofitting existing diesel engines to run mainly on hydrogen may be a fast way for large fleets to rapidly reduce their carbon footprint without junking existing assets
Prof Shawn Kook / UNSW
UNSW researchers Professor Shawn Kook (right), Xinyu Liu (back left) and Jinxin Yang (front left) with the diesel-to hydrogen retrofit test rig
Prof Shawn Kook / UNSW

UNSW researchers have prototyped and tested a retrofit system that converts diesel engines to run on 90% hydrogen, radically reducing both carbon dioxide and nitrous oxide emissions while boosting efficiency by an impressive 26% in the process.

Running 10% diesel, the process is not a full green conversion for diesel engines, but it does offer a way for certain businesses to hugely reduce their emissions output without wastefully junking existing assets that could still remain useful for a long time.

The retrofit system keeps the diesel injection system, but adds hydrogen injection directly to the cylinder, as well as independent control of injection timing for both the hydrogen and diesel systems. It doesn't require particularly high-purity hydrogen, and the team has demonstrated that its "stratified" hydrogen injection technique, which creates pockets of higher and lower hydrogen concentrations in the cylinder, reduces the incidence of nitrous oxide emissions below that of a straight diesel.

The overall carbon dioxide emissions drop by some 85%, to around 90 grams/kWh of energy – that would certainly represent a solid intermediate step towards total decarbonization for many operations using large fleets of diesel vehicles.

Of course, it relies on hydrogen being available – which, in most areas, is not yet the case. But as the key green vehicle alternative to lithium batteries, hydrogen's time may be coming. Lithium supply shortages look set to rock the battery EV market in the coming few years, right when government regulations start kicking in to seriously accelerate the transition to zero-emissions driving in many jurisdictions. And green hydrogen projects are springing up all over the globe.

UNSW researchers Professor Shawn Kook (right), Xinyu Liu (back left) and Jinxin Yang (front left) with the diesel-to hydrogen retrofit test rig
Prof Shawn Kook / UNSW

Still, for the time being, the UNSW team is working to get its diesel engine retrofit systems commercialized within the next two years, and it's targeting industrial fleet and generator operators like mining operations, many of which already have hydrogen piped to the site. Again, this is currently unlikely to be green hydrogen, so the initial uses might effectively just be transferring their emissions to some Haber-Bosch plant down the street. But as the green hydrogen industry ramps up, it'll be important for investors to know there's reliable and growing demand from vehicles out there already using hydrogen and looking for a cleaner solution.

“We have shown that we can take those existing diesel engines and convert them into cleaner engines that burn hydrogen fuel," said Professor Shawn Kook, lead author on a paper just published in the International Journal of Hydrogen Energy. "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. 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.”

For a lower-friction approach – albeit one with less impressive results – there are other retrofit systems being developed, like the HYDI direct injection device, which generates its own hydrogen as you drive, and injects it into the air-fuel mixture to help the diesel ignite faster and more completely. It requires nothing but an occasional water top-up, so it's completely non-reliant on hydrogen fueling infrastructure, and it reduces fuel consumption by 5-13%, while also cutting down on emissions.

Source: University of New South Wales

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8 comments
Chase
I'm pretty sure the diesel engines are also designed to take advantage of diesel's lubrication properties, rather than just the burning. Taking 90% of the lubrication away from the combustion chamber is likely to have some effects on overall longevity of the motors, something very important to consider if they want to use this in the trucking industry. Think about propane and natural gas engines that can only run, what, a couple thousand hours before needing a full rebuild?
Jose Corazon Bautista
Its high time as opec has curtailed supply to control it since saudi aramco says it is depleting, risky to a world relying on fossil fuel, & in effect, surging fuel prices; we needed alternative solutions
Malcolm Jacks
What about existing petrol cars, can they be retro fitted with such a system??
paul314
Can the engines run on biodiesel for the remaining liquid fuel?
2wheelfun
About 30 years ago I had a person who said he designed a system that sure sounds just like what is being described here for diesels. He said he built such a system and was used by a trucking company in California and they were achieving the same increase as being described in this article. He said the government stepped in and had there DOT people staged at stops on the highway and removed the devices. Seems like the real give away was the trucker log books and the fuel consumption used didn't match up for there collection on fuel taxs. Imagine that, a device that can make the world a better place and burn less fuel being shut down for $$$$$ to the government and you could bet that the oil industry had a play in the stop of these devices. The device has been around forever and called a hydrogen generator and is a simple process with a simple device. The more research I did is where people were putting them on gasoline vehicles and don't produce increased mileage due to the energy required to make the hydrogen due to the burn efficiency of hydrogen and gasoline. But with diesel is where the magic happens where the burn becomes very efficient even with the energy required to make the water to hydrogen conversion. I had a engineer who put it to the test years ago and said yes it is true and explained it has to do with the way they mix and combust. Times have changed and the oil industry and the government now have to look at the climate of the world and release knowledge on devices that were available long ago but were withheld for $$$$$$
jerryd
The problem is the cost of H2 and storing the H2 in energy and equipment are 2-3x more than drop in synfuels.
And should be run on gasified biomass which is H2/CO syngas for heat and power on demand.
Biodiesel can lube the injectors just like it does in most diesels added after taking the sulfur out which lubed the injectors before. The valves, cylinders have their own oil lube system.
FB36
It is extremely bad idea to use hydrogen as fuel for land/sea/air transportation because it is pretty much explosive!
Imagine a future world w/ all kinds of hydrogen vehicles, tanker trucks, gas stations everywhere!
Are we seriously thinking that there will be never any accidents/leaks/ruptures/mishandling to trigger massive explosions?
Not to mention, there is actually no need at all to use hydrogen as fuel!
All light/small vehicles are already becoming fully electric & all heavy/big land/sea/air vehicles just need us to start producing biodiesel/biofuel at large scales!
(From all possible industrial/agricultural/forestry waste/biomass & trash & sewage!)
-dphiBbydt
There are two types of hydrogen for vehicular transport. There's dirty hydrogen - the stuff made from methane which produces prodigious amounts of CO2, requires wasteful cooling, compression and transport to fueling locations - and dumb hydrogen - the stuff which uses green electrons to inefficiently create hydrogen gas from water, then wastefully cool, compress and transport. Analysis of dumb hydrogen shows that well over 95% of green electrons are wasted in the generation-to-motion equation. Far better to transmit green electrons on wires and put them straight in to batteries - a process far more efficient. If these guys want to continue using their CO2 and PM2.5 polluting friction engines they would do far better just to make synthetic or bio-diesel.