Mixing diesel and hydrogen provides significant emissions reductions

Zoom in / Diesel engines can be modified to burn a mixture of diesel and hydrogen.

A team of engineers at the University of New South Wales (UNSW) in Sydney has discovered a way to run a diesel engine on a mixture of diesel and hydrogen, significantly reducing its emissions.

Why do we even need a diesel-hydrogen hybrid when there are already so many great electric cars available? Electric vehicles are certainly great for households, but they still don’t match the performance of heavy diesel engines in some contexts, such as mining, long-distance transportation, power generation, and agriculture.

Currently, there are 26,000 diesel trains in the United States, and there are potentially millions of trucks, generators, and other industrial equipment that require diesel to deliver optimal performance. It could take decades for electric vehicle technology to replace diesel engines in such industries. While it is easy for the average person to sell an old car and buy a new electric car, such changes come at a high cost to the industries.

So we’ll likely be stuck with diesels for a while. But what if there was a way to reduce carbon dioxide2 Emissions from their current equipment by 85 percent?

This is what UNSW’s hydrogen and diesel hybrid engine technology promises. The researchers claim that their modified diesel engine can run on 90 percent hydrogen with an improved efficiency of more than 26 percent. In a press release, Sean Cook, one of the study’s authors and a professor at the University of New South Wales, said, “We have shown that we can take existing diesel engines and turn them into cleaner engines that burn hydrogen fuel.”

He added: “This new technology significantly reduces carbon dioxide2 emissions from existing diesel engines, so it can play a huge role in reducing our carbon footprint a lot, especially in Australia with all the mining, agriculture and other heavy industries in which diesel engines are widely used.”

Dual fuel system

A diesel vehicle has a diesel injection unit that fires fuel into the combustion chamber. The engine piston compresses the fuel-air mixture to a high pressure and temperature, causing it to ignite. This creates the pressure that drives the engine.

During this process, the diesel engine produces carbon dioxide and nitrogen oxides (NOx), which are harmful to our environment. The researchers say that direct mixing of hydrogen with diesel in the combustion chamber will increase NOx pollution. To get around this problem, they developed a diesel-hydrogen dual fuel system that used a timed high-pressure hydrogen injection unit inside a diesel engine that was already equipped with a diesel injection unit.

According to Cook and his team, the concentration of the gas — hydrogen, in this case — can change within different sections of the combustion chamber. These differences can affect chemical reactions and control the amount of NOx an engine produces. The researchers used the timing of the hydrogen injection to limit the production of nitrogen oxides.

By using hydrogen as 90 percent of the fuel, they were able to reduce carbon dioxide in the engine2 Exhaust up to only 90g per kWh. That’s 86 percent less carbon dioxide than what a standard diesel engine can emit. Moreover, NOx emissions were also found to be significantly reduced. “We’ve shown in our system that if you stratify it – that is, in some areas there is more hydrogen and in others there is less hydrogen – then we can reduce NOx emissions to less than those of a pure diesel engine,” Cook said. .

Although it took the researchers 18 months to develop their first hybrid engine, they claim they can now convert any diesel engine design to a dual-fuel system in two months.

Hybrid engine designs made easy

Traditional methods of hydrogen production involve the oxidation of hydrocarbons, which leads to carbon dioxide2 emissions. However, if hydrogen is produced using renewable energy, it can be a much cleaner energy source than electricity from the grid. While there are still emissions associated with using diesel fuel, this is a trade-off against the challenges of recycling lithium batteries.

The vision behind this hydrogen and diesel direct injection engine system is to provide industries with a practical solution to the problem of carbon emissions. Mining companies using a variety of diesel-based machinery and equipment alone produce up to 7 percent of global greenhouse gas emissions. Fueling the growth of these sectors with hydrogen fuel can greatly improve the health of our planet.

Cook and his colleagues have already patented a hydrogen-diesel, dual-fuel direct-injection system, and they plan to bring it to market within the next year or two.

International Journal of Hydrogen Energy, 2022. DOI: 10.1016/j.ijhydene.2022.08.149

Rupendra Brahambhatt is an experienced journalist and filmmaker covering science and culture for news agencies and magazines around the world.

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