Researchers at Lund University in Sweden have developed an innovative car fuel system that reduces greenhouse gas emissions. The system uses a unique liquid that, when combined with a solid catalyst, turns into hydrogen fuel for the car. After use, the spent fluid is removed from the vehicle's tank, recharged with hydrogen, and ready for reuse. This process creates a closed-loop system that significantly reduces environmental impact.
In two research papers, the Lund researchers demonstrated that this method works, and while it is still basic research, it has the potential to become an efficient energy storage system in the future.
Ola Wendt, professor at Lund University's Department of Chemistry and one of the authors, says: „Our catalyst is one of the most efficient, at least according to publicly available research.
Addressing climate impact and exploring hydrogen gas
Finding alternative ways to produce, store and convert energy to reduce carbon dioxide emissions from fossil fuels is essential to reduce the impact on climate. One of the most talked-about options is hydrogen gas, which many see as the future solution for energy storage. Nature stores energy in chemical bonds, and hydrogen has a high energy density relative to its weight.
„However, gas can be difficult to handle, so we are looking at liquid fuel charged with hydrogen that can be delivered at a pump, similar to what happens at gas stations today,” says Ola Wendt.
This concept is called LOHC (Liquid Organic Hydrogen Carriers) and is not new. The challenge lies in finding a catalyst as efficient as possible that can extract hydrogen from the liquid.
The system is intended to work using a liquid „charged” with hydrogen. The liquid is fed through a solid catalyst that extracts the hydrogen. It can be used in a fuel cell – which converts chemical fuel into electricity – while the „spent” liquid goes into another tank. The only emission is water.
Refueling and mass production
Spent fluid can be emptied at a filling station before refueling with fresh, charged fluid. This would mean large-scale production of the product comparable to today's oil refineries.
„We replaced 99 percent of the hydrogen gas in the liquid,” says Ola Wendt.
Researchers are also calculating whether the fuel could be used for larger vehicles such as buses, trucks and airplanes.
„With the big tanks they have, you can cover the same distance as you can with a diesel tank. You transfer 50 percent more energy compared to compressed hydrogen,” says Ola Wendt.
Elements and Challenges
The solvents used are isopropanol (a common ingredient in screenwash) and 4-methylpiperidine.
Does it sound too good to be true? Yes – for now at least, there are many challenges. One is that the lifetime of the catalyst is short. Another, catalyst-based iridium is a precious metal.
“But we estimate that a car needs two grams of iridium. „This can be compared to today's exhaust-cleaning catalytic converters, which contain around three grams of the precious metals platinum, palladium and rhodium,” says Ola Wendt.
It is a technological solution based on fundamental research. Ola Wendt believes that the concept will be ready in ten years – if the decision to move to a finished product is economically viable and there is interest from society.
How hydrogen is produced is another problem – today, most production is not climate-friendly. Hydrogen must be stored and transported in an efficient way, which is not so straightforward today. There are also risks associated with refueling with pressurized hydrogen. The Lund researchers hope to solve this with their method.
„Ninety-eight percent of today's hydrogen is fossil-based, produced from natural gas. The byproduct is carbon dioxide. From an environmental point of view, it doesn't make sense to make hydrogen for steel, batteries and fuel using natural gas,” says Ola Wendt, but a lot of research on „how green” is. He explains what is going on. Hydrogen” can be produced by splitting water into hydrogen and oxygen with the help of renewable energy.
At the same time, Ola Vent believes that political decisions are needed to find the right place for renewable and climate-friendly alternatives.
„It has to be cheap, and that will take political decisions. Like fossil fuels, renewables are unlikely to compete with something you dig out of the ground, where the only cost is transportation,” he concludes.
References: Kaushik Chakraborty, Alice Spangenberg, Vasudevan Subramanian, Andreas Hederstedt, Omar Y. Abdelaziz, Alexei, Christian Wahlberg, re. and Ola F. Vent, 27 July 2023, Catalysis Science & Technology.
Alexey V. Bolukiev, Rein Wallenberg, Jens Uhlik, Christian B. Huldberg and Ola F. Vent, 020 March 2020, 020 2020, 020 029 ChemSusChem.
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