Electric vehicles are currently the main replacement for automobiles powered by internal combustion engines, but a number of other alternatives are being touted as potential parts of the drive to reduce greenhouse gas emissions.
Like EVs, these alternative pose their own peculiar challenges for lubricants, according to speakers at roundtable discussion here Tuesday during the annual meeting of the Independent Lubricant Manufacturers Association.
Automobiles are one of the largest sources of greenhouse gas emissions, so governments around the world are pushing to replace models that use internal combustion engines running on conventional gasoline or diesel.
To date EVs are by far the most popular type of replacement, having reached global sales of around 14 million in 2023. EVs pose a number of challenges for lubricants, such as the high amount of heat generated by their batteries, the need to prevent copper corrosion and accommodate electrical charges, and the high speeds of electric motors that require superior foam control.
During the roundtable Tuesday, ILMA CEO Holly Alfano mentioned numerous other technologies touted as alternatives to internal combustion engines running on conventional fuels: compressed natural gas and propane, both of which burns cleaner than gasoline or diesel; renewable natural gas, which generates less greenhouse gas when produced because it does not a petroleum product; biodiesel, renewable diesel and renewable gasoline blend, which likewise have lower carbon footprints; hydrogen and ammonia, which do not generate carbon dioxide when burned; and methanol, which can be produced from carbon dioxide.
Hydrogen can be used in fuel cells or as a drop-in replacement for conventional fuels. The latter approach is more efficient, Chevron Oronite Senior Research and Development Engineer Dinesh Bansal said, but generates higher temperatures than gasoline or diesel, requiring greater high-temperature performance from the lubricant.
In addition, burning hydrogen generates water instead of carbon dioxide. That’s good for reducing greenhouse gas emissions, but the water can cause another type of problem.
“If you burn hydrogen, you generate water, and that water is going to want to go somewhere, probably in the sump,” said Luc Girard, a consultant at Sanjuro Solutions.
Ammonia presents a different challenge because it can be corrosive to the engine.
“People who study combustion don’t like ammonia as a fuel,” Bansal said. “Policy makers like it, it is zero-carbon, but it brings certain challenges.” Engines running on hydrogen or ammonia would have shorter lubricant drain intervals than those running on diesel or gasoline, he added.
Bansal said some problems stem from the engine design rather than the fuel. Plug-in hybrids run first on battery but also contain an internal combustion engine that kicks in when the battery charge runs down.
“If the [ICE] engine is only used for short ranges, then the biofuel [in the sump] does not get burned off, and it accumulates in the sump,” he said. “We can’t control that with the formulation of the lubricant.”
Renewable fuels exacerbate this problem because they have higher flashpoints than petroleum fuels and are less prone to burn off.
Roundtable participants also discussed the approaches governments are taking to change car parcs and the fuels they run on, complaining that they are being too restrictive by prescribing specific solutions rather than allowing industry find the best approach.
“I would prefer that they ask industry to reduce emissions and they not tell industry the way to go,” said Stephan Baumgaertel, president of the German Lubricants Industry (VSI).
“Yes,” Alfano chimed in. “They are inhibiting innovation and technology.”
Baumgaertel summarized the challenge of transitioning to energy that does not contribute to climate change.
“The idea is to use the energy we have on earth, but unfortunately the energy is present in regions where we can’t use it, for example in the desert, in the Sahara or wind energy in Patagonia,” he said. “We need to find a way to tranfer this energy to North America, to Europe, to Asia where the energy is needed.”
He contended that German industry has a potential solution – synthetic fuels made by combining green hydrogen with carbon from carbon capture. The resulting liquid could be transported via existing pipelines, he said, and could also be a drop-in replacement for gasoline or diesel.
“That’s a vision that we have,” Baumgaertel said. “Unfortunately, German law does not permit these fuels.” Industry in the country has asked the government to reconsider its position.