Fluids, oils, and greases are essential to the maintenance and performance of internal combustion engines (ICEs). However, in an era of mobility defined by the quest for lower environmental impact, the pollution potential of these products is problematic.
Motor fluid production generally starts with a petroleum base oil, which makes it non-dissolvable in water. According to The Massachusetts Department of Environmental Protection (MDEP), one litre of motor oil can pollute over one million litres of water by making it toxic to animals and plants. The oil generally enters water supplies after being leaked on the road, flowing into drains and then subsequently into lakes and streams. The scale of the problem is such that over eight million litres of oil enter the US water supply annually.
Compared to ICE, McKinsey & Co estimates that electric vehicles (EVs) use up to 300% less fluids across their lifespan. This is because EV powertrains lack the complex moving parts of ICE. Therefore, while still needing coolant and driveline fluids, the former does not require the quantity or diversity of the latter. The rising popularity of EVs could immediately offset vehicle fluids’ impact by decreasing volume, but what about the materials themselves?
In terms of EV fluids, coolant for the vehicle’s battery is arguably the most important. However, far from being a homogenous market, there are currently two prevailing product portfolios addressing this requirement: dielectric—or non-conductive—which cools through submersion, and water-glycol, which cools the battery indirectly.
Formulated from a three-part mixture of mono-ethylene glycol (MEG), water and a small quantity of additives, water-glycol is the prevailing coolant used in EVs as of 2022. The thermal management process involves feeding fluid through tubes arranged around the battery to regulate its temperature between the optimum operating range of 20 to 32 degrees Celsius. The traditionally used MEG is a petrochemical product that draws on non-renewable feedstocks like petroleum and natural gas. However, alternatives are possible.
Marvin Strüfing, Sales Director at UPM Biochemicals (UPM), tells Automotive World that his company has developed a glycol product—BioPura—from sustainable certified beech wood. A global leader in wood-based renewable chemicals, UPM has been on a mission to accelerate change in the industrial sector for over a century: “We’re now a Tier 2 supplier to the automotive industry, and BioPura is already known to the supply chain of several leading European automakers.” The bio-MEG that UPM has developed accounts for approximately 95% of the raw material needed for manufacturing EV coolant concentrate, which Strüfing calls “the start of a brand-new category of sustainable chemicals.”
As pointed out in a 2019 study from the Massachusetts Institute of Technology Energy Initiative (MITEI), EV value chains are far from optimal. Batteries contribute up to 40% more upfront EV production emissions than an equivalent ICE vehicle, offsetting the original goal of electrification: lowering emissions. To neutralise this, OEMs must explore avenues for long- term carbon reduction across a vehicle’s lifespan. Incorporating lubricants and coolants that aren’t made from fossil fuels presents a distinct opportunity for automakers to broaden their sustainability strategies.
Scaling the solution
Strüfing states that bio-MEG will be scalable for mass production in the near term. In 2020, UPM announced an investment of €750m (US$745m) in a new biorefinery in Leuna, Germany. Production is expected to begin in late 2023, with a total annual capacity of 220,000 tonnes.
To be an effective solution, fossil fuel-free EV fluids will also need to incorporate seamlessly into automotive supply chains that are already struggling with procurement, most notably with regards to semiconductors. “Fossil fuel-free battery coolant has essentially the same supply chain, so it is easy for OEMs to implement,” states Strüfing. “In terms of pure performance, bio-MEG is also the same as non-renewably sourced equivalents.”
It should be noted, however, that the future of water-glycol cooling itself has been called into question. While it is certainly more effective than air cooling, the lag between the heat being generated and reaching the coolant creates inefficiency. By being allowed to flow freely over the battery itself, this is a performance issue not shared by dielectric coolant. According to McKinsey & Co, this opens up the possibility that dielectric fluids could supplant water-glycol in the sports, performance, and premium EV markets by 2035. However, current industrial dielectric fluids use toxic polychlorinated biphenyls (PCBs) to provide the necessary electrical insulation. If unaddressed, this would impede the eco-friendly solution that bio-MEG-based coolant is on the verge of providing.
The future of coolant
So, what does this mean for the environmental sustainability of EV coolant? Two notable Tier 1 EV fluid manufacturers—Castrol and Shell—have already introduced dielectric fluid product lines. Castrol has also stated that indirect thermal management coolants have a place, but their application will be limited as “extreme operations such as sustained ultra-fast charging” become a more commonplace EV requirement.
After all, why are [OEMs] building EVs in the first place? To reduce carbon emissions
Meanwhile, market research firm Mordor Intelligence estimates that the automotive coolant industry will be worth over US$6.4bn by 2027, a 38% increase on 2021’s figure. Driving this growth, it claims, is the broad availability of glycols in developing countries, thus enabling new products and innovation. This suggests that indirect cooling is and will necessarily be an integral part of global EV growth, even if it is not an optimal long-term solution.
Indeed, Strüfing says that OEM interest and engagement with UPM on bio-MEG is presently very strong: “Some automakers are actively testing fossil fuel-free coolant and others are convinced it presents a significant area for development. After all, why are they building EVs in the first place? To reduce carbon emissions, so a CO2-neutral battery coolant in inevitable.” Vehicles are changing, and so are the fluids that maintain them. Indirect cooling is an integral part of global EV growth, even if it is only a short-term solution. If automotive is truly striving for a more eco-friendly future, incorporating cleaner coolant—glycol-based today, but perhaps even dielectric tomorrow—will be an essential part of that transformation.