The whole point of EVs is to cut down on the use of hydrocarbons and reduce CO2 emissions, but Shell thinks it has a strong case for reintroducing them, at least for one very specific area.
Cooling electric vehicle batteries is becoming more of an issue as increased charging speeds and more performance applications test the limits of standard indirect cooling.
Indirect cooling for EVs is similar to that used by combustion engines. A jacket surrounds the battery pack and a water/glycol mix is pumped around. But that has its limits. To effectively and quickly reduce temperatures you need to swamp the cells themselves, and for that you need a so-called dielectric fluid -- one that does not conduct electricity.
This is immersion cooling. Automakers such as Fiat Chrysler Automobiles, Mercedes AMG and McLaren are investigating it for high-speed EV projects says Chris Dobrowolski, Shell's E-fluids coordinator for motorsport.
The racing connection is that dielectric fluid is also used in Formula E battery packs built by Atieva (aka Lucid) and supplied to the teams by McLaren Applied Technologies.
Shell makes a suitable dielectric fluid and wants to find more customers, but does not supply Formula E.
There are good reasons for automakers to channel fluid directly to the cells. It creates a more compact battery pack, slows the cell aging process and creates higher power density, according to Shell. But mostly of all it reduces the damaging effects of rapid charging. "That's really what matters," Dobrowolski said.
Shell believes automakers will not mind introducing a hydrocarbon fluid. It's not oil-based but refined synthetically from methane using a gas-to-liquid method. Organic waste could be used to produce this methane, Dobrowolski said.
Formula E uses dielectric fluid instead of water partly for safety reasons. "As soon as you have water sloshing about a high-voltage battery there's definitely some risk," said Anthony Law, head of motorsports batteries for McLaren Applied Technologies.
There are good reasons to use it outside racing too.
"Immersion cooling is absolutely applicable to road cars, particularly when you're using a battery at very high power," Law said.
But there are disadvantages as well. Dielectric cooling fluid is thicker than water/glycol mixture, and therefore heavier. Filling the cell area completely further increases the amount and therefore weight. It also requires more energy to pump around (Formula E cars have a separate battery to power cooling fluid pumps).
In short, it's not suitable yet for standard EVs. "We're talking niche-end road car applications," Law said.
Alternatively, it could also be used to protect electric supercar batteries from repeated rapid charging at track days.
