How ethanol could help boost EV range
Written by Jonathan Eisenthal
The apparent Achilles’ heel of electric vehicle technology is range. The majority of EV makes and models cannot match the typical range of a gasoline-powered car or light-duty truck, especially in winter months. Combine this with considerations of charging infrastructure in low population density areas, or the needs of people whose work takes them across long distances, and EV technology needs help.
To combat range anxiety, some EVs have small gasoline engines that charge the battery as the car drives, allowing it to go further between charges. Because these range-extender engines don’t have a direct mechanical connection to the car’s wheels, they can operate within the most efficient speed and load ranges and use advanced engine technologies.
One such technology, called thermochemical recuperation, or TCR, uses exhaust waste heat to create a higher-energy fuel.
Fascinating research just completed at the Murphy Engine Research Laboratory (MERL) at the University of Minnesota found that higher ethanol blends increase the efficiency of TCR-equipped range extender engines.
Prof. Will Northrop and his team equipped a range extender engine inside a BMW i3 with the TCR technology. Northrop worked on this project for the past three years with the MERL’s research scientist, Seamus Kane, and several PhD candidates who gained valuable experience.
[More: Watch Prof. Northrop discuss his research]
The BMW i3 is one of several available EV models with a range extender engine. Though BMW discontinued the model in 2022, the concept has reappeared in the marketplace in the new Dodge Ram 1500 EV, and Ford has a patent for a range extender that would work with its F-150 Lightning EV pickup.
“We all know higher blends of ethanol, if blended properly, can lead to really higher efficiency and lower emissions from engines,” Northrop said. “Add to that, the decoupling of the engine from the driveshaft and wheels, not only to run at ideal speeds and loads, but to optimize the operation, so the engine doesn’t have to handle transients. (Engines don’t like to idle. It’s a really inefficient operating mode.) You can really optimize these range extender engines, and get high compression ratios, low emissions and yield a lot of benefits.”
Northrop and Kane hope to take this project off the lab bench and test it on the road, in real vehicles. Northrop envisions many options for using ethanol in a formulation dedicated for this kind of engine. He could foresee convenience stores selling pure denatured ethanol range extender fuel modules that would work like propane tanks for your grill — buy a full fuel module and then swap the empty the next time you need more fuel.
“I am even thinking this could be an add-on device that would sit in the bed of a pickup truck, or that would be a genset for your car that would sit there and charge. Some vehicles have bi-directional plugs which would make set up very simple,” Northrop said. “This technology could even work as an aftermarket product.”
This research was funded by the Minnesota Corn Research & Promotion Council, which directs the resources of Minnesota’s corn check-off.
