PNNL invention partitions ethanol from gasoline to enable octane on demand; could lower emissions

In Washington, an onboard separation technology developed by U.S. Department of Energy’s Pacific Northwest National Laboratory researchers is the first to use chemistry—not a physical membrane—to separate ethanol-blended gasoline into high- and low-octane fuel components and could pave the way for increased fuel economy and lower greenhouse gas emissions as part of an octane-on-demand fuel-delivery system.

The onboard separation technology is designed to work with a car’s existing fuel. An octane-on-demand system can then meter out the appropriate fuel mixture to the engine depending on the power required: lower octane for idling, higher octane for accelerating.

Studies have shown that octane-on-demand approaches can improve fuel economy by up to 30 percent and could help reduce greenhouse gas emissions by 20 percent. But so far, the pervaporation membranes tested for octane on demand leave nearly 20 percent of the valuable high-octane fuel components in the gasoline.

In proof-of-concept testing with three different chemistries, PNNL’s patent-pending onboard separation technology separated 95 percent of the ethanol out of commercial gasoline. The materials are also effective for separating butanol, a promising high-octane renewable fuel component.