Flex Fuels and Hybrid Electrification Will Change Heavy Trucks

by Kevin Clemens (Design News) ... “We’ve been working for a number of years on ways to make engines for cars and trucks cleaner and more efficient, and we’ve been particularly interested in what you can do with spark ignition [as opposed to the compression ignition used in diesels], because it’s intrinsically much cleaner,” said Massachusetts Institute of Technology (MIT) Energy Initiative and Plasma Fusion and Science Center research scientist Daniel Cohn. Chon has been researching a variety of fuels and the use of hybrid spark ignition-electric technology in heavy trucks—his research is presented in an MIT news release. In the MIT release it is noted that, “Compared to a diesel engine vehicle, a gasoline-powered vehicle produces only a tenth as much nitrogen oxide (NOx) pollution, a major component of air pollution.”

A flex-fuel engine configuration for a heavy truck that allows it to run on gasoline, ethanol, methanol, or blends of these, would have the potential to emit far less greenhouse gas than pure gasoline engines do, according to the news release. Cohn notes that the incremental cost for the fuel flexibility is very small. If run on pure methanol or ethanol derived from renewable sources such as agricultural waste or municipal trash, the net greenhouse gas emissions could even be zero. “It’s a way of making use of a low-greenhouse-gas fuel” when it’s available, “but always having the option of running it with gasoline” to ensure maximum flexibility, Cohn says.

(T)his flex-fuel hybrid option could provide a way for such trucks to gain early entry into the marketplace by overcoming concerns about limited range, cost, or the need for excessive battery weight to achieve longer range. Cohn said, “We think that’s going to be very challenging, because of the cost and weight of the batteries.” Cohn and his researchers estimate to reach the range of a current diesel engine truck would require somewhere between 10 and 15 tons of batteries “That’s a significant fraction of the payload” such a truck could otherwise carry, Cohn said. “Batteries are great, but let’s be realistic about what they can provide,” he said.

“We think that the way to enable the use of electricity in these vehicles is with a plug-in hybrid,” Cohn said.

In order to match the efficiency of diesels, a mix of alcohol with the gasoline, or even pure alcohol, can be used, and this can be processed using renewable energy sources, they found.”

The combination of flex-fuel and hybrid electrification allows them to address two major challenges at once. “We don’t know which is going to be stronger, the desire to reduce greenhouse gases, or the desire to reduce air pollution. In the U.S., climate change may be the bigger push, while in India and China air pollution may be more urgent, but this technology has value for both challenges,” said Cohn. READ MORE