Diesels are efficient and inexpensive, but they are also a prime source of nitrogen oxide and greenhouse gases. The Department of Energy is investing heavily in electric and hydrogen-based engines, but such alternatives aren’t quite ready for primetime.

According to Daniel Cohn, a research scientist for the MIT Energy Initiative, we can’t afford to wait…

Fleet owners may discover that the flex-fuel hybrid concept offers an affordable option to bridge the gap between traditional carbon-burning technologies and practical clean energy solutions.

Cohn and a group of researchers at MIT are working on just such an evolutionary solution: a flex-fuel gasoline-alcohol engine design in a hybrid powertrain complemented by battery power. Their approach combines already existing engine systems to preserve the efficiency and economy of diesel for long-haul trucks while drastically reducing the polluting downsides of diesels.