Getting the world off dirty diesels

Gasoline-alcohol engines for heavy-duty trucks

Several years ago, Daniel Cohn and Leslie Bromberg took on the challenge of designing a low-emissions, fuel-efficient replacement for the polluting diesel engines traditionally viewed as the only viable option for powering today’s 18-wheelers and other heavy-duty trucks. Using a series of sophisticated computer models developed by Bromberg, they’ve now produced a conceptual design for an engine that should be up to the task.Credit: Stuart Darsch

We need to replace diesel engines with other internal combustion engines that are much cleaner and produce less greenhouse gas.

Daniel Cohn

Using computer simulation analysis, MIT researchers have developed a conceptual design for a half-sized gasoline engine that would be as efficient and powerful as the full-sized diesel engines now used in heavy-duty trucks—without their high emissions of air pollutants and greenhouse gases (GHGs). The small, highly turbocharged, spark-ignition engine gets an extra boost from injected alcohol when it needs to work hard to move a heavy load, especially while accelerating or climbing a hill. The computer analyses show that the gasoline-alcohol design could slash emissions of nitrogen oxides by 90% and also increase power by up to 50%. Cutting the injected alcohol by mixing it with water or making other changes could reduce alcohol consumption. But if reducing GHGs is a priority, the engine could instead run on 100% ethanol or renewable methanol. The engine requires modest changes to an existing engine, so it could come into commercial use quickly and at lower cost than comparable diesels.