Chopping off aviation NOx emissions

A concept for airplane propulsion is estimated to eliminate 95% of aviation’s NOx emissions, and thereby reduce the number of deaths associated with these chemicals each year by 92%.

Engineers at the Massachusetts Institute of Technology (MIT) developed the concept inspired by emissions-control systems used in ground transportation vehicles. Many heavy-duty diesel trucks today house post-combustion emissions-control systems to reduce the NOx generated by engines. The researchers now propose a similar design for aviation, with an electric twist.

In the new hybrid-electric, or “turbo-electric” design, a plane’s source of power would still be a conventional gas turbine, but it would be integrated within the plane’s cargo hold. Rather than directly powering propellers or fans, the gas turbine would drive a generator, also in the hold, to produce electricity, which would then electrically power the plane’s wing-mounted, electrically driven propellers or fans.

The emissions produced by the gas turbine would be fed into an emissions-control system, broadly similar to those in diesel vehicles, which would clean the exhaust before ejecting it into the atmosphere.

“This would still be a tremendous engineering challenge, but there aren’t fundamental physics limitations,” says Steven Barrett, professor of aeronautics and astronautics at MIT. “If you want to get to a net-zero aviation sector, this is a potential way of solving the air pollution part of it, which is significant, and in a way that’s technologically quite viable.”