Hybrid aircraft concept 'could prevent 92% of premature deaths from aviation nitrogen oxides'

A new hybrid-electric aircraft concept from MIT engineers could reduce emissions of nitrogen oxides (NOx) by 95%, the researchers have said.

NOx are a major source of air pollution and have been associated with asthma, respiratory disease and cardiovascular disorders. Previous research has shown that the generation of these chemicals by global aviation results in 16,000 premature deaths each year. The Massachusetts Institute of Technology team hopes the new system could reduce associated early deaths by 92%.

The concept was inspired by emissions control systems in ground transport vehicles. Many heavy-duty diesel lorries house post-combustion emissions control systems to reduce NOx generated by engines. The researchers have proposed a similar design for aviation, with an electric twist.

Emissions control devices cannot be installed behind aircraft jet engines, as they would interfere with thrust. Instead, the team said their new ‘turbo-electric’ design would use conventional gas turbines, but integrated within the cargo hold.

Rather than directly powering propellers or fans, the gas turbine would drive a generator in the hold to produce electricity, which would then power wing-mounted 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,” said 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.”

The details of the design were published in Energy and Environmental Science. 

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