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Demand for air travel is projected to rise roughly 5 per cent a year, a figure that is never far from the minds of University of Toronto engineers working to reduce the industry’s environmental impact.

Currently, air travel is responsible for 5 per cent of man-made greenhouse gas emissions. But the industry’s goal is a 50 per cent reduction in carbon dioxide emissions by 2050, says Professor David Zingg, director of the University of Toronto Institute for Aerospace Studies (UTIAS) and a Canada Research Chair in Computational Aerodynamics and Environmentally Friendly Aircraft Design.

“That means we need to take into account the growth in air travel. So not just a 50 per cent reduction per passenger kilometre, but 50 per cent overall,” said Zingg.

To that end, UTIAS engineers are developing and evaluating unconventional plane designs to reduce their drag and weight, both of which cause a plane to use more fuel. Use less fuel, produce fewer emissions.

UTIAS engineers are also designing the most efficient engines for combusting fuels – including biofuels, which promise to lower emissions even further.

Currently, there are some demonstration flights in which one engine is partially powered using biofuel, but Zingg says it will be several years before such technology is commercially viable.

Why combustion physics matter

That’s why UTIAS' associate director, Professor Ömer Gülder, is studying high altitude combustion not only of biofuels, but also of hydrocarbon fuels. He wants to better understand the physics of combustion so we can reduce emissions and increase energy output for both types of fuels.

“Combustion produces 85 per cent of the world’s energy usage, so any improvement in using these fuels will be beneficial,” he said.“There are still basic gaps in our knowledge even though we’ve been using conventional hydrocarbon fuels for 150 years.”

The research is particularly tricky because the stakes are much higher up in the air, where atmospheric pressure and temperatures are extreme.

“If worse comes to worst, a truck stops on a highway. When you are flying, if that happens, it’s not desirable,” said Gülder.

How not to obsolesce an entire airplane fleet

While the bulk of work at the University of Toronto in this field happens at UTIAS, engineers in other engineering departments are also influencing the aerospace industry’s sustainability.

Mechanical and industrial engineering professor Murray Thomson, for example, is collaborating with European colleagues in a program called ALFA-BIRD (Alternative Fuels and Biofuels for Aircraft Development) to research biofuel combustion in jet engines.

Thomson runs super-computer simulations to uncover the type of emissions biofuels give off and how well they work when blended with conventional jet fuel.

“The thing about aviation fuels is you have to be able to put them in an existing engine and know it will work. You can’t modify the engine,”said Thomson. “Airplanes are around for a long time – 30 years or more. You can’t obsolete the entire fleet. Airplanes are too valuable.”

This story first appeared in .