Comment: How aviation can reduce carbon emissions

To lower emissions in the nearer term, we need technologies that can be applied to aircraft flying today. A key example for reducing aircraft fuel burn and emissions is the Pratt & Whitney GTF engine family, which use geared fan architecture to enable a 16% to 20% improvement in fuel efficiency and CO2 emissions for narrow-body aircraft. GTF engines give greater propulsive efficiency, while the GTF Advantage engines for the Airbus A320neo family improve fuel efficiency and reduce CO2 emissions by another 1%, making the engine a total of 17% better than the previous standard while still providing greater thrust capability.

Considering fuel accounts for as much as 40% of an airline’s cost base, a 17% reduction is a huge advantage. In Australia, Qantas recognised this advantage when it chose to power its future narrowbody fleet — namely its A220 and A320neo family — with GTF engines.

Some of the more radical technologies that Pratt & Whitney is developing include hybrid-electric and hydrogen-fuelled propulsion systems. Pratt & Whitney and sister company Collins Aerospace have partnered with De Havilland Canada to develop a 2-megawatt hybrid-electric demonstrator that integrates electric motors and batteries on a Dash 8-100 regional turboprop. This demonstrator is expected to deliver a 30% reduction in emissions compared to today’s most efficient regional turboprop engines. The first test flight is earmarked for 2024.

As an energy-rich fuel that can be readily combusted in a turbine without emitting CO2, hydrogen holds significant potential. In the 1950s, Pratt & Whitney designed and built a hydrogen-burning turbine engine as part of the secret Lockheed Skunkworks ‘Project Suntan’, which was intended to develop a high-altitude military reconnaissance aircraft. Ultimately, the project was cancelled due to the cost and complexity of storing large amounts of liquid hydrogen aboard an aircraft and establishing sufficient fuel production facilities on the ground.

Today, the company is looking to overcome these challenges by developing high-efficiency hydrogen-fuelled engine technology in partnership with the U.S. Department of Energy. The intercooled turbine engine (HySIITE) project is designed to use water vapour recovery and hydrogen steam injection to achieve a 35% efficiency improvement and 80% NOx emission reduction compared to modern engines for single-aisle aircraft. Such technology could play an important role in making hydrogen a viable solution for aircraft operators. However, this technology will still take some years to develop, certify, and scale up.

Achieving net zero emissions for aviation may be a daunting goal, but the aviation industry is resilient and has a strong track record of overcoming challenges through innovation and technology.