General Electric’s aviation unit and its joint-venture partner Safran of France on Monday said they are developing new airplane engines that aim to cut emissions by more than a fifth of today’s levels.

GE Aviation and France’s Safran together produce some of the most commonly used aircraft engines under their CFM joint venture. Together they launched a new program, called CFM Rise, that will develop and test new technology that could enter service in the mid-2030s, the companies said.

The global aviation industry contributes about 2% of global carbon emissions and aircraft manufacturers and airlines have been scrambling to find ways to reduce that, while balancing with, what before the pandemic was, strong growth in travel demand.

GE and Safran’s CFM joint venture makes engines for the Boeing 737 Max and also for the Airbus A320neo family. Competitor Pratt and Whitney, a unit of Raytheon Technologies also makes engines for the Airbus 320.

The RISE program will work on technology that could reduce fuel consumption by more than 20% and also be compatible with sustainable aviation fuel and hydrogen, they said.

The companies plan to design an engine that is open fan, which is unlike the covered jet-engines on commercial aircraft.