President Joe Biden’s administration is targeting one of the tougher sources of climate-warming greenhouse gases with a plan that calls for the U.S. aviation sector to reach net-zero emissions by 2050.

Aviation has been more challenging to decarbonize than automobiles, which can essentially run on batteries, but Biden’s 40-page plan released Tuesday calls for increasing production of sustainable airplane fuels and developing new aircraft technologies. It also urges increasing operational efficiencies to reduce the amount of fuel that is burned during flights.

The proposal marks the latest stage of Biden’s climate plans through regulatory action while his legislative agenda proceeds slowly in Congress. It follows his previous efforts to limit methane emissions from oil wells and aim for half of all cars sold in the U.S. to be capable of emissions-free driving by the end of the decade.

Transportation Secretary Pete Buttigieg is scheduled to announce details of the plan during an appearance at the United Nations Climate Change Conference in Glasgow, Scotland on Tuesday.

“The Climate Action Plan we are announcing today is ambitious yet achievable, and will help create a sustainable aviation future,” Buttigieg said in a statement. “This plan shows we can combat climate change while growing the economy and creating good-paying American jobs.”

Airlines have for years been been working to develop alternative jet fuels, said Scott Sklar, director of sustainable energy at George Washington University’s Environment & Energy Management Institute.

“Petroleum is their largest cost and it has very high peaks historically that puts them on the brink of bankruptcy,” Sklar said. “So having domestic fuels that can either be blended or replace petroleum at those higher cost peaks makes them more stable over the long-term period.”

The long lead time to achieve zero emissions highlights the unique challenges to reducing greenhouse gas emissions in the aviation sector. The huge costs of developing new, more efficient aircraft along with stringent safety requirements means it can take decades to achieve improvements through fleet changes.

NASA and the Federal Aviation Administration are working with the industry to speed development of more efficient aircraft and engine technologies that could result in a 30% fuel savings, according to an FAA release. They predicted the new aircraft could start entering the U.S. fleet in the 2030s.

There are also efforts to reduce fuel burn during taxiing, takeoff and landing, as well as optimizing flight trajectories, according to the department.

“The U.S. has led in aviation for decades, and we must continue that leadership by building a sustainable aviation system,” FAA Administrator Steve Dickson said in a statement. “Our freedom to fly requires us to take action.”