Tens of thousands of flights carry millions of passengers around the globe on a daily basis.
Needless to say, the environmental impact of this is fairly large--but both airlines and aircraft makers are keen to reduce that impact and lower their own costs, too.
Specifically, Boeing aims to seek approval for the use of "green diesel" in jet fuel.
Green diesel is made by transforming oils and fats, made from cooking oil, plant oils and waste fats, into a "renewable diesel".
It's not, as you might expect, just a different word for biodiesel, as the two fuels are made using different processes: Green diesel is made by splitting large oil molecules into smaller usable ones using hydrogen, where biodiesel is produced through a chemical reaction between vegetable oils and alcohol.
The important thing is that green diesel can be blended with aviation fuel and used in commercial flights.
Boeing says official approval of the fuel will cut carbon emissions from airliners, without boosting costs for operators--the diesel currently costs around $3 a gallon (including government incentives), about the same as jet fuel.
Research is still ongoing into the fuel's suitability in terms of efficiency and reliability, but the airplane maker says the fuel can be blended with jet fuel--and that it is currently working with the FAA and other industry partners to pave the way for its approval.
If approved, it could help stem the aviation industry's contribution to global carbon emissions--2 percent as of today, but expected to climb to 3 percent by 2050.
Dutch airline KLM already runs biofuel routes to reduce its own emissions, and some believe that biofuels could be the best way of reducing emissions in the aviation sector. Costs could be lower too, as some airports would be able to produce their own fuels on-site.
Current green diesel production capacity could supply up to one percent of global commercial flights each year--but if Boeing succeeds in getting the fuel certified, that could climb even higher in future.