“Hour by hour, there is just about nothing you as an individual can do that is worse for the health of the planet than to sit on an airplane,” says NASA’s Peter Kalmus.
Aviation accounts for about 3 percent of global carbon emissions, but has other warming impacts, too. As Axios reported, those emissions are projected to rise significantly in coming decades alongside the growth of air travel, absent aggressive adoption of climate-friendly tech. What is the potential for growth? Start with this fact: An estimated 80 percent of the people on the planet have never flown. That is one reason that by 2050 we can expect to reach 10 billion passengers per year, double the pre-pandemic rate.
Concern about aviation’s emissions has fueled a movement that encourages travelers to use trains and buses instead of planes. It’s called flygskam, a Swedish term best translated as “flying shame.”
But are we prepared to give up the many benefits of air travel? They are economic, diplomatic, and cultural. “Look, we simply have to get there,” said Jennifer Holmgren, CEO of LanzaTech, as she discussed solutions with a writer for National Geographic. Her company is pioneering the development of aviation fuel from unorthodox sources such as waste to replace the standard kerosene jet fuel. “Everyone agrees: Airplanes simply can’t keep flying around on fossil kerosene. But there is no magic solution to this problem.”
Many experts are pinning their hopes on what are called “sustainable aviation fuels” or SAFs. On December 1, United Airlines flew the world’s first passenger flight powered by 100-percent SAFs from Chicago to Washington.
The U.S. Department of Transportation Department (DOT) has drawn up a plan for reducing greenhouse gas emissions from the U.S. aviation sector, with a 2050 target of net-zero. “A very big part of the plan seeks to help spur development and uptake of SAFs for long-haul flights,” wrote Ben Geman of Axios.
“I don’t know how you decarbonize [aviation] without SAFs,” Congressman Sean Casten (D-Ill.) told Axios’ Andrew Freedman. Casten, who was on the United flight from Chicago, is backing the Sustainable Skies Act (H.R. 3440), which would promote SAF research, development and production.
But as Freedman noted, SAFs won't eliminate aviation’s carbon footprint because the amount of emissions depends on the feedstocks used to make the fuel. The New York Times’ Hiroko Tabuchi reported, “Scientific studies have long shown that biofuels can be as polluting as fossil fuels.” If the biofuels are made from, say, soy or corn, there will be emissions from production and transport of those raw materials.
Alexander Laska of Third Way told Jeremy Beaman of the Washington Examiner, “We need to look at the entire lifecycle of the feedstock from how it's grown and harvested, how it’s transported, how it's refined, and blended.” United Airlines, Tabucki wrote, “is looking to a more promising source of sustainable fuel: forest waste, like fallen branches, or leaves and stalks left over from growing crops.” The EU, as part of its effort to create an SAF mandate, is likely to impose restrictions on the kinds of biofuels that can be used.
One way to speed the adoption of cleaner fuels, Sam Howe Verhovek wrote in National Geographic, is to create a carbon tax on kerosene jet fuel.
Liquid hydrogen and electric power may help meet the challenges posed by this hard-to-decarbonize transportation sector. At the moment, the weight of batteries is a significant limitation, but there are signs that electric-powered flight could play a notable role in local and regional travel. “Enthusiasts say that within 15 to 20 years, electric airliners could be carrying as many as 50 people a few hundred miles” wrote Verhovek.
While of critical importance, airplanes’ fuel is not the only way to tackle aviation’s emissions. Another goal of DOT’s Aviation Climate Action Plan is to help speed efficiency gains, with a target to "demonstrate a suite of aircraft technologies by 2030 to achieve a 30% improvement" relative to today's best tech.
Congress may boost the aviation sector’s progress on emissions by passing the Build Back Better bill. The House-passed version includes $1 billion for an alternative fuel and low-emission aviation technology program, which would fund grants and cost-sharing agreements with companies producing SAF and other technologies.