Despite many skeptics, the global aviation industry is setting targets to reach net-zero greenhouse gas emissions by 2050.
To meet those targets, new startups and established businesses are racing to provide as many possible solutions to aviation’s fossil fuel dilemma. In fact, there're so many options it's hard to determine what will actually work to reduce the carbon footprint of airplanes (besides flying less) and decarbonize flying.
Aviation releases one-sixth the amount of carbon dioxide produced by cars and trucks, according to the World Resources Institute, a nonprofit research group. The number may seem small, but if it were a country, global aviation would rank in the top ten of greenhouse gas emitters, ahead of Brazil, Mexico, and the U.K.
Before the pandemic, aviation was one of the fastest-growing sources of greenhouse gas emissions, burning more and more fuel each year, rising by about 2 percent annually since 2000. Commercial air travel accounts for between 3 and 4 percent of total U.S. emissions, a number that the United Nations expects to triple by 2050, vastly outpacing previous predictions. If the world is to limit global heating to 1.5C by this time, net-zero emissions must be reached, a goal that can’t be reached by modern flight.
Today’s aircraft engines are more efficient than ever before, but improvements to reducing fuel consumption are left in the dust, with only about a 1 percent reduction per year.
With the slow improvements, some governments aren’t waiting on the industry’s delayed take-off to sustainability.
In June of 2020, the U.K. government established the creation of the Jet-Zero Council, a green recovery partnership focused on the adoption of sustainable technologies to reach the goal of zero-emission flights by 2050.
But, is such an ambitious goal possible when at the same time, many of Europe’s airlines are lobbying for looser emission rules?
Earlier this month the opening of the Farnborough International Airshow, a huge aviation show in London, provided a fitting backdrop to the political wrangling in Europe. At the show, discussions about climate change replaced much of the usual buzz over big airplane orders. The show opened as U.K. authorities issued the first extreme heat warning in England’s history. As reported by Associated Press, two nearby airports closed their runways, one reporting that heat caused the surface to buckle.
The aviation industry needs to confront climate change, Jim Harris, who leads the aerospace practice at consultant Bain & Co., told AP. He added that with airlines recovering from the jolt of the pandemic, hitting net zero by 2050, the central goal of the U.K.’s new jet-zero plan, is now the industry’s biggest challenge. But at present, it’s unclear if, or how that will happen.
“There is no obvious solution, there is no one technology, there is no one set of actions that are going to get the industry there,” Harris told the outlet. “The amount of change required, and the timeline, are big issues.”
Aviation is on the Mission Possible Partnership’s list of the seven most difficult sectors of the economy to decarbonize, along with shipping and trucking, steel, aluminum, cement/concrete, and chemicals manufacturing. Aviation is so “hard to abate” for a multitude of reasons. These issues range from difficult technological solutions, hidden extra climate effects, an association between flight and personal freedoms, and a disproportionately wealthy and powerful customer base.
Mission Possible Partnership is an alliance of climate leaders led by the Energy Transitions Commission, Rocky Mountain Institute, We Mean Business, and the World Economic Forum, in conjunction with McKinsey & Company as a knowledge partner.
In a recent briefing on how to decarbonize the aviation sector, their research showed that the only way to fix the issue is with a multi-pronged approach, scaling up production in sustainable aviation fuels (SAFs), especially those powered by electricity, and renewable options for flight such as hydrogen and battery-powered aircraft. Reaching net-zero emissions by 2050 is possible, but changes need to happen fast.
Let’s take a closer look at each of these solutions, starting with what MPP projects may be the biggest recipient of sustainability investments: SAFs.
Can sustainable aviation fuel solve the problem?
For the longest, jet kerosene from fossil fuels was the only option available for airplanes. Fuel-efficiency aircraft have improved over time. While innovation in relation to engines, for example, has reduced carbon emissions, substituting fossil-based jet kerosene with more sustainable fuels, will most significantly slash aviation emissions in the long run.
That’s where SAFs come in. SAFs are low-carbon alternatives that deliver the performance of traditional petroleum-based jet fuel without the carbon footprint. They’re made from renewable biomass and waste resources like animal fats, sea scum, and even foot scraps. According to MPP, if the industry has any hope of decoupling itself from greenhouse gas emissions, SAFs including biofuel and power-to-electricity liquids or PtLs must scale up.
PtLs are a type of SAF that synthetically produces liquid hydrocarbons. This is done when climate-neutral CO2 is captured via, for example, direct air carbon capture, turned into carbon feedstock, and synthesized with green hydrogen to create liquid hydrocarbons, a synthetic equivalent to kerosene.
However, biofuels are the only SAF option today. By the late 2020s, PtL is projected to enter the market at a large scale and become cheaper in the mid-2030s.
Startups around the world are working toward increasing available SAFs. In fall 2021, United Airlines committed to buying 5.7 billion liters of SAFs from Alder, the largest such aviation deal at that time. Recently, Boeing partnered with the startup to scale SAFs globally.
But Alder isn’t the only startup helping airlines quit fossil fuels. Another example is LanzaJet, a Chicago-based biotech startup developed by LanzaTech. In 2018 they began operating the world’s first commercial plant, converting industrial waste gasses to fuel, using the secret ingredient microbes from rabbit poop.
LanzaJet is also working with a leading iron and steel company in China to ferment carbon monoxide from steel mills to convert its ethanol into the same hydrogens and carbons that make up traditional fuel. In 2018, Virgin Atlantic successfully used LanzaJet’s jet fuel on a commercial transatlantic flight. And most recently, the company received $50 million in funding from the Microsoft Climate Innovation Fund to construct the world’s first alcohol-to-jet SAF plant.
In Sweden, another company, RenFuel, is taking to the forest for fuel. Linden is a natural polymer that gives trees strength but is considered a waste product in the paper industry. RenFuel is converting this material into an oil called Lignol, a biofuel suitable for planes. The company is currently developing a Lignol plant, right next to a paper mill, that’s expected to produce 185,000 tons of Lignol a year.
Other startups have turned to recycled carbon by using recaptured CO2 and renewable energy to produce sustainable aviation fuel via a power-to-liquids process. To scale this up, startup Twelve has recently partnered with Alaska Airlines, United Airlines has significantly invested in Dimensional Energy, and startup SkyNRG has partnered with the direct air capture company Climeworks.
SAF startups are steadily taking off. Still, SAF producers only produce 100 million liters of fuel per year for an industry that consumed more than 360 billion liters in 2019, before the pandemic cut that in about half. By 2030, the market for SAF may grow 70-fold to nearly $15.7 billion, according to Markets and Markets. If SAF scales up at that projection, it will likely play the largest role making flight sustainable.
What role do hydrogen and batteries play?
While SAFs will be the leading game changer in aviation emissions, they can’t do it alone.
MPP also predicts that hydrogen aircraft could enter the market in the 2030s and scale up through 2050, the point at which they could account for roughly a third of aviation’s energy demand.
Companies are already testing the idea. Recently, Aerospace giant Rolls-Royce partnered with airline easyJet to develop and test hydrogen combustion engine technology for aircraft. The goal of the collaboration, called H2ZERO, “is to demonstrate that hydrogen has the potential to power a range of aircraft from the mid-2030s onwards,” Rolls-Royce said in a statement.
According to the company, the firms will conduct an “early concept ground test” of a Rolls-Royce engine using hydrogen technology in the U.K. this year. They aren’t the first. In May, Airbus announced it was launching a U.K.-based facility focused on hydrogen technologies.
Battery-powered aircraft are also poised to play a role in the industry’s solution, albeit a small one. According to a recent study even if the technology takes off as promised, battery-powered planes will play only a minuscule role in curbing climate pollution from passenger air travel, reports Canary Media. The reason is that batteries cannot handle the kind of weight and distance needed for large, long flights.
“The idea is that, yes, electric aircraft don’t do much [for carbon emissions], but you still want to use them wherever you can,” said Jayant Mukhopadhaya, a Berlin-based researcher for ICCT and lead author of the new report.
Still, companies are investing in electric aircraft and a fleet of startups are making those investments into reality.
Last year, United Airlines and its regional partner Mesa Air Group invested in a $35 million funding round for Heart Aerospace, a Swedish startup that’s making electric 19-seat aircraft. The airlines also agreed to purchase 200 of the startup’s planes, the first of which are expected to be delivered for commercial use by 2026.
United is no stranger to backing renewable aircraft startups. Another of their investments is ZeroAvia, which is developing a hydrogen fuel-cell aircraft. The startup recently partnered with Edmonton International Airport to bring hydroelectric flights to Canada.
United’s partners are among a handful of startups working with major corporations to commercialize battery-powered flights. U.S. commuter airline Cape Air has placed orders for a nine-seat passenger plane made by Israeli startup Eviation, while German logistics giant DHL has ordered a cargo version. Italian startup Tecnam is building an electric nine-seater, while Los Angeles–based Wright Electric is working on a 100-seat plane designed for routes up to one hour long, and Vermont’s BETA Technologies is building cargo and passenger electric vertical aircraft inspired by the bird, the Arctic tern.
Flight towards the future
Decarbonizing aviation is possible, but the industry-wide effort would have to dramatically shift its focus.
Currently, many big airlines rely on carbon offsets to reduce their carbon footprint. By buying an offset, a company or individual effectively pays somebody else to take steps to reduce greenhouse gasses such as planting trees. But the benefits of offsets are difficult to measure, hard to know, and all too often represent a cop-out by big companies.
At Farnborough’s airshow, seven big players in the industry signed letters of intent to discuss buying carbon removal credits to offset the emissions from air travel, including Airbus, Air Canada, Air France-KLM, EasyJet, International Airlines Group, LATAM Airlines Group, Lufthansa Group, and Virgin Atlantic.
One of these companies, Air France- KLM, was recently sued by Dutch environmental groups for greenwashing.
At the core of the lawsuit was the company’s conflated advertising and reliance on carbon offset credits, a common practice in the airline industry.
MPP includes carbon removal as a part of the solution, but not the end-all-be-all that many airline companies make it out to be.
Green technology is here. Yet, there are still not enough incentives for airlines to use it. Sustainable aviation fuel costs at least twice as much as traditional jet fuel. Fuel already accounts for up to 30 percent of an airline’s operating costs, so for more airlines to use sustainable fuel, it’ll need to become less expensive. Because issues like costs have hindered the adoption of SAFs, for example, governments are using policies to regulate aviation emissions, such as the US and EU’S SAF mandates.
Like most decarbonization efforts, fixing the aviation industry is not a “one solution is the best solution,” scenario. Luckily, a multitude of solutions is out there. To get the industry to zero emissions, however, all airlines must be all aboard.