The True Cost of Flying: Can Aviation Ever Be Sustainable?

It wasn’t that long ago that visions of personalized jet packs filled the popular imagination. Yet the reality is that air travel today remains remarkably similar to its early days in the 1960s. The basic design—a metal tube with wings—has barely changed, and 99.9% of flights are still powered by the same old kerosene-based jet fuels derived from crude oil.  

As more cars go electric and bicycles take over many of the world’s cities, air travel remains rooted in its polluting past. Change seems inevitable, but how soon? Sustainable jet fuels and electric planes are often touted as the future—but how close are they to becoming a reality? When, if ever, will flying truly become sustainable? 

Spotlight on Sustainable Aviation Fuels 

The aviation sector’s greatest decarbonization challenge is powering planes without fossil fuels. The pressing need for sustainable aviation fuels (SAFs) means everyone from the Chinese government to NASA, the US Department of Energy and the World Economic Forum is backing innovation. SAFs remain the only viable route for airlines to meet their commitment to the Paris Agreement’s target of limiting global warming to 1.5°C by reaching net-zero emissions by 2050. (read more about the impact of flying in our previous post)  

SAFs already exist, as demonstrated last year by Virgin Atlantic’s first flight from London to New York using only fuel derived from natural fats, including coconut oil. The challenge is that these fuels are biofuels produced from animal or plant materials such as fats, corn, sugar, and palm oil. Scaling them to meet the demands of 38.7 million annual flights is impractical, given the vast land required to grow such feedstocks. Research estimates that producing sufficient biofuels from sugarcane alone would need 482,000 square miles of land—an area equivalent to California, Oregon, Washington, Nevada, and Louisiana combined. This explains why SAFs currently account for just 0.1% of aviation fuel use, compounded by their cost, which is three to five times higher than conventional jet fuel. 

Research and development aimed at overcoming these hurdles is thriving. California-based startup Unifuel has introduced a chemical process that improves scalability by cost-effectively converting feedstock byproducts into SAFs. Meanwhile, scientists at the US Argonne National Laboratory have created SAFs from wastewater sourced from breweries and dairy farms, and researchers at the University of Georgia have developed them using logging waste. These innovations highlight the growing momentum behind efforts to make sustainable fuels viable on a larger scale. 

Hydrogen and electricity 

Hydrogen has also been proposed as a potential alternative jet fuel but presents distinct challenges. Its environmental impact depends on how it is produced. The genuinely low-carbon option, green hydrogen, uses renewable energy to split water. Yet it remains rare and costly, as most of the hydrogen currently available is grey hydrogen, produced by splitting fossil gas. The core issue is that renewable energy generation remains far too limited to support green hydrogen production at the scale required for aviation. 

Weight poses another significant challenge. Although hydrogen fuels are lighter than conventional jet fuels, they require four times the volume to generate the same power, resulting in heavier fuel tanks. Compounding the issue, hydrogen must be stored as a liquid at an extremely low temperature of -253°C (-423°F), necessitating specialized equipment that adds further weight. A study by McKinsey concludes that these limitations make hydrogen viable only for short to medium-haul flights of up to 2,500 km—the distance between London and Istanbul. 

Research is also being conducted into aircraft electrification, bringing different issues. While biofuel SAFs are compatible with current aircraft, going electric would require a new global fleet run on batteries and a new charging infrastructure, representing a vast financial outlay. Plus, batteries with enough energy for long flights are simply too heavy. 

Multiple innovators are at work on this problem, like Beta Technologies in Vermont, US, which offers electric planes that hold five passengers. However, battery storage issues mean they’re only designed for journeys of around 100 to 150 miles. In California, Joby Aviation and Archer Aviation are also developing small battery-powered aircraft for short distances, while established manufacturers like Airbus, Boeing and Embraer are creating electric aircraft, too.  

Wider Supply Chain Innovation  

While SAFs present the aviation sector’s greatest sustainability challenge, upgrading the broader value chain—from aircraft manufacturing to spare parts and airport operations—is equally crucial. Innovation in these areas takes many forms. Most significantly, enhanced aircraft design can boost fuel efficiency and reduce carbon footprints, so NASA is investing $11.5 million.  

Among aviation design experts, the consensus is that airplane wings look set to become longer and thinner. Manufacturers Airbus and Boeing say that this design change could boost fuel efficiency by up to 10%. At the same time, research is underway into a new generation of ultra-lightweight materials – like biomass carbon fibers made from algae or self-healing nanocomposites that can repair cracks by itself. Even cabin design is to be revolutionized, as demonstrated by aerospace supplier Diehl Aviation’s Future Cabin, featuring a bionic structure, mirroring that of a leaf or a dragonfly’s wing, that can reduce weight by nearly a third. 

The future design of airports will largely depend on which sustainable fuel technologies prevail. In the meantime, Singapore’s Changi Airport offers a glimpse of what’s possible. Terminal 4 is adorned with a living wall of over 20,000 plant species, helping to lower ambient temperatures and improve air quality. The terminal also incorporates energy-efficient motion sensors and lighting, water-saving fixtures, and rooftop solar panels, showcasing how airports can integrate sustainability into their infrastructure. 

In the realm of maintenance, repair, and operations, UK-based AJW Group is demonstrating the raft of straightforward changes that make a difference. In addition to recycling or repurposing components, it’s swapped to biodegradable tape and recyclable packaging when sending out parts, and chemical cleaning solutions are ditched in favor of aqueous-based ones. It’s also invested in renewable energy across its operations while installing rainwater harvesting technology. 

Efficiencies can also happen during flights. New technology enables pilots to access data that shows them how to manage fuel better. French tech specialist OpenAirlines has developed a digital tool, called SkyBreathe®, which leverages AI to analyze over 15 million flights, intending to issue recommendations that reduce fuel consumption and CO₂ emissions. In the meantime, tweaking specific flight paths has been shown to cut contrails – the white lines planes create in the sky – that have a warming effect on the planet as important as the one caused by aviation’s CO2 emissions, according to a study by NGO Transport and Environment. 

Outlook 2050 

By 2050, will passengers be buckling up in carbon-neutral, long-winged aircraft with interiors inspired by nature’s ergonomics? Perhaps—but only if significant technological breakthroughs are achieved. Despite the capital flooding into SAF research, biofuels remain impractical at scale, while hydrogen- and electric-powered planes are still in their infancy. 

The race is now on to overcome one of decarbonization’s toughest hurdles and make sustainable air travel a reality before time runs out.