When the Covid-19 pandemic hit, I remember climbing to the top of a hill overlooking the San Francisco Airport and hearing silence. For the first time in the 8 years I lived here, the tarmac was still and the air free of planes. I thought, wow, it’s unbelievable we can put a halt to flying so quickly - and deep inside thought this was the chance to make a dent in the climate problem.

Fast forward to 2024, and flights now exceed pre-pandemic levels at over 40 million flights a year. That’s alot of peanuts and cookies! Between 1990 and 2019, both passenger and freight demand has approximately quadrupled.

Worldwide, aviation accounts for 2.5% of all carbon dioxide (CO2) emissions and 12% of all CO2 emissions from transportation. A single long-haul flight can create more carbon emissions in a few hours than the average person in 56 different countries will generate in an entire year.

Myth #1: Airlines Have Not Reduced Energy Use

Since the 1990s flying has become more than twice as energy efficient. Traveling one passenger-kilometer in 1990 used 2.9 megajoules (MJ) of energy. By 2019, this had more than halved to 1.3 MJ. This efficiency has come from improved design and technology, larger planes that can carry more passengers, and a higher ‘passenger load factor’. Empty seats are less common than in the past.

The carbon intensity of that fuel — how much CO2 is emitted per unit — has not changed at all. We used standard jet fuel in 1990 and are using the same stuff today. Therein lies the challenge in taking a bite out of carbon emissions.

Myth #2: It Doesn’t Matter How Long Your Flight Is

When people think about going away for vacation, they often think of flying to a faraway land. However, long-distance air travel has a large environmental impact. Atmosfair has created an index for Airlines to report on all things emissions.

The study found that a long flight creates more emissions than an entire year of a single person’s food, energy, and basic transportation output.

However, in terms of fuel efficiency, as every plane has to take off, climb to a certain altitude, and land, medium-haul flights are more efficient than short-haul and long-haul. This study also shows that there are two factors that have the largest effect on reducing carbon dioxide emissions. These are the type of aircraft and the passenger occupancy.

Medium- and long-haul flights are the greatest culprits, accounting for 73% of aviation’s carbon emissions. According to the Aviation Environment Federation, UK nonprofit group that monitors aviation’s environmental impact, a return flight from London to Bangkok can produce more emissions than you’d save by following a vegan diet for a year.

Myth #3: Sustainable Aviation Fuels Don’t Impact the Environment

November 2024 marked a milestone in the field of aviation. Virgin Atlantic's Flight100, a Boeing 787, embarked on the world's first transatlantic flight from London to New York powered entirely by biofuel – fuel derived from organic matter rather than fossil fuels.

The fuel, known in the industry as Sustainable Aviation fuel (SAF), is derived from renewable or recycled waste such as corn grain, oil seeds, algae, other fats, oils, and greases, agricultural residues and more. It boasts substantially fewer carbon emissions — up to 70 percent less than traditional jet fuel. SAF is an alternative fuel made from non-petroleum feedstocks that reduces emissions from air transportation. SAF can be blended at different levels with limits between 10% and 50%, depending on the feedstock and how the fuel is produced. According to the International Civil Aviation Organization (ICAO), over 360,000 commercial flights have used SAF at 46 different airports largely concentrated in the United States and Europe.

An estimated 1 billion dry tons of biomass can be collected sustainably each year in the United States, enough to produce 50–60 billion gallons of low-carbon biofuels. These resources include:

• Corn grain

• Oil seeds

• Algae

• Other fats, oils, and greases

• Agricultural residues

• Forestry residues

• Wood mill waste

• Municipal solid waste streams

• Wet wastes (manures, wastewater treatment sludge)

• Dedicated energy crops.

Many scientists and international regulatory bodies have concluded that growing crops to make aviation fuel does not reduce emissions on a full lifecycle basis (from crop production through to processing and consumption). To meet the needs of the aviation industry, forests and grasslands would have to be converted, which releases stored carbon.

Sustainable aviation fuels are also inefficient - 1.7 gallons of corn ethanol are needed to make 1 gallon of sustainable aviation fuel. When accounting for total emissions, including loss of land, production emissions and loss of soil organic carbon due to tillage, the impact of using ethanol would be as high as 782 MtCO2. This represents a net increase in emissions of approximately 340 Mt when compared to burning the same amount of petroleum-based jet fuel, equivalent to the emissions from 75 million gas-powered passenger vehicles.

Myth #4: Using Hydrogen in Airplanes is Unsafe

We might think of the Hindenburg when we think hydrogen, but substantial progress has been made on hydrogen fuels since the.

Hydrogen, which can be made from water using renewable electricity, could be the ultimate solution for aviation if fuel handling and storage challenges can be resolved. Several companies are developing planes powered by hydrogen fuel cells for use in short- to medium-haul flights, similar to battery-powered planes. Hydrogen could also be burned in modified jet engines, a concept that Airbus is hoping to commercialize by 2035.

Hydrogen, for example, is bulky and difficult to store in large quantities. It either needs to be kept as a highly compressed gas or as a very cold liquid. To be sustainable, it has to be made in a "clean" way, from renewable sources – and supplies now are very limited. Airbus has bet big on hybrid hydrogen aircraft, announcing three futuristic ZEROe aircraft concepts, including one trippy, funhouse mirror-looking plane called the “Blended Wing Body.” The aerospace company ambitiously aims to have a mature hybrid hydrogen aircraft ready for commercial flights within the next two decades.

Myth #5: We Can Make All Planes Electric

The batteries that would be needed for long-haul flights are currently too heavy to be used, but battery-powered short-range flights have already been proven viable. Companies in the U.S. plan to produce battery-powered planes that can serve commercial flights ranging from 100-150 miles in the coming years. There are dozens of companies racing to create functional electric powered planes.

When an all-electric passenger airplane took a test flight in 2022, it didn’t have much room on board—the design, from a startup called Eviation, has space for only nine passengers. Other battery-electric planes in development are also relatively small, and studies have suggested that all-electric planes can only carry up to 19 people.

Scandinavian Airlines (more commonly known as SAS) opened bookings aboard its first electric planes—the 30-seat ES-30 model, developed in partnership with Heart Aerospace—which will take to the skies in 2028.

Dutch startup Elysian is challenging that assumption with its plans for a fully electric regional aircraft, with a range of 500 miles (805 kilometers) and space for 90 passengers, capable of reducing emissions by 90% — which it aims to fly commercially within a decade.

Myth #6: Consumers Don’t Care About Sustainable Travel

As people become more aware of climate change impacts, more are concerned about their day to day actions, and how that makes them look in front of others. In Sweden, there’s the widely publicized flygskam (flight shame), which leads some to smygflyga (flying in secret) and others to tagskryt (bragging about rail over air travel). All have been largely popularized by the “flight free” movement: a relatively small number of people who have vowed to give up flying for one year (the non-profit We Stay On The Ground has yet to reach its target of 100,000 pledges.)

An international survey from aerospace company Lilium has found that 65% of respondents believe it’s time for sustainable air travel.

The survey also found that US adults aged 18 to 34 are 2.5 times more likely to focus on sustainability when making travel decisions compared with those aged 55+.

Cost was cited as the most important factor for making travel decisions, with 54% of all respondents ranking this highest. This was closely followed by 46% of all respondents citing comfort as a factor in making travel plans, and convenience of access cited by 39%. While most electric plane companies fovus on sleek designs that will provide comfort, most will come at a higher expense.