Technically, carbon-free flight has already happened.
Solar Impulse, developed by visionary entrepreneur Bertrand Piccard, is a solar plane that flew around the world without using any fuel. The catch? The two-seater craft flew at 30 mph and had a wingspan larger than a commercial jet, which was needed to accommodate the solar panels necessary to power the plane, and seats that doubled as toilets to save space.
While promising, there’s a big difference between a flight on a two-seater plane and a wide-body commercial airliner with 200 passengers making a commercially-viable long-haul trip.
Though radical new technologies are predicted to be developed by 2035, “there are economic and commercial constraints that might delay or even prevent their implementation,” according to an International Air Transport Association report.
What’s grounding airline innovation?
The pandemic has ripped into the aviation industry — as of July 30, the number of travelers passing through the U.S. Transportation Security Administration checkpoints is still down almost 74% from the same week last year, based on TSA data.
Airlines have been one of the largest beneficiaries of government bailout payments in the U.S., airlines received $25 billion as part of the U.S. government’s CARES Act in April 2020.
Economists suggest the pandemic could be an opportunity to make aviation greener. Many have suggested making bailout money conditional to sustainability measures since so many airlines are asking for the government’s help.
France, so far, has been one of a few countries to actually do this — the country has created climate conditions for its bailout of airlines, seeking to make Air France the most environmentally friendly airline in the world. Of course, this hasn’t happened in the U.S., as the industry is reluctant to change to the large-scale investment required for carbon-free flight.
“We will continue to use jet fuel as far as the eye can see,” Delta CEO Ed Bastian said in a CNN interview in February 2020. “We’ll be investing in technologies to reduce the impact of jet fuel, but I don’t ever see a future where we eliminate jet fuel from our footprint.”
Sustainability movement grows with climate concerns
The aviation sector accounts for about 2% of global carbon dioxide emissions, according to IPCC 4th Assessment Report in 2007, but aviation’s impact on climate change isn’t just about CO2. Aircraft emissions lead to other greenhouse gasses including ozone and cirrus clouds, which might enhance the greenhouse effect, according to the report.
As each “generation” of planes go by — about every 20 years, planes generally become 15% more fuel-efficient — they burn less jet fuel per mile traveled due to improvements in their design: lower fuel consumption diesel engines, flying lower in the sky and the incorporation of lighter-weight materials.
For example, the Boeing 787 Dreamliner — a wide-body aircraft with two center aisles designed to hold more passengers for long-haul flights — entered into service after 2011 and is between 20 and 25 percent more fuel-efficient than its predecessor: the Boeing 767.
Even though airplanes have become more fuel-efficient over time, the IATA reports a greater number of flights overall have led to a net increase in CO2 emissions. The number of registered carrier departures has doubled to 40 million flights from 2000 to 2018 according to data from the World Bank and the IATA, which is the trade organization for the world’s airlines.
Sustainable aviation fuels are in development but have yet to become cost effective, the International Civil Aviation Organization (ICAO) reported. Sustainable fuels could make up to 2% of fuel consumption by 2025, the U.N. agency for the industry found. And Boeing and FedEx demonstrated a biofuel-powered commercial plane in 2018.
Futuristic designs bring promise
Airplanes are expected to gradually become more fuel-efficient until 2035, according to the IATA Technology Roadmap report, because evolutionary designs improve the airplane of today — “tube and wing” crafts with turbofan engines without making major changes to the craft or propulsion source.
From 2035 and beyond, the IATA projects that radical new technologies will drastically change commercial aviation through the propulsion source and the geometry of the plane. Radical technologies have greater potential for fuel efficiency and are quieter, the IATA reported.
Electric propulsion is predicted to enter the market in small, two to five passenger “aero taxis” between 2020 and 2025. Larger, hybrid-electric planes that can hold over 80 passengers are expected around 2030, according to the IATA — but these numbers are fragile estimates.
AeroDelft’s Project Phoenix is a hydrogen fuel cell-powered two-seater plane currently in development. The project anticipates the first hydrogen-powered commercial aircraft prototype will arrive in 2030. Other revolutionary propulsion technologies include the open rotor and electric and hybrid-electric technologies, which are in development.
NASA’s Environmentally Responsible Aviation program has developed advanced propulsion technologies along with FAA-led U.S. research program CLEEN (Continuous Lower Energy, Emissions, and Noise). The ICAO report predicts that new propulsive technologies will help increase fuel efficiency through 2037.
There are several futuristic-looking designs for the frame under development, such as the blended wing body — including “flying wing” styles such as “the flying V”.
The SR-71 Blackbird, a military stealth plane from the Cold War, is an example of a blended wing body. This blended wing body allows more of the craft to generate lift, and reduces drag without a conventional wing and body junction based on an article in the Journal of Aircraft.
Furthermore, disruptive technologies — transportation systems that could replace air travel completely — include the hyperloop for shorter distances and supersonic flight for long-distance travel.
Is the future of air travel green?
Air travel is projected to increasingly affect global climate. Through 2050, emissions from international aviation that affect the global climate and local air quality are expected to increase between two and four times 2015 levels, the ICAO environmental report notes.
The industry has big goals for environmental protection. Internationally, there’s the idea of carbon taxation among commercial air. The ambitious goal of halving global CO2 emissions from aviation by 2050 is another aspect of CORSIA — Carbon Offsetting and Reduction Scheme for International Aviation, a global market-based scheme where different players trade shares of emissions among 69 signatories.
If the aviation industry is to achieve its goal of 50% reduction in carbon emissions by 2050, radical change is necessary.
"When people speak about pioneering spirit, very often they believe that pioneers are the ones who have new ideas,” Piccard said in a 2010 TED Talk. “It’s not true. The pioneers are not the ones who have new ideas because new ideas are so easy. The pioneer is the one who allows himself to throw overboard a lot of ballast: habits, certainties, convictions.”
In a hot air balloon trip, ballasts are the sandbags that weigh down the balloon — sometimes necessary but often need to be released. There’s a risk in letting go of ballast, as you can’t get it back once it’s gone.
The world has already seen the kind of ingenuity that comes out of necessity and circumstance — from Howard Hughes’ Spruce Goose, the largest plane ever built — to Piccard's Solar Impulse. It would take much more space to describe all of the possible carbon-reducing technologies in development. Most of them require massive change, but some don’t.
Investors and flight companies might start seeing their bottom line go down because of changing consumers after the pandemic, but before the industry starts dropping ballasts, radical change is unlikely.
Jillian Lynch is a senior international affairs major. Contact Jillian at firstname.lastname@example.org.