Flying sustainably is not an option. And it is more than the industry’s license to grow. The freedom to fly at all may depend on eradicating carbon emissions.
The new industry target will take a combination of sustainable aviation fuels (SAF), radical airframe designs, cutting edge propulsion methods, efficiency gains, carbon capture technology, and offsetting.
And it will be an enormous undertaking given that projections suggest 2050 demand will be in the region of 10 billion passengers per year. If the industry carried on flying as it is today—a business-as-usual approach—by 2050 it would have emitted approximately 21.2 gigatons of CO2.
Willie Walsh, IATA’s Director General, notes that industry partners must play their part. “The cost and effort of breaking our industry’s dependance on fossil fuels cannot fall on the backs of airlines alone,” he says. “We don’t have electric cars because drivers built them. The energy transition for road transport is happening because governments created a policy framework that supported innovation. The market reacted by developing cost-efficient electrification solutions that appealed to consumers. The technology roadmap for sustainable aviation is more complex. But the mechanism to deliver change is the same.”
The Biden Administration in the United States provides an example of what can be done. It has taken a whole-of-government approach to incentivize the production of at least 11 billion liters of SAF by 2030.
But further efforts are necessary:
- ICAO must lead governments in a global approach
- Governments must set policies supporting carbon-reducing innovation, SAF production, and the Carbon Offsetting Reduction Scheme for International Aviation (CORSIA)
- A patchwork of national environment taxes must be avoided
- Fuel-producers need to bring large scale, cost-competitive SAF to market.
- Airports must make sure airlines have access to SAF in airports at no additional cost compared with jet fuel
- Governments and air navigation service providers must eliminate inefficiencies in air traffic management—all of which are inexcusable even without a sustainability mandate
- Aircraft and engine manufacturers must produce radically more efficient airframe and propulsion technologies.
Sustainable Aviation Fuels
Sustainable aviation fuels (SAF) will be the main driver in airline efforts to reduce emissions at source.
SAF can reduce CO2 emissions 80% or more. They are produced from a number of sources (feedstock) including waste oil and fats, green and municipal waste and non-food crops. They can even be produced synthetically via a process that captures carbon directly from the air. Crucially, SAF feedstock does not compete with food crops or water supplies, nor contribute to forest degradation.
By 2025, it is estimated that there will be 11 technical pathways to producing SAF. And by 2050, SAF could contribute about 65% of the reduction in emissions needed by aviation to reach net-zero carbon emissions in 2050
A massive increase in production will be required though. The largest acceleration is expected in the 2030s as policy support becomes global, SAF becomes competitive with fossil kerosene, and credible offsets become scarcer.
“Building new factories to refine SAF takes time,” says Sebastian Mikosz, IATA’s SVP, Environment and Sustainability. “Investments commenced several years ago are only now coming on stream. These facilities will help to push up production, but we have to push for much more if we are to meet a goal of 5% of commercial jet fuel demand by 2030. The big oil producers must now step forward and support SAF in a substantial way. Political support—using appropriate policies—is also crucial.”
Positive incentives are the most effective policy tool, according to IATA, as they reduce project risk and allow organic supply and demand to develop into a sustainable market.
In contrast, IATA opposes mandates forcing airlines to use a certain quantity of SAF as this typically results in higher prices, and so diverts resources that could be deployed for other environmental investment.
Other avenues for government support include:
- Globally recognized sustainability standards
- Applying higher incentives for aviation over ground transport, which has other energy alternatives
- Supporting sustainable aviation fuel research and development and demonstration plants
- Implementing policies that de-risk investments into SAF production plants and engaging in public-private partnerships for SAF production and supply
- Ensuring policy timeframes match investment timeframes.
Offsetting and carbon capture
The industry plan for net-zero carbon emissions foresees a rapid decline in the use of offsets as in-sector solutions take over. But offsetting mechanisms, including carbon capture technologies, will be vital in the next decade or so and continue to be integral to achieving the overall industry target.
The Carbon Offsetting Reduction Scheme for International Aviation (CORSIA) is the main pillar. CORSIA aims to stabilize aviation’s net CO2 emissions at 2019 levels from 2021 onwards and will be implemented in phases.
From 2021 until 2026, only flights between countries that volunteer to participate in CORSIA will be subject to offsetting requirements. To date, 107 States have volunteered to join CORSIA for 2022, representing about 77% of all international aviation activity. From 2027, virtually all international flights will be subject to mandatory offsetting requirements, covering more than 90% of all international aviation activity. Exceptions include developing countries and small island states.
The criteria for offsetting measures are being closely scrutinized. Forestry and natural climate solutions are already available. Some 15-20% of the world’s greenhouse gas emissions come from deforestation but there are challenges in reversing this trend. Reforestation and protection must be permanent, and the needs of indigenous communities must be considered, for example.
Offsetting measures on the horizon include direct air capture (DAC), which removes CO2 directly from the atmosphere. It is estimated that up to 30,000 large DAC facilities would capture some 30 gigatons of CO2 per year. Virgin Atlantic is partnering with Storegga Geotechnologies and Carbon Engineering to accelerate the use of direct air capture of CO2.
Carbon capture utilization and storage (CCUS) is a technology that can capture up to 90% of the CO2 emissions produced from the use of fossil fuels in electricity generation and industrial processes.
Although technically feasible already, some argue that CCUS technology could facilitate a prolonged use of fossil energy, rather than pushing investment towards low carbon and renewable energy. The Intergovernmental Panel on Climate Change (IPCC) has, however, stated that CCUS will be critical to limit global warming and the International Energy Agency has indicated that CCUS could reduce global CO2 emissions by 19%.
Operations and infrastructure
Emissions reductions from operations and infrastructure efficiency may be relatively small compared with larger projects but they are usually quick to implement and can be significant in the near term. Already, operational and infrastructure efficiencies have resulted in a 55% improvement in fuel burn per passenger kilometer since 1990.
Retrofitting winglets enables airlines to save more than 4% in fuel, and reduce aircraft noise and NOx emissions, for example. Over 9,000 aircraft have been retrofitted, saving over 100 million tonnes of CO2 since 2000.
Airport improvements include:
- Fixed electrical ground power at gate
- Airport collaborative decision making
- Surface congestion management (reducing taxiing delays).
Even so, many operational improvements remain unrealized, particularly in the area of air traffic management (ATM). It is estimated that some 6%–10% of wasted emissions in Europe could be recovered through more efficient air traffic management. The Single European Sky initiative has made slow progress, however, stalled by institutional resistance and a lack of political leadership.
Similarly, NextGen in the United States could benefit from a faster rollout. Meanwhile, ICAO Aviation System Block Upgrades—a series of modernization projects—could deliver global fuel and CO2 savings of up to 3.0% in 2025 if blocks 0 and 1 are fully implemented.
Sustainable flights using the ideal trajectories and air traffic procedures are possible and there have been many demonstrations. Recently, British Airways flew a “perfect flight” that reduced CO2 emissions 62% compared with a previous perfect flight more than a decade ago. Such demonstrations prove what could be achieved with improved ATM.
New aircraft technologies
The overall fuel efficiency of the industry fleet is about 80% better than 50 years ago. Geared turbofan engines and further advances in design will drive a further 15%-25% fuel efficiency improvements over the next two decades.
But from the mid-2030s, radical new propulsion technologies and advanced designs promise even greater benefits. The first step is likely to be hybrid-electric concepts. When combined with a new airframe body, such as a blended wing, CO2 reductions of up to 40% are possible. Smaller, fully electric aircraft could also appear around this time. Norway has the goal of operating all domestic and short-haul flights electrically by 2040. Electric flights would completely eliminate CO2 emissions.
Hydrogen is another possibility. It is lighter than jet fuel but takes up much more space. Much larger tanks and fundamental changes in the aircraft fuel system are therefore needed. Entry into service is envisaged around 2035.
New airframe designs will need to be developed to realize the potential of new propulsion methods. A canard wing has the main wing being set further back behind small forewings. These could be in production from 2035-2040. A blended wing uses the entire plane to generate lift, enabling huge fuel savings. Strut or truss-braced wings would enable larger more efficient engines to be used, such as open rotors.
Both Airbus and Boeing are working on radical new designs as are other airframe manufacturers. Airbus has established a Wing of Tomorrow program.
“Wing of Tomorrow, a crucial part of Airbus’ R&T portfolio, will help us assess the industrial feasibility of future wing production,” says Sabine Klauke, Airbus Chief Technical Officer. “High-performing wing technology is one of several solutions—alongside sustainable aviation fuels and hydrogen—we can implement to contribute to aviation’s decarbonization ambition. Wing of Tomorrow is also an example of how large-scale industry collaboration will be critical to achieving our sector’s agenda for a more sustainable future.”