Since the dawn of the jet age in the 1960s, commercial aviation has grown dramatically. In 1960, there were about 7 million flights. Sixty years later, that number has grown to nearly 40 million flights.
In that timeframe, we have seen considerable improvements in airplane fuel efficiency, from 12 passenger-miles per gallon (20 liters per 100 passenger-kilometers) in 1960 to 58 passenger-miles per gallon (4 liters per 100 passenger-kilometers) in 2019.[1] Today, the average flight consumes about as much fuel per passenger-kilometer as driving alone in a hybrid-electric car.[2]
At the same time, total life-cycle emissions from aviation increased by a factor of 15 from 73 million tonnes of CO2 in 1960 to 1100 million tonnes in 2019. Despite dramatic improvements in energy efficiency, the amount of people flying has increased even faster.
Emissions intensity is a metric that is increasingly used to track aviation’s progress towards decarbonization goals because it captures the effects of fuel efficiency, as well as the carbon intensity of the fuels used by airplanes.
Looking at the history of emissions intensity in aviation, we see the same story as fuel efficiency—massive improvements, but still not enough to keep up with traffic growth. This is because the carbon intensity of aviation’s primary energy source—jet fuel— has stayed relatively constant over this time.
In Cascade, you can now explore how this metric changes when different sustainability strategies are applied to the aviation system. In addition, you can now compare the forecast emissions with real data on historical emissions from aviation dating back to 1960.
Looking towards 2050, we see opportunities to change this trend. The emissions intensity of aviation is expected to decrease through a combination of better fuel efficiency (resulting from improvements in aircraft technology and operational efficiency) and the introduction of low-carbon fuels.
A key element to decarbonizing aviation will be to transition from conventional jet fuel—derived from fossil fuels—to fuels derived from renewable energy. The plot below shows how conventional jet fuel could be displaced by Sustainable Aviation Fuel (SAF), hydrogen, and electricity in one scenario.
SAF has the potential to directly replace fossil-derived jet fuel and can be produced from renewable feedstocks such as waste fats, oils, and greases, agricultural wastes, and renewable electricity. Renewable electricity is used to produce green hydrogen via electrolysis of water. Whether green hydrogen is used to as a feedstock to produce SAF or used directly in hydrogen-powered aircraft, aviation is going to need a lot of it in the future.
This data shows us decarbonizing aviation will be a collective effort, requiring coordinated action across aviation, energy, policy, and finance to produce renewable fuels for aviation at scale.
Want to see how this works for yourself? Start by exploring Cascade’s insights on renewable energy, then build your own scenario to evaluate aviation’s demand for energy in the future.
