Leeham News and Analysis
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Leeham News and Analysis
- AIN Media Group Agrees to Acquire Leeham News & Analysis June 17, 2025
- Five for Five: Air India crash points to systemic problems at Boeing that CEO Ortberg must fix June 15, 2025
- Airbus sees Boeing as medium-term competitor, with Comac next June 14, 2025
- Boeing bullish on 20-year forecast, despite short-term headwinds June 14, 2025
- Embraer’s 20-year market forecast under 150 seats: fewer turboprops, jets about the same June 14, 2025
Bjorn’s Corner: Air Transport’s route to 2050. Part 26.
By Bjorn Fehrm
June 13, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We have examined different ways to lower global warming over the course of the series. Over the last weeks, we have summarized what practical results we can expect from the different alternatives we have to reduce global warming from Air Transport. We looked at the following alternatives:
Bjorn’s Corner: Air Transport’s route to 2050. Part 25.
By Bjorn Fehrm
June 6, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We examined alternative, lower-emission propulsion technologies four weeks ago and compared them the following week to the industry’s typical improvement in fuel consumption over time. Then, we examined the improvements that SAF can offer by 2050. Last week, we complemented the picture with the different Emission Trading Schemes (ETS) that exist globally.
Now, we discuss what warming contrail avoidance could achieve in reducing global warming.
Figure 1. A summary of the CO2 and non-CO2 Effective Radiative Forcing (ERF = warming effect) contributions from Air Transport. Source: The report “The contribution of global aviation to anthropogenic climate forcing for 2000-2018” by Lee et al. (2021)
Bjorn’s Corner: Air Transport’s route to 2050. Part 23.
By Bjorn Fehrm
May 23, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We have since we started in October last year looked at:
- Alternative, lower emission, propulsion technologies, ranging from electric aircraft with batteries as energy source, different propulsion hybrids, and new concepts for Jet-Fuel and Hydrogen gas turbine engines.
- We have also looked at recent research into the role of CO2, NOx emissions and Contrails generated by airliners.
- Three weeks ago, we summarized the present situation around SAF, Sustainable Aviation Fuel.
We examined Alternative 1’s emissions improvement two weeks ago and compared it to the normal improvement in new airliners’ fuel consumption last week. Now, we examine the improvement that SAF can offer compared to the other two.
Bjorn’s Corner: Air Transport’s route to 2050. Part 22.
By Bjorn Fehrm
May 16, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We have since we started in October last year looked at:
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- Alternative, lower emission propulsion technologies, ranging from electric aircraft with batteries as energy source, different propulsion hybrids, and new concepts for jet-fuel and Hydrogen gas turbine engines.
- We have also reviewed recent research on the role of CO2, NOx emissions, and Contrails generated by airliners.
- Two weeks ago, we summarized the present situation around SAF, Sustainable Aviation Fuel.
We examined Alternative 1’s emissions improvement last week and now compare it to the normal improvement in fuel consumption, and thus emissions, that the airline industry is continuously working on.
Bjorn’s Corner: Air Transport’s route to 2050. Part 21.
By Bjorn Fehrm
May 9, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
Since we started in October last year, we have looked at:
- Alternative, lower emission propulsion technologies, ranging from electric aircraft with batteries as energy source, different propulsion hybrids, and new concepts for Jet-fuel and Hydrogen gas turbine engines.
- We have also reviewed recent research on the role of CO2, NOx emissions, and Contrails generated by airliners in global warming.
- Two weeks ago, we summarized the present situation around SAF, Sustainable Aviation Fuel.
Last week, we listed some base data about the present situation for Global Air Transport. We will now use this data to calculate the effect of air transport on global warming from the three alternatives.
Bjorn’s Corner: Air Transport’s route to 2050. Part 20.
By Bjorn Fehrm
May 2, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We have since we started in October last year looked at:
- Alternative, lower emission, propulsion technologies, ranging from electric aircraft with batteries as energy source, different propulsion hybrids and new concepts for Jet-fuel and hydrogen gas turbine engines.
- We have also reviewed recent research on the role of CO2, NOx emissions, and Contrails generated by airliners.
- Last week, we summarized the present situation around SAF, Sustainable Aviation Fuel.
Before we proceed, we shall examine some facts about the scale of the emission/global warming influences from Air Transport.
Figure 1. A picture of global Air Transport flying different routes. Source: Flightradar24.
Bjorn’s Corner: Air Transport’s route to 2050. Part 19.
By Bjorn Fehrm.
April 25, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
Over the last Corners, we examined the non-CO2 effects of Air Transport that contribute to global warming. Contrails had the largest effects, even larger than the CO2 emissions from Air Transport.
To complete the review of our progress with lower emission actions for Air Transport, we will examine the present situation with SAF, Sustainable Aviation Fuel.
Figure 1 The main production pathways to SAF. Source: Clean Skies for Tomorrow report. Click to enlarge.
Bjorn’s Corner: Air Transport’s route to 2050. Part 17.
By Bjorn Fehrm
April 11, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We now examine the non-CO2 effects of Air Transport that contribute to global warming. Of these, contrails have the largest impact, Figure 1.
In the last Corner, we described encouraging results from airline flight trials with warming contrail avoidance. What is required to move from trials to warming contrail avoidance for regular flights?
Figure 1. A summary of the CO2 and non-CO2 Effective Radiative Forcing (ERF) contributions from Air Transport. Source: The report “The contribution of global aviation to anthropogenic climate forcing for 2000-2018” by Lee et al. (2021).
Bjorn’s Corner: Air Transport’s route to 2050. Part 16.
By Bjorn Fehrm
April 4, 2025, ©. Leeham News: We do a Corner series about the state of developments to improve the emission situation for Air Transport. We try to understand why development has been slow.
We now examine the non-CO2 effects of Air Transport that contribute to global warming. Of these, contrails have the largest impact.
Contrails form when aircraft gas turbine engines emit soot particles into water vapor-saturated areas with low temperatures, where the soot particles act as condensation nuclei and the droplets freeze into ice crystals.
The report from Lee et al. (2021) lists non-CO2 effects as more important for Global Warming from Air Transport than CO2 emissions from burning hydrocarbon fuels, Figure 1.
Figure 1. A summary of the CO2 and non-CO2 Effective Radiative Forcing (ERF) contributions from Air Transport. Source: The report “The contribution of global aviation to anthropogenic climate forcing for 2000-2018” by Lee et al. (2021).
Bjorn’s Corner: Air Transport’s route to 2050. Part 14.
By Bjorn Fehrm
March 21, 2025, ©. Leeham News: We do a Corner series about the state of developments to replace or improve hydrocarbon propulsion concepts for Air Transport. We try to understand why development has been slow.
Last week, we examined MTU’s WET engine concept, which utilizes a water capture process in a Turbofan to lower emissions, such as NOx, and reduce the water content in the exhaust, thereby reducing contrail risk. The week before, we looked at a similar concept, focused on a hydrogen burn process from Pratt & Whitney called HySIITE.
Both concepts capture water in the turbofan’s exhaust and can then release it in a way that avoids contrail generation. Contrails have garnered significant attention in recent years, as research has raised the possibility that persistent contrails can contribute as much or more to global warming than the CO2 released during the Turbofan combustion process in an airliner.
We will spend the next Corners digging deeper into the question of air transport’s non-CO2 effects that contribute to global warming. Contrails have the largest impact on these non-CO2 contributions.
Figure 1. The complex interaction of different heat radiation and blocking processes in our atmosphere. Source: The report “The contribution of global aviation to anthropogenic climate forcing for 2000-2018” by Lee et al.