Skip to content

Category Archives: Sustainability & Innovation

Posted inEnvironment, Safety, Sustainability & Innovation

On the rise: Aviation’s Non-CO2 emissions   

Except for a handful of aviation academics and experts looking into the climate warming impact of non-CO2 emissions, the topic was largely avoided in the past decades. Now the issue is on the rise, and it is time to inform the sector 

The rise of Non-CO2 emissions 

In 2020, EASA kicked off the debate into non-CO2 in aviation by publishing “Updated analysis of the non-CO2 climate impacts of aviation and potential policy measures pursuant to EU Emissions Trading System Directive Article 30(4)[1]”. This sector report followed many years of research on non-CO2 emissions in aviation, describing the radiative forcing (ergo climate warming) impact of non-CO2, contrail modeling and warming impact assessment. The academic and EASA results show non-CO2 emissions warming impact may be equal to or even twice as high as CO2 emissions.   

In recent years, several EU research projects as well as contrail trials were set up by flight planner Flightkeys and network manager EUROCONTROL. Most recently, the topic has been picked up by EU legislators in the form of a heavily debated (and lobbied [2]) Monitoring, Reporting and Verification (MRV) framework. In the meantime, the academic front continued their research. Under leadership of the DLR, Imperial College, MIT and others, progress is being made on atmospheric physics that explains where contrails form, prediction; and mitigation strategies. Google Research is including satellite imagery data to further improve the models. (figure 1). Finally, Breakthrough Energy’s Reviate team is specializing in predicting contrail formation and has developed an interface to allow airlines to build contrail avoidance into their flight planning. 

Figure 1: Reviate Contrails map

Considering the recent action and new insights around the topic, many aviation stakeholders are likely (and rightly) wondering: “Is this relevant for me and if so, why?”. To answer that question, let’s first dive into what non-CO2 emissions are.

Contrail formation 

The main non-CO2 emissions from aviation in terms of climate warming impact, are nitrogen oxide (NOx) emissions, water vapor emissions, but above all formation of persistent contrails that contribute at least 86% of the total non-CO2 emissions in aviation. Contrails are cirrus clouds that form as a result of aircraft engine soot particle and water vapor emissions reacting with the water vapor in the atmosphere. These clouds can have both a cooling effect by reflecting sunlight, and a warming effect when they block heat radiating off the earth. The total warming effect is larger than the cooling effect. This leads to a net warming effect.

Figure 2: Contrail impact (Reviate)

Globally, only around 5% of all flights form over 80% of the warming contrails. Adjusting a small portion of flight operations could lead to a considerable reduction of warming impact. There are two main methods being advanced to reduce (warming) contrail formation. First is the use of alternative fuels that produce less soot and thereby less contrails, though the effect of this seems limited with current SAF targets [3]. The second method is the avoidance of contrails by adaptation of the flight path to avoid atmospheric areas that are prone to contrails (so called “ice super saturated regions”). This way, contrails are not formed regardless of the engine emissions. At To70 we have teamed up with Breakthrough Energy and several airlines and flight planners to work on contrail avoidance in the EU innovation fund application “Contrail Pilots”.

Airports

Although airports do not seem to have a significant role (yet), they are interested in the topic. For airports, non-CO2 emissions historically focus on local emissions (Particulate matter, nitrogen oxides) emitted during taxi, takeoff and landing. In a project To70 did for the Roundtable on sustainable biomaterials (RSB), we assessed the role of airports in reducing aviation non-CO2 emissions to improve local air quality and to reduce contrail formation. The key takeaways presented to RSB focused on (1) stakeholder engagement to increase the use of targeted SAFs, (2) identifying opportunities for optimal SAF supply chains and (3) the development of market shaping strategies that incentivize the use of SAF to reduce non-CO2 emissions. In terms of flight path or airspace changes, airports do not have a significant role as of yet though these are being explored. 

Air Navigation Service Providers

At first glance, ANSPs would seem to be the most impacted by non-CO2 emission mitigation strategies that involve adjusting the flight’s route and profile, as they govern airspace. They should be well informed on the topic and have a clear grasp of potential changes. However, recent developments and trials by flight planners show that pre-tactically changing flight plans to avoid ISSRs may be sufficient to reduce contrail formation. The ANSP or network manager would see incidental but high impact flight plan adaptations due to contrails mitigation but would not have to adapt their own systems. On the other hand, EUROCONTROL has run initial trials to reduce contrail formation through tactical adjustments of flights within the airspace rather than by the flight planner on the ground.

These strategies for airports, ANSPs and other aviation stakeholders are currently being further developed and tested. At To70, we see the need to inform stakeholders and support them in taking action to reduce non-CO2 emissions. Beyond our support to the EU MRV and airport non-CO2 insights, To70 is able to provide knowledge on environmental impacts of non-CO2 emissions as well as knowledge on the practical implementation of mitigation strategies. We can provide this from an operational airport, airline, government policy and ANSP perspective. We look forward to reducing non-CO2 emissions together with the sector.  


[1] Updated analysis of the non-CO2 climate impacts of aviation and potential policy measures pursuant to EU Emissions Trading System Directive Article 30(4) – Report from the Commission to the European Parliament and the Council | EASA (europa.eu)

[2] Airlines divide over new EU rules on monitoring and reporting of their non-CO2 emissions – GreenAir News

[3] Teoh, Roger, et al. “Targeted use of sustainable aviation fuel to maximize climate benefits.” Environmental Science & Technology 56.23 (2022): 17246-17255.


Ream more Articles and News

Posted inEnvironment, Strategy, Sustainability & Innovation

Airports as Catalysts: Driving SAF Adoption Through Incentive Funds 

In an era marked by global efforts to combat climate change, the aviation industry faces growing scrutiny. Forecasts predict a substantial increase in passenger air travel in the coming years, amplifying concerns over the industry’s carbon emissions and underscoring the need for immediate action. This is where Sustainable Aviation Fuel (SAF) emerges as a groundbreaking solution to mitigate carbon emissions in aviation. Given that SAF can substantially reduce carbon emissions by up to 80% throughout its lifecycle compared to traditional jet fuel[1], airport incentives are needed to drive the production and adaption of SAF. 

Airports, acting as critical hubs within the aviation ecosystem, have a pivotal role in facilitating the availability and uptake of SAF. One powerful mechanism adopted by several airports is the SAF Incentive Fund, a strategic initiative designed to bridge the price gap between SAF and traditional jet fuel for airlines. The comprehensive details of the SAF Incentive Fund are outlined in the SAF Catalogue, a collaborative effort led by Stargate, To70, the University of Hasselt, and supported by Brussels Airport Company. 

How the SAF Incentive Fund works 

The SAF Incentive Fund is typically set up by the airport authority, often in collaboration with industry partners or stakeholders. The specific subsidy amount is determined based on various factors, including the type of SAF (e.g., biofuels or synthetic e-fuels), the current market price of SAF, and the fund’s available resources. 

Airlines that choose to refuel with SAF at the airport can apply for subsidies from the SAF Incentive Fund. This application process typically involves providing details about the SAF purchase, including the quantity, type of SAF, and associated costs. 

Once the application is approved and the subsidy amount is determined, the airport disburses the subsidy to the airline. This can be done in various ways, such as providing a fixed amount or a percentage of the price difference between SAF and traditional jet fuel. 

By doing so, the financial assistance effectively reduces the net cost of SAF for the airline, making it more economically viable compared to traditional jet fuel. 

Leading Airports in Establishing SAF Incentive Programs 

Several leading airports like Schiphol, Swedavia, Heathrow, Dusseldorf, and Milan have already taken action by establishing SAF Incentive Funds to accelerate the aviation industry’s transition to sustainable practices. 

Impact of SAF Adoption at Leading Airports 

In 2022, Heathrow became the first airport globally to launch a SAF Incentive Program that covers up to 50% of the extra cost of SAF, thereby reducing its financial burden on airlines. Heathrow now has set an ambitious objective to triple the percentage of SAF used at the airport in 2023 to approximately 1.5% and become one of the world’s leading airport users of SAF[2]. 

Furthermore, at Schiphol Airport, when airlines refuel with SAF, they receive subsidies of €500 per metric tonne of SAF (biofuels) and €1,000 per metric tonne of e-fuels (synthetic kerosene). To ensure a sufficient supply of SAF, Schiphol supported Neste (their SAF supplier) in acquiring a share of AFS (the fuel distributor at the airport). While Neste’s current production sits at 100,000 tonnes, the company has ambitious plans to scale up output in Rotterdam and Singapore to 1.5 million tonnes[3] 

These examples illustrate how airports can utilize financial incentives to stimulate SAF production. Such actions send a clear market signal about SAF’s crucial role in the long-term decarbonization of aviation. In addition, they encourage investments that can enhance production volumes and subsequently reduce costs.  

Taking Action as an Airport 

The growing number of airports joining SAF Incentive Funds reflects a rising commitment among airports to take a leading role in sustainability. However, many airports often lack clarity on the specific steps required to establish such initiatives. To address this need, we provide guidance on the SAF incentives as described in the Stargate SAF Actions Catalogue to efficiently kickstart a SAF Incentive Program.  

The following figure shows the step-wise approach: 

  1. First, the airport selects a funding mechanism from a variety of choices, as depicted in the first step of the figure, to generate revenue for the SAF fund. 
  2. Next, the airport establishes the conditions for the size of the SAF fund. These may be influenced by airport-specific factors, such as annual fuel consumption, as well as price-related factors like the market price of Jet A1. 
  3. Finally, airlines can apply for the SAF fund, and the airport grants the subsidy by covering a portion of the SAF premium expenses.  

By following these steps, airports can establish a fund to stimulate SAF adoption on their premises. To70 can support airports to apply these steps within their own unique context, – and provide analysis and eventual testing and implementation. By doing so, airports can use their unique infrastructure position and promote sustainable practices among relevant stakeholders. 


[1] Jiang, C., & Yang, H. (2021). Carbon tax or sustainable aviation fuel quota. Energy Economics, 103, 105570. 


Check out our open vacancies around the globe!