The Altitude Carbon Protocol introduces a certification framework to advance carbon neutrality within the aviation sector. This initiative establishes a comprehensive approach to account for and mitigate CO2 emissions across the entire lifecycle of fossil-based aviation fuels, ensuring robust decarbonization aligned with global sustainability goals.

Permanent carbon dioxide removal (CDR) will play a limited but essential role in achieving net-zero emissions, as some emissions are technically impossible to eliminate. For a small portion of these emissions, CDR presents the most cost- and resource-efficient mitigation strategy. While aviation is frequently highlighted as a key sector for CDR application, current political strategies and industry roadmaps largely focus on sustainable aviation fuels (SAF) as the primary solution.

The cost competitiveness of electro fuels/Biofuels depends heavily on two factors: fossil fuel prices and electricity costs. Electro fuels require substantial amounts of hydrogen, consuming seven times more electricity than the BAU+DACCS scenario. Cost parity with BAU+DACCS is achieved only when fossil fuel prices rise significantly or electricity costs drop to exceptionally low levels. Conversely, high electricity prices or low fossil fuel prices favor the BAU+DACCS pathway.

Bio-jet fuels are generally more cost-effective than electro fuels, with the most affordable option being HEFA (Hydro processed Esters and Fatty Acids), derived from fats. In many scenarios, HEFA is less expensive than the BAU+DACCS approach. However, its potential to replace conventional jet fuel is significantly limited by feedstock availability.

Other biofuel pathways, such as gasification of municipal solid waste and ethanol-to-jet conversions, are either comparable in cost to the BAU+DACCS model or more expensive. Additionally, biofuels carry potential drawbacks, including emissions from land-use changes and risks of land grabbing. Currently, bio-SAF production accounts for just 0.2% of global jet fuel consumption. Even with full utilization of all available biofuel production methods, electrofuels or carbon dioxide removal (CDR) technologies would still be required to address the significant remaining gap.

Beyond cost, feasibility and resource requirements must also be considered. Scaling up zero-emissions electricity for electrofuel production poses significant challenges. Despite improved efficiency, electrofuels demand 9,000–10,500 kWh per tonne of CO₂. Replacing just one-third of current aviation fuel with electrofuels would require over 2,500 TWh annually—equivalent to 10% of global electricity consumption. By comparison, neutralizing the same emissions with DACCS would require 410 TWh. It’s worth noting that DACCS is just one of several permanent CDR methods, but it is used here for comparison.

Currently, most aviation decarbonization pathways primarily rely on sustainable aviation fuels (SAFs), with carbon dioxide removal (CDR) playing a minor role. For instance, the International Air Transport Association (IATA) roadmap assumes 100% SAF usage, incorporating CDR solely to offset lifecycle emissions from biofuels and non-zero-emission electricity. The European Union has set ambitious SAF targets, requiring 2% of aviation fuel to be SAF by 2025 and 70% by 2050.

The optimal aviation decarbonization strategy will likely involve a balanced mix of sustainably and cost-competitively produced biofuels, with the remainder of fuel consisting of fossil jet fuel offset by permanent carbon dioxide removal (CDR). Additional measures such as efficiency improvements and demand reduction, for example through the expansion of high-speed rail networks, will also play crucial roles. Electric planes could address short-distance flights, while power-to-liquid electrofuels might gain prominence if more resource-efficient production methods are developed, abundant low-cost electricity becomes available, or fossil jet fuel production becomes significantly more expensive.

This approach suggests that airlines are not ideal candidates for standard Science-Based Targets initiative (SBTi) net-zero frameworks, which limit the use of CDR to offset only the last 10% of emissions. Reductions achieved through expensive alternative fuels with substantial energy demands are not inherently superior to carbon removal strategies.

The Clean Flight Protocol provides a meticulous accounting system that encompasses all emissions—from crude oil extraction and refining to fuel combustion in aircraft engines. The certification requires a full lifecycle assessment (LCA), integrating both CO2 and non-CO2 greenhouse gasses such as methane and nitrous oxide. This approach ensures comprehensive monitoring and management of emissions to uphold the highest standards of environmental accountability.

To neutralize the carbon footprint of fossil-based kerosene, Clean Flight Protocol employs verified carbon removal credits generated from diverse activities proven to sequester atmospheric CO2 effectively. These credits undergo rigorous validation to guarantee long-term carbon storage, safeguarding the integrity of offset claims and ensuring their compatibility with regulatory frameworks such as the forthcoming EU Carbon Removal Certification Framework.

The Altitude Carbon Protocol represents an advancement in aviation transition to sustainability. By enabling the certification and trade of sustainable aviation fuel (SAF) credits in open markets, the protocol empowers industry stakeholders to immediately contribute to decarbonization. This initiative reflects international best practices and reinforces the aviation sector's commitment to climate action.

Altitude invites feedback from stakeholders through an open public consultation process to ensure the protocol remains dynamic, inclusive, and effective in addressing the challenges of sustainable aviation. This collaborative effort underscores Altitude 's commitment to driving innovation and setting a benchmark for environmental integrity in the industry.