As we consistently face critical junctures in the battle against climate change, the aviation industry is no longer jetting off into the clear blue sky’s as it continues to emerge as a significant contributor to greenhouse gas emissions (GHG). Designated as a Scope 1 mobile source of GHG emissions by the EPA, the aviation industry is currently responsible for 25% of all transportation fuel consumption and 12% of transport source CO2 emissions1. Efforts to increase energy efficiency while reducing emissions via alternative fuels have been underway since 2011, but more so now than ever before as domestic and international travel demands continue to recover and surpass pandemic and pre-pandemic levels, leading to upticks in corporate and government investments in sustainable air fuel (SAF), the bio-based alternative to traditional jet fuel. The International Civil Aviation Organization (ICAO) defines SAF as a net GHG emission reduction fuel derived from non-petroleum feedstocks, while meeting ASTM fuel standards5. Its production and consumption patterns respect biodiversity and conservation of natural resources, contribute to supply chain development, and avoid competition with food and water sources. In lieu of traditional kerosene jet fuel, SAF could allow airliners and other aviation companies to reduce reducing life cycle carbon emissions by 80%, equivalent to 450 million tons in the coming years, contributing to sustainability while gaining a competitive edge in the global bioeconomy, but comes at a significant cost1.
In this comprehensive three-part article series, we will delve into the complex and nuanced world of SAF, exploring its potential to revolutionize commercial and private air transportation, the challenges and opportunities it presents, as well as its promising future as a dominant catalyst in our domestic and global bioeconomy.
The production of sustainable aviation fuel (SAF) is a challenging and intricate process facing various obstacles from a market perspective, predominantly as offtake volume agreements with member airlines continue to rise. 2021 SAF volume agreements leveled off near 9 billion liters, up from 415 million liters in 20202. Matching this pace of SAF demand coupled with high cost of production and limited availability is a significant hurdle for the aviation industry to clear if renewable jet fuel is to meet the 2050 goal deadline3 as there are not enough production facilities to meet the growing demand. This creates a supply-demand imbalance, inhibits cost parity, and further hinders its widespread adoption with prices up to eight times higher than standard fuel, presenting a significant challenge for airlines to justify its use in place of conventional Jet A fuel. In order to match this level of domestic and global SAF demand, one way is to maximize cost effectiveness of feedstock and their respective conversion methods6.
The conversion of biomass feedstocks into advanced biofuels requires complex chemical and biological processes that necessitate advanced technologies and infrastructure, which can be expensive to develop and maintain, but existing biomanufacturing plants contain necessary technologies that could also be applied to alternative bioprocesses.
One of the more pressing challenges facing the sustainable aviation fuel (SAF) supply chain is the issue of feedstock availability. SAF production relies on feedstocks derived from waste materials, crop residues, and dedicated energy crops, but as demand for SAF continues to grow, there is a risk of feedstock shortages, which could lead to price increases and supply chain disruptions. Moreover, advanced biofuels derived from cellulose, hemicellulose, lignin, sugar, starch, and waste materials, including food, animal, agricultural, and biomass, are generally more expensive to cultivate and process4.
An important consideration in assessing the viability of biofuels is the full fuel lifecycle, which encompasses all stages of biofuel production and distribution, including feedstock generation, extraction, distribution, and consumption. Using ethanol as a glaring example, this crop-based green fuel has been touted a promising drop-in blendstock additive due to its lower emissions profile but is unsuitable as an SAF component due to several factors. Ethanol has a lower energy density than conventional jet fuel, which limits SAF range and necessitates additional fuel for a given distance, potentially undermining the environmental benefits of using SAF. Additionally, ethanol is hygroscopic, increasing susceptibility to water absorption leading to issues such as the formation of ice crystals at high altitudes, potentially resulting in engine damage or failure7. The production of ethanol also involves the use of large amounts of crops, causing environmental degradation and loss in biodiversity. Several startup companies and government partnered institutions are researching and employing alternative conversion routes (we will touch more on this in our next article), but scaling science continues to be problematic.
Lastly, there is a lack of uniformity regarding international regulations for SAF, leading to different certification schemes and quality standards across different regions, stunting its development in the global market. The lack of regulatory framework also hinders operative consistency on the global scale, making it inherently difficult to create a stable market platform for biofuel. The regulatory certification processes that do exist to ensure the final product meets sustainability standards, is a complex pathway that costs a significant amount of time and capital especially for small-scale producers trying to penetrate the market. In terms of US domestic compliance, there is a system in place for biofuel certification, but it is costly and rather time-consuming. Certification from the Federal Aviation Administration (FAA) and meeting ASTM fuel standards are requisite for airplanes and jet engines to be used for commercial flight and must meet the definition of “advanced biofuel” established in the Clean Air Act in compliance with the EPA, which necessitates 50% or less measured GHG emissions in its baseline lifecycle5. Biofuel manufacturing also requires Original Equipment Manufacturing (OEM) led ASTM approval, which costs hundreds of millions taking up to seven years to complete the approval process. The fuel approval pathway follows a multi-tiered process to meet ASTM standards begins with the specification of the new fuel’s complete chemical makeup and determining its “fitness for purpose.” After successful preliminary screening, the fuel sample undergoes rig testing to meet manufacturer specifications and operability limits. Final testing is conducted using aircraft jet engines. However, because SAF is becoming a federal prioritization, BETO, FAA, and DOD have initiated expedited SAF screening and testing protocols for potential green gas blends with the help of a clearinghouse annex to reduce the overall time and cost needed for approval but is not enough to streamline SAF integration5.
Overall, the high cost of production, limited availability, lack of government incentives, and absence of a uniform regulatory framework are significant challenges that must be overcome to make SAF economically viable and widely adopted in the aviation industry. For the US to mitigate these challenges and risks, proactive engagement as well as industry stakeholder and policymaker collaboration is essential. As will the development of effective strategies and solutions for biomass availability and infrastructure, improving efficiency in SAF production processes, and promoting policies that support a stable and diversified SAF supply chain can safeguard long-term sustainability of the aviation industry and mitigate potential national security risks.
The biotech industry has encountered challenges stemming from excessive enthusiasm, resulting in companies being overvalued but underdelivering, with renewable biofuel as a frontrunner. Consequently, biotech’s highflyers with lofty valuations have been adversely affected by this trend with companies expending more resources than its market capitalization, illustrating this situation. Nonetheless, the industry has learned valuable lessons from its past mistakes, presenting an ideal opportunity to leverage new knowledge from past trial and error, and achieve a turning point. Early engagement with corporate entities in the renewable aviation fuel industry, such as the recent voluntary pledges announced by United Airlines and various aviation industry players aiming to promote climate-friendly air transport, is crucial to accomplish this goal. A Memorandum of Understanding between the US Department of Agriculture (USDA), the Department of Energy (DOE), and the Department of Transportation (DOT) recently announced the SAF Grand Challenge Roadmap to further support commitments to manufacture 100% sustainable fuel and integrate it as a primary fuel source, by assuring $1 billion in grant funding toward sustainable aviation aiming to rely entirely on biofuel rather than carbon offsets2. These organizations possess the manufacturing expertise necessary to comprehend scaling requirements and what is commercially viable. It is also crucial to pinpoint feasible targets that can be produced on par with commodity chemicals from the traditional chemical industry. The government must be aware of the manufacturing facilities, cost targets, and scaling objectives, which is why corporate involvement is indispensable. SAF currently does not receive the same level of government incentives and subsidies as other renewable energy sources, such as wind or solar. Without adequate policy support, the cost of production and distribution of SAF remains high, making it less competitive compared to conventional fuels. Corporations understand their costs, which is vital for formulating guidelines on cost and scale targets and clarifying objectives for startups.
By adopting this approach, we can effectively identify startups that may require more time to achieve success and implement strategies to expedite their path to success. Once success is attained, it will restore investor confidence, and private capital will become available when investors have trust in the industry. Therefore, establishing a public-private partnership is crucial to leverage both private and public resources to support early-stage businesses. Private capital plays a critical role in securing public and Federal capital for early-stage ventures. Moreover, the success of these early-stage ventures can create new opportunities for the government to access private capital. Currently, the aviation biofuel industry has faced few successes, leading to growing investor skepticism and reluctance to invest. Therefore, creating a public-private partnership is crucial to ensure that both sides are contributing to the industry’s growth. This collaborative effort will create a conducive platform for early-stage businesses to succeed while also attracting private capital to invest current and future ventures6.
In part two, we will examine the challenges companies and their new technologies address as they tackle and solve the issues of scalability, energy density and affordability. Learning from the both past failures and successes as they grow every closer to actual and substantual decarbonization and GHG emission reduction.
References
Direct Emissions from Mobile Combustion Source-
https://www.epa.gov/sites/default/files/2020-12/documents/mobileemissions.pdf
SAF Grand Challenge Roadmap-
https://www.energy.gov/sites/default/files/2022-09/beto-saf-gc-roadmap-report-sept-2022.pdf
FAA: 2021 Aviation Climate Action Plan-
https://www.faa.gov/sites/faa.gov/files/2021-11/Aviation_Climate_Action_Plan.pdf
Air Pollution Prevention & Control: Emission Standards For Moving Sources-https://uscode.house.gov/view.xhtml?req=(title:42%20section:7545%20edition:prelim)
US DOE: Sustainable Aviation Fuel Review of Technical Pathways-
https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf
Global Sustainable Aviation Fuel Market by Fuel Type-
https://www.researchandmarkets.com/reports/5178303/global-sustainable-aviation-fuel-market-by-fuel?utm_source=CI&utm_medium=PressRelease&utm_code=r4v99z&utm_campaign=1660395+-+The+Worldwide+Sustainable+Aviation+Fuel+Industry+is+Expected+to+Reach+%2415.7+Billion+by+2030+&utm_exec=jamu273prd
Turning Carbon Dioxide into Sustainable Fuel-
https://www.united.com/en/us/newsroom/announcements/united-and-oxy-low-carbon-ventures-announce-collaboration-with-biotech-firm-cemvita
The third wave of biomaterials: When innovation meets demand-
https://www.mckinsey.com/industries/chemicals/our-insights/the-third-wave-of-biomaterials-when-innovation-meets-demand
Aviation Emissions, Impacts & Mitigation: A Primer-
https://www.faa.gov/regulations_policies/policy_guidance/envir_policy/media/primer_jan2015.pdf
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