When giants fall: A multi-lens case study on the Airbus A380’s market exit amidst the rise of sustainable twinjets

Aligning sustainable aviation fuel research with sustainable development goals: trends and thematic analysis

Sustainable Aviation Fuel (SAF) has risen as a key saving grace for the airline industry to mitigate emissions and help achieve its sustainability goals. However, although SAF has several environmental values, the procurement of SAF on a large-scale encounter various challenge. Such challenges are high production costs, scarce feeder stock, technical matters, supply chain issues, and regulatory aspects. SAF production calls for a large amount of investment funds to be spent on infrastructure, technologies of research and development, and the cutting-edge refining technologies, which at the moment preclude the application of the product on a large scale and render the product prohibitively expensive if compared to the conventional jet fuel. Moreover, the fragmented environment of the regulatory landscape in different regions increases uncertainties in long-term procurement agreements and obstructs the regulatory Climate for SAF at the global level. Nevertheless, there are possible ways to meet these challenges. More synergies among governments, airlines, fuel manufacturers, and technology providers, coupled with rewards and policy advocates, can bring about this change. Also core to meeting these procurement challenges are improved production technologies, scaling up of SAF production facilities, and standardization of certification processes. With these challenges, the future of SAF procurement is looking bright, with possibilities of lower cost and greater availability as technology advances and regulations consider sustainable aviation practices more favorable. This paper identifies the key issues in SAF procurement, offers solutions to these barriers, and makes room for a sustainable and economically viable future for aviation fuel.

Sustainable aviation fuels (SAFs) are currently considered a key element in the decarbonization of the aviation sector, offering a feasible solution to reduce life cycle greenhouse gas emissions without requiring fundamental changes in aircraft or infrastructure. This article provides a comprehensive overview of the current state of SAFs, including their classification, production technologies, economic aspects, and environmental performance. The analysis covers both currently certified SAF pathways, such as HEFA and FT-SPK, and emerging technologies like alcohol-to-jet and power-to-liquid, assessing their technological maturity, feedstock availability, and scalability. Economic challenges related to high production costs, investment risks, and policy dependencies are discussed, alongside potential mechanisms to support market deployment. Furthermore, the article reviews SAFs’ emission performance, including CO2 and non-CO2 effects, based on existing life cycle assessment (LCA) studies, with an emphasis on variability caused by feedstock type and production method. The findings highlight that, while SAFs can significantly reduce aviation-related emissions compared to fossil jet fuels, the magnitude of benefits depends strongly on supply chain design and sustainability criteria. There are various certified pathways for SAF production, as well as new technologies that can further contribute to the development of the industry. Properly selected biomass sources and production technologies can reduce greenhouse gas emissions by more than 70% compared to conventional fuels. The implementation of SAFs faces obstacles related to cost, infrastructure, and regulations, which hinder its widespread adoption. The study concludes that although SAFs represent a promising pathway for aviation climate mitigation, substantial scaling efforts, regulatory support, and continued technological innovation are essential to achieve their full potential.

The cost of sustainable aviation fuel (SAF) is approximately 2-3 times that of fossil jet fuel, which severely restricts the promotion of SAF. Among the SAF production processes certified by industry standards, the Fischer-Tropsch (F-T) and Hydroprocessed Esters and Fatty Acids (HEFA) processes achieve the highest commercial promotion potential. Based on life cycle assessment and techno-economic evaluation, the possibility of SAF competing with fossil jet fuel at near-equal or near-price parity was investigated, considering the sustainability advantages of SAF. The Danish EDIP environmental assessment method was adopted to quantitatively evaluate seven types of environmental impact factors throughout the life cycle of bio-jet fuel produced by FT and HEFA. The results showed that the CO 2 emissions of F-T and HEFA mainly occurred in the production stage, accounting for as high as 89.12%, while emissions in the stages of agricultural and usage were relatively small, accounting for only 8.41% and 2.46%, respectively. The top three environmental impact characterization indicators were eutrophication potential (EP), global warming potential (GWP), and acidification potential (AP). In terms of energy consumption, the demand for primary energy mainly occurred in the usage stage of jet fuel, which was significantly different from the distribution characteristics of other pollutants. To produce 1 kg of jet fuel, the F-T and HEFA processes required 10.36 kg and 4.36 kg of raw materials, respectively. The costs were 11,066 CNY/ton and 8,430 CNY/ton, respectively. Considering fuel taxes, carbon taxes, and carbon trading, the SAF blending ratio ranged from 0% to 100%, and the fuel cost of airlines increased with the increase in the blending ratio. The fuel cost of airlines using 100% SAF was approximately 1.4 times that of fossil jet fuel, while the SAF price was 1.5 times that of fossil jet fuel.

Life Cycle emission of selected Sustainable Aviation Fuels – A review

As the regulations related to greenhouse gases (GHG) emissions from fuel become stricter, fundamental changes are being effectuated to achieve the Paris Agreement agenda. Since the aviation sector contributes to 2.5 % of the global CO2 emission, it is imperative to tackle this conundrum imminently by reducing the CO2 emission from commercial flights, which are the main contributors to CO2 emission in the aviation sector. Sustainable aviation fuel (SAF) has garnered tremendous attention in achieving carbon neutrality in the aviation sector. SAF is a suitable alternative since little to no modification of the aircraft is required for SAF usage. There are many challenges when it comes to implementing the use of SAF, including the large-scale production of SAF and the cost associated with the production of SAF. Therefore, this paper aims to provide an overview of various factors related to the global implementation of SAF, considering the latest supporting policy frameworks and from the perspective of feedstock. It examines how existing SAF pathways contribute to large-scale production and explores the role of emerging technologies—from potential feedstocks to the latest advancements. The paper delves into several emerging technologies, including hydrothermal liquefaction, aqueous phase reforming, pyrolysis, and photofermentation, discussing their potential in SAF production and the challenges they present. Furthermore, this paper analyses the life cycle assessment (LCA) and the techno-economic analysis (TEA) of different feedstocks and processes for SAF production.

It is recognized that Sustainable Aviation Fuels (SAF) will play a significant role in the decarbonization of air mobility and various pathways and feedstocks are considered for their production. This may lead to differences in chemical and physical properties when compared to conventional, fossil, aviation fuel (CAF). SAF available today are blended with CAF and after blending they are compliant with the Jet Fuel norm (ASTM1655). But the goal of achieving 100% SAF could be problematic, as the absence of aromatics, one of the characteristics of SAF produced today, could lead to leaks in the seal. Adding renewable aromatics (Synthesized Aromatic Kerosene, or SAK) to the SAF is therefore seen as an opportunity to reach 100% SAF without impacting the aircraft and airport’s fuel infrastructures, potentially enabling a faster decarbonization of the sector. In this study, we have compared the emissions of a 100% SAF which contains 9% of SAK issued from the biomass (SAF-SPK/A) with a CAF. Performance and behavior: The tests did not identify any performance differences between the two fuels, including turbine reactivity and equipment degradation. This was later confirmed by Bell Helicopter during an experimental test flight campaign. Emissions: the lower CO2 impact is mainly due to the life cycle analysis of the SAF, but the test also showed reduced CO2 emissions during the combustion. While NO and NOx were found equivalent, significant reduction in CO and soot (Smoke Number, SN) were measured: −20 to −50% depending on the mass fuel flow. These improvements could be explained by the lower content of aromatics as well as the nature of these aromatics and this will be further investigated in future studies.

Evaluation of performance variables to accelerate the deployment of sustainable aviation fuels at a regional scale

The growing demand for air connectivity, coupled with the forecasted increase in passengers by 2040, implies an exigency in the aviation sector to adopt sustainable approaches for net zero emission by 2050. Sustainable Aviation Fuel (SAF) is currently the most promising short-term solution; however, ensuring its overall sustainability depends on reducing the life cycle carbon footprints. A key challenge prevails in hydrogen usage as a reactant for the approved ASTM routes of SAF. The processing, conversion and refinement of feed entailing hydrodeoxygenation (HDO), decarboxylation, hydrogenation, isomerisation and hydrocracking requires substantial hydrogen input. This hydrogen is sourced either in situ or ex situ, with the supply chain encompassing renewables or non-renewables origins. Addressing this hydrogen usage and recognising the emission implications thereof has therefore become a novel research priority. Aside from the preferred adoption of renewable water electrolysis to generate hydrogen, other promising pathways encompass hydrothermal gasification, biomass gasification (with or without carbon capture) and biomethane with steam methane reforming (with or without carbon capture) owing to the lower greenhouse emissions, the convincing status of the technology readiness level and the lower acidification potential. Equally imperative are measures for reducing hydrogen demand in SAF pathways. Strategies involve identifying the appropriate catalyst (monometallic and bimetallic sulphide catalyst), increasing the catalyst life in the deoxygenation process, deploying low-cost iso-propanol (hydrogen donor), developing the aerobic fermentation of sugar to 1,4 dimethyl cyclooctane with the intermediate formation of isoprene and advancing aqueous phase reforming or single-stage hydro processing. Other supportive alternatives include implementing the catalytic and co-pyrolysis of waste oil with solid feedstocks and selecting highly saturated feedstock. Thus, future progress demands coordinated innovation and research endeavours to bolster the seamless integration of the cutting-edge hydrogen production processes with the SAF infrastructure. Rigorous techno-economic and life cycle assessments, alongside technological breakthroughs and biomass characterisation, are indispensable for ensuring scalability and sustainability.

Ambitious fossil-free targets imposed on the aviation industry worldwide demand a large volumetric supply of sustainable aviation fuel (SAF) to meet. Sweden's commitment to a 30% volume SAF blending target by 2030 attracts interest in local production. However, the sustainability of local production is largely unknown. Addressing this gap, we aim to explore potential SAF technology pathways and assess their environmental performances in Sweden. To do so, we utilize a socio-technical system (STS) approach for pathways selection and prospective life cycle assessment (LCA) for environmental impact assessment. As a result, we identify two lignocellulosic-based and two electrofuel-based pathways and evaluate their global warming potential, mineral depletion potential, ionizing radiation, land use, freshwater ecotoxicity and human toxicity impact in comparison to jet fuel. Our findings show that the well-to-wake global warming potential (100 years) of 30% SAF is on average 20% lower than that of jet fuel, with non-carbon dioxide species emitted in flight being the major contributors, prompting the need for urgent research efforts to mitigate their potential impacts. Under the assumption that no burdens are allocated to waste material used as feedstock, lignocellulosic-based 100% SAF has a well-to-pump climate impact (100 years) ranging from 0.6 to 1.5 g CO2−eq/MJ compared to jet fuel's 10.5 g CO2−eq/MJ. In contrast, the well-to-pump climate impact (100 years) of electrofuel-based 100% SAF (ranging from 7.8 to 8.2 g CO2−eq/MJ) is only marginally lower than that of jet fuel, mainly attributed to emissions from steel and concrete produced for wind turbine manufacturing. In general, the use of electricity generated by wind power could shift the potential environmental burden associated with jet fuel from global warming to mineral depletion, land use, freshwater ecotoxicity and human toxicity. The STS approach underscores the need to prioritize changes in systems underpinning SAF production, in turn supporting policy and investment decision making.

With demand for jet fuel expected to more than double by 2050 and triple by 2070, continued and accelerated efforts to decarbonize the global aviation sector are needed to curtail rising emissions and avert the worst outcomes of climate change. In response to this call-to-action, the United States has unveiled the Sustainable Aviation Fuel (SAF) Grand Challenge, which seeks to expedite the development of alternative fuel pathways that offer a minimum of a 50% reduction in life cycle greenhouse gas emissions compared to conventional jet fuel. However, there is growing concern on whether sufficient biomass will be readily available to satisfy the projected sharp rise in demand for SAF. Carbon dioxide point-source emissions combined with rising supply from direct air capture efforts have the potential to complement and offset any supply gaps for biomass-derived SAF and other use cases. Independent of the chosen feedstock and conversion technology, numerous challenges persist across SAF production in seeking to drive down fuel cost and carbon intensity. To hit the 2030 target of 3 billion gal/yr, this means about a 100% compound annual growth rate in volumetric SAF production (about 130 times scale-up) will need to be realized. To achieve the stretch goal of 35 billion gallons of SAF per year by 2050, volumetric production must increase by a factor of 12 from the 3-billion-gal/year 2030 target of SAF Grand Challenge. The comparatively longer runway for 2050 combined with significant production volume growth suggests a more inclusive "all-hands-on-deck"-style approach will likely play a role. A key component in success lies in the coordinated research, development, demonstration, and deployment efforts by multiple federal agencies and industry partnerships.

The aviation industry is a major contributor to greenhouse gas emissions, responsible for approximately 2% of global emissions. Sustainable Aviation Fuel (SAF), if produced from renewable or waste-based feedstocks, can reduce greenhouse gas emissions by up to 80% compared to traditional jet fuels. The push towards SAF is not the only response to the growing environmental concerns but is also a result of stringent regulations set by entities such as the EU commission. The aim of the paper is to analyse the SAF supply challenges and the current policy frameworks to incentivise supply of SAF. This analysis reviews the supply from a regulatory and industrial production policy perspective, both against the EU mandates of SAF (Refuel EU) and the proposed use of SAF (e.g., CORSIA/ETS). Further literary analysis explores why a supply gap arises. The role of technology and the need for a standardised method for measuring the life cycles of energy conversions are also important factors for increasing SAF supply. The paper concludes with policy recommendations.

The production of biomass‐based sustainable aviation fuel (SAF) is gaining traction to reduce the carbon footprint of the aviation sector. We performed a techno‐economic analysis to estimate the break‐even price and life cycle carbon emissions of the SAF derived from carinata (Brassica carinata) in the Southeastern United States. Carinata has the potential as a feedstock for SAF production in the selected region due to higher yield, low fertilizer use, co‐product generation (animal feed, propane, and naphtha), and compatibility with current farming practices. The system boundary started at the farm and ended when the SAF is delivered to an airport. Without co‐product credit or other subsidies such as Renewable Identification Number (RIN) credit, carinata‐based SAF was more expensive ($0.85 L−1 to $1.28 L−1) than conventional aviation fuel ($0.50 L−1). With co‐product credit only, the break‐even price ranged from $0.34 L−1 to $0.89 L−1. With both co‐product and RIN credits, the price ranged from ‐$0.12 to ‐$0.66 L−1. The total carbon emission was 918.67 g CO2e L−1 of carinata‐based SAF. This estimate provides 65% relative carbon savings compared with conventional aviation fuel (2618 g CO2e L−1). Sensitivity analysis suggested a 95% probability that relative carbon savings can range from 61% to 68%. Our study indicates that carinata‐based aviation fuel could significantly reduce carbon emissions of the aviation sector. However, current policy support mechanisms should be continued to support manufacturing and distribution in the Southeastern United States.

Sustainable Aviation Fuel (SAF) has emerged as a pivotal solution for decarbonizing the aviation sector, which contributes 2-3% of global CO₂ emissions. SAF, derived from renewable feedstocks such as waste oils, agricultural residues, and synthetic fuels, can reduce lifecycle greenhouse gas (GHG) emissions by up to 80% compared to conventional jet fuel. However, its production and supply face significant economic and sustainability challenges, including high costs, limited feedstock availability, and scalability issues. This research employs Life Cycle Assessment (LCA) and Techno-Economic Analysis (TEA) to evaluate the environmental and economic viability of SAF production pathways. Key findings reveal that feedstock selection and conversion technologies significantly influence SAF's carbon footprint and cost competitiveness. While waste-based feedstocks and advanced pathways like Power-to-Liquid (PtL) offer substantial GHG reductions, their high production costs and infrastructure requirements remain barriers to widespread adoption. Policy mechanisms such as tax credits, carbon pricing, and blending mandates are essential to bridge the cost gap and incentivize SAF production. Additionally, industry collaboration and technological innovation are critical for scaling SAF production and integrating it into existing supply chains. This study underscores the need for a holistic approach, combining robust policy frameworks, sustainable feedstock sourcing, and cross-sector partnerships, to align SAF production with U.S. decarbonization goals and accelerate the transition to a low-carbon aviation sector. Future research should focus on optimizing feedstock logistics, advancing conversion technologies, and assessing the long-term impacts of policy incentives to ensure the economic and environmental sustainability of SAF.

The use of sustainable biofuels in the aviation sector with correspondingly high reduction in specific GHG emissions will make an important contribution to reducing GHG emissions from air traffic. It is expected that airports in Europe will be supplied with JET A-1 blends that also contain various types of sustainable aviation fuels (SAF) in variable proportions (“multiblend”). This article presents the results of a study assessing the environmental impact of various sustainable aviation fuels (SAF) and multiblends, including all relevant parts of their value chains, starting from SAF production to mixing of different SAF with conventional JET A-1 and finally the use of the produced multiblend. The results of the life cycle assessment indicated that the production of some SAF caused less GHG emissions than others due to the use of waste or residues as SAF feedstock or the use of by-products to meet the internal process energy demand. A detailed assessment of GHG emissions of the studied multiblend JET A-1 showed a reduction in greenhouse gas emissions of up to 35% compared to fossil JET A-1.