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Historical trend in air traffic volume. Source: International Air Transport Association (IATA) [24].
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The past oil crises have caused dramatic improvements in fuel efficiency in all industrial sectors. The aviation sector-aircraft manufacturers and airlines-has also made significant efforts to improve the fuel efficiency through more advanced jet engines, high-lift wing designs, and lighter airframe materials. However, the innovations in energy-sav...
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... interesting trend is that air travel volume rather increased while airfares rose, regardless of high oil prices. Figure 3 shows that air travel demand increased continuously throughout the 1970s and 1980s. Passenger and freight volume showed a visible dip only in the early 1990s due to economic depression and intense competition [24] and after September 11, 2001. ...Citations
... The range of acceptable values for coefficient a22, which represents the reduction of emissions due to technological innovation (in engines, fuel, and management) were obtained from previous studies 12,32,33 . Coefficient a12 is an estimate of the cancellation effects, due to socio-economics factors such as the above mentioned increased operating costs related to climate change impacts 34,35 or to environmental consciousness [36][37][38][39] . ...
Since 1999, every report released by the International Panel on Climate Change has advocated a decrease in the greenhouse gas emissions associated with aviation in order to preserve the current climate. This study used a two variable differential equations model with a non-linear control term to address several aspects of the emissions stabilization issue. By optimizing the control term parameter, several management alternatives can be obtained based on the properties of the phase plane of the model solutions, as identified by a stability analysis. The system can be stabilised around an equilibrium point that maintains the present number of passengers, or maintains the emissions level or is nearest to its present state. Each of these options entails different issues of growth or reduction in the number of passengers and/or the emissions rate, directly obtained from the model results. The last option seems especially novel and promising, since only short-distance flight passengers are severely reduced, while long-distance and international passengers are allowed to growth, and their associated emissions are reduced to below 50 percent of their actual value. Moreover, in a scenario of slow growth in air traffic, these rates could improve, with fewer reductions in the number of short-distance passengers.
... The fermentation of carbohydrates produced by the hydrolysis of biomass can be accomplished both thermally and biochemically, which results in the production of bio alcohols (Hu et al., 2022a;Wu et al., 2017;Fu et al., 2015). The fermentation of direct sources of sugar results in the production of alcohol (Lee and Mo, 2011). Wood, agricultural waste, and wastes and residues from forests are some of the biomass feedstocks that can synthesize bioalcohol (Chouak et al., 2022). ...
Renewable energy sources are gaining prominence as petroleum-based fuels deplete, necessitating alternative options. The aviation industry, facing increasing demand for both conventional and alternative fuels, is exploring blue hydrogen as a cleaner substitute for traditional jet fuels. This paper evaluates recent advancements in blue hydrogen production methods and hydrogen carriers such as ammonia, metal hydrides, formic acids, carbohydrates, and liquid-organic-hydrogen carriers (LOHC).
Developed economies are actively researching biofuels as potential alternatives to petroleum, offering reduced emissions, enhanced fuel security, and improved sustainability. The power-to-liquid (PtL) method is employed to assess a sustainable alternative fuel, chemically matching regular jet fuel using water, CO2, and renewable energy. The study examines various biofuels and their application in aviation, comparing the techno-economic and environmental performance of PtL fuels to fossil and biomass-derived jet fuels. To estimate combustion flue gas properties, a model using Aspen Plus is developed, simulating the performance of a CFM56–7B turbofan engine with alternative fuels. Biodiesel, ethanol, n-butanol, 70% NH3–30% H2, and CH4 are evaluated, demonstrating comparable temperatures to conventional jet fuels. The NH3-H2 blend, while exhibiting lower thrust, limits the aircraft range due to reduced thrust compared to JET-A1 and kerosene-gasoline fuels. Ethanol shows slightly better thrust and range performance than the NH3-H2 blend but still falls short of conventional jet fuels. Biofuel and n-butanol emerge as promising replacements, demonstrating comparable thrust and range performance, with only a 15% reduction in aircraft range compared to JET-A1 fuel. The study provides valuable insights into the potential of these alternative fuels, emphasizing the need to consider combustion flue gas temperatures and their impact on existing power plants.
... Most scholars believe that environmental innovation is important to improve carbon emissions. This array of researchers based their argument on the fact that environmental innovation is an all-encompassing technology that has minimal emissions outputs and also is such that targets low carbon emissions (Carri on-Flores & Innes, 2010; Dauda et al., 2021;Gu et al., 2019;Lee & Mo, 2011;Mensah et al., 2018;Mongo et al., 2021;Niu, 2021;Wang & Zhu, 2020;Yuan et al., 2021). However, Chen and Lee (2020) argued that the positive influence of environmental innovation might not occur if the country falls within the middle and low-income, low-technological, and low-carbon emission countries. ...
... This study will make an incremental contribution; first, this study will contribute to the literature on green energy and financing. Unlike previous studies (Carri on-Flores & Innes, 2010; Lee & Mo, 2011;Mongo et al., 2021;Yuan et al., 2021) focus on general technological innovation, which could be misleading because it is not mainly focusing on carbon emission reduction or carbon neutrality. We make a difference by employing only the technological innovations related to environmental performance (i.e., cut across all stretchers of environmental systems, climate change technology, and sea and ocean economy). ...
... Environmental technology has significantly shaped society, the economy, and the environment. For instance, Lee and Mo (2011) argued that environmental innovation in biofuel is associated with reducing carbon emissions with no economic implication. Similarly, Carri on-Flores and Innes (2010) found that US toxic pollution has witnessed tremendous reduction following the use of environmental innovation and policy stringency. ...
This study investigates the impact of environmental-technological innovation and energy credit rebates on carbon reductions in Australia and its global comparison. We applied a system generalized method of moment (S-GMM) on a dataset of 11 years (from 2008 to 2019) for Australia and 23 top green scheme economies. The main findings suggested that Australia's environmental innovation and energy credit rebates are associated with carbon reduction. Similarly, we found that environmental innovation is associated with carbon reduction in the 23 top green schemes economies, but energy credit rebate increases carbon emissions. This is due to the weak green financial system in the 23 top green schemes economies. We robust our findings, and the result confirmed a robust alternative model. These findings offer numerous essential policies for the government and stakeholders in the energy and environmental sectors. More specifically, it recommends more investment in environmental innovation and an overhaul of the green financial market.
... Although these values are widely accepted and used in most of the referenced studies, they are subject to uncertainties which, in the case of emissions, may be due to the approximations used in the computational models, as indicated among others by [34][35][36][37][38][39]. The range of acceptable values for the parameter a 22 , which represents the reduction of emissions due to technological innovation (in engines, fuel, or management) was obtained from Ref. [23] and also from [40,41]. According to these studies, the coefficient could range from −0.015 to −0.04. ...
In this study, we introduce a sensitivity analysis of modelled CO2 aviation emissions to changes in the model parameters, which is intended as a contribution to the understanding of the atmospheric composition stabilization issue. The two variable dynamic model incorporates the effects of the technological innovations on the emissions rate, the environmental feedback, and a non-linear control term on the passengers rate. The model parameters, estimated from different air traffic sources, are subject to considerable uncertainty. The stability analysis of Monte Carlo simulations revealed that, for certain values of the non-linear term parameter and depending on the type of flight, the passengers number at some equilibrium points exceeded its initial value, while the emissions level was below the initial corresponding one. The results of two global sensitivity analyses indicated that the influence of the non-linear term prevailed on the passengers number rate, followed distantly by the environmental feedback. For the emissions rate, the non-linear term contribution dominated, with the technological term influence placing second.
... Nevertheless, all these earlier crises had long-term effects beyond passenger disruptions. For instance, the proclaimed oil embargo in 1973 led to airlines being forced to become more fuel-efficient (Issawi, 1978, Nygren et al., 2009, Lee and Mo, 2011. The terrorist attacks on September 11th, 2001, can be felt until to date in terms of changes to aviation safety and security measures (Blunk et al., 2006, Lyon, 2006, Blalock et al., 2007. ...
The COVID-19 pandemic can be considered an unparalleled disruption to the aviation industry in the last century. Starting with an at-that-time inconceivable reduction in the number of flights from March 2020 to May 2020, the aviation industry has been trying to navigate through and out of the crisis. This process is accompanied with a significant number of scientific studies, reporting on the direct and indirect impact of the COVID-19 pandemic on aviation and vice versa. This paper reviews the impacts in context of the recent literature. We have collected nearly 200 well-published papers on the subject in the years 2021 / 2022 and dissected them into a framework of eight categories, built around: airlines, airports, passengers, workforce, markets, contagion, sustainability, and economics. We highlight the essence of findings in the literature and derive a set of future research directions and policy considerations which we deem important on the way towards pandemic-resilient aviation.
... Among others, hydrogen fuel, liquefied fuels (e.g., propane, butane), alcohols (e.g., ethanol, methanol), biofuels (combustible liquid manufactured from renewable sources, such as animal fats and plants oils) and synthetic fuels (fuel produced from the synthesis process, such as the Fischer-Tropsch process) are considered [11]. An interesting option is to replace bioethanol with biobutanol in the blend, as it has numerous advantages, e.g., it is 25% more caloric when compared to bioethanol; it is less hygroscopic, less corrosive, and less aggressive to fuel systems; and most importantly, it emits less pollutants when burned [12,13]. The sustainability of the crops used to produce biofuel is important to ensure that the production of feedstock does not interfere with the supply of food or freshwater, and in turn contribute to higher food prices due to competition with food crops. ...
Care for the natural environment, which can be observed in the tightening of emission standards, has enforced the search for new fuels, especially renewable sources of natural origin. The article presents the results of theoretical and experimental considerations on the impact of aviation biofuels on the materials used for sealing flange joints. The fuel type selected for the test is compatible with aviation fuels. Fuels have been enriched with a bio-additive that changes the technical and physical properties of the fuel. The tested gaskets were made of soft, aramid-elastomeric materials that were flat in shape and without reinforcement. Their commercial names are AFO and AFM. Tests were carried out with the use of a simple flange joint with a fuel reservoir at 373 K. Both fuel loss and the pressure drop on the gasket were measured during a 1000 h period of time. The experiments showed that the seals preserved the technical parameters in the presence of the tested fuels. The fuel loss did not exceed the accepted limits, which demonstrates the suitability of the tested materials for utilization with new types of fuel. However, no unequivocal conclusions can be drawn about the positive or negative impact of bio-additives on the sealing material due to the fact that both an improvement and deterioration in tightness under certain circumstances were observed. Based on the experimental data, a mathematical model was proposed that makes it possible to predict the service life of the gaskets in flange joints in contact with the investigated types of fuel. The potential application of the research results is practical information about the impact of biofuel on the gasket, and hence the information about the possibility of using traditional sealing materials in a new application—for sealing installations for the production, transmission and storage of biofuels.
... Lastly, aircraft induced cloudiness (AIC), if persistent, potentially has a large contribution to global warming which is often neglected [9,10]. The emissions can be reduced with technological advancements made in the future, however, it seems that the growth of the industry is outpacing these advancements [11]. Therefore, a different approach is needed to reduce the climate impact. ...
This paper studies the climate impact of propeller aircraft which are optimized for either minimum direct operating costs, minimum fuel mass, or minimum average temperature response (ATR 100). The latter parameter provides a measure of the global warming impact of the aircraft design, considering both CO2 and non-CO2 effects. We study turboprop-powered aircraft in particular because these offer higher propulsive efficiency than turbofan aircraft at low altitudes and low Mach numbers. The propeller aircraft are designed for medium-range top-level requirements, employing a multidisciplinary design optimization framework. This framework uses a combination of statistical, empirical, and physics-based methods, which are verified using existing engine and aircraft data. For this medium-range design case, a climate impact reduction of 16% can be realized when shifting from the cost design objective to the climate objective. The optimal solutions for the fuel mass and climate objectives are nearly identical as CO 2 and other fuel proportional climate effects are the main contributors. The effects of NO x and contrails are lower than for the turbofan aircraft due to the lower cruise altitude of the propeller aircraft. Compared to turbofan data, propeller-powered aircraft can achieve a further 33% reduction in climate impact, comparing both climate-optimal designs. This reduction is lessened to 23% when the propeller aircraft is constrained to achieve the same mission block time as the turbofan aircraft. Note that these reductions in ATR 100 require a propeller efficiency of 88%. Overall, the results show that the utilization of propeller-powered aircraft in the medium-range category can further reduce the climate impact compared to climate-optimal turbofan aircraft designs.
... Many of these aviation innovations were linked to the exponential increase in military technological capabilities that were developed both during and after World War II. The 1970s saw the introduction of wide-bodied aircraft (i.e., double aisles), such as the Boeing 747 Jumbo Jet, and broad-based improvements in fuel efficiencies (Kilpi, 2007;Lee and Mo, 2011) in response to the OPEC oil crisis. Collectively, these innovations made it possible to fly large numbers of people great distances at high speed in relative comfort and low cost, thus ushering in the era of international mass tourism. ...
... These studies can be divided into two categories. First, the studies that reviewed measures available for fuel-efficiency or CO 2 emissions improvement potential (Braun-Unkhoff and Riedel, 2015;Grote et al., 2014;Hileman et al., 2013;Lee and Mo, 2011;Mü ller et al., 2018;Singh et al., 2018), and second, the studies that investigated by focusing on one or more factors (Brueckner and Abreu, 2017;Hsu and Eie, 2013;Singh et al., 2019a;Vaaben and Larsen, 2015) for the reduction in aviation fuel consumption and its CO 2 emissions. These studies identified various factors and talked about their importance and contribution. ...
Purpose
In the past four decades, substantial air traffic growth has triggered enthusiasm in the aviation sector. At the same time, this growth has posed challenges to its financial and environmental sustainability commitments. A buzz has been centered on introducing and supporting aviation sustainability initiatives. These challenges have led to acknowledging the need to reduce aviation fuel consumption, a function of multiple factors. The different stakeholders having a diverse type of interplay govern the effective implementation of the factors at different decision levels (strategic, tactical and operational). Thus, the present study aims to critically examine various decision levels involved to understand opportunities and requirements related to aviation sustainability.
Design/methodology/approach
In this study, the best–worst method is used to quantify different decision levels’ role on various factors affecting aviation fuel consumption.
Findings
The results of this study signify that tactical-level decisions are most influential in reducing aviation fuel consumption with the highest impact (0.41) followed by operational-level decisions (0.30) and strategic-level decisions (0.29), respectively.
Research limitations/implications
The results point toward the critical role of middle-level hierarchy, i.e. aircraft manufacturers, airlines and others in the aviation industry’s sustainable growth. Thus, middle-level stakeholders must be inspired and empowered to act, being at the center they link the other two levels.
Originality/value
This study has added to the body of knowledge by exploring the decision-making competencies needed by different aviation sector stakeholders. It also presents the possible options available in the sector and the role of stakeholders at different levels in exploiting and implementing the sustainable aviation sector changes.
... Additionally, innovations create value because of an urgent need for new sustainable developments, more personalized services, creating a safer and more secure environment. Prior studies on air transport innovation have been based on technical approaches (Tinoco and Johnson, 2010;Lee and Mo, 2011). Moreover, despite the acknowledged importance of innovation in reducing aviation macro problems, little is known about how these advances shape the sector to change the industry towards a more sustainable paradigm (Lee and Mo, 2011;Grampella et al., 2017). ...
... Prior studies on air transport innovation have been based on technical approaches (Tinoco and Johnson, 2010;Lee and Mo, 2011). Moreover, despite the acknowledged importance of innovation in reducing aviation macro problems, little is known about how these advances shape the sector to change the industry towards a more sustainable paradigm (Lee and Mo, 2011;Grampella et al., 2017). In this context, this research is valuable because of the importance of leading innovations in products, services, and processes in the aviation sector; few previous studies have provided a clear and precise description of how to successfully conduct innovation adoption to create value (Chen and Chen, 2010). ...
This study identifies relevant innovations and discusses value creation in the aviation industry between 2000 and 2019. Aviation experts with experience in innovation were selected and invited to complete a survey identifying the leading innovations in the industry. This study contributes to recent aviation history by offering a list of innovations and a discussion of technological path dependency and value proposition with examples. This overview is helpful to academics and practitioners to verify how these innovations have shaped the industry worldwide, making it more efficient, agile, sustainable, and safe. The innovations selected comprise consolidated technologies and emerging advances introduced in the timeframe proposed. 33 innovations primarily related to incremental and technical typologies that add value to products were mapped. In addition, this study provides insightful findings by classifying the value created for the aviation sector into five innovation clusters: (1) aircraft technology, adding value in terms of efficiency and sustainability; (2) innovation in passenger services, creating more personalized services and enhancing the customer experience; (3) innovation in flying, adding value in terms of safety and the security environment; (4) business and operational management, improving procedures and revenue; (5) and general applications, adding value in terms of Aviation 4.0 (increases in automation and data exchange, including cyber-physical systems, the Internet of Things(IOT) and cloud computing).