Table of Contents
Summary
The paper presents a discussion concerning the future of the aviation industry regarding the looming projected shortages in fossil fuels that propel the commercial aircrafts. The paper recognizes that the current regulatory policies and advances made in improving the efficiency of the aircraft engine do not reduce the overall emissions from the aviation industry overshadowed by the increasing number of aircrafts and number of travels. The paper concludes that the present technology allows for the use of biofuels in the aviation industry with minor technical changes to the aviation technology.
Introduction & Background
The world airlines have committed to reversing their carbon footprints to prevent their environmental impact (Jong et al., 2017, p. 6). The commitment constrains the future of air travel and aviation. The undertaking has driven a renewed aeronautical research in a bid to shape the future of aviation. The research has focused on lower drag aerodynamics, more efficient engines, lighter structures, electrification systems, and streamlined operations recently (Jiuping, Meihui & Ting, 2015, p. 6285). Studies reveal that the efficiency of the jet engine has increased by 2% a year since the invention of the first engine. Countries have set long-term targets to maintain or increase the rate of reduction of specific fuel consumption and carbon emissions.
The International Civil Aviation Organization has introduced a global climate stabilization goal to reduce the carbon emissions from airlines by 70%. The organization, however, reports that the air transport carbon emissions are increasing despite the plans to reduce the emissions. The sudden increase in air transport owing to the increasing tourist activities explains the rising amount of emissions. The high growth rates in the air industry make it unlikely to reduce the overall emissions through technical engine progress (Jiuping, Meihui & Ting, 2015, p. 6285). Further reports that the fossil fuels are soon running out will make travel more expensive necessitating research studies on alternative fuels to ensure sustainability of the aviation industry.
The possible alternative fuels for transportation include methanol, denatured ethanol, and other fuel mixtures containing the above in different proportions, natural gas, liquefied petroleum gas, hydrogen, coal-derived fuel gas, biofuels, and electricity. The above fuels can address the impending energy crisis and environmental problems caused by the excessive use of fossil fuels in the aviation industry (Poltronieri, 2016, p. 2). Biofuels have obvious environmental and economic advantages.
Prolonged use of fossil fuel in the aviation industry is likely to generate a sharp increase in the global greenhouse gas emissions and radiative forcing through 2050 because of the particularity of the aviation emissions (Kumar, Fujii & Managi, 2015, p. 1438). The above problem can be addressed through the extensive use of offsets and large-scale production and use of aviation biofuels.
The use of the biofuels has however received mixed reception in the vehicle transportation sector where the commercial, environmental and social impacts have been evaluated to establish the sustainability of the biofuels (Silva, Gouveia & Reis, 2014, p. 1043). The carbon neutrality of the biofuels as used in the aviation sector has also attracted renewed attention (Kumar, Fujii & Managi, 2015, p. 1438). Despite the above challenges the aviation industry remains to face numerous challenges in future concerning the reduction of emissions, cost of fossil fuels and overall operation.
Results & Discussion
Aviation has facilitated the growth of global commerce through connecting people for business and tourism, defense and a range of political and humanitarian activities. Studies suggest that the aviation industry will grow steadily that by 2026 the industry will contribute $973 billion to the global GDP directly and $1.1 trillion indirectly (Jovanovic & Vracarevic, 2016, p. 1975). The benefits of the aviation industry will, of course, come with risks through emissions that currently account for 3% of the total global carbon emissions. The demand for aviation is expected to be high in China, India and Middle East. The increasing population and the need to travel to other countries in the global age will substantially increase the overall amount of emissions from airlines (Kumar, Fujii & Managi, 2015, p. 1438).
Aircraft emit many various compounds in addition to carbon dioxide that has an impact on the atmospheric forcing. The compounds include nitrogen oxides, volatile organic compounds, black carbon, carbon monoxide and organic carbon (Kumar, Fujii & Managi, 2015, p. 1438). The aircrafts also emit aerosols and sulphur dioxides with post radiative effects leading to warming effects.
The rise in kerosene prices and increasing crude oil prices will soon prove unsustainable for the aviation industry to operate at its worth (Jovanovic & Vracarevic, 2016, p. 1975). Global recognition of the above challenges has provided numerous technologies to make liquid fuels form both natural gas and coal. The technologies are however more expensive than that converts crude oil into jet fuel and emit larger amounts of carbon during the process. The fossil fuels, despite the large deposits available, are not renewable as well and will soon run out necessitating the need for an alternative renewable fuel with lower or no carbon emissions for the aviation industry (Poltronieri, 2016, p. 2). The call for the use of biofuels in aviation is still a grey area in research requiring extensive collaboration between the government and public and private sectors.
Various governments have recognized the growing interest in aviation biofuels to comply with the various regulatory standards that aim at reducing global carbon footprint (Poltronieri, 2016, p. 2). The interest has created public, private partnerships such as the commercial aviation alternative fuel initiative (CAAFI), and the aviation initiative for renewable energy (Jovanovic & Vracarevic, 2016, p. 1975). The organizations have established their activities in China, Brazil, Qatar, Australia, Mexico, USA, and Canada. The group works to advance the aspects of aviation biofuels including the value chain, conversion technologies, and the resulting fuel types.
Some commercial airlines have recognized the efforts made by the groups and have been direct participants in the development of aviation biofuels. The airlines include British Airways, Qantas, Lufthansa, and Iberia. Some of the airlines have used and are using the aviation biofuels in scheduled passenger flights such as the Air France, KLM, AeroMexico and Thomson Airways. Jet engine manufacturers such as Rolls Royce and airframe producers such as Airbus are also participating in testing and approval of aviation biofuels through certification entities such as ASTM. The figure below shows the feedstock conversion pathways for aviation biofuels.
Natural gas has also become more popular as a clean fuel for the future aviation industry. The debate is still ongoing however concerning some natural gas reserves. The liquefied petroleum gases have been proposed as alternative aviation fuels (Kumar, Fujii & Managi, 2015, p. 1438). The gases, however, have storage and transfer problems associated with cryogens. The natural supply of the LPG is not sufficient to support the aviation industry either. Alcohols, methanol, and ethanol have as well been proposed as aviation jet fuels, but the latter has poor mass and volumetric heats of combustion that they are not satisfactory for a commercial aviation fuel (McWilliams, 2017, p. 81). The above deductions leave the cryogens, methane, and hydrogen as the possible candidates to replace the kerosene type aviation fuel after biofuels.
The present aviation engine design does not support the use of cryogenic fuels and will require a different technology if the cryogenic fuels were to be used in aviation. Methane and hydrogen fuels will require proper insulation from the thermal effects of the ambient temperature since their boiling points are below the ambient temperature. The cryogens will also require larger tanks and insulated and located in the fuselage instead of the wings in the modern aircraft design to minimize boiling off losses and the large size. Hydrogen has a higher energy output per unit content thus will require smaller storage tanks and fuselages.
The thermodynamic processes associated with the storage and use of cryogens in commercial flight has many challenges for the fuel delivery system that it does not warrant a practical solution to the fossil fuel problem in the aviation industry at the moment. Hydrogen tanks will require the use of helium as a pressurant that will increase the cost to unsustainable levels. Methane can be used with dissolved nitrogen. However, the solubility of nitrogen in methane presents a challenge. Inert gas pressurization requirements for the existing aircraft pump designs make the methane, hydrogen, and cryogens an impractical solution at the moment. However, the use of the above fuels might be warranted by the conditions and circumstances that may affect the aviation industry in future because of expected improvements in technology.
The present technology and operating conditions only allow for the use of biofuels as an alternative aviation fuel in the future aircrafts. The biofuels obtained from animal and vegetable fats do not require significant improvements to the jet engine to run on the biofuel. The sources of the fuels are renewable thus sustainable to a considerable extent (Poltronieri, 2016, p. 2). Biofuels will have numerous points of entry in the supply chain through distribution, storage and tanking of the aircraft flights. The distribution will occur through direct aircraft fuelling and on filed storage. The former strategy involves supplying the fuel directly from the producer to the storage facility of the aircraft while the latter involves the supply of the fuel to large storage facilities at the airports (Wormslev, 2016, p. 14). The biofuels do not require any complex storage facilities and could use the present storage technologies employed for the kerosene-type jet fuel.
Conclusion
The rising cost of crude oil and increasing attention to the environmental pollution from the use of fossil fuels put the aviation industry at risk of an unsustainable operation. The renewed attention has necessitated research on the possible alternative fuel that can ensure sustainable commercial aviation operations. Hydrogen, methane, and cryogens are equally possible candidates for use as an aviation fuel. The fuels, however, present numerous technical problems that prove unsustainable to the present aviation industry. The use of the fuels would require significant and costly modifications to the present aircraft technology making it all expensive. The evaluation leaves the biofuels as the possible candidates to the present challenges witnessed in the aviation industry as more research is conducted on the cryogenics, hydrogen, and methane.
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