Sustainable Fuel in the Aviation Industry - Term Paper Example

Introduction Aviation fuel consumptions continue to increase at a high rate and emit gasses to the environment. At the moment, it is estimated that aviation industry accounts fro 3.5% of net CO2 emissions globally. However, the Intergovernmental Panel on Climate Change projects that by 2050; aviation industry would be emitting about 15% of total global CO2, and therefore contributing considerably to global warming (King and Inderwildi, 2010, 47). In spite of this, governments and companies continue to aggressively market the aviation industry with the aim of increasing revenue, keeping up with increasing number of air passengers and helping in economic growth. Indeed, it is estimated that the number of air passengers would continue to increase, and this would as well increase the amount of carbon dioxide emitted in the air by aviation industry. This has heightened the need for a more sustainable fuel to be used in the aviation industry. However, many experts asset that this attempt would not be successful, it is against this background that this essay critically evaluates the research that maintains “efforts to produce a more sustainable fuel to power aircraft are not technically and ethically feasible”. To begin with, the term sustainability will be explained, and the main topic discussed. Sustainability There are various definitions of sustainability; the most widely quoted definition of sustainability comes from World Commission on Environment and Development (1987, p 43) that states “sustainable development is development that meets the needs of the present without compromising the needs of future generations to meet their own needs.” According to Pearce and Warford (1993, p. 53) define sustainable development, “as the development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs." From these definitions, there are two important aspects, the aspect of needs and the aspect of limitations. Conventional aviation fuel The conventional fuel currently used in aviation industry by aircrafts is a kerosene type, obtained from petroleum sources. Farries and Eyers (2008, 43) explains that the quality, properties as well as attributes of this form of fuel depends on jet fuel specifications to provide safe and effective consumption of the fuel. For, example the requirement for commercial jet fuel in the UK is Defence Standard 91-91 (Farries and Eyers, 2008, 43), this type of fuel is as well used by many other countries across the world, to determine the standard of jet fuel. In the USA, the equality to Def Stan 91-91 is ASTM D1655, which as well forms the standard of the Air Fuel Quality Requirements for Jointly Operated Systems (AFQRJOS) “key points” applied by the oil industry. Jet fuel requirements are principally, but not entirely, property-driven, meaning that they identify and put limits on arranges of physical and chemical properties, which are essential in ensuring that fuel is appropriate for bring used in aircraft. Hook and Kjell (2009, 38) explains limitation is put on flash point of the fuel, this ensures that the fuel is handled safely, and has the right energy density. Apart from these physical properties, the fuel specifications as well have some limits on chemical composition, with restrictions placed on the levels permitted on aromatic compounds and the amount of sulphur contained in the fuel. The annexes in the Defence Standard 91-91 have extra restrictions on the fuel. Kerosene sustainable fuels Fischer-Tropsch Fuels The most widespread type of kerosene-like alternative fuels are those obtained from the Fischer-Tropsch (FT) process. The feedstock in this process is any carbon-containing source for example coal, biomass or gas. Supposing normal crops like corn and soybeans are used in this process, the fuel produced is normally identified as 2nd generation biofuel. In any fuel source, the objective is to transform the feedstock into synthesis gas, which is later converted to liquid fuel through the catalytic Fischer-Tropsch chemical reaction. The liquid fuel obtained is then upgraded or improved to fuel composition that can power aircrafts and jet. The main advantage of these kinds of fuels with regard to enhancing quality and performance of jet fuel is their potential for being applied as “drop-in” replacements and therefore they would not need major changes to the current fleet of aircrafts (Bishop and Grayling, 2003, 30). In addition, sulphur can be eliminated form these fuels and the amount of aromatic components present in particulate formation can be controlled. Kerosene-like fuels obtained from biomass Biomass can also be used as feedstock for alternative aviation fuels. The benefit of using biomass over coal is its high potential of renewability and it is carbon neutral due to the use of carbon dioxide during biomass growth. However, as noted by Koroneosk and Moussiopoulo (2001, 104) there are several issues regarding the operation of biomass fuel stocks, owing to the fact that it is not possible to sustain its supply and the true impact of carbon dioxide and other greenhouse gases emitted. Non- kerosene alterative fuel Bioethanol Bioethanol is derived from fermentation of sugars in plants for example sugar cane or beet, which is later, processed to produce ethanol. Bioethanol is highly used as a component of automobile gasoline, particularly in Brazil where it is blended up to 85% (Renewable Fuels Agency, 2008). Since it is produced through fermentation processes, ethanol production has a huge likelihood of reducing carbon dioxide emissions. Nonetheless, the use of bioethanol in aviation industry is still not certain due to energy balance aspect. More so since the main sources for this type of fuel are sugar and starch crops, its use results in direct competition with food safety. Prachi (2007, 81) notes that there is need for advanced technology to be applied to improve on these limitations, and suggests that switchgrass could be used to produce better yields of ethanol. Biodiesel Biodiesel is obtained from esterification of plant oils, for example sunflower or animal fats like tallow. As explained by Speight (2008, 10) the fuel currently being produced is used as a pure biofuel, or in most cases as a blend component of usual diesel. Biodiesel presents possibility of making huge savings due to reductions carbon dioxide emission. However, despite of this benefit, there are other benefits that should be considered including the social and biodiversity effect of biofuel crops (Agrawal et al. 2007, 4833). Hydrogen Hydrogen was firs used to fuel aircraft engines way back in 1937 (Boggia and Jackson, 2002, 294). Later in 1957, the US air force carried out hydrogen flight tests on B52 aircraft. In 1980s the Russian also carried tests on TU155 that indicate the feasibility of commercial aircraft being powered by liquid hydrogen. Supported with various studies, the concept of hydrogen fuelled aircrafts is better understood. Indeed, in the Cryoplane Project, AIRBUS and its partners suggested that it’s possible to have a hydrogen fuelled aircraft in the near future (Boggia and Jackson, 2002, 294). However, the economical feasibility of commercial aircrafts powered by hydrogen fuel is still under doubt. Whereas, hydrogen fuel have previous been used in gaseous state for lifting airships, resulting in the spectacular fires in R101 and Hindenburg airships, its use as a propulsion fuel in commercial aircrafts is still not known (Upham, 2003, 67). When it comes to high speed in aircrafts, the amount of gaseous hydrogen required leads to a lot of drag. Still as observed by Tarka, et al. (2009, 30) liquid hydrogen, when used at low temperatures and under proper pressure, present a potential alternative. Liquid hydrogen burning Agrawal et al. (2007, 4833) explains that when hydrogen is burned in the air to produce water as a primary product. It does not produce high amounts of carbon dioxide, carbon monoxide, sulphur dioxide or hydrocarbons. But, the high temperature combustion results in the oxygen and nitrogen in the atmosphere to combine and form and under pressure; it becomes difficult to store and to reduce drag. In hydrogen fuelled aircrafts, gaseous hydrogen would be used, for effective combustion. Technical issues regarding these sustainable fuels When crops are used for biomass production, it results in direct competition for these crops as source of food, bringing about tough social and political issues owing to the priorities of this nitrogen, just like it happens in hydrocarbon fuels. When used in the aircraft, the problem with liquefied hydrogen is that in low temperature crops as source of food. More so the vast land required for more biomass to be used in the aviation industry could result in deforestation as well as drastic losses in biodiversity. Indeed, the issue of land availability for use of biomass- obtained renewable aviation fuels has further been stressed by research done by Daggett et al. (2006, 143)named “production of present technology biojet fuel.” In the study, they established that production of this kind of fuel from normal biomass feed stocks, where a blend of 15% would be used in conventional aviation fuel, would require 2 billion gallons of biofuel from biomass, to reach the required amounts of the US domestic aviation industry. To produce such amounts would need 34 million acres of open land. There as well exists a considerable commercial limitation to widespread adoption of non-kerosene fuels in aviation industry. Apart from the considerable fuel supply network problems, the commercial aviation industry has got another issue for consideration, the high level of fleet optimisation. More so, Svensson (2005, 1636) explains that in selecting an airplane to buy, airline companies look for airplanes that meet their planned needs for range and payload, together with other aspects of fuel consumption, fleet commonality and maintenance. Whereas conversion to using another type of fuel by airplane could, in theory be realistic, the resultant modification in range/payload capacity will lead to a considerable impact on the capacity of a carrier’s fleet to go on longer routes through the airline routes. It is possible to have workarounds, but it is not feasible to stop to refuel, or building bigger fuel tanks in the commercial aviation industry. Hydrogen presents a high energy component per unit mass, nearly 2.8 times that provided by kerosene, nonetheless, liquid hydrogen requires four times higher volume per unit energy compared to kerosene. This means that liquid hydrogen would require four times bigger fuel tank to carry equivalent energy, and this would require bigger aerodynamics shape, which would add more drag and weight. This eventually means that more fuel would be needed and the initial savings on fuel would not be realized. More so, commercial amounts of sustainably-produced hydrogen needed by the aviation industry are not available. It will also require a fleet switch-over to one that uses hydrogen and this poses a big logistic challenge, and it will require nearly 10 years (Evans, 2007, 113). Ethical issues regarding these sustainable fuels Biofuels, kerosene-like Fischer-Tropsch Fuels and hydrogen are the only sustainable alternative fuels that can power aircrafts. However, from economically challenge of sustainable aviation fuels, there is the ethical challenge. Firstly, as already noted, biofuels will not be cheaper or more efficient than conventional fuels, since they ill still depend on large amount of fossil fuel inputs to maintain them. Speight (2008, 10) argues that it is not possible to attain sustainable fuels, within the current agricultural and economic context. This is because it will only worsen the economic inequality, increase hunger and unless a reduction of fossil fuel required for growing many of the energy crops is done, biofuel fuels will remain expensive and inefficient, and thus there would be no difference in fuel needs of aviation industry. Other ethical issues associated with these fuels need to be addressed. As noted by Astyk (2006) the rapid adaptation of biofuels production results in problems like deforestation and possible displacement of people. At the same time, there is an issue of sustainability and greenhouse gas emission, some of the suggested alternative fuels like biofuels from crops may not be sustainable in the long ran, and they still produce greenhouse gases though small in amounts. Accordingly Astyk (2006) concludes that an ethical production of sustainable fuel can only be achieved, through an ethical agriculture, ethical economy, ethical culture and ethical society. All these sound tremendously overwhelming, and, indeed much challenging than simply getting a field of corn and producing sustainable fuel. Conclusion The use of sustainable fuels where carbon dioxide is recycled for example biofuels and hydrogen represents a vital option for the aviation industry. Whereas non-kerosene fuels may present better results due to their low carbon dioxide emission, they are currently not accepted for use as sustainable fuels because of their physical and chemical properties. The differences are relatively big and major compromises are needed in the operation of current aircrafts, if there is any hope of powering them using these fuels. The potential of using hydrogen as sustainable fuel in aircrafts is comparatively easy. It is possible to build hydrogen powered aircrafts. However, the limitations and challenges prevent widespread acceptance unless the background situation changes. Gas turbines that are used in commercial aircraft can be powered with different fuels. However, the type of fuels that have enough energy density and properties for successful commercial transport is very small. In general, the “efforts to produce a more sustainable fuel from biofuels and hydrogen to power aircraft are still currently are not technically and ethically feasible”. Bibliography Agrawal R, Singh NR, Ribeiro F and Delgass W (2007): "Sustainable fuel for the transportation sector". 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