Alternative Aviation Fuels

Question: Discuss about theAlternative Aviation Fuels. Answer: Introduction Civil aviation enjoyed very strong growth over past decade. That growth is forecast to the, continue for foreseeable future, environmental implication of that growth is proportional. Due to limited availability of AVGAS because of that its resources are reducing. Energy resources those are able to offset that trouble are renewable energy resources because of their wide availability and no or less environmental impacts. Industry that should be considered from global perspectives is aviation industry, particularly with respect to fuel supply. This report is qualitative assessments of range of the renewable fuels option for the jet aircraft end by identifying FT kerosene, biodiesel and hydrogen fuel are the most promising options. Renewable Aviation Fuels This study reviewed and identified renewable fuels option for aircrafts. The renewable fuels considered were described below-: Bio-Diesel Bio-diesel is defined as the mono alkyl ester of the fatty acid that is obtained from either etherification of oleaginous crop such as soybeans and canola/rape, or by from waste products of oil.We can use Bio diesel as kerosene extender, that means kerosene can be mixed with kerosene for aircraft use. The industrial oil and food lead research into the bio diesel as kerosene extender, is mainly particularly interested in the soybean methyl esters, which has been assessing concentrations of about 10-30% by the weight. Advantage By using biodiesel blended with kerosene can reduce carbon emissions. It is imagined but not yet confirmed that blended biodiesel In kerosene is capable to give air quality emission advantage over 100% kerosene in same way that internal combustion biodiesel gives quality air emission benefits as compare to the mineral diesels ICEs. Disadvantage There are no. of disadvantage with use of bio diesel as kerosene extender. Biodiesel blend compromise kerosene performance in very cold temperature that is encountered at the high altitude. That happens because of biodiesel blended in the kerosene raises the fuels cloud point. The temperatures at which fuel become cloudy or hazy because of formation of the micro crystal those if present can blocked fuel filters, fuel lines and plugs etc. Biodiesel comprise high proportion of polyunsaturated and unsaturated fatty acid that makes biodiesel susceptible through oxidation to the degradation, which in turns introduces possibilities of the storage problem. Fischer- Tropsch Kerosenes Kerosene can be produced synthetically by means of Fischer- Tropsch or by other synthetic fuels production process, from wide variety of the carboniferous feedstock which includes biomass. Fischer- Tropsch fuel is manufactured in three steps procedure: Syngas generation: Synthesis gas is generated by conversion of feedstock. Synthesis gas is composition of H2 and carbon monoxide. Hydrocarbon synthesis: Production of synthetic crude by catalically conversion of syngas into misture of wax and liquid hydrocarbons. It is actual step of Fischer- Tropsch synthesis. Upgrading: The mixture of FT hydrocarbons is then upgraded through the fractionated and isomerization and hydrocracking into desired fuels. Advantages Fischer- Tropsch kerosenes derived from biomass feed stocks would brings fuel cycle CO2benefits compared to the mineral kerosenes, and can also largely eliminates SOx emission since fuel is completely free from sulphur. Fischer- Tropsch kerosene is physically and chemically similar to the mineral kerosenes. As such that is broadly compatible with handling facility and, current fuels storage and notwithstanding with currently used jet engine. Disadvantage It is virtually free from sulphur and it has a very low aromatic content that leads to the lubricity poor. This trouble can be solved by means of aromatic fractions and additives. As compared to mineral kerosenes it has little bit less energy density, because it is an iso-paraffinic. The reduction in aircraft maximum range can impact on the long- haul flight. That reduction in range is relatively small and however will be the offset partially by increase in aircrafts efficiency those are predicted for continue in short term medium. Nuclear Aircraft nuclear design considers 2 design, the indirect and direct turbojets. With direct designs, air can enters through compressor one or more stages turbojets. Then it is directed through reactor cores. The air, acts as coolant of reactor, which is heated it passes through core, and then it can be directed toward turbine sections of turbojet, from there it outs through tailpipe. In the indirect design of turbojet coolant fluid is used in the closed circuit so as to enter in the reactor. Heat is transferred to the air through the heat exchangers that enters in turbojets by entering in the turbine section by passing through the compressor. Major problem with design of nuclear aircraft is that it is its safety and weight. Example, in early time a nuclear designed propulsion system was weighted about 80 tones. From which reactor weighs 5 tones and shielding weighs approx. 50 tones. Safety concern, either emission of radiation while operation, or explosion in case of accident are major concern. LiquefiedNatural Gas There is particular strategic interest in development of LNG because of its higher reserves than oil. LNG aircraft CO2 emission are approx. 25% lesser than the kerosene aircraft, although with use of bio-methanes the CO2 fuel cycle benefit could be greater. Hydrogen Hydrogen as jet fuel gives environmental benefit if it is extracted through biomass gasification or by water electrolysis process by using electricity generated from renewable energy resources. In hydrogen combustion primary combustion product is ware and secondary emission product is nitrogen oxides. Hydrogen combustion not produces harmful products like CO, SO, unburned hydrocarbon, CO2. But these are emissions of kerosene burning process. That volumetrically lower energy density clearly describes that hydrogen aircraft should accomplish with large fuel storage tank as compare to conventional aircrafts. Conclusions Biodiesel, FT kerosene and Hydrogen, these all has potential to bring saving in aviation sector non-renewable energy use. For hydrogen major research efforts has been required for production of appropriate new engine designs and airframe those appear unlikely from commercial hydrogen aircrafts are seen from several decade. For safety reason, the aviations industries are particularly resistant to unproven or new technology fuel; those provide strong commitment in favors of use of finite supply of the renewable fuel for the alternative purpose. Renewable energy resources are not limited as no-renewable energy resources like AVGAS and there is no or very less harmful environment impacts. Because of their wide availability major research is conducted on these resources mainly of hydrogen because of its high energy content and combustion kinetics. Renewable source sources could used to displace non- renewable sources. References BIO-TIC, Aviation Biofuels, Funded by the European Union, Visited 8 Sep 2016, Available: www.industrialbiotech-europe.eu/new/wp-content/uploads/2014/09/Aviation-Biofuels-summary-final1.pdf IATA, 2013, IATA 2013 Report on Alternative Fuels, International Air Transport Association, Montreal- Geneva, 8th Edition, Visited 8 Sep 2016, Available: https://www.iata.org/publications/documents/2013-report-alternative-fuels.pdf Novelii P., 2011, Sustainable way for Alternative Fuels and Energy in Aviation, European Commission, Visited 8 Sep 2016, Available : https://www.icao.int/environmental-protection/GFAAF/Documents/SW_WP9_D.9.1%20Final%20report_released%20July2011.pdf