Global environmental and safety concerns may require use of alternative fuels and the elimination of leaded fuels to address emissions and volatility concerns. Blends of biofuel such as Jet-A have led to as much as 50% emissions reductions during operations, both on the ground and in the air. Even blends of as little as 10% have been shown to produce a substantial effect on emissions.
There are a number of potential routes available, including synthetic kerosene or Fischer-Tropsch fuels from coal or biomass. There is also the possibility to use bio-fuels such as Fatty Acid Methyl Esters (FAMEs) in aviation, and plans to test these are in hand. One potential issue in developing these biofuels, however, is determining what feedstocks they should use. For instance, the proliferation of palm oil-based fuels could lead to an increase in demand for palm plantations, which could drive deforestation. Companies have used materials ranging from non-edible animal waste to sustainable corn to develop their biofuels.
Alcohol-to-Jet (ATJ) fuels may be the next big advance in terms of reducing the aviation industry’s reliance on petroleum and improving its carbon footprint. Gevo, a Finnish company, has developed a method of converting bio-gased isobutanol to an ATJ paraffinic synthetic kerosene, which is currently in use by Alaska Airlines and other providers. According to analysis, if Alaska Airlines replaced just 20% of its fuel supply at Sea-Tac Airport with ATJ, it could reduce carbon emissions by 142,000 metric tons.
While emissions concerns and the rising price of jet fuel are driving sustainable fuel innovation, issues of feedstocks and startup costs remain prominent. Many biofuel companies, including Cool Planet, have stalled out or shifted the focus of their operations, due to the costs of operating a full-time facility reaching hundreds of millions of dollars.
Engine failure/degradation due to:
– fuel specifications with differing properties such as lubricity, lower aromatic content, etc.
– cross contamination with incompatible fuels in pipelines
Contamination levels from particular refineries may exceed allowable limits. Sources of contamination can include water, particulates or biodegradation (which forms a gummy residue in the fuel), bacterial growth or overuse of biocide used to control bacterial growth.
The migration of fuel specifications in response to environmental and economic pressures needs to be controlled to assure the performance, reliability and safety of aircraft fuel systems and engine hardware.