Faced with increased air traffic and the environmental commitments taken by governments and enterprises, airlines are redoubling their efforts to be able to propose new sources of hydrocarbons, which are not only green but also meet the various very strict aeronautical constraints.
Portrait of the situation
The aviation sector has clearly identified the importance of finding alternative solutions to kerosene, which today still represents 100% of aircraft fuel. Firstly, in the long run, the supply of kerosene (estimated to be between four and six billion tons per year) will no longer meet the industry’s demand (air traffic consumes about 11% of the world’s fuel) which will grow 1.5% per year until 2030. As well, pollution related to air traffic constitutes a serious problem, especially affecting urban areas near airports (soot particles, unburned fuel, noise, etc.). Although aircraft account for only 2% of greenhouse gas emissions, aerospace operators have set ambitious goals – even though they are not affected by the Kyoto Protocol, nor directly by the Cop 21 – such as reduction of CO2 emissions by 50% between 2005 and 2050. In addition, the International Civil Aviation Organization has deployed a system to offset any new net increase in CO2 by purchasing carbon credits.
Biofuels, a history of generation
The solution includes these so-called non-fossil energies, which come from waste or biomass and which can reduce greenhouse gas emissions between 50% and 90% compared to kerosene. After the first generation of biofuels (ethanol from alcohol fermentation of sugars from agriculture – sugar cane, beet, grains), the aviation sector is now interested in second generation biofuels, lignocellulosic biomass that does not compete with food, from wood, elephant grass or grain straw. This second generation stands out from the first thanks to its larger resources, lower raw material costs and better environmental footprint. At the current time we can say that a third generation of biofuels is in the making (in research and development) and is based on microalgae. The yield per hectare is three times higher than that for oilseeds, and its development by photosynthesis allows its fumes and liquid effluents to be recycled.
Aviation, a demanding sector
Developing biofuels for the aviation sector is a daunting challenge, given the various constraints and requirements that it is subject to. The fuel produced must be able to be used globally and therefore meet international requirements relating to fuel quality – Jet A/A1 for civil aviation – at the end of a long and costly process. The fuel must also show adaptability and resistance to any test in terms of temperature (range of 100 degrees between high altitudes and the tarmac), pressure, and not just that… Being the only hydraulic fluid on board, biofuel must also play the role of radiator and be very stable against oxidation. Currently, some airports include biofuels in the kerosene for certain commercial flights, such as Los Angeles (30% biofuels), Oslo, Geneva, Toulouse… and the list is soon to be lengthened.
Although development of this market may well be long, costly and fraught with contingencies (the need to have a barrel between $200 and $250 for the fuels to be profitable), it is more than necessary for the future of both air traffic and our planet.