As you can see from the diagram below, a continuous cycle of carbon emission and sequestration is created by growing the feedstock, refining it into jet fuel, then the resulting CO2 being re-absorbed by the next batch of feedstock through photosynthesis. The overall reduction in carbon intensity through the use of biofuels is significant and they have the added advantage of being usable by aircraft already in operation.
To accelerate the development and commercialisation of sustainable alternative fuels, a number of prominent international airlines joined together in 2008 to create the Sustainable Aviation Fuel Users Group (SAFUG). All their members have signed a sustainability pledge, which not only relates to emissions directly, but also to wider sustainability issues.
Members of SAFUG have committed to a number of common standards, including ensuring that feedstocks are developed without competing with food crops, minimising the impact on biodiversity, improving socio-economic standards for farmers who grow the plant matter used as a feedstocks and not clearing areas with high conservation value to grow these feedstocks.
The work of SAFUG is likely to play a very important role in helping the aviation industry realise its goal of carbon neutral growth by 2020, as well as the 50% reduction in CO2 emissions by 2050. With the right amount of support from governments and other industries, sustainable alternative fuels could in the coming years become the norm and replace traditional fossil-based jet fuel altogether.