Synthetic fuel blends approved for aviation
Blends of standard jet fuel with synthetic fuels may be soon be approved for routine aviation use. US-based standards organisation ASTM International has issued a new specification setting out the criteria that blended fuels will have to meet.
Airbus and Shell are among the organisations welcoming the move. Both companies were involved in a trial of alternative fuels when, on 1 February 2008, an Airbus A380 with Rolls-Royce engines flew using a 40 per cent blend of synthetic fuel derived from natural gas (GTL) supplied by Shell.
The new specification, ASTM D7566 'Aviation Turbine Fuel Containing Synthesized Hydrocarbons', approves the use of a 50 per cent synthetic jet fuel in commercial aviation. Synthetic liquid jet fuels can be made from biomass, natural gas or coal. All of these are known as xTL fuels.
“This breakthrough paves the way for a 100 per cent xTL blend made entirely from bio feedstock, such as woodchip waste”, said Christian Dumas, Airbus vice president sustainable development and eco-efficiency. “This new specification is a major step towards reducing aviation’s environmental footprint."
GTL kerosene for aviation is one of five GTL products that will be produced in commercial volumes by the Pearl GTL project, currently under construction by Qatar Petroleum and Shell. The project will produce around one million tonnes of GTL kerosene a year, which Shell says is enough to power a typical commercial airliner for half a billon kilometres (equivalent to carrying 250 passengers around the world 4,000 times) when used in a 50 per cent blend to make GTL jet fuel.
The publication of the specification follows two years’ research and discussion by the ASTM specification group, a consensus body consisting of producers, equipment manufacturers and consumers of aviation fuel.
This initial version of ASTM D7566 provides criteria for the production, distribution and use of aviation turbine engine fuel produced from coal, natural gas or biomass using the Fischer-Tropsch process. However, the standard is structured to accommodate other types of synthetic fuel produced from non-conventional feedstocks and processes as they are developed. These new fuel types can be added to ASTM D7566 in annexes after they are qualified.