For this combined population of 45 m people, they sought to test the benefits of "existing, readily acquirable technologies that would reduce greenhouse gas emissions from fossil fuels".

BBC: Olympic flame and rings at dusk PA

And earlier this month, Airbus, in association with Shell, Rolls Royce and Qatar Airways, began a research project to test 'Gas to Liquid' (GTL) technologies that convert lower-emission natural gas and other synthetic fuels into liquid kerosene.

CNN: Flight of biofuel fancy?