Boeing has had to redesign its cabins and improve the fuel-efficiency of its aircraft-and is doing rather well as a result.

Besides aircraft powered by biofuel and new lightweight fuel-saving designs, such as Boeing's 787 Dreamliner, there is plenty of other kit promising to help make aircraft more efficient.

Much research has been driven by efforts to save jet fuel. Having more than doubled in price in recent years, it now accounts for about half of airlines' operating costs.