Jet fuel is now the largest expense for most of the airlines, and for American carriers each penny increase in the price per gallon costs nearly $200 million a year. Aviation is responsible for about 2% of the global emissions of green house gases, and that share will rise as air travel continues to grow. So the industry is scrambling to build greener airplanes to save weight and improve energy efficiency, with an eye towards reducing the operating costs and emissions. In short, a revolution in jet engines is about to occur, with radically different designs that use gears to cut fuel consumption, noise and pollutants.
In the longer term, the fuel itself may change. Scientists are looking for an aviation version of ethanol, something that can be made from plants rather than petroleum. The conventional hydraulic system will be replaced with electric motors, saving the weight. The geared Jet engines will enter the commercial airline service around 2013, if all goes well. So, lets all hope for a cleaner and leaner ‘ Jet Age ‘ and for ' Eco-Aviation '.