Traffic jams are a great hate of environmentalists, queues of cars and lorries, bumper to bumper, engines running, pumping out tonnes of pollutants. Aircraft are another, accused of an aerial onslaught on the atmosphere. Queues of aircraft, held in traffic jams before take-off and needlessly burning an estimated 320 million gallons of fuel every year, are the stuff of activists’ nightmares.

Moreover, as airports become more congested, aircraft are being forced to idle their enormous engines on taxi-ways for longer, adding about three million tonnes of carbon dioxide to the atmosphere every year. Not surprisingly, pressure is growing on the airlines to cut this pointless fuel burn.

Wheeltug, a small British engineering firm, has developed a compact but powerful motor that will steer aircraft out to the head of a runway by remote control, saving up to 1,000 tonnes of CO2 per plane peryear. Delta Airlines is testing the device and plans to install it on future aircraft.

Flying is responsible for 3 per cent of global CO2 emissions, but air travel is seen as a luxury while the big CO2 emitters — power generators and cars — are less easy to give up. Moreover, aviation is a softer target than heat or electricity generation, so flying has become a political issue. Both Gordon Brown and David Cameron have published airline-targeted initiatives.

With carbon taxes looming for European carriers, Wheeltug has developed a multiphase AC motor, which produces a lot more torque than a normal engine and allows a small unit to shift a heavy aircraft.

Sir Richard Branson, the chairman of Virgin Atlantic, raised the idea of towing out to runways last year, but the suggestion was scoffed at by a number of airline executives. Tugs have been used at airports for many years, but airlines do not like them because they have a habit of being in the wrong place when needed.

Chris Bourne, a spokesman for Wheeltug, says that the new mini-engine will be controlled by the pilot and fitted to the aircraft’s wheel. “Airlines are coming under pressure to cut their emissions and the tug is an easy way to make a difference,” Mr Bourne said.

According to studies being done with Delta, the tug will save about 500kg of CO2 per flight on a Boeing 737. A passenger flying on a 737 for about one hour will have a carbon footprint of 60kg. The savings are estimated at 850 tonnes a year for a 737 and 1,100 tonnes for a bigger aircraft.

Delta, which has a right to buy 8.6 per cent of Wheeltug in the future, plans to install the tug on its new fleet of 737s, which will start to operate in 2009. Other airlines and aircraft manufacturers are also looking at the technology.

Cutting emissions while aircraft are waiting on the ground is just one of the ideas being considered by the aviation industry. Carriers including British Airways and Emirates have called on air traffic controllers and airports to prevent the stacking that goes on above or near to busy destinations such as London Heathrow. Executives also argue that protesters objecting to Heathrow’s proposed third runway or to the expansion at Stansted Airport, in Essex, are contributing to CO2 emissions by causing congestion and stacking.

Tim Clark, the managing director of Emirates, believes that airlines could cut a further 20 per cent from their emissions by renegotiating flight paths. Existing flight paths are based on 1940s routes that required aircraft to stay near refuelling stops.

Richard Dyer, aviation spokesman for Friends of the Earth, said: “Any measure like towing planes or improving air traffic control are welcome, but it is still a drop in the ocean compared with the pace of growth in this industry.”

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