Aircraft engines operate most efficiently at high altitude, so keeping the engines off when the aircraft is on the ground can save a lot of fuel. Airlines estimate the system will result in a 4% total fuel savings - which will also reduce the airline's greenhouse gas emissions.
The electric motors would be powered by the aircraft's Auxiliary Power Unit (APU) which is designed to supply power to the aircraft when the main engines are turned off.
Aircraft will no longer have to wait for aircraft tugs to push the aircraft back from the gate.
This system will reduce wear and tear on aircraft brakes and extend engine life.
This should also make the aircraft ramp a much quieter place.