APU-OFF is an innovative service and change in business model for providing power to grounded aircraft on the airport apron. The objective is to ensure adequate air-conditioning and electricity to planes during turn-around, so they don't need to use the Auxiliary Power Unit (APU). The APU is a small jet engine, fitted to planes, to generate electricity and provide compressed air, for air-conditioning and main engine starting, when the main engines are stopped. As jet engines, APUs make a lot of noise and polluting emissions, particularly compared to alternatives, like ground-based diesel generators and air-conditioners, making them unpopular with airport authorities and local residents. APUs are also relatively inefficient, consuming a lot of expensive aviation fuel. There are clear advantages for airlines and other stakeholders to using alternatives to the APU.
However, today, much of the equipment provided is inadequate, resulting in pilots resorting to use the APU, with all its downsides (noise, pollution, cost), and operating ground equipment, consuming fuel and generate noise and emissions being redundant.