Originally Posted by
TURIN
In addition to the above, Ground power has a tendancy to drop off line under heavy loads. At the moment, an unexpected and non normal shutdown of the 787 computer systems will cause hours of resets and tests before dispatch.
Also, if you want air conditioning on ground, and there is no conditioned air available on stand, then either a 3rd GPU is required or run the APU.
With the carbon bootprint (and non-CO2 emissions like soot and nitrous oxides) from (perhaps) three diesel GPUs grumbling away next to the aircraft, perhaps running a nice new clean turbine APU is looking like a better idea!
(Some of the ground power might come from fixed installations powered from the building mains but how many stands have 3 of those available, or even two - and how much dirtier is a diesel GPU than a Jet A1 APU?)