Eckhard,
Heat energy, and kinetic energy (exhaust) come to mind.
Power plants use turbines to produce electrical power, however of course, like the stopped aircraft, the power plants are not moving.
I'm sure the quote/myth is really meant to mean "there is no power (ie energy) gained by the aircraft" (except possibly warmer brakes).
However I've seen it referred to as "the aircraft is producing no power", clearly incorrect.
Hawk