Ground Power Unit (GPU) Vs. Auxiliary Power Unit (APU)
These terms are sometimes used interchangeably, so we will look at the similarities and differences between these systems in this blog post.
First, both systems perform the same function of providing power to the aircraft independently of the aircraft battery and/or the engine driven generators.
The differences begin with the mobility of the systems. APUs are basically a small turbine engine built into the aircraft itself to provide pneumatic starting power for the engines as well as continuous power for on-board aircraft systems. GPUs, on the other hand, are not part of the aircraft and can either be mobile or fixed in place. They provide electrical power, but not pneumatic power.
The other major difference is efficiency. While APUs run on the aircraft’s fuel supply and power the aircraft they are in, GPUs are independent and run on either diesel or electrical power. Additionally, GPUs can also be used on multiple aircraft as opposed to just one making them much cheaper to operate for extended periods of time.
When there is a choice to make between these systems, GPUs win hands-down in terms of efficiency and flexibility. They do fall short when it comes to starting pneumatically started engines, but they perform well with electrically started ones.