When an aircraft is on the ground, it still needs a reliable and consistent source of electrical power. From lighting and air conditioning to complex onboard systems and avionics, many of an aircraft’s essential functions rely on electricity even before the engines start. That’s where Ground Power Units (GPUs) come into play.
What Are Ground Power Units?
A Ground Power Unit (GPU) is an external power supply that provides electricity to an aircraft while it is parked on the ground. In simple terms, it acts as a plug-in power source, supplying energy for pre-flight checks, maintenance, and passenger comfort without the need to run the aircraft’s engines or auxiliary power unit (APU).
This not only saves fuel and reduces emissions, but also cuts noise pollution at airports — an increasingly important factor as the aviation industry works to minimise its environmental footprint.
Why Aircraft Need External Power
Before take-off, an aircraft’s systems must be fully operational. Technicians and crew rely on a stable electrical supply to power up navigation instruments, communication systems, cabin lighting, galleys, and environmental controls. Using a GPU for this process avoids burning costly jet fuel simply to generate electricity.
Moreover, during longer ground operations or maintenance work, GPUs provide continuous, reliable power to ensure that the aircraft’s batteries remain charged and sensitive electronic systems are not damaged by fluctuating voltages.
Types of Ground Power Units
There are several different types of GPUs, each suited to specific operational needs and environments:
- Fixed Ground Power Units
These are permanently installed systems found at airport gates or hangars. They are usually powered by the local electrical grid and deliver stable, clean power directly to the aircraft. Fixed GPUs are highly efficient, low-maintenance, and designed for continuous use at busy terminals.
- Mobile Ground Power Units
As the name suggests, mobile GPUs, like those supplied by Red Box Aviation, are portable units that can be moved around the airfield to service aircraft parked remotely or undergoing maintenance. They may be mounted on trailers, trolleys, or vehicles. Mobile units are often diesel-powered or battery-powered, making them ideal for flexibility and quick response operations.
- Hybrid and Battery-Powered GPUs
In recent years, the aviation sector has seen a shift towards electric and hybrid GPUs. These greener alternatives use battery technology to deliver quiet, emission-free power, which is particularly valuable for airports focused on sustainability. Some hybrid models combine electric drive with a backup combustion engine for extended range and versatility.
- 400Hz and 28V DC GPUs
The type of power output depends on the aircraft being serviced.
- 400Hz AC GPUs are typically used for large commercial aircraft, matching the standard frequency of onboard electrical systems.
- 28V DC GPUs are more common for smaller aircraft, helicopters, and private jets, which require lower-voltage direct current.
How GPUs Have Transformed Aircraft Ground Operations
In earlier decades, preparing an aircraft for flight relied heavily on running the onboard auxiliary power unit (APU) — a small turbine engine that generates power and compressed air. While effective, the APU consumes aviation fuel, emits CO₂ and noise, and adds wear to the aircraft’s systems.
The introduction of efficient and widely available GPUs has revolutionised ground handling operations. Airlines and maintenance teams can now:
- Carry out pre-flight checks without starting the engines.
- Maintain cabin comfort and lighting during boarding.
- Perform longer maintenance or cleaning tasks without draining batteries.
- Reduce turnaround times by providing instant, reliable power on arrival.
This shift has also influenced aircraft design itself. As GPUs became a standard feature at airports worldwide, manufacturers could optimise onboard power systems and reduce reliance on heavy, fuel-hungry APUs during ground operations — contributing to overall efficiency and lower operating costs.
Beyond Aviation: Other Uses of Ground Power Units
While GPUs are synonymous with airports, their usefulness extends well beyond aviation. Similar power systems are used in a variety of industries and applications where reliable, portable electricity is essential:
- Military Operations: To power radar systems, communication equipment, and vehicles in the field.
- Marine and Shipyards: Supplying docked vessels with electrical power for maintenance and onboard systems without running engines.
- Rail Transport: Providing power to trains during servicing or at depots.
- Construction and Remote Worksites: As a dependable power source for tools and lighting in off-grid environments.
- Events and Emergency Response: Supplying temporary power for field hospitals, concerts, and disaster-relief operations.
The Future of Ground Power Units
The ongoing drive towards electrification and sustainability is shaping the next generation of GPUs. Advances in lithium battery technology, smart energy management, and renewable charging solutions are creating more efficient, quieter, and cleaner ground power systems.
As airports transition towards net-zero operations, electric GPUs will play an even greater role in reducing emissions and improving energy efficiency on the ground — powering not only aircraft, but the future of sustainable aviation infrastructure.
In summary, Ground Power Units have become an indispensable part of modern aviation, bridging the gap between aircraft and airport infrastructure. From pre-flight preparation to long-term maintenance, GPUs enable safer, quieter, and more efficient operations — and their expanding role across other industries highlights just how vital this technology has become in keeping the world powered and moving.
