Guide to diesel-powered mobile ground power units for airports and MROs. Towable and self-propelled GPU from Hobart, TLD, ITW GSE, and Guinault for ramp operations.
What Are Diesel Ground Power Units?
Diesel ground power units are the mobile workhorses of airport ramp operations — self-contained generators that produce 28V DC (or 400Hz AC for commercial aircraft) anywhere on the airfield without needing a mains power connection. When an aircraft parks at a remote stand, a maintenance area, or a military dispersal pad, a diesel GPU provides the ground power that fixed installations can't reach.
How They Work
A diesel GPU combines a diesel engine, an alternator, a rectifier (for DC output) or frequency converter (for 400Hz AC output), and output regulation electronics in a towable or self-propelled package. The diesel engine drives the alternator, which produces raw AC power. For 28V DC aircraft, a rectifier converts this to DC with appropriate filtering and regulation. For commercial aircraft, a frequency converter produces 115/200V at 400Hz. Output capacity ranges from 1,500A to 6,000A+ peak for DC units, and 60 kVA to 180 kVA for AC units.
Manufacturer Comparison
Choosing the Right Diesel Ground Power Unit
Diesel GPUs occupy a specific niche: they provide the portability that TRUs lack and the unlimited endurance that battery GPUs can't match. An airport that parks aircraft at remote stands without fixed ground power needs diesel GPUs to avoid running APUs — which burn expensive jet fuel, generate noise complaints, and produce emissions that airports are under increasing pressure to reduce.
The trade-offs are real. Diesel GPUs are expensive ($40,000 to $200,000+), heavy, require regular maintenance (oil changes, filter replacements, cooling system service), and produce their own emissions and noise — though far less than an aircraft APU. They also need fuel logistics: diesel storage, fueling procedures, and spill containment. For most private operators and small FBOs, a mains-powered TRU or battery GPU is more practical.
Diesel GPUs make economic sense at three scales: airports where fixed ground power can't reach every parking position, military flight lines where power infrastructure may not exist, and MRO facilities that need to move high-capacity ground power between aircraft in large hangars. The ability to deliver 3,000A+ peak at 28V DC from any position on the ramp, without extension cords or infrastructure, is the diesel GPU's unique value proposition.
Environmental regulations are driving change. Tier 4 Final diesel emission standards have pushed manufacturers toward cleaner engines, and some airports now mandate idle-reduction technology or electric alternatives for gate operations. The trend is toward fixed electric ground power at gates (TRUs and 400Hz converters) supplemented by diesel GPUs only where fixed power isn't feasible.
For a step-by-step approach to selecting the right GPU for your aircraft, see our GPU Sizing Guide. For a comparison of lead-acid vs lithium technology, read Lead Acid vs Lithium GPUs.
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Frequently Asked Questions
When does a diesel GPU make more sense than a TRU?
A diesel GPU makes sense when you need high-capacity ground power at locations without reliable AC mains — remote parking stands, military dispersal pads, construction-phase airport areas, and field operations. If mains power is available, a TRU is less expensive, quieter, and maintenance-free.
How much fuel does a diesel GPU use?
Fuel consumption varies by output load, typically 3 to 15 gallons per hour. A Hobart 4400 at full load (28V DC, continuous output) consumes approximately 5 to 8 gallons per hour. Still far less than an aircraft APU, which burns 40 to 100+ gallons of jet fuel per hour.
Can a diesel GPU start a Gulfstream G650?
Yes. Large diesel GPUs from Hobart and TLD deliver 5,000A+ peak at 28V DC — sufficient for the G650's Rolls-Royce BR725 engines. Diesel GPUs are one of the few portable options with enough current capacity for large-cabin business jets.