Battery Application Solutions for Dry Dock: Shore Power, Welding and Yard Mobility
Battery Application Solutions for Dry Dock: Shore Power, Welding and Yard Mobility
A dry dock is a factory that floods. When a vessel is pumped dry, the whole yard switches on at once: dewatering pumps, temporary lighting strings, welding sets, ventilation fans for confined-space work and the gantry or crawler crane that moves plate and equipment. That concentrated load lands for a two or three week window and then largely disappears. Purpose-built battery application solutions let a yard serve that spike without renting a second generator or paying a punishing peak-demand charge, and they keep critical loads alive when the shore supply trips.
The Shape of a Docking Load
Unlike a process plant, a dry dock load is event-driven. Dewatering dominates the first 12 to 36 hours, welding and fabrication peak in the middle, and lighting plus ventilation run continuously because much of the work happens inside tanks and double bottoms where there is no daylight. Peak demand can be three or four times the yard’s baseline, so the commercial case for storage rests on peak shaving as much as on fuel.
Where Batteries Beat Diesel
A diesel generator running at 25 percent load for a lighting string wastes fuel, wets-stacks and needs an operator. A battery bank sized to the overnight lighting and ventilation load runs silently for eight to ten hours and recharges from shore power or the generator at its efficient point. For welding, a battery-buffered distribution point absorbs the violent load steps of multiple inverter welders striking an arc at once, which otherwise forces the generator to overspeed or the voltage to sag below the point where welds fail.
Dry Dock Power Options
| Load | Diesel genset | Battery + shore | Battery hybrid |
|---|---|---|---|
| Lighting & ventilation | Poor part-load | Best | Good |
| Welding surge | Good | Limited | Best |
| Dewatering pumps | Good | Best (soft start) | Best |
| Noise in hull | Poor | Silent | Low |
| Fuel per docking | High | None | Low |
Sizing by Load Block
Work from the docking plan, not the nameplate total. List each load block — pumps, lighting, welding, ventilation, crane — with its kilowatt draw and duty hours, then size the battery to the largest block that can be shifted or islanded. In practice a 500 kWh to 1 MWh container covers lighting, ventilation and pump starting for a mid-size yard, while a 300 kW to 600 kW power conversion system handles the welding surge. Anything above that should remain on the generator, with the battery riding the transients.
Safety in a Salt and Steel Environment
A dry dock is a wet, conductive, chloride-rich workplace with hot work happening metres away. Locate the container outside the hull footprint and above any water that could enter the dock, on a plinth with drainage. Specify IP65 enclosures, marine-grade coatings on the frame, and stainless or tinned busbars. Because battery enclosures sit beside confined-space work, require gas detection interlocked to ventilation and a clearly marked emergency stop that yard crews are trained on during induction.
Shore Power and Peak Shaving
Many yards can now take a cold-ironing style shore connection, but the tariff often includes a demand charge based on the highest 15-minute draw of the month. Charging the battery slowly at night and discharging into the docking peak flattens that spike, and the saving frequently pays the storage faster than the fuel saving does. Ask the utility whether a demand-response or interruptible tariff is available for a yard that can shift a megawatt on request.
Yard Mobility and Temporary Power
Smaller batteries pay for themselves in the yard itself: battery-electric service carts, portable power units that replace the trailing cables strung along a dock floor, and mobile lighting towers. Removing trailing cables from a wet steel deck removes one of the most common trip and damage hazards in ship repair, and nothing needs refuelling at the bottom of a dock.
What to Ask a Supplier
Ask for a load-profile study rather than a catalogue quote, and require the transient response specification in writing because welding and pump starting are what actually stress the system. Confirm marine coating and enclosure certifications, demand a spill and thermal-runaway plan suitable for a confined-space environment, and check that spare parts and service are available at your port.
People Also Ask
Can a battery replace a dry dock generator entirely? Usually not for welding and crane peaks. The economics work best as a hybrid: the battery carries lighting, ventilation and pump starting, the generator covers heavy transients and recharges the bank.
How is the battery protected from salt water? Through siting above the water line, IP65 enclosures, marine-grade coatings and plated or stainless conductors, plus drainage and gas detection in the enclosure.
Does storage really cut the electricity bill? Yes, often mainly through peak-demand shaving rather than energy arbitrage, because a docking creates a short, very high peak that sets the monthly charge.
What maintenance is realistic for a working yard? A quarterly visual and thermal inspection, annual torque and insulation-resistance checks, and remote monitoring of cell temperatures and state of health.
Written by Karl at China Battery Technology. Request a quote.
