Shore Power: Cold Ironing at Port

Berth Power Source

Ship & Grid Parameters

Hotel load 450 kW

Dwell time at berth 18 h

Shore power adoption 100%

Grid carbon intensity 220 gCO₂/kWh

Live Readouts

Instantaneous draw

0 kW

Source

Shore

CO₂ avoided this visit

0 kg

Fuel cost saved this visit

How it works

A docked ship still needs power for lighting, pumps, refrigerated ("reefer") containers and crew systems — its hotel load. Without shore power it burns diesel in its auxiliary generators the whole time it's berthed. Cold ironing (shore power / Alternative Maritime Power) lets it shut those engines down and plug into the local grid instead, exactly like an aircraft on stand or an EV at a charger.

Energy at berth:   E = P_load · t_dwell            (kWh)
Baseline (all-diesel) emissions:
                   M_diesel = E · f_diesel           (kg CO2)
With shore power at adoption fraction f:
                   M_mixed  = E · [f·g_grid + (1−f)·f_diesel] / 1000
CO2 avoided:       ΔM = M_diesel − M_mixed = E · f · (f_diesel − g_grid) / 1000

where f_diesel ≈ 750 gCO₂/kWh is a typical marine auxiliary-diesel-generator emission factor and g_grid is the local electricity grid's carbon intensity (a coal-heavy grid can erase most of the benefit; a hydro/wind/nuclear-heavy grid nearly eliminates dockside emissions).

Hotel load — how much power the ship's onboard systems draw while berthed.
Dwell time — how long the ship stays connected at the berth.
Shore power adoption — the fraction of dwell time actually plugged into shore power rather than running the diesel gensets (infrastructure limits, cable capacity or crew procedure can keep this below 100%).
Grid carbon intensity — the CO₂ per kWh of the local electricity supply; this is what shore power is actually competing against.

Real ports (Los Angeles, Long Beach, Rotterdam, Shanghai) now mandate or incentivize cold ironing at container and cruise berths specifically because it removes near-shore diesel exhaust — the single largest source of port-adjacent air pollution — without needing the ship's engine technology to change at all.

🔌 Shore power connected

Shore power (grid) Diesel exhaust

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