Explainers
Shore Power in Alaska: How Cruise Ships Plug In and Why It Only Works Sometimes
Princess plugged in at Juneau in 2001 — the first cruise ship shore-power connection in the world. 25 years later the Alaska grid still can't always supply it. Here's why.
When a 4,000-passenger cruise ship docks for ten hours in Juneau, what powers the lights, kitchens, AC, elevators, and the entire hotel operation? Most cruise ships keep their diesel generators running at idle the entire time — about 6 megawatts continuous, equivalent to the electricity demand of 3,000 homes. A growing number plug into the dock instead and shut their engines off entirely. Princess Cruises did this for the first time in Juneau in 2001 — the first cruise ship shore-power connection in the world. Twenty-five years later, the technology is broadly adopted but the Alaska grid still can't always supply it.
Quick facts
| Field | Detail |
|---|---|
| Term | Shore power, also called "cold ironing" |
| What it eliminates | ~95% of in-port air emissions from the ship |
| Typical load | ~6 MW continuous for a 4,000-passenger cruise ship |
| First cruise shore-power connection | Princess Cruises, Juneau, 2001 |
| 25th anniversary | 2026 |
| Seattle shore power | Pier 91 + Pier 66, completed Oct 2024 ($44M retrofit) |
| Seattle 2026 plug-in connections | 11 home-ported ships |
| Seattle 2027 mandate | All home-ported ships must connect |
| AEL&P (Juneau) supply rate | ~25% of average year requests; 0% in low-water years |
| Áak'w Landing (new Juneau dock) | Shore-power capable from day one (opens 2028) |
What "shore power" actually does
A modern cruise ship has two electrical loads: the propulsion load (the main engines that move the ship), and the hotel load (everything else — HVAC, lighting, galleys, elevators, water makers, sewage treatment, lounges). The propulsion load is essentially zero in port (the ship isn't moving). The hotel load is the constant ~6 MW that has to be supplied somehow.
Two ways to do that:
-
Auxiliary diesel generators on the ship. Standard practice. The ship runs 1–3 diesel auxiliaries to supply the hotel load. They emit local NOx, SOx (when burning higher-sulfur fuel), and PM2.5 directly into port-area air. Less than the main engines under steam, but still material — and concentrated where people live and work in cruise-port downtowns.
-
Shore power (cold ironing). A high-voltage cable from the dock (typically 6.6 kV or 11 kV) connects to a receptacle on the ship. The ship's electrical bus switches over to shore power; the auxiliaries shut off. Smell of diesel exhaust on the lower decks goes to zero. Local emissions go to roughly zero. The ship is now drawing power from the shore-side grid the same way a docked apartment building would.
The catch is that both ends have to support it: the ship needs the equipment (a "shore power coupler" and an electrical bus that can switch), and the dock needs the equipment (cable hangars, transformers, frequency converters where needed, and grid capacity for the load).
The Princess-Juneau 2001 milestone
In 2001, Princess Cruises and Alaska Electric Light & Power (AEL&P) partnered to install the world's first cruise-ship shore-power connection at the Juneau cruise dock. Princess refit a few of its ships with the necessary onboard equipment; AEL&P installed dockside cabling and grid connection. The first ship connected was the Princess Star (or possibly the Coral Princess, sources differ on the exact ship; Princess marketed it as "Princess shore power").
The 2001 deployment was experimental. It worked. By 2010 several other cruise lines had followed — Holland America's R-class ships (including MS Volendam) refit for shore power; Norwegian's some-ships followed. By 2020 most newbuilds shipped with shore-power capability standard.
2026 is the 25th anniversary of that first Juneau connection. Princess marked the 20th anniversary in 2021 with a press release; the 25th is approaching this season.
What Seattle did in 2024
Seattle's two cruise terminals — Pier 91 (Smith Cove) and Pier 66 (Bell Street) — completed a $44 million shore-power retrofit in October 2024. The retrofit brought all three cruise berths (two at Pier 91, one at Pier 66) to full shore-power capability.
The Port of Seattle's targets:
- 2026: 11 home-ported ships will connect to shore power during the season
- 2027: All home-ported cruise ships in Seattle MUST connect to shore power when at berth (Port Commission mandate, June 2024)
Seattle's shore-power supply comes from Seattle City Light, which runs on the Pacific Northwest hydro grid. Capacity is not the constraint at Seattle — Seattle City Light's grid is large enough to absorb cruise-ship loads without strain. Seattle's challenge is getting all the homeport ships outfitted with the equipment.
Why Alaska's grid is the bottleneck
Juneau is different. Juneau runs on hydroelectric power supplied by Alaska Electric Light & Power (AEL&P), which draws from Snettisham Hydroelectric Project (~78 MW capacity) and a few smaller stations. AEL&P serves the entire Juneau area — residential, commercial, and (when available) cruise ships.
Cruise-ship loads are enormous relative to Juneau's grid. Six megawatts per ship × five ships in port = 30 MW continuous load — almost half of AEL&P's total hydroelectric capacity. AEL&P has publicly stated it can supply enough capacity for cruise-ship shore-power requests only about 25 percent of the time in an average water year — and 0 percent in a low-water year when the hydro reservoirs run down.
Practically, this means:
- Cruise ships that arrive in Juneau may or may not be able to plug in, depending on the day, the season, and the grid's reservoir state.
- The dock has the infrastructure. The grid is the constraint.
- AEL&P has been studying additional generation capacity for years; nothing dramatic is on the immediate horizon.
This is the honest catch in Alaska shore-power coverage. The 2001 milestone proved the technology. Twenty-five years later, the grid still can't fill the demand.
Áak'w Landing — built for it from day one
Juneau's new fifth cruise dock, Áak'w Landing, is being built shore-power-capable from day one. Construction begins summer 2027; the dock opens for the 2028 cruise season. Both new berths will have shore-power infrastructure ready to go.
What this doesn't fix is the AEL&P grid capacity. Five docks instead of four doesn't make the hydroelectric system any larger. The installed plug capacity expands; the available grid capacity to supply those plugs stays the same. Áak'w Landing's design has been explicit about this — the dock supports the future, but the future also needs investment in additional Juneau-area generation.
What other Alaska ports are doing
| Port | Shore power status (2026) |
|---|---|
| Juneau | Yes (since 2001); grid capacity ~25% of requests |
| Seattle (Pier 91 + Pier 66) | Yes (since Oct 2024); grid capacity not the constraint |
| Vancouver, BC | Yes (since 2009 for Canada Place); good grid capacity |
| Skagway | Studying; not currently installed |
| Ketchikan downtown | Studying; not currently installed |
| Ketchikan Ward Cove (NCL private) | NCL has explored; not yet committed |
| Sitka | Not installed |
| Whittier | Not installed; new dual-berth terminal opened Sept 2024 without it |
| Seward | Not installed |
The pattern: shore power is expensive to retrofit and requires both port-side capital and grid-side capacity. Vancouver and Seattle's grids can support it; Juneau's can support it sometimes; smaller Alaska ports either can't afford the install or don't have the grid to back it.
What changes if you're a passenger
For passengers, shore power is mostly invisible:
- You won't smell diesel exhaust when the ship is at berth (if you're paying attention to that — most don't).
- Local air quality at the cruise pier is significantly better. This matters most in Juneau, where the cruise pier is right on the downtown waterfront and downwind of cruise emissions.
- You may notice quieter ship operations in port — auxiliary diesels make audible noise at the pier-side restaurants and walkways. Shore-powered ships are silent.
- No itinerary impact. Whether your ship plugs in or runs auxiliaries doesn't affect your day or your itinerary.
Shore power is one of those infrastructure stories where the user-visible difference is small but the system-level difference is large. Ten hours of cleaner air in downtown Juneau, multiplied by 600+ cruise calls per season, is meaningful. But you'd be hard-pressed to point to it from the lido deck.
Related on CruiseMigration
- LNG Cruise Ships Explained: Why the New Hulls Run on Liquefied Natural Gas — the other half of the cruise-emissions story
- Áak'w Landing: Juneau's Fifth Cruise Dock
- Juneau's 2026 Cruise Passenger Caps
- Juneau port tracker
Sources
- Port of Seattle — Cruise Ship Shore Power Facts
- Port of Seattle — From Spark to Shore Power: How Watts Marine helped electrify the cruise industry
- Princess Cruises — 20th anniversary of shore power in Juneau (2021)
- Cruise West Coast — What is shore power
- Travel Agent Central — Tidelands lease signed for Áak'w Landing
- Port of Seattle — Cruise season opens with 330 calls
- Port Economics, Management and Policy — Cruise ship store loading and cold ironing
Frequently asked questions
- What is shore power for cruise ships?
- Shore power — also called cold ironing — is when a cruise ship's hotel load (lights, kitchens, HVAC, etc.) runs from a high-voltage shore-side cable instead of the ship's auxiliary diesel generators. The ship's engines shut down completely while at berth. This eliminates approximately 95 percent of in-port air emissions from the ship.
- When did cruise ships first start using shore power?
- Princess Cruises plugged in for the first time in Juneau, Alaska in 2001 — the first cruise port in the world with shore power capability. 2026 marks the 25th anniversary of that engineering milestone.
- Do all Alaska cruise ports support shore power?
- No. Juneau supports it (since 2001) and Seattle's Pier 91 and Pier 66 added shore power in October 2024. Most other Alaska ports — Skagway, Ketchikan downtown, Sitka, Whittier, Seward — do not currently have shore-power infrastructure for cruise ships, though several are studying or planning installations.
- Why doesn't shore power work all the time even where it's installed?
- Juneau runs on hydroelectric power supplied by Alaska Electric Light & Power (AEL&P). AEL&P estimates it can supply enough capacity for cruise-ship shore power only about 25 percent of the time in an average water year — and 0 percent in low-water years when the hydro reservoirs run down. The infrastructure exists; the grid capacity is the constraint.
- Will Áak'w Landing support shore power?
- Yes. Juneau's new fifth cruise dock, Áak'w Landing — breaking ground summer 2027 and opening for the 2028 season — is being built shore-power-capable from day one. The dock infrastructure will be ready, but the AEL&P grid-capacity constraint stays the same regardless of how many docks have plugs.
- How much electricity does a cruise ship at idle need?
- A typical 4,000-passenger cruise ship at idle in port draws approximately 6 megawatts — about the same as the constant electricity demand of 3,000 average homes. That's the load that has to be supplied by either the ship's diesel generators or the shore-power grid.