The Roald Amundsen, an expedition cruise ship that can carry 500 passengers and is designed for rough waters, set out last Monday on its maiden voyage silently, on electric power.

It can plug in to charge its batteries when it's in port, but with a schedule reaching to the far poles of the world, the ship cruises mainly like a conventional hybrid, using extra power from its marine gasoil engines to charge a bank of batteries that can maneuver it for up to an hour on electricity alone.

The Amundsen is headed from the northern port of Tromsoe, Norway to Alaska, via the Northwest Passage first discovered by the ship's namesake Norwegian explorer in 1903. After that, it's going to Antarctica in October, where Mr. Amundsen was also the first explorer to reach the South Pole in 1911.

Studies have shown that huge cruise and container ships produce more pollution than millions of cars and trucks.

The ship is operated by the Hurtigruten cruise line. CEO Daniel Skjeldam told Reuters the batteries are "a way of reducing emissions significantly without having charging stations available."

"We expect batteries to be an important part of shipping in the years to come, but of course we don’t expect our ships to be able to operate only on batteries, because the ship can sail up to 18-20 days in areas where there are no charging points,” he said to Reuters.

Hurtigruten did not specify the size of the battery banks on the ship, but said the hybrid system can reduce fuel consumption by about 20 percent. Skjeldam says the company has a second hybrid expedition cruise ship on order, and has left room in the design of the Roald Amundsen for larger batteries to be added as battery technology improves.

The Roald Amundsen isn't the first ship to plug-in, of course. Skjeldam says it was inspired by Norway's pure-electric ferries. But it is the first long-haul, ocean-going hybrid ship.

As to whether the ship will actually be charged in port, Skjeldam says few ports have charging facilities, and only one in Norway, in the port of Bergen, the country's second-largest city. Tromsoe does not.