Brittany Ferries is to run the first new ferry from the UK to be powered by liquefied natural gas (LNG).
The French firm says the £225 million vessel would be “the most environmentally-friendly ferry in UK waters”.
LNG emits about 25% less carbon dioxide during combustion than marine fuel oil and burns with no smoke.
It is entirely free of sulphur and is very low in nitrogen oxide emissions, according to the ferry company.
The vessel will be the biggest in the company’s fleet and is due to enter service in time for summer 2017.
Operating on longer routes between the UK and Spain, the new-generation ferry will carry almost 2,500 passengers and replace the company’s current flagship Pont-Aven.
Brittany Ferries group commercial director Mike Bevens said the launch of the new ship would “mark the beginning of a new era in ferry travel”.
He said: “This represents a huge investment which will benefit not simply our customers but the environment as well.
“Unlike other forms of transport, such as aircraft or trains, every one of our ships is different, each possessing its own unique character.
“This addition to our fleet will be no exception, but will incorporate all the best features of our other vessels so as to provide our customers with a truly exceptional experience.
“No other ferry in the UK will come close to offering this new ship’s range of facilities and its launch will mark the beginning of a new era in ferry travel.”
The new ferry will have an indoor swimming pool, two cinemas, restaurants, pet kennels, and 30 pet-friendly cabins.
It will weigh more than 52,000 tonnes, have a top speed of 24.5 knots and be capable of carrying 800 cars.
Brittany Ferries and French shipyard STX France have been co-operating for two years on a study regarding the feasibility of powering a cruise-ferry by LNG.
The ship will be built by STX France in St Nazaire.