Construction work on two pioneering battery-powered ferries is under way, with the cutting of the first steel at the Ferguson shipyard in Port Glasgow.
The 900-tonne ships are said to be the world's first sea-going roll-on roll-off diesel-electric hybrid ferries.
They will be owned by Caledonian Maritime Assets (CMAL) and operated by CalMac Ferries, which runs Clyde and Hebrides Ferry Services.
The first vessel is expected to enter service next year.
The ferries will be built to accommodate 150 passengers and 23 cars and are designed for short routes, including the link between Skye and Raasay.
The £22m contract will involve installing new green technology, including battery banks supplying a minimum of 20% of the energy consumed on board.
They will also have diesel generators on board, to top up the charge.
The ferries' batteries will be charged overnight while they are moored on the islands they will serve.
It is hoped in the future energy from local wind, wave or solar systems will be used to charge the batteries.
Ferguson will be working alongside Glasgow-based ship design specialists Seatec and electrical specialists Tec-Source to deliver the project, which is supported by a Scottish government loan and additional funding of £450,000 from the European Regional Development Fund.
CMAL chief executive Guy Platten said: "The cutting of the first steel marks an exciting new stage of the project, as the build begins on the world's first sea-going ro-ro passenger hybrid ferries.
"The project demonstrates CMAL's commitment to leading the way in innovative ferry design and we look forward to seeing the project reach fruition when the first of the vessels goes into service in early 2013."
Environment Minister Stewart Stevenson said: "The detailed design and the construction of the world's first battery-operated sea-going vehicle ferry, both being carried out by local companies, highlights Glasgow and the Clyde as a major player in a modern world.
"It is absolutely fantastic that a new generation of ship-building is starting on the Clyde, a river which has a rich and proud ship-building history."