The grand old sailing ship looks like a ghost vessel as she makes her way down the River Thames. Towing her, though much smaller, is a dark tugboat, belching smoke. The backdrop is a murky sunset reflected in the water, symbolising a sad fact: it is the vessel's final voyage before she is scrapped.  

This is the scene shown in William Turner's The Fighting Temeraire, voted Britain's favourite painting in a BBC poll. The Temeraire was a 98-gun Royal Navy ship that fought at the Battle of Trafalgar in 1815. For Turner, her scrapping 23 years later was proof that romantic sailing ships were being eclipsedLiterally, to be blocked from view. It can also mean to be out-done by something.  by steam-driven vessels.

But sail may be about to make a comeback, thanks to a remarkable new project called Oceanbird. Set to launch in 2025, it has been described as "the vessel from the future".

Its designers hope that it will dramatically reduce the carbon emissions from shipping, which amount to 940 million tonnes a year. Although it will have a diesel engine to power it when there is no wind, it is projected to use 90% less fuel than a regular cargo ship.

It will also reduce the risk to sea creatures, which are sometimes killed by ships' propellers, and the damage done to the seabed's ecosystems by thunderously loud engines.

Other solutions to the emissions problem have been suggested, such as ships powered by electricity or hydrogen. But the batteries needed would be impractically large. Another alternative, biofuels, would involve planting vast areas of crops which would reduce biodiversity.

The key to the Oceanbird's design is its five sails - or "wings", as its designers call them. Instead of the traditional sheets of canvas, they are made of rigid steel - but they are highly manoeuvrable.

For one thing, they are telescopic, so their height can be varied from 20m to 80m. They can be lowered to go under bridges and to make the ship more stable in high winds.

Each can be rotated 360 degrees, and all five can be in different positions, allowing the ship to make maximum use of the wind.

Oceanbird should be able to cross the Atlantic with a cargo equivalent of 7,000 cars in eight days. Although it would be 50% slowerOceanbird would take 12 days to cross the Atlantic rather than the eight it would take a normal ship of the same size.  than a conventional ship, it would be outweighed by the savings on fuel.

The first ocean-going sailing ships are thought to have been built as long ago as 3,000 BC, by the inhabitants of what is now Taiwan. The Ancient Egyptians also had sailing boats, but they could only be used on rivers and coastal waters. And because early sails were inefficient, they needed oarsmen as a backup.

Not until the 15th Century, when the PortugueseA prince known as Henry the Navigator played a major role in encouraging the country's explorers. developed the caravelBased on fishing boats, it had triangular sails which made it possible to beat against the wind., were Europeans able to start exploring the oceans. Navies still depended on galleysShips propelled mainly by oars, often with slaves as the rowers. until the Battle of LepantoA major naval battle in which a coalition of Catholic states defeated the Ottoman Empire's fleet.  in 1571.

The fastest sailing ships ever were the clippersThey were particularly important for making fast deliveries of tea from China to Europe. built in the 19th Century, during what was known as the Golden Age of SailGenerally considered to be from the middle to the end of the 19th Century.. One called The Champion of the Seas covered 535 miles in a single day.

Yes: If we are to solve the climate crisis, we cannot continue to use ships with huge carbon emissions. Reverting to wind power, used more efficiently thanks to new technology, is the obvious solution.

No: The world works to much tighter timetables today than it did in the age of sail. We simply cannot rely on cargo vessels whose arrival time depends on how favourable the winds happen to be.

Or... The golden age of sail is remembered for beautiful ships travelling at high speeds. The new ships will travel at moderate speeds and probably not be beautiful. So it could be a bronze age of sail. 

Eclipsed - Literally, to be blocked from view. It can also mean to be out-done by something. 

Slower - Oceanbird would take 12 days to cross the Atlantic rather than the eight it would take a normal ship of the same size. 

Portuguese - A prince known as Henry the Navigator played a major role in encouraging the country's explorers.

Caravel - Based on fishing boats, it had triangular sails which made it possible to beat against the wind.

Galleys - Ships propelled mainly by oars, often with slaves as the rowers.

Battle of Lepanto - A major naval battle in which a coalition of Catholic states defeated the Ottoman Empire's fleet. 

Clippers - They were particularly important for making fast deliveries of tea from China to Europe.

Golden Age of Sail - Generally considered to be from the middle to the end of the 19th Century.