Hope it goes well, decarbonising freight could be big.
Huuge
Uh, it has no mention at all at the properties of the turbine. All it says is the exterior dimensions of the thing, 5m diameter. No mention of optimal wind speed, or power output.
I don’t think it really outputs power, it operates more like a sail. It looks like a cylinder on the front of the ship. It says it can function in winds at or below 80mph.
You’re right it’s supposed to work like a sail. I’m very sceptical because it says it can save up to 30% fuel. No chance any sail with that footprint can save that much fuel. At least with electrical generators you can benefit from wind in any direction at any time, even when anchored.
It’s more efficient than a sail of the same size, or they would’ve just installed a sail of the same size to reduce the moving parts.
AFAICT it’s more efficient because it acts like a plane wing/turbine blade with suction instead of literally just being blown on - basically, a turbine blade gets its speed from 1) being pushed sideways by the wind hitting the 45° plane, but also 2) the wind goes mostly over the rear of the wing, meaning there’s a high pressure at the back of the wing and a low pressure in front of the wing, which sucks the wing forward.
So this rotor sail uses the same suction trick, where the wind goes faster along the side that’s spinning with the wind and slower along the side that’s spinning against the wind, and the faster wind will have lower air pressure than the slower wind, thus sucking the rotor sail towards the faster wind side. But since the rotor sail is fixed to the ship, it sucks the entire ship forward.
The 30% fuel savings are pretty trivial, I could make it 80% if you give me a day and a sledgehammer to make the engine’s efficiency even worse. Maybe it’s running a two-stroke engine (not a marine two-stroke, just a regular two-stroke).
I’ve heard they work well. Something about the magnus effect produces thrust. I forget the details, but it doesn’t function at all like a traditional sail.
