so these things are actually happening. it's not "wind-powered" it just gets assistance from the wind when possible. there are also other issues here, you've got a higher center of gravity, the sails weigh a lot so you can't carry as much cargo, etc.

they're talking about a 7-10 year payback for installing the sails. I bet that doesn't pan out but they're going to do it anyway because muh carbon footprint