Sails just don't provide all that much motive force, and they're far too unreliable (wind dies down, it doesn't matter how much sail you have.)
Maybe the GP was thinking more along the lines of general 'green' tech -- wind turbines, solar panels, etc? It would certainly be cool to see more of those to supplement existing propulsion systems on ships, and that would help reduce the amount of fuel burned for shipping, which uses some of the dirtiest fractions of petroleum.
Combining technologies would absolutely be a great way to pivot, as the article shows. Maybe it’s a dumb question, but why don’t we have sails on modern ships as a supplement?
I just lament that we basically completely abandoned such a great mechanism (sails) so haphazardly just because coal was cheap & reliable; now the environment pays the price.
Sails take quite a bit of space to store, they aren't exactly the lightest thing, and you need training and coordination of the sailors to deal with them. They also probably just dont provide enough benefit to offset the costs -- as I said before, sails don't actually provide that much force.
There are a lot of smaller boats that have both sail and mechanical engines, but that only works because they're small enough that the sails can provide a significant amount of force. And if you look at the transition period between the Age of Sail and Age of Steam, there were a lot of boats and ships that had both sail and steam engines. The sails were mainly relegated to backup, or to help out the steam engines, but these hybrids existed.
At 10 mph wind, sails generate about 0.256 pounds of force per square foot (according to random website found via google). Therefore your several ton cargo ship gets next to nothing from sails.
Comments
I can't imagine there would be that many.
Sails just don't provide all that much motive force, and they're far too unreliable (wind dies down, it doesn't matter how much sail you have.)
Maybe the GP was thinking more along the lines of general 'green' tech -- wind turbines, solar panels, etc? It would certainly be cool to see more of those to supplement existing propulsion systems on ships, and that would help reduce the amount of fuel burned for shipping, which uses some of the dirtiest fractions of petroleum.
Combining technologies would absolutely be a great way to pivot, as the article shows. Maybe it’s a dumb question, but why don’t we have sails on modern ships as a supplement?
I just lament that we basically completely abandoned such a great mechanism (sails) so haphazardly just because coal was cheap & reliable; now the environment pays the price.
Sails take quite a bit of space to store, they aren't exactly the lightest thing, and you need training and coordination of the sailors to deal with them. They also probably just dont provide enough benefit to offset the costs -- as I said before, sails don't actually provide that much force.
There are a lot of smaller boats that have both sail and mechanical engines, but that only works because they're small enough that the sails can provide a significant amount of force. And if you look at the transition period between the Age of Sail and Age of Steam, there were a lot of boats and ships that had both sail and steam engines. The sails were mainly relegated to backup, or to help out the steam engines, but these hybrids existed.
I just looked into the economics of rotor sails.
On average, they save $400/day ($146,000/year) in fuel costs (2017) or about ~10% of fuel consumption. In real terms, it's not much.
They cost about €1-2 mil ($1.1-2.3). Under the most ideal circumstances, that is a ~8 year payback, which is fairly long.
In order for the economics to work out, oil prices need to be higher and externalities (CO2 emissions) need to be included in the price.
We do. They just don't look like sails. This is a Maersk ship.
https://en.wikipedia.org/wiki/Rotor_ship#/media/File:Norsepo...
Low tech magazine has some practical examples of ships that operate sails in addition to fuel to lower fuel-usage: https://www.lowtechmagazine.com/2007/09/sailing-ship-re.html
At 10 mph wind, sails generate about 0.256 pounds of force per square foot (according to random website found via google). Therefore your several ton cargo ship gets next to nothing from sails.
We use the form factor quite differently. A game and watch is about the size of a cell phone these days.