There are types of sails or wind power that have been investigated to reduce carbon output / efficiency of tankers but they never seem to have been deployed at

There are types of sails or wind power that have been investigated to reduce carbon output / efficiency of tankers but they never seem to have been deployed at scale in any sense. Basically a kite-surfing tanker. It seems like until we get tiny compact fusion energy we'll always end up running off the cheapest oil products, as they make the most sense economically. Without any actual incentive to switch, not a single shipping company will.