Sails have been relied on for about 5,000 years to move ships without using any fuel. It's probably safe to say that anything that's been in use for 5,000 years straight is a halfway decent idea, and a U.K. company called B9 shipping is bring back the sail with a new cargo ship design that doesn't need any fossil fuels at all.
A staggering 90% of consumable goods are transported by sea, which means that when fuel costs go up, the cost for everything goes up. Furthermore, global shipping emits as much carbon into the atmosphere as the entirety of some country called Canada. With this in mind, B9 Shipping is taking inspiration from racing sailboats and luxury yachts and applying it to cargo ships with a set of high efficiency, low maintenance DynaRig sails.
DynaRig is the ideal sail system for modern ships. There's no rigging, which is half of what made sailing such a pain in the poop in the first place, and the other half (managing the sails properly to get the best speed in a given direction) is all handled by a computer. The masts are made of carbon fiber and support several sails each, and when you don't want them, each sail tidily retracts back into its boom. Here's how the DynaRig system looks on a modern luxury yacht, the Maltese Falcon:
Now, the reason that sails lost out to engines in the first place is that sometimes the wind is just dead foul for where you want to go. With sails, your only option would be to beat against the wind in long, inefficient zigzags (or just wait for better weather), and since global commerce will not wait for man nor beast, knuckling under to the fickle whims of Tāwhirimātea is really not an option. The B9 cargo ship will have engines: in fact, the engines will be responsible for driving the ship about 40% of the time. The difference is, the engines will be powered entirely by biogas, derived from sources like municipal food waste, making them carbon-neutral.
B9 Shipping says it's currently working on a testing program to come up with the most efficient sail and hull designs, and it should start building a full-scale prototype later this year.