I think the problem is the efficiency, a wind turbine is limited to about 60% by Betz law[0] and most today seem to have 35-45% efficiency. Which means with all

I think the problem is the efficiency, a wind turbine is limited to about 60% by Betz law[0] and most today seem to have 35-45% efficiency. Which means with all losses included I think it's hard to see a headwind helping, same with how the apparent wind shifts forward, which would make a weak stern wind not help anything and the turbine just be drag. They are making trials with wind "turbines" using the magnus effect[1], they seem to save about 300 tons of fuel per year, but since the article doesn't include the ships yearly total amount it is hard to put it into a relation to anything. https://safety4sea.com/tests-from-rotor-sail-technology-on-viking-grace-indicate-savings/ https://safety4sea.com/tests-from-rotor-sail-technology-on-v... I think ships is one of the applications where hydrogren could be feasable. Batteries are hard when you have to have the range from China to Europe or NA without stops and the density of hydrogen could maybe solve that. Especially since compared to cars the distribution network is more easily centered around large harbours and routes which is already used to handling dangerous goods. Though the competition is going to be synthetic hydrocarbons and all they need are producers, the entire world is already devoted to transporting them. [0] https://en.wikipedia.org/wiki/Wind_turbine https://en.wikipedia.org/wiki/Wind_turbine [1] https://en.wikipedia.org/wiki/Magnus_effect https://en.wikipedia.org/wiki/Magnus_effect