Long distance shipping is currently mostly burning "resid" it's the bottom-of-the-bottom or the barrel. It's 3.5% sulphur and it's not worth much more than the cost of transporting it from the refinery to the port.
The idea that shipping companies will go straight for the expensive options of as synfuel, green ammonia (the deaths alone for the crew will be horrific), or green hydrogen is absurd.
