The problem with banning is its inflexibility. For example, let's say you have a bunker-fueled emergency generator for a hospital that you use only when the power goes out. The pollution it emits is negligible. But by banning bunker fuel, you'll have to replace the emergency generator, at considerable expense and environmental cost.

With taxes instead, you:

1. bunker fuel will only be used when there's high value for it, and you won't have to add a plethora of exemptions into the regulation

2. have a revenue center for the government instead of a cost center - revenue that can be used to subsidize green initiatives