Maersk says savings can be added to those generated by slow steaming.
Saving fuel works economically and environmentally, says carrier.
Tougher sulphur regs need enforcing to make them work.
Lower bunker prices and consumption helped lift profits.
Bunker suppliers have raised concerns over container lines' plans.
Terminal operator earmarks $26 million for infrastructure.
'We want to inform our customers how we're approaching this, and what's involved,' says senior director.
A to G rating scheme used as basis for reducing port fees.
Concept would call for building of fourth set of locks.