Energy Efficient Technologies and Ship Capacity
If new equipment is installed to improve ship energy efficiency of a ship and reduce GHG emissions, then the first questions need to be clarified are: Will this additional equipment alter the ship gross tonnage, and will this additional equipment alter the ship’s lightweight?
If a ship is designed with GHG reducing equipment that increases the gross tonnage, there will be a financial penalty over the whole of the lifetime of the ship as port dues are often calculated on the gross tonnage of the ship. This situation could be resolved by amending the 1969 Convention at the IMO so that allowances can be made for installation of equipment that reduce GHG but this has proved to be very difficult to do even for safety reasons. The ship-owner or manager must take these considerations into account when deciding if it is viable to install any new equipment to reduce GHG emissions on a new or existing ship if it is to be modified leading to an increase in the measured gross tonnage (MariEMS 2017).