In the simplest terms possible there are three basic things in fuel eu maritime (it’s not an exhaustive list just the main points):
The GHG energy intensity index. This is the major point. There’s a formula in the annex for the calculation. It is mainly affected by the use of shore side electricity and the type of fuel you used. You can think about it using the formula as the cii, based on your actual fuel consumption but with some key differences. The well to wake emissions are calculated so the origin of the fuel maters. It matters if the lng is produced green or not for example. The other thing is that the Co2 the N2O and the CH4 are all included based on their climate warming potential. In the same fashion as cii there are limits that get stricter as time goes by. The use of shore side electricity (onshore power supply, ams,cold ironing) helps to achieve the limit. The interesting part is the units that the GHGIE index uses that are gCO2equivalent/Mj. This means that you CAN’T achieve the limit as the time goes by without changing the energy source to be less polluting. It is not an energy efficiency regulation. It’s an alternative energy source regulation. This remains true even if you include to the consumption only EU trips or global trips.
It includes the concept of pooling the emissions of different ships.
Based on how far off the target your actual ghgie is there is a monetary cost.
For passenger ships and container ships it becomes mandatory to have shore side electricity equipment onboard.