What is the EEXI and does it have an effect on your vessel’s operations?
As a part of the strategy from IMO to reduce carbon emissions from Shipping by 40% before 2030, a set of regulations on vessel design and operations are suggested to enter into force by 2023.
With regards to the design of the vessels, a number of reduction factors of the CO2 emissions for different vessel types are given in the regulations. The reduction factors are given in relation to the EEDI reference line with a percentage factor. As an example, bulk carriers in a certain DWT range are to reduce emissions by 20% towards the EEDI reference line.
Vessels built under the EEDI rules all have an attained EEDI and can use this one to benchmark against the reduction factors to see if they fulfill the rules. Vessels that are built before the EEDI rules came into place will have an attained EEXI, where the EEXI is the “EEDI for existing ships”. Existing ships will then benchmark their EEXI against the reduction factors, as for the EEDI ships.
Efficient design vessels might meet the requirements (as for Vessel C on the figure above) or might not meet the requirements (as for Vessel A and B above). Vessels that do not meet the requirements will need to improve their design efficiency by the percentage that can be calculated based on the EEDI/EEXI.
There are different ways to improve the design efficiency:
- Reducing the power on the main engine by applying an Engine Power Limiter (EPL).
- Retrofit Energy Efficiency Technologies or to change to carbon neutral fuels.
- Scrap the ship and buy a new to replace it.
For many vessels, the most straight forward solution is to insert an EPL, it can either be done manually by a plug or electronic pending on the engine type. If the available power after the limitation is sufficient to operate the vessel safe and efficient, this probably also be the most cost-efficient method to use.
Since operating a vessel, the most safe and efficient way not always is in line with what the market wants, there might be some conflicts in the magnitude of the power reduction. If this is too high, the vessel might not meet the “need for speed” to comply with a charter contract. If a vessel is in a long-time charter and it suddenly cannot meet the contract conditions, there might be an issue with the charterer. Or if in the spot market, it cannot meet the available speed clauses in the contracts and not get cargo.
So, the owner/operator of the vessel would be interested in the least power reduction as possible. If looking at the way the EEXI is calculated, the simplified formula looks like this:
The factors to change the EEXI are then:
- Reducing Power by the EPL
- Removing/reducing Carbon from the fuel (remove/reduce the Cf)
- Increase the Deadweight (DWT), needs a design change, possible to some extent for some vessels.
- Increase the reference speed (Vref)
If we look specifically at the Vref, then for an EEDI vessel, the Vref is found by the sea trial when the vessel is new. The sea trial is witnessed by class and are done under agreed standard conditions.
For vessels that do not have an EEDI, there might have been new build sea trial conditions that were not alike, there could be different methods at different yards and perhaps, the relevant information do not exist. Therefore, it can be difficult to find the “right” Vref for a vessel when calculating it for the EEXI.
A method has then been suggested, where a calculation based on statistical parameters from various databases + the vessels engine MCR leads to a Vref,app, which then will be used to calculate the vessels EEXI. Unfortunately the Vref,app almost always ends up being to some extent lower than the vessels Vref, if it was calculated by using the sea trial information available.
So, a lower Vref will give a higher EEXI and thereby a necessary higher power reduction to meet the rules.
To get to a more fair description of the vessel, BIMCO/RINA has come up with a proposal where in-service sea trials at two loading conditions will be used to determine the Vref. The two conditions should be: one, at the condition to where the original newbuild sea trial was given and two, to the EEXI condition. The measurements will produce a set of speed/power curves at two conditions and the two curves will be calibrated towards the original sea trial curve, a similar method as for the way Vref is found for EEDI vessels.
The in-service sea trials are not to be witnessed by class. In the BIMCO/RINA proposal, the in-service sea trials are described with regards to conditions, measurements and procedures. The measured data and the calibrations are to be controlled by class and they will verify the Vref.
The proposal can be studied in detail by following this link:
As an example of the differences for different vessel sizes – in this case bulk carriers – the following show the potential of using the BIMCO/RINA method:
|Cape Size, 2010
*All calculations are at PME = 75% MCR and Scantling DWT.
It is the hope that the proposal will get support and it can be agreed upon as a measure to determine an existing vessels Vref. It is expected that all this will enter into force in 2023 and ship owners should get prepared and align a strategy for their fleet of vessels.
If you want the calculations done for your fleet or an overview of your options, please contact us in VesOPS, we are the performance experts and we are ready to assist you.
Phone: +45 2939 2960