Frequently Asked Questions

  • What is the objective/effect of ESI

    The aim is to achieve a genuine reduction in emissions of NOx, SOx and particulates, as well as CO2 in the longer term, to be achieved by initiating changes in behaviour among ship owners/operators and ports

  • How can the effect be measured retrospectively?

    Bringing about changes of behaviour to use clean fuels and research in cleaner engines will take time. It will also be more effective when as many parties as possible sign up, support the initiative and participate. Initially the targets will focus on getting as many ports and - above all - as many ships as possible to participate.

  • What are the target groups

    Target groups are all seagoing vessels, in the sense that the intention is to achieve changes in behaviour among ship operators / owners through incentives; this will happen even faster if many ports and service providers for these ships and users of these ships join the scheme too, and are also willing to promote these changes. That is why these parties also form part of the target groups. Seagoing vessels and ports are regarded as the primary target groups, and the remaining potential incentive providers as secondary target groups.

  • As a ship or an incentive provider do I have to pay a fee to participate in the ESI?

    Ship Owners pay no fees for participation in the ESI Initiative. Incentive Providers are expected to contribute in the costs for any changes, additions, renewals, improvements, etc. of the ESI Website that have to be made from time to time.

  • Is there a punishment for not having a good ESI score?

    The ESI is a system that can be used on a voluntary basis by ports and ships, and as a system for giving incentives, with responsibility for the accuracy of the data resting with the ship owners/operators. This may be checked by participating Incentive Providers thru auditing vessels as and when required. This approach has been discussed with the organisations representing shipping companies and consensus has been agreed. A condition stipulated by IAPH is that Incentive Providers may use the system only as a bonus system.

  • When using a NOx-reduction technique, what value for NOx-emissions should be entered ?

    The EIAPP certificate issued for such an engine would show the reduced value for the NOx-emission expressed in g/kWh. This value should be entered in the appropriate column. Where in certain cases, these values are not included in the EIAPP certificate contact should be made with the ESI Administrator ( to see whether the results of an independent survey may be entered into the data base.

  • Can more than one person be authorized to enter an account for a Ship Owner or a Port/IP, respectively ?

    No, since only one email address per account can be registered. If the representative for the account would like to provide several persons in its organisation access to the account, it should be done through providing these persons with the login details of the account. It is suggested that login details are used that are not person dependant, e.g. "". Pass words that are randomly produced by the ESI database are somewhat cumbersome; participants are advised to change them to something more convenient yet secure.

  • Is an Onshore Power Supply(OPS) system installed on board ?

    The opening page of "Ship Input" under the tab "Ship" contains the following question: "Is the ship fitted with an Onshore Power Supply OPS Installation (irrespective of use)?". This question can only be answered "Yes" where the ship is fitted with an installation that would allow power supply from the shore capable of providing the vessel’s full load when carrying out all operations in port that the vessel has been designed for, such as cargo operations, pumping, lifting, etc. It should be ensured that the period between initial berthing and supply of power from the shore installation does not exceed three hours; logging details shall be produced and retained on board. However, where occasionally additional power from the ship is needed to carry out such operations, this power may be provided by on board generators; the period that such units are in operation shall however not exceed 5 % of the time that the ship is berthed in port at any one occasion; logging details shall be produced and retained on board. Under these conditions the ship maintains its OPS status. On smaller vessels such an installation would have a capacity about 0.5 to 1 MVA and in larger passenger vessels this would amount to 10 to 15 MVA. The installation is in addition to a standard shore power breaker for use during repair periods. Where such an installation is fitted, the ship board power generators can - and in some ports will - be switched off when the ship is at berth in a port. Classification Societies such as LR, BV, DNV-GL, etc. would as a matter of routine include such an installation in the ship’s electrical plan/manual; occasionally a separate OPS certificate is issued. However, the presence of a certificate cannot serve as the sole proof that the installation is capable of providing the power for all ship operations that may have to be carried out in port. A positive answer will result in the addition of a fixed bonus of 35 ESI sub-points to the formula to calculate the ESI Score, irrespective of its use in port. To keep the ESI data base reliable and accurate as a source for providing incentives, it would be appreciated to ascertain the correctness of your answer to this question. An incorrect answer will eventually lead to the exclusion of the ship from the ESI database for a period of six months.

  • What is a Ship Energy Efficiency Management Plan SEEMP) and an Energy Efficiency Operational Indicator (EEOI) ?

    MEPC 63 (March 2012) adopted - inter alia - important guidelines (resolution MEPC.213(63)) aimed at assisting the implementation of the mandatory regulations on the Ship Energy Efficiency Management Plan. The Ship Energy Efficiency Management Plan (SEEMP) is an operational measure that establishes a mechanism to improve the energy efficiency of a ship in a cost-effective manner. The SEEMP also provides an approach for shipping companies to manage ship and fleet efficiency performance over time using, for example, the Energy Efficiency Operational Indicator (EEOI) as a monitoring tool. The Ship Energy Efficiency Management Plan (SEEMP) is mandatory for all ships as from 1 January 2013. The guidance on the development of the SEEMP for new and existing ships incorporates best practices for fuel efficient ship operation, as well as guidelines for voluntary use of the EEOI for new and existing ships (MEPC.1/Circ.684). The EEOI enables operators to measure the fuel efficiency of a ship in operation and to gauge the effect of any changes in operation, e.g. improved voyage planning or more frequent propeller cleaning, or introduction of technical measures such as waste heat recovery systems or a new propeller. The SEEMP urges the ship owner and operator at each stage of the plan to consider new technologies and practices when seeking to optimize the performance of a ship. The ESI Working Group while acknowledging the above, has been considering a number of approaches to include an adjustment in the ESI score to take account of enhanced fuel efficiency of ships leading to reduced emissions of CO2 and consequent reductions in Green House Gases. A detailed discussion on this subject may be found in ”Calculating the ESI CO2 score” on page 7 of the “ESI Fundamentals” that may be opened by clicking on the appropriate link in the section ”Fundamentals & Presentation” on the ESI Home Page.

  • Could some more information be provided on how the ESI SOx sub points are calculated ?

    For the calculation of the ESI SOx sub points the following fuel categories have been defined: HIGH 0.50 < S % < 3.50 (previously HFO or High sea) MID 0.10 < S % < 0.50 (previously HFO LS/MDO or ECA) LOW 0.00 < S % < 0.10 (previously MDO LS or Port) The MID category is included to allow more ships to benefit from the sub-points that are given for the use of low sulphur fuel. MDO/Gasoil with a sulphur content over 0.5 % is included in the HIGH category. Fuel oils with a sulphur content of less than 0.1 % have cleaner emission characteristics and their use is mandatory in (Sulphur) Emission Control Areas (S)ECA’s; in certain ports and their approaches comparable requirements are in place. These characteristics are the reason that the MID and LOW category fuels carry more weight in the formula for determining the ESI SOx. Furthermore the calculation method is designed to stimulate the use of the cleanest fuel and this is done by giving bonus points if clean fuels are bunkered in favour of those with higher sulphur contents. The maximum number of sub-points that may theoretically be obtained is 100 where HIGH fuel with sulphur content between 3.50 and 0.50 % carries a weight of 30 sub-points while MID and LOW fuels weigh in with both 35 sub-points. The formula to calculate the ESI SOx sub points is x * 30 + y * 35 + z * 35 where x = the relative reduction of the average sulphur content a of HIGH; y = the relative reduction of the average sulphur content b of MID and z = the relative reduction of the average sulphur content c of LOW. The data of the Bunker Delivery Notes (BDNs) for fuels delivered on board of a vessel in the previous two quarters are used for the calculations. We take a simple example and assume that in a particular two quarter period the vessel bunkered all three types of fuel with the following data: HIGH 100 tonnes @ 2.00 % S (a), MID 100 tonnes @ 0.30 % S (b) and LOW 50 tonnes @ 0.05 % S (c). The next data we need to consider are the baselines for the various fuels and that is where the IMO rules come into the picture with 3.50 % S for HIGH and 0.1 % S for LOW; the ESI Working Group has set the baseline for MID at 0.50 %. The relative reduction may now be calculated as follows: • HIGH: x = (3.50 – a) / 3.0 = 0.5, • MID: y = (0.50 – b) / 0.4 = 0.5 and • LOW: z = (0.10 – c) / 0.1 = 0.5. We can now calculate the ESI SOx sub points for these two quarters: ESI SOx = 0.5 x 30 + 0.5 x 35 + 0.5 x 35 = 15.0 + 17.5 + 17.5 = 50.0 (16.13). In the main formula for calculating the ESI Score, the sum of the sub-scores is divided by 3.1; the result of this division is the number shown in brackets. Now, how is the use of cleaner fuels rewarded in the calculation: actually the average sulphur content for any fuel type that is more polluting and that is not bunkered is set at the lowest value of its category viz. 0.5 and 0.1 % S for HIGH and MID fuel oils respectively; consequently the full amount of sub-points for any dirtier fuel allowed but that is not bunkered, is given as a reward. Continue with the above example and assume that the ship doesn’t bunker any HIGH but only MID and LOW fuels and the above rule would result in ESI SOx = 1.0 x 30 + 0.5 x 35 + 0.5 x 35 = 30 + 17.5 + 17.5 = 65 (20.97). Further cleaning up of the act and only bunkering LOW fuel oil would lead to the even higher value for ESI SOx = 1.0 x 30 + 1.0 x 35 + 0.5 x 35 = 30 + 35 + 17.5 = 82.5 (26.61). The latter is however only applicable for vessels that have sailed in- and outside (S)ECA’s during the reporting period; where ships sailed in (S)ECA’s only, the 30 sub points for the HIGH range are not added. The reason for this is that incentives are not provided for mandatory items and in (S)ECA’s vessels may only use LOW fuel oil; however, if the vessel did actually sail outside the (S)ECA while continuing to only use LOW fuel oil, the HIGH bonus will be added. In order to prove this, - the number of days spent or - the name(s) of a maximum of two ports visited outside the (S)ECA during the reporting period has to be entered into a box in a section of the data entry page that will open after appropriate questions have been answered positively.

  • With irregular supplies of MDO/Gasoil LS how are data entered to maintain representative weighing in the ESI Score ?

    It is recognized that there may not be general availability of LOW fuel oil in all ports of the world requiring vessels that are using these fuels to bunker at longer and/or more irregular intervals than would normally be expected. In such cases the ESI Administrator may be consulted for assistance to enter BDNs into the data base. As a general approach in considering this issue it is assumed that the period between two LOW fuel oil bunker supplies does not exceed one year; where no supplies have taken place in the 6 month reporting period, any fuel supplied during the two quarters preceding the reporting period may be evenly split over the three or four quarters respectively of that whole 9 or 12 month period provided that at least one port was visited in any such quarter.

  • Are data that are entered into the data base verified or certified ?

    The ESI approach is relying on self declaration and does not require any data to be verified or certified by third parties; the data provided are randomly checked for inconsistencies and for obvious mistakes. In practice, whenever high scores are observed, the data will be scrutinized and where they seem to be somewhat unlikely, the data provider/ship operator will be invited to provide copies of the underlying BDNs and certificates to the ESI Administrator; in the past years there were just a few cases that warranted a closer inspection and in all cases the data were correct. However in addition, a few ports that are incentive providers and employ professional ship inspectors have been authorized to perform audits on ESI’s behalf. Please refer to the Terms of Use, section 10.4 Auditing.

  • How to deal with varying NOx emission values in EIAPP certificates?

    Certain vessels are provided with two sets of EIAPP certificates viz. one set with data for nominal power output and another set for reduced power or turbo charger cut out; in other cases engines have been fitted that can be operated using either HIGH or MID fuel oil. Where such situations give rise to varying NOx emission values, the emission values resulting in the lowest ESI NOx sub points should be entered in the appropriate boxes of the ESI NOx questions.

  • Is a list available that shows all the Incentive Providers ?

    To receive a copy of the latest list of Incentive Providers please contact the ESI Administrator at

  • Will be the use of LNG rewarded with points

    The use of LNG will be rewarded indirectly. There are a lot of beneficial points in the sub scores NOx and SOx possible. At the NOx sub score the LNG engines have normally an emission level of Tier 3, which is rewarded with minimum 53 NOx sub points. At the SOx sub score the use of LNG creates a high amount of points due to the Sulphur content of Zero.


  • ECA         Emission Control Area
  • EEOI        Energy Efficiency Operational Indicator
  • EIAPP      Engine International Air Pollution Prevention
  • IAPP         International Air Polllution Prevention
  • IMO          International Maritime Organization
  • PM10        Particulate Matter < 10 µm
  • SEEMP    Ship Energy Efficiency Management Plan