Regarding the change in the evaluation method of RIGHTSHIP GHG rating from 1Q 2023, a webinar on the new GHG platform was held on November 24, 2022, and the main changes are explained below.
Summary
The RightShip GHG Rating evaluation method will be changed in 1Q 2023, and the GHG Rating of each ship may change according to the change in the evaluation method. The new rating method will adjust the calculation of CO2 emissions (g-CO2/ton.mile), which is the basis of the GHG rating evaluation, for a given ship speed, thereby reducing the tendency for the EPL methodology to overly improve the GHG rating and evaluating the vessel's true performance.
Please see below for a detailed explanation.
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Update on 31st Jan. 2023
RightShip post a news about GHG rating on 30 Jan. 2023 on their webpage. According to that news, they are currently testing new methodology with live data points received through our EEXI platform submission channel. Also, they will provide the industry with a review period of the new methodology before it will go live. This will ensure everyone has time to adjust to the new methodology. Please note there's no information provided when the new methodology go live.
Please find below link
https://rightship.com/insights/update-our-ghg-rating-methodology-incorporating-eexi
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The current GHG Assessment Methodology is based on CO2 emissions (g-CO2/ton.mile) calculated by EEDI or EVDI and evaluated within a peer group of ships of the same type (±10% DWT) and rated with a GHG rating (A～G). However, the GHG rating method will be adjusted due to the introduction of the main engine power limitation (EPL) associated with EEXI, which will start on January 1, 2023.
The new GHG platform changes include
- The number of times the EPL can be applied and the minimum main engine output for EPL application was previously limited, but will now be allowed in Rightship when necessary to comply with the EEXI regulations.
- Change in GHG assessment methodology
New GHG Assessment Methodology compares vessels of the same type operating at the same speed (common speed), and excessive GHG rating improvements such as EPL will be suppressed.
The webinar introduced case studies in which GHG ratings increased from F to B and decreased from D to G, based on the new GHG rating calculation method.
Specifically, the GHG score is calculated based on the lowest speed of a vessel in peer group, with the speed corrected for all vessels in that peer group, and the GHG rating (A~G) is then evaluated. The GHG rating (A~G) is calculated by simply comparing the results of Attained EEDI or EVDI calculations or the evaluation after EPL (g-CO2/ton.mile) within a peer group, to a ship's speed and then re-evaluating.
New GHG Assessment Methodology formula
Vref = ship's speed (knots) under the following conditions
- EEXI/EVDI and EEXI (without EPL)
Ship's speed (knots) at 75% of main engine maximum output (MCR) in EEDI conditions*, used in Attained EEDI/EEXI and EDVI calculations.
- EEXI (with EPL)
Ship's speed (knots) at 83% output of the maximum main engine output (MCRlim) as limited by EPL in EEDI conditions*, used in the calculation of Attained EEXI.
* EEDI condition: Summer load draft, but 70% DWT draft for containerships.
As a specific example.
The webinar presented the following five cases of vessels in the peer group. The situation for each vessel is not described in detail, but we explain with additional information that may be inferred.
Lowest speed in a peer group : 12.64 knots (Ship 6)
Estimated compliance status of each ship
Ship 5 : EPL constructed to comply with EEXI regulations (G → G)
Ship "X", Ship 7 : Vessel already compliant with EEXI regulations and EEDI value is equivalent to EEXI value (C → F / A → A)
Ship 6 : Ship which is not EEDI compliant and has been re-dataed for EEXI regulation with some improvement in performance (D → G)
Ship 8 : Ships that have been equipped with fuel consumption improvement measures (energy-saving devices, low firction AF paints, etc.) for the EEXI regulations (F → B)
As a result of the above, the improvement of GHG rating for EPL-constructed ships is suppressed, and ships with good original performance and those with improved performance tend to be rated higher.
The new GHG platform is based on the EEXI Vref, but if no EEXI technical file is submitted, the Vref will be calculated based on the existing EEDI/EDVI Vref, which will result in an underestimation in the case of vessels that have had an EPL constructed to comply with the EEXI regulations. If a vessel has not submitted a file, it will be calculated based on the existing EEDI/EDVI Vref.
For reference, the table below shows a comparison of EEDI and EEXI Vref corrected for speed on actual vessels which will apply EPL related to our company.
The Rightship webinar can be viewed at the following link.
RightShip: Our GHG Rating evolution - webinar recording
Attached is a document regarding the new GHG rating methodology that is available on the Rightship website.
The document can be accessed by entering the required information in "The RightShip's GHG Methodology" under "The GHG Rating" on the left-hand side of the screen at the following link.
Technical information | Rightship
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