Calculating and Comparing CO2 Emissions from the Global Maritime Fleet
RightShip has created a tool, the GHG Emissions Rating tool, to help charterers to select the most energy efficient vessels/ terminals and insurers/ banks to provide preferred rates to owners of more efficient vessels and also to reward ship owners for investing in technology for energy efficiency.
RightShip has developed an Existing Vessel Design Index (EVDITM) and a Greenhouse Gas (GHG)Emissions Rating. Similar to the IMO MEPC’s EEDI, RightShip’s EVDITM measures a ship’s CO2emissions, however, unlike the EEDI, the EVDITM can be applied to existing ships. The GHG EmissionsRating is a practical measure derived from the EVDITM that allows relative comparison of a ship’s CO2emissions to vessels of a similar size and type. Ship types are largely consistent with those used byIMO MEPC.
RightShip’s report (please click below) on Calculating and Comparing CO2 Emissions from the Global Maritime Fleet details the methodology of the EVDITM and GHG Emissions Rating andcontains practical examples of their application to the shipping industry.
The GHG Emissions Rating allows comparison of a ship’s theoreticalCO2 emissions relative to peer vessels of a similar size and type using a simple A – G scale. While the A – G benchmarking scale is simplisticand easy to understand, the methodology using an algorithm to calculate the GHG Rating is complex.
A vessel’s GHG Emissions Rating is presented using the standard European A – G energy efficiencyscale and relative performance is rated from A through to G, the most efficient being A, the leastefficient being G.
Newer is Not Always Better or More Efficient
By using appropriate mathematical techniques, a meaningful comparison between vessels can beachieved and as shown by the Figures below, newer vessels do not always perform as well as theirexisting peers.
Figure below shows bulk carriers delivered over the last 22 years between 75,000 and 80,000DWT using the A – G GHG Emissions Rating scale. The x-axis shows DWT and the y-axis displaysEVDITM. The IMO MEPC reference line has been overlaid as a comparison and right across this DWTrange there are a large number of vessels above and below the line. This makes sense as thereference line is reflective of 92.89% of bulk carriers delivered during the IMO MEPC referenceperiod as noted in MEPC 62/6/4.
The second figure below shows this same DWT spread and deliveries since 2007 onwards. If newervessels are always more efficient, we would expect all of the bulk carriers built in the last five yearsbetween 2007 and 2012 to be below the reference line in Figure 9, which is clearly not the case.More efficient and less efficient vessels are always evident if we apply a consistent framework togauge efficiency.
Improving a Vessel’s GHG Emissions Rating
A raft of retrofits and upgrades such as changes to ship design, propulsion and machinery may helpto improve a vessels’ GHG Emissions Rating. Any upgrade or retrofit which has been verified by aclassification society can be submitted to RightShip to enable the GHG Emissions Rating to berecalculated.A vessel’s EVDITM does not take into account operational measures such as slow steaming or ecospeeds. By focusing on design and then supplementing results with operational metrics, a moremeaningful outcome is achievable – enabling a like-for-like comparison
Learn more details about RightShip’s GHG Emissions Rating tool by clicking at the report