The maritime and shipping industry – with more than 50,000 ships on the water – emitted 1.056bn t of CO2 in 2018, about 3pc of total global greenhouse gas (GHG) emissions. The recent Maritime Environment Protection Committee (MEPC) meeting in June 2021 laid down a concrete plan for minimising GHG emissions from ships by 50pc until 2050. According to the MEPC 76 meeting, vessels are required to calculate an Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII) from 2023. What does this mean and what steps should be taken?
Understanding and calculating EEXI
Starting from 2023, each vessel above 400 Gt will require a one-off EEXI calculation to confirm that the vessel meets the energy efficiency design standards. An International Energy Efficiency (IEE) certificate will be awarded if the vessel meets those standards.
Take for instance, a basic 82,000 dwt Kamsarmax vessel with no energy saving devices installed:
| Main engine (ME) maximum continuous rating (MCR) | 14,280 kw |
| ME specific fuel oil consumption (SFOC) | 171 gms/kwhr |
| Auxiliary engine (AE) MCR | 5pc of main engine MCR (Assumed as per EEXI guidance) |
| AE SFOC | 187 gms/kwhr |
| Vessel’s speed on the power speed curve (Vref) | 15.09 knots at 75pc MCR |
| Fuel Constant | 3.151 |
| Reduction factor | 20 |
| EEDI/EEXI reference line parameters | A = 961.79 |
| C = 0.477 |
| Required EEXI: | [1-(Reduction factor/100)] * [EEXI reference line parameters A*{(Vessel’s DWT)^(minus EEXI reference line parameters C)}] |
| (1-(20/100)) * (961.79*((82000)^(-0.477))) = 3.49 grams/ton-mile | |
| Attained EEXI: | [( pc of MCR * MCR * Fuel Constant * ME SFOC) + (5pc * MCR * Fuel Constant * AE SFOC)] / [DWT * Vref] |
| ((0.75*14280*3.151*171)+(0.05*14280*3.151*187))/(82000*15.09) = 5.00 grams/ton-mile |
Based on the above calculations, the vessel does not meet EEXI’s requirements, because the attained EEXI (5.00 gms/t-mile) is greater than the required EEXI (3.49 gms/t-mile). So the vessel will have to reduce its MCR to comply with the EEXI regulation, and to attain the IEE Qualification.
| IEE Qualification: | [Required EEXI * (DWT * Vref)-( 5pc * MCR * Fuel Constant * AE SFOC)/(MCR * Fuel Constant * ME SFOC) |
| (3.49*(82000*15.09)-(0.05*14280*3.151*187))/(14280*3.151*171) = 0.506 |
Based on the calculation above, the vessel can meet compliance standards if the main engine runs at 50.6pc MCR, where the attained EEXI matches the required EEXI. The vessel will be given the IEE certificate, if the main engine’s MCR continues to operate below 51pc and adjusts to the corresponding speed on the power speed curve (13.24 knots in this instance).
The formula to calculate EEXI was derived from the Energy Efficiency Design Index (EEDI). EEDI is applicable to new ships built on or after 1 January 2013. Vessels built on or after 2013, with a valid IEE are not required to calculate EEXI. Some of the variables used in the EEXI formula are listed below:
EEDI/EEXI reference line parameter values:
| Ship type | A | B | C |
| Bulk Carrier | 961.79 | dwt | 0.477 |
| Gas Carrier | 1,120 | dwt | 0.456 |
| Tanker | 1,218.8 | dwt | 0.488 |
| Container ship | 174.22 | dwt | 0.201 |
| LNG carrier | 2,253.7 | dwt | 0.474 |
| Reference line | = a * b ^ (-c) |
| Required EEDI / EEXI | = [1 – (Reduction factor/100)] * Reference line |
EEDI reduction factor:
| Reduction factors (in percentage) for the EEXI relative to the EEDI reference line | ||
| Ship type | Ship size | Reduction factor |
| Bulk carrier | 200,000 DWT and above | 15 |
| 20,000 and above but less than 200,000 DWT | 20 | |
| 10,000 and above but less than 20,000 DWT | 0-20* | |
| Gas carrier | 15,000 DWT and above | 30 |
| 10,000 and above but less than 15,000 DWT | 20 | |
| 2,000 and above but less than 10,000 DWT | 0-20* | |
| Tanker | 200,000 DWT and above | 15 |
| 20,000 and above but less than 200,000 DWT | 20 | |
| 4,000 and above but less than 20,000 DWT | 0-20* | |
| Containership | 200,000 DWT and above | 50 |
| 120,000 and above but less than 200,000 DWT | 45 | |
| 80,000 and above but less than 120,000 DWT | 35 | |
| 40,000 and above but less than 80,000 DWT | 30 | |
| 15,000 and above but less than 40,000 DWT | 20 | |
| 10,000 and above but less than 15,000 DWT | 0-20* | |
| LNG carrier | 10,000 DWT and above | 30 |
| * Reduction factor to be linearly interpolated between the two values dependent upon ship size. The lower value of the reduction factor is to be applied to the smaller ship size. |
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Are vessels compliant once EEXI is achieved? What is CII?
The Carbon Intensity Indicator (CII) is a measure of how efficiently a ship transports goods or passengers – linking carbon emissions to vessel capacity and vessel movement. The ship is given an annual rating ranging from A to E. All vessels above 5,000 Gt are required to attain and document an annual operational CII, to be verified against the required annual operational CII, according to the MEPC 76.
The ship is then given an annual rating ranging from A to E, by comparing the attained annual CII of a ship with the direction and distance it deviates from the required CII (DD vector for short).
| Ship type | Ship size | DD vectors (after exponential transformation) | ||||
| exp(d1) | exp(d2) | exp(d3) | exp(d4) | |||
| Bulk carrier | dwt | 0.86 | 0.94 | 1.06 | 1.18 | |
| Gas carrier | 65,000 dwt and above | dwt | 0.79 | 0.89 | 1.12 | 1.36 |
| less than 65,000 dwt | dwt | 0.85 | 0.95 | 1.06 | 1.25 | |
| Tanker | dwt | 0.82 | 0.93 | 1.08 | 1.27 | |
| Container Ship | dwt | 0.83 | 0.94 | 1.07 | 1.19 | |
| LNG carrier | 100,000 dwt and above | dwt | 0.91 | 0.98 | 1.05 | 1.11 |
| less than 100,000 dwt | dwt | 0.77 | 0.91 | 1.12 | 1.37 | |
Taking the same basic 82,000 dwt Kamsarmax vessel used above:
| Average Speed | 13.24 knots (basis 50.6pc MCR) |
| Sailing days | 292 days (75pc sailing 25pc at port) |
| Distance travelled | 92,786 nm |
| Average fuel consumed | 32t/day |
| Fuel Constant | 3.151 |
| Sailing days | 292 days (75pc sailing 25pc at port) |
| CII reference line parameters | A = 4,977 |
| C = 0.626 | |
| 2023 CII reduction factor | 5pc |
| Required CII: | [CII reference line parameters A * {DWT^(minus CII reference line Parameter C)}]*[1-(CII reduction factor/100)] |
| ((4977*(82000^(-0.626))*(1-(5/100))) = 3.97 grams/ton-mile | |
| CO2 emitted per annum: | Fuel consumed * 1,000,000 (convert tons to grams) * Fuel constant |
| 9344*1000000*3.151 = 29,443e^6 grams | |
| Ton-mile: | DWT*Distance sailed |
| 82000*92786 = 5,595e^6 | |
| Attained CII: | CO2 emitted per annum / ton-mile |
| 29443e^6/5595e^6 = 3.87 grams/ton-mile | |
| Annual rating: | Attained CII / Required CII compared to DD vector |
| 3.87/3.97 = 0.97 (C rating) |
A basic Kamsarmax with an annual rating of 0.97 is between DD vectors d2 (0.94) and d3 (1.06), and so receives a C rating. The annual rating would be an A for a bulk carrier, if it was at or lower than 0.86 (d1), and B if it was above superior boundary (0.86), but equal to or below the lower boundary (0.94). Vessels that receive A, B, or C ratings, will be issued a statement of compliance. Vessels that receive a D for three consecutive years, or an E rating, will be given a year to develop a corrective action plan that will enable the vessel to achieve at least a C rating. The Statement of Compliance to these vessels will not be issued unless the corrective action plan is reflected in a Ship Energy Efficiency Management Plan (SEEMP) and is verified by the administration or authorised organisations (vessel classification societies).
What are the various ways to implement SEEMP and make a vessel EEXI and CII compliant?
- Proper maintenance of the vessel’s hull at dry dock.
- Coating the vessel’s hull with good paint to increase hydrodynamic performance.
- Improve the vessel’s steering configurations.
- Have a more efficient aft-ship, propeller, and rudder arrangements.
- Reduce energy consumption in main and auxiliary engines, auxiliary machineries, air conditioning, and other minor energy consumers.
- Weather routing and choosing the best route for transportation of cargo.
- Using efficient energy saving devices.
- Slow steaming of the vessel.
- Using of alternative fuels instead of high-sulphur fuel oil or very low-sulphur fuel oil (VLSFO).
As a note, SEEMP plans cannot be applied across a company or fleet-wide, as these plans are ship specific and have to be implemented according to the vessel type, cargoes carried, ship routes, and other relevant factors.
