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The EEDI is a tool for controlling CO2 emissions from ships and is primarily applicable to new ships. It was first developed by the IMO in 2003 and draft guidelines on its voluntary implementation were developed in 2009 with input from flag states and other industry bodies. The EEDI is voluntary at present but will possibly become mandatory in 2013.
Once it is mandatory, the EEDI’s regulatory mechanism will allow CO2 to be controlled in much the same way that MARPOL Annex VI has regulated NOx and SOx emissions – through phased reductions in limits.
The key regulatory elements are:
The required baseline EEDI for each ship type.
The percentage of EEDI reduction relative to the reference line.
At present, smaller size vessels are excluded from EEDI control.
In order for a ship to comply, it's attained EEDI must be less than or equal to the required EEDI for the ship type and size.
The first stage of implementation will apply to the following ship types above 400 gt:
– bulk carriers
– gas carriers
– container ships
– general cargo ships
– refrigerated cargo ships
– combination carriers
Other ship types, such as ro-ro and cruise vessels are being investigated for inclusion in later phases of implementation and turbine, diesel-electric and hybrid propulsion types will initially be excluded.
EEDI verification will require input from the shipyard, shipowner and a recognized organization (RO) in order to achieve certification under the guidelines. Pre-verification will occur at the design stage whereas final verification will be conducted after sea trials and upon commissioning.
EEDI equation can be expressed as following:
The Energy Efficiency Design Index (EEDI) is already being adopted on a voluntary basis and will possibly become mandatory from 2013, but how does the EEDI equation apply to your ship, and how can a good rating be achieved?
A formula for efficiency
The EEDI is a formula for calculating ships’ specific CO2 emissions (per ton-mile). The equation certainly looks complicated, but it can be divided into four sections, each one applicable to the ship’s machinery or the technologies being used on board.
Sections one and two of the formula calculate the CO2 produced by the ship’s propulsion and auxiliary power systems. Section three accounts for any secondary energy usage by machineries such as shaft propulsion motors and generators. And section four subtracts the CO2 saved through innovative energy saving technologies like kites or sails.
The resulting CO2 figure is divided by the ship’s transport work or ‘benefit to society’ (in effect, the ship’s capacity multiplied by its speed) to arrive at the final EEDI.
For each of the four sections, the listing is done of some of the existing and developing technical measures which may be considered in order to achieve a better EEDI, and also highlighted are other general measures which will influence the EEDI overall.
These general measures are not just limited to reducing speed, and indeed speed reduction may not suit to every ship’s need. Other options include simple hydrodynamic (underwater) and aerodynamic (above water) design modifications and the application of advanced coatings
Dragging the EEDI down
Air flow around the deckhouse before (left)and after (right) the modifications, showing the achieved wind drag reduction
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