Today’s operating profiles
The EETA approach compares the energy efficiency of specific vessels with the benchmark of the entire world fleet in the respective segment based on technical details and common operating profiles. The profiles, gradually differentiated by vessel size, are based on actual data of numerous representative vessels tracked by the Automatic Identification System (AIS) and reflect today’s slow steaming practice.
Bunker consumption and transport work
Based on knowledge about the vessel’s key technical parameters, specific speed power curve formulas are applied in the EETA tool to determine the corresponding engine loads and consumption by sailing mode and speed. Aggregated over the annual operating profile, these numbers yield the vessel’s annual consumption, which is used as the numerator of the efficiency indicator. The transport work, distance sailed multiplied by the vessel’s transport capacity forms the denominator term.
Benchmark vs. global peer group
The existing vessel’s energy efficiency is benchmarked with the EETA tool in “bunker costs per 1,000 cargo miles”. The EETA value of the vessel (for a defined bunker price) is compared with the EETA values of all vessels of the defined peer group. The model yields the annual consumption advantage/disadvantage vs. the peer group average in tons and USD, and it provides the ranking of vessels within the peer group. The peer group can be defined by the user based on multiple parameters such as sub-segment, cargo intake, vessel age, beam, draft, LOA, design, cargo equipment and ice class.
Improvement potential from retrofitting
In addition to the assessment of the vessel as is, improvement potential from the application of energy efficiency retrofit measures shall be assessed. For a first outside-in cost/benefit assessment of energy saving potential and retrofitting costs of seven common, distinct and detailed retrofitting measures are considered. The measures include bow retrofit, propeller optimization, installation of propulsion improvement devices, main engine part load optimization, installation of a frequency-controlled shaft generator, auxiliary system optimization and capacity enhancement. Some measures can favourably be combined, while others mutually exclude each other. The best suitable combination is chosen. Payback times, neglecting financing costs, are calculated in an integrated perspective, in other words the consumption reduction is fully reflected in a charter rate increase.
Technical data considered and disclaimer
The assessment of the existing vessel is based on a set of technical data taken from the latest version of the IHS Maritime & Trade “World Register of Ships” database and extensive project experience of DNV GL reflected in the DNV GL EETA tool. Key technical data required for the EETA model are visible and can be checked against own information. Modifications made to the vessel after delivery may not have been reported to IHS and, thus, are unknown to DNV GL Maritime Advisory. (You may send us an email to get the data change request form to be directed to IHS.)
Further vessel details such as outline specifications or general arrangement drawings have not been made available to DNV GL. Hence, DNV GL cannot guarantee that the estimated savings potential and costs for an individual vessel can be realized. Operational efficiency measures – such as trim optimization, new hull coating, hull and propeller cleaning – have not been evaluated, but are assumed to further increase savings potential and chartering probability, even if not affecting the asset value. The costs of retrofitting measures are given per vessel. If a class of sister vessels is to be retrofitted, the fixed engineering cost can be distributed over the vessels and improve the business case for the individual vessel.