TWO-STROKE ENGINES
EEXI COMPLIANCE: CHOICE OF OPTIONS FOR VLCC OWNERS
Credit: Euronav
The expected entry into force of EEXI rules in 2023 will affect the VLCC sector significantly and may accelerate the disposal of older tonnage, Kari Reinikainen hears
From a technical point of view, owners have many options in principle to achieve the 10%+ emissions reductions required to make their vessels compliant. However, the commercial considerations that affect decision making are extensive, particularly as the Energy Efficiency Existing Ship Index (EEXI) regulations are planned to take effect from the start of 2023, a year after the Ballast Water Management Convention. There is a wide range of options available for VLCC owners to comply planned EEXI legislation and a lot depends on the strategic choices of the owner, said Andreas Wiesmann, General Manager of Global Sales for 2-Stroke Engine Services, Piet van Mierlo, Team Leader of Propellers Product team and Stavros Zacharias, Global Sales Development General Manager for 2-stroke Services at Wärtsilä, the Finnish technology group. The first choice an owner needs to make whether to retain the design speed of its ships or to opt for a lower output of main engine. The latter option usually requires the replacement of the propeller and rudder, which often means the engine has to be de-rated, as the load curve is no longer optimal. A number of energy saving solutions can be installed as well. Air lubrication can be interesting on ballast voyages, but when laden the deep draft of a VLCC means that a lot of power would be needed to produce the necessary pressure for the system to work. However, this can be done by using the main engine, which simplifies matters and reduces the cost. The installation of wind-assisted propulsion would be viable from a technical point of view and would not reduce the cargo capacity of a ship. However, the capital cost of
12 | NOVEMBER 2020
8 Advances in engine technology and vessel design have driven improvements in the fuel efficiency of modern VLCCs, such as Euronav’s 299,320dwt Alice (pictured)
investing in such solutions reduces its attractiveness: a VLCC would require four Flettner rotors, for example. Capex considerations also apply to the conversion of an existing VLCC to dual fuel operation, in addition to the work involved in installing an LNG fuel tank and the fuel gas supply system and related equipment. Locating the fuel tank on deck minimises the impact of cargo capacity. Such a conversion represents the best option to future proof a vessel, as it would also allow the use of other fuels, such as methanol or ammonia. But it is difficult to assess which fuels are likely to be the best ones towards the end of the lifespan of a vessel: advances in technology and potential changes in legislation means this may change in future. Nikolaj Peter Lemb Larsen, Chief Naval Architect, Hydrodynamics and Aerodynamics at Force Technology in Denmark said that by de-rating the main engine, replacing the rudder and propeller plus installation of energy saving devices it is possible to reduce the energy consumption of a VLCC by some 10% to 15%, although there can be variations between vessels. The work can be carried out in stages to spread the cost over a number of years if the owner prefers it this way, but then the savings will also emerge gradually as a result. PRESSURES ON AGEING VLCCS The planned EEXI regulations mean that a VLCC in operation today would have to meet a 15% reduction factor relative to the EEDI reference line, which could be quite a task for existing vessels, especially the largest vessel, said Catrine Vestereng, Business Director Tankers at DNV GL - Maritime.
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