By Capt. Atul Vatsa,
Vice President, Compliance (Environmental, Marine & Safety)
Fuel efficiency has become a key component for shipping companies with the cost of fuel often accounting for more than half of the total cost of operation.
With propulsion consuming major part of the fuel that a vessel consumes, it is vital to look at how the energy consumption for propulsion can be minimized.
There are two key drivers for improving efficiency; optimizing the hull design of the vessel and reducing efficiency losses by improving operation.
Owners may optimize their new building as much as possible and for existing vessels, they may evaluate retrofitting.
Operationally, how well we maintain the vessel and cooperate with different units is vital.
What is in our hands is to reduce efficiency losses by improving operations. Some drivers that need to be focused on, are as follows:
- Weather Routeing / Voyage Planning – Using weather routeing services, and reviewing the course throughout the voyage can ensure that energy losses due to impacts from adverse weather are minimised.
- Trim Optimisation – Every vessel has a range of optimum trim for a given speed and draft. It should be endeavoured to maintain vessel’s trim accordingly, through appropriate load planning and distribution of ballast and cargo (and bunkers, to a limited extent). It needs to be ensured that vessel’s stability and stress allowance conditions are not compromised in the process. Fuel savings of up to 4% can be affected through good trim optimisation. For certain ship types, in particular those with higher speeds, slimmer body, pronounced bulbous bow and flat stern, trim will have more impact.
- Speed Optimisation – Depending on the voyage distance and indications on lay can, most economical speed should be adopted, in close co-ordination with the charterer. Using high speed for advanced arrival will result in higher energy consumption in comparison to operating at lower speed and arriving closer to the berthing time. For deciding on optimum speed, impacts on energy consumption from need to run auxiliary blowers and auxiliary boilers at low speed should also be factored in.
- Ballast Management – Carrying less ballast (less displacement) will assist in energy efficiency, provided vessel’s stability and trim optimisation is not compromised. Also maintaining minimal sediment levels leads to more cargo capacity and energy efficiency. Further, employing gravity assisted ballasting, and sequential ballast exchange (instead of flow through ballast exchange) are more energy efficient practises.
- Hull Condition – Through regular evaluation of main engine power consumption and comparison against ideal power requirement, deterioration in hull and propulsion conditions can be picked up early for remedial measures to reduce resistance timely.
Main ship-board staff impact on improving operations
- The Master: The commitment to ship-board energy efficiency is vital to motivate entire crew in that direction. Good weather routeing and vessel speed optimisation are the areas through which Master can significantly contribute towards fuel efficiency.
- The Chief Officer (2nd in command): Plays a significant role regarding cargo loading/unloading operations, ballast management operations, trim optimisation, etc.
- The Chief Engineer: Plays a major role in technical evaluation of condition and performance of engines and other machinery for improving efficiency.
- The Second Engineer: By virtue of being the most engaged person in the engine department regarding the day to day operation and maintenance of various systems, plays a significant role in ensuring that all machinery performs efficiently and is utilised optimally.