GHG reduction

The emission of greenhouse gases (GHG) such as carbon dioxide (CO2) and nitrous oxides (NOx) as well as pollutants such as sulfur oxides (SOx) and particulate matter (PM) into the earth’s atmosphere by the burning of fossil fuels to drive ships is of increasing concern internationally.

While other aspects of ships and shipping play their own part in this environmental concern, a key factor is the underwater ship hull. This is subject to biofouling, as micro-organisms and vegetable and animal matter naturally attach to a ship’s hull. A fouled hull carries with it a fuel penalty. The worse the fouling, the slower the ship will sail at a given RPM. Or, put another way, the more power will be required to keep the ship sailing at a given speed. This means higher fuel consumption. Depending on the degree of fouling, this can be as much as 85% more. Higher fuel consumption results in a greater volume of greenhouse gases and other emissions which pollute the earth’s atmosphere.

The way to keep the fuel penalty as low as possible from the point of view of the ship hull is also clear:

1. Design the hull so that it is hydrodynamically efficient.
2. Apply a coating which is smooth, remains smooth and does not add to the hull’s resistance.
3. Keep the hull free of fouling. Don’t sail with even a medium slime. Routine monitoring and in-water cleaning on the right type of hull coating will accomplish this.
4. Inspect the ship before sailing and, if the hull is fouled, clean it before leaving port.

Even if the ship is delayed for half a day before sailing, this time will be made up in the crossing as the clean hull will permit faster sailing with lower fuel consumption. IMO BLG 15/9 Annex 1 pages 9-12 provide detailed recommendations for in-water inspection, cleaning and maintenance which, if followed using trained and experienced personnel to carry out the work, will lead to greatly reduced fuel consumption.

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