Air Cavity Systems require that the bottom of the vessel is structured in a way that allows air to be trapped below the vessel. Various tests have shown that, in addition to extra cost for the specialised structure, it is very difficult to maintain the quantity of air and that provision of extra air eliminates the savings.
Air Lubrication Systems, abbreviated to ALS and sometimes called ‘bubble’ or ‘bubbler systems’, work on a very different principle by maintaining a constant injection of air bubbles to the flat bottom of a ship. The air reduces the friction/ resistance/drag which means that the power needed for propulsion can be reduced, thereby saving fuel and the subsequent emissions.
Silverstream Technologies’ air lubrication system is specially designed to use very little energy thus the fuel savings are increased.
When the air is applied there is an increase of speed due to the reduced resistance. In today’s market the ship would adjust to normal operational speed and benefit from fuel reduction and lower OPEX cost. However, in some instances, it might be advantageous that the owner/operator can obtain higher speeds with the same power by installing this system.
Our system is about fuel efficiency, about saving fuel, and, by saving fuel, emissions are reduced. We believe ‘green’ is used too casually in the shipping debate and is intrinsically linked to fuel savings; more efficient ships will automatically drive more environmentally friendly ships.
Regarding the IMO EEDI index which addresses the reduction of greenhouse gasses (GHG) or CO2, air lubrication is acknowledged as a technology that will be included in the overall efficiency calculation.
EEOI, SEEMP and ISO 19030 are concerned with measurement and monitoring of performance. This is certainly an area that would benefit from the simplicity of verifying our system, by switching it on and off at short intervals.
Not directly, yet very much so, indirectly. The huge reduction required of sulphur oxides and nitrous oxides – also called SOX and NOX – demands either cleaner fuels or abatement systems. However, the cost of cleaner fuels such as MDO, MGO, ULSFO, VLSFO etc., are significantly higher than normal heavy bunker fuel, HFO or IFO380 and therefore fuel reduction becomes even more relevant.
No matter how a ship owner chooses to improve the efficiency of a fleet, whether with changes to the hull, bulbous bow, fins, ducts, waste heat recovery system or similar, air lubrication will be synergistic.
In the case of specialised paints, the constant flow of air discourages marine growth on the flat bottom of the vessel, our system would complement antifouling painting or coating, which, first and foremost addresses fouling on the sides of the vessels.