How is the saving measured and verified?
Air lubrication in general is one of few technologies that can be measured ‘live’ simply by switching the air ON and OFF. When our System is turned on, we can almost instantly observe a drop in shaft power and an increase in speed, as the frictional resistance is reduced.
Silverstream Technologies has undertaken considerable work with our partners to independently verify the results of our installations. Third parties including Lloyd’s Register, HSVA, the University of Southampton, Carnival and Shell have conclusively proven that our Silverstream® System generates between 5-10% fuel and emissions savings, depending on the vessel.
What is the difference between Air Cavity, ALS and Air Lubrication systems?
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. In addition, these systems can also cause drag when they are not in operation.
Uniquely within the market, our air lubrication technology harnesses fluid shearing – a natural phenomenon that occurs when two fluids of differing density move past each other – to create a micro bubble carpet across the full flat bottom of hull. This phenomenon is also known as the Kelvin-Helmholtz instability,
This rigid, friction-reducing microbubble carpet maximises the emissions reduction and efficiency savings potential of our technology. Unlike other solutions on the market, we have perfected and patented this low energy requirement novel technique for generating our fuel-saving microbubbles.
Our extensive, full-scale experimental work conducted at HSVA provides us with a clear understanding of how our bubble carpet is formed and interacts with a variety of ocean conditions. Our experts have full knowledge of the relationship between ship speed, draft and the air flow requirements of our technology to generate maximum efficiency gains.
What impact does Air Lubrication have on the speed of the vessels?
In essence, our System provides additional operational flexibility to a vessel. When the bubble carpet forms, an increase in speed can be observed due to reduced frictional resistance. This means owners can choose: they can either adjust to normal operational speed and benefit from fuel or emissions reduction, or choose higher speeds with the same power requirement.
How long would an installation take?
For standard, repeat installations we typically complete and commission our System within 20 to 24 weeks from order. We continuously provide support to our customers throughout the entire installation, commissioning and operational process.
We want to work closely with our customers and partners. Working on a consultative basis, our naval architects and engineers can recommend a solution or configuration of our System that works on a vessel and fleet basis.
In addition to supplying the technology, we can support customers by preparing installation specifications and recommending installation and logistics partners, in addition to provision of operating manuals and crew training services.
Installing a clean technology on a vessel is no simple task, which is why we follow a robust and proven process.
Does the Silverstream Technologies system conflict with other fuel saving measures?
Our technology is complimentary with any other fuel saving measure taken as a part of vessel design. In fact, leading operators are installing our technology at the centre of a suite of clean technologies on their most modern vessel designs.
Where does the Silverstream® System sit within the industry’s sustainability journey?
Our technology is simple: it works by reducing the power required to propel a vessel through the water, resulting in reduced fuel consumption and emissions. We do this by reducing the impact of a key component of ship resistance – friction between the hull and the water.
Does the Silverstream® System help me comply with EEDI and EEXI requirements?
Our technology provides assurance: air lubrication is an advocated clean technology recognised under the IMO’s Energy Efficiency Design Index (EEDI) for newbuilds. Furthermore, air lubrication will also be one of the key means for current vessels to improve their efficiency rating on the IMO’s impending Energy Efficiency Existing Ship Index (EEXI) – a commercial requirement as decarbonisation targets tighten.
Does air lubrication increase cavitation?
Cavitation is a vapour bubble formed in a low pressure zone that when subject to high pressure will collapse. This collapse can generate an intense shock wave. The shock wave leading to erosion of adjacent structures.
Air in water results in a vapour bubble containing considerably more vapor. On collapse the increased vapour dampens the shock wave. The result is less intense and thus erosion less.
Off-loading of the propeller through the impact of reduced resistance reduces the potential for the propeller to cavitate.
Observation since deployment of the Silverstream® System have shown propellers and adjacent structures to be free of any signs of caviations.
Will air lubrication negatively impact hull coatings?
We are working closely with coatings manufacturers across the industry on multiple fronts. Dry dock inspections of our technologies after multiple years of operation have shown little to no biofouling of system components. Leading coatings manufacturers have confirmed that they do not expect any detrimental impact on hull coatings from using our technology.