Technology Solution

FAQs

How are the emissions savings of the Silverstream® System measured and verified?

Air lubrication in general is one of few maritime clean 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 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 the Silverstream® System generates between 5-10% net fuel and emissions savings, depending on vessel type.

How long does a system 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 work closely with our customers and partners, often on a consultative basis. Our naval architects and engineers can recommend a solution or configuration of our system that works on a vessel or a 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 the provision of operating manuals and crew training services.

What impact does air lubrication have on the speed of a vessel?

The Silverstream® 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: either adjust to normal operational speed and benefit from fuel or emissions reduction, or opt for higher speeds with the same power requirement.

Does the Silverstream® System conflict with other fuel saving measures?

Our system is complementary to 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.

Does the system help me comply with the IMO’s EEDI, EEXI and CII requirements?

Our technology provides assurance: air lubrication is an advocated clean technology recognised under the IMO’s Energy Efficiency Design Index (EEDI) for newbuilds. It is also one of the key means for existing vessels to improve their efficiency rating on the IMO’s Energy Efficiency Existing Ship Index (EEXI) – a commercial requirement as decarbonisation targets tighten.

Additionally, the IMO’s operational Carbon Intensity Indicator (CII) demands that ships of 5,000 gross tonnage and above must ascertain their operational carbon intensity, to ensure the continuous improvement of the vessel’s operational emissions output within a specific rating level. Fuel agnostic, clean technologies like the Silverstream® System are well suited to supporting applicable vessels reduce their carbon intensity and meet this regulation.

What is the difference between air cavity systems and air lubrication technology?

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 uniform microbubble carpet across the full flat bottom of the hull. This phenomenon is also known as the Kelvin-Helmholtz instability.

This 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.

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 shockwave which leads to the erosion of adjacent structures.

Off-loading of the propeller through the impact of reduced resistance lessens the potential for the propeller to cavitate. Observation of the deployment of the Silverstream® System has shown propellers and adjacent structures are free of any signs of cavitation.

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 system 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.

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.

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