Page 43: of Maritime Reporter Magazine (December 2022)

THE PATH TO ZERO AIR LUBRICATION

Theory and lab results are one thing, proving success in a always ask me: ‘If I invest 500kW in compressing the air and real-word environment is another. For this Kapteijn points to pumping it underneath the ship against the hydrostatic pres- installation of its system on a Tharsis Sea-River Shipping ves- sure at the wing. What do I get?’ Well, in loaded condition, sel, a 110-m ship engaged in trade between the Netherlands, you get a one for two payoff. If the ship is loaded, so low in

Germany and the UK. The system was installed on M/V Thar- the water, what you get is about 1000kW back. And so your sis, and according to Kapteijn has “demonstrated net fuel sav- left with 500kW net gain. But in ballasted condition, when the ings of 7–10%. We ? tted the ? rst three bands with the spacing ship is much higher up in the air and the amount of ? at bottom of about 15 to 25 meters and lo and behold, when we tested it, as a percentage of the total wetted surface of the ship is a lot it did better than we expected,” said Kapteijn. better, then you get almost four times as much.” “What we found is that the key to effective lubrication was To give shape and scale to the kit that must go onto a ship, to ? nd the right bubble size, to inject the right volumes and to Kapteijn discussed a pending installation onboard an 11,000 do that as ef? ciently as possible, but also to have control over dwt bulker. “Here we have ? ve wings; four wings are the what we call the boundary layer underneath the ship, because width of the ship almost, so that’s about 40 meters … the ? rst all the magic of air lubrication happens in a very small dis- wing is smaller because it’s closer to the bow. In the end, you tance away from the skin of the ship,” said Kapteijn. So we’re end up with something like 1300 oscillators, those little de- talking about, early on something like a few centimeters, and vices. This is a device that is 12 x 16cm and it’s only 55mm then further along the ship, the boundary layer gets bigger. If thick. Eight of these are on a wing every meter so on this par- you’re able to control the way in which the air is injected into ticular ship, we have close to 1300 of these oscillators. We use that boundary layer, you reduce the losses that you get, and three 400 kW compressors, but effectively we use between therefore you use the minimum amount of air to create the air loaded condition that is around 900-1000 kW depending on lubrication effect.” the conditions of the sea. And in ballasted condition, we use

While most focus simply on the energy and emissions saved about 400-550 kW. He said maintenance on the MPS system as a result of the system, Kapteijn warns that you must be is nearly negligible, as “there’s nothing there. The wonder- mindful, too, of the energy consumed by the system in order to ful thing about these ? uidic oscillators is that they contain no get a true value on the overall savings. “What we’re trying to components, they are just channels of air switching up and ? nd out is how can we reduce the energy invested in lubrica- down, and pressing the air through these little holes. So the tion to the minimum so that you can get maximum net gains maintenance would mostly be limited to maintaining the com- from the system,” he said. “To give you an example, people pressors.

MV Tharsis at Neptune Marine yard in The Netherlands awaiting FluidicAL installation inlate 2020.

Image courtesy Marine Performance Systems

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