Noah Silberschmidt, the founder and CEO of UK-based Silverstream Technologies, explains that water isn’t as kind as you may expect. For more than a century, massive steel ships have ploughed the oceans, causing friction between ship and water that is seemingly inescapable and unexpectedly costly. Silberschmidt, on the other hand, claims that millions of microbubbles, each less than a millimetre in diameter, may be used to minimise friction.
Ship owners are always on the lookout for innovative methods to cut back on fuel use and emissions as part of the ongoing effort to improve maritime efficiency. In the running is Silverstream Technology’s Silverstream System, a hull-mounted device that produces a continuous stream of air bubbles from the ship’s bow to the stern..
Advances in technology have made it possible for the business and its competitors to modify older ships or include air lubricating systems into new vessels.
When a ship’s hull is surrounded with bubbles, there is less resistance between it and the water. You can feel the difference between softly bubbling hot tub water and motionless water by sliding your hand through.
Air lubrication, according to Silberschmidt, can cut fuel usage by 5-10% over time. It may not seem like much, but Silberschmidt estimates that shipping companies may spend $5 to $10 million year on fuel for a single vessel of ordinary size, even if they save just a few percent.
The cruise lines Silberschmidt claims that Silverstream’s gadgets have already been put on several of Norwegian and Carnival’s ships, and additional installations are expected in the near future.
But blowing bubbles isn’t free. For a big, flat-bottomed ship, compressing air and positioning it such that bubbles run continuously down the hull takes a lot of energy. By filling the ship’s air release units (tiny cavities integrated into the ship’s underbelly) with air, Silverstream has reduced its total energy consumption. As a result of the pressure differential between air in the cavities and the saltwater below, bubbles occur. When a ship moves, a phenomenon known as Kelvin-Helmholtz instability develops, causing air to mix with the water and float backward beneath the ship.
The bubble carpet itself, according to Silberschmidt, is “Mother Nature–generated” because it relies on physics. He explains that the water is like the white frothy crests on the tops of waves you may see on a windy day at the beach because of the light, bubble-rich composition.
However, according to Anthony Molland, retired professor of engineering at the University of Southampton in England, specific conditions are necessary for air lubrication to operate. In stormy seas, for example, the carpet’s effect may be insignificant, and ships must go fast to keep the bubbles flowing.
For example, if you blast bubbles out and your ship isn’t travelling very quickly, “the bubbles just come out the side and don’t perform any work at all,” he says.
It is worth it to Silberschmidt if the strategy succeeds, since “in this world we have to do anything we can,” he adds.