Air bubbles used to contain oil spills
Although it may have missed the entry deadline for the Wendy Schmidt Oil Cleanup X-CHALLENGE, a new technology for containing oil spills at sea was recently unveiled. Developed by Norwegian research organization SINTEF, the system uses a curtain of air bubbles to contain spilled oil for easier removal, or to form a barrier around protected areas.
The bubbles come from perforated rubber hoses, which are attached to an air compressor, and mounted on a grating - the current prototype is 12 meters (39 feet) long and 1.5 meters (5 feet) wide. The hoses and grating are submerged 2 meters (6.5 feet) beneath the surface of the water, where they create a dense wall of bubbles.
As the bubbles rise to the surface, they carry the surrounding water with them. Upon reaching the surface, that water creates a horizontal current that floating oil is unable to cross.
The scientists had already tested the system on calm water, and wanted to try it in more chaotic conditions. To do so, they recently conducted trials in gale force winds at Norway's Trondheim Fjord, which is known for its strong currents. In order to minimize any risk to the marine environment, bark was used instead of oil.
The bubble curtain was able to keep the bark contained in currents up to 70 centimeters (27.5 inches) per second, or 1.5 knots. By comparison, according to the researchers, conventional oil booms can't handle much above 50 cm (19.7 inches) per second, or about 1 knot. The curtain was also observed to reduce wave action on the surface.
"In principle, there are no limits to the strength of the currents in which this equipment could operate," said senior scientist Grim Eidnes, of SINTEF's Department of Marine Environmental Technology. "The more air that the compressor can force out of the hoses, the stronger the current it can tackle. But to double the effect of the bubble curtain on the current, we would have to increase the air by a factor of eight, so the limitation actually lies in the compressor power available."
Besides being able to operate in stronger currents than traditional booms, another advantage of the bubble curtain is the fact that boats would still be able to move across it. That said, the researchers see it being used in conjunction with booms, not instead of them. They are now working on making the system longer, more flexible, and easier to deploy.