Salvage Tech: Remote Oil Removal
Suppose that the wreck of a container ship lies at the bottom of an ocean, let’s say the Atlantic. The wreck is on its side, at a depth of 2500m below the water’s surface. The pressure at this depth is a crushing 3659 pounds per square inch – many times higher than the human frame can withstand, even if protected by an atmospheric diving suit.
Now suppose that inside the ship’s tanks are 500 tonnes of heavy fuel oil. For the time being, the oil is safely contained. But eventually, the corroding effects of the water, the motion of the deep sea currents, or the natural decay of the vessel’s hull will cause the oil to escape into the surrounding ocean. This may happen all at once as the vessel breaks apart, or over an extended period. Either way, the environmental impact will be severe.
In previous decades, there wouldn’t have been many options available for dealing with the type of scenario outlined above. There are in fact an estimated 3 million shipwrecks around the world, together constituting a significant cause of pollution to the world’s oceans. Some of them are particularly notorious polluters, like the Jacob Lukenbach, a Korea bound freighter which sank off the Californian coast in 1953. The wreck achieved a belated infamy after news emerged that is was responsible for a spate of mysterious oil spills along the Californian coast in the early 2000’s.
Had the Jacob Lukenbach sunk today, the result might have been different. Technological advances in the fields of remote vehicle operation, monitoring software and magnetic sealing technology have provided salvors with new tools to remove oil from submerged wrecks, even at great depths or in the most challenging conditions.
The Moskito
Developed by Norwegian salvage contractors Miko Marine, the Moskito is smaller than you might expect. At 115kg in weight, and a little over half a cubic meter in size, this “remotely operated hot cap” tool is easy to transport and guide into position. But it can be used to syphon hundreds of gallons of heavy fuel oil, diesel or crude oil from a sunken vessel.
Nicolai Michelsen, Miko Marine’s Managing Director, outlined to KNect365 Maritime what a traditional oil spill operation typically involves: “you would have to weld on a flange, mount a valve, open the valve, drill to make an opening into the hull. Then you would retrieve the drill, close the valve, unscrew the drill, and then connect your hoses. That is what you had to do twice to remove oil from a wreck.” Undertaking such a complicated operation remotely is understandably challenging, so deploying divers is usually the only option.
By contrast, the Moskito simplifies this process into what Michelsen describes as “one uninterrupted and continuous operation that can be undertaken at practically any water depth”. Guided to the sunken vessel by a remotely operated underwater vehicle (ROV) – or by divers if conditions permit – the Moskito magnetically fixes itself to the hull. An operator above water is then able to control the device remotely using Miko Marine’s in-house software.
At the core of the machine is a 600 Watt drill, capable of penetrating hull thicknesses up to 20mm. Once the drilling is complete, the Moskito’s pumping system syphons harmful oil out of the vessel, and into a tank, for safe disposal back on land. Depending on the depth of the sunken ship, Michelsen tells us, the tanks can either be lowered onto the seabed for retrieval once the operation is complete, or mounted directly on-board the salvage vessel.
By using the Moskito, salvors are able to condense three crucial stages of an oil removal operation – securing the pumping apparatus, drilling through the hull, and fastening valves and hoses – into a single step. This reduces the risk of potentially costly mishaps, and makes the use of ROV’s a more workable option. Operating the Moskito itself, Michelsen says, “is probably less challenging than driving a car”, although it still requires a trained operator.
Risk & Experience
Even with these added assurances, there is always a risk involved with removing oil in a marine environment. To assist Moskito operators, Miko Marine have developed “procedures based on our design, and on our experience, on how to handle unforeseen circumstances,” Michelsen says. “If you drill through a stiffener you know exactly what to do. If you hit something you didn’t expect, you have methods and procedures to handle that.”
So far the machine has been used on three salvage operations around the world: one in Chile, one off the Swedish coast, and one in the Singapore strait. The last of these, the Thorco Cloud salvage operation, was undertaken in current speeds of up to 5 knots. To pull an operation off in these circumstances, “you need to balance the characteristics of the Moskito with the support tools,” Michelsen says. Despite difficult conditions, the operation was a success – 400 tonnes of heavy fuel oil were safely removed from the sunken vessel.
Thanks to technologies like the Moskito, salvors now have more options for dealing with potentially polluting wrecks, and better chances of success. Hopefully that should help environmentalists, insurers and shipowners sleep a little easier knowing that the next big casualty is around the corner.
