Remote imagery, boom wings, speed sweepers and oil skimmers are extending the capabilities and efficiencies of oil spill responders using tugs or specialised vessels
Technology involved in oil pollution control and marine fire-fighting has evolved to improve the efficiency of operations and reduce the risks to responders. There have been developments in remote imagery, boom systems, autonomous surface vehicles and skimmers that can enhance identification of oil spillages and increase the amount of oil that can be recovered.
IMarEST’s chairman of the Responses to Marine Pollution Special Interest Group, Matthew Sommerville, summarised the latest developments in pollution control at the International Salvage Union conference in London in March. He explained that balloons with multiple cameras are being used to provide imagery of spillages. “They provide a live feed of oil recovery operations,” he said, “but they are not ahead of a vessel”.
For more advanced imagery, flying drones and autonomous surface vessels with cameras can be used for counter pollution and surveys. “They can land on moving platforms and operate in cold and hot conditions,” said Mr Sommerville.
He also outlined developments in booms for containing oil pollution. This includes boom wings that mean emergency responders can “operate at speeds up to 4 knots compared to just 0.7 knots with conventional booms”.
A boom wing means a single tug, or other vessel, can move at these speeds with a V-shaped containment unit. Or a boom can be used to recover oil in a current. This helps to direct an oil slick towards a skimmer and recovery unit at the inside apex of the V shape.
Skimmers are being developed to operate in more extreme environments, said Mr Sommerville. “They can operate in ice with increasing efficiency and people are looking at autonomous skimmers with prototypes coming this year,” he said.
Some of these technical developments were presented during the Interspill exhibition also in London in March. During this event, Tug Technology & Business spoke to a number of these manufacturers and equipment providers.
Desmi has developed a boom wing and skimmer system that enables oil recovery at speeds up to 3.5 knots without oil slipping below the boom, said sales manager Mehdi Banisi. This is all part of Desmi’s speed-sweep system that includes a Ro-Kite as a wing, a Ro-Skim weir skimmer that is integrated within the apex of the booms and umbilicals for transferring collected oil to storage tanks.
Mr Banisi explained that oil is funnelled towards a specially designed oil recovery unit that includes three 900 mm vortex screens that are fitted with circular floats that disrupt the laminar flow of the surface oil and water, which creates a stable area for oil recovery.
A Ro-Skim or a Desmi Octopus in-line skimmer that is integrated with this speed-sweep, or free-float Terminator, Helix and Giant Octopus skimmer can be used for separating oil from the surface water.
“Ro-Kite replaces the need for a second vessel that is used in conventional responses, which saves money for clients”
“Ro-Kite replaces the need for a second vessel that is used in conventional responses, which saves money for clients,” said Mr Banisi. Its movement through water is parallel to a deployment vessel and enables the boom to open into its V-shaped configuration.
Oil can also be burnt as a method of removing it from the sea. For this remedy, Desmi supplies Pyrobooms in a static or speed-sweep configuration. These have been tested to be fire-proof for up to 24 hours, said Mr Banisi. Desmi has also developed drones for surveillance and for igniting these fires.
“A drone can operate up to 1 km from the vessel and administer an igniter that means a person does not need to be in a dangerous position.” All these developments mean responders can “collect oil faster, burn oil further out or skim and pump quicker,” Mr Banisi concluded.
Allmaritim offers four different types of the Current Buster that can be deployed in a current with speeds up to 4 knots without losing any of the contained oil. When this equipment is used with a BoomVane, a responder can operate as a single-vessel sweep system, said Allmaritim key account manager Andreas Stien.
“Oil is directed to a built-in separator that has a skimmer and pumps oil back to a tank,” he said. One of these four types is designed for flowing shallow water, such as in estuaries. It has a draught of 1 m and has been used in Alaska and Yukon River, Canada.
Current Busters are being used by Brazil’s OceanPact for oil spill containment. These are deployed on daughter craft that are contracted by international oil companies operating in Brazil, such as Statoil and Total.
These Current Busters have oil-water separators built in for higher recovery rates, said OceanPact commercial officer João Vitor Serra. “This separates oil from the water and means 75% of the oil can be collected, which is a huge increase in efficiency,” he said.
Empteezy introduced six types of oil containment booms in different sizes at the exhibition. Its export director Lars Birkedal said these are:
There are two sizes of fence booms, of 450 mm or 650 mm in height, that can be deployed from a reel in static water, such as in marinas and harbours. Permanent booms come in 15 m or 25 m lengths of 600 mm or 850 mm height, for long-term harbour deployment. Flotation is provided by foam-filled floats that are bolted onto rigid skirts.
Curtain booms have buoyancy and weight ratios that are suitable for wave action in sheltered water. They come in 450 mm, 650 mm and 900 mm height in 25 m strips. A silt boom is designed for containing silt within inland waterways.
Air-filled booms are suitable for deployment from response vessels where foam-filled booms would be too bulky, said Mr Birkedal. Empteezy offers two sizes in 25 m lengths of 850 mm and 1,200 mm.
Lamor has tested a skimmer that can be used in solid ice. An icebreaking version of its Sternmax skimmer was trialled over the past three years on icebreaking escort tug Arctia’s Ahto in the Gulf of Bothnia, Finland. Tests were also carried out in Arctic conditions in March 2017. Ahto was designed by ILS Ship Design & Engineering with an ice class of 1ASuper (Tug Technology & Business, Q1 2018).
Lamor chief operating officer Rune Högström explained how Sternmax can break up to 1.1 m of ice and then uses oleophilic brushes to drive slush ice and oil into the skimmer. This was deployed on an A frame on the stern of Ahto. Tests proved that the vessel’s propulsion can induce a current to pull oil from below the ice and concentrate it in an area for recovery. Sternmax can recover up to 560 m3/hr.
Lamor also presented its free-floating skimmers and oil transfer pumps. For example, the Minimax 25 floating skimmer has been redesigned as a modular unit that can be deployed in Arctic conditions. It can be assembled and disassembled by hand and recovery units, such as oleophilic brushes, discs and drums can be interchanged, said Lamor sales manager Philip Smith. “This depends on the viscosity of the oil to be recovered,” he said.