Swiss solution for oil slicks

Traditional methods of combatting oil slicks have not been adapted to the development of new materials Keystone Archive

It may be landlocked and it may produce no oil, but Switzerland is at the forefront of efforts to minimise the damage caused by oil spills at sea.

Researchers at Lausanne’s Federal Institute of Technology (EPFL) have come up with a more modern and effective way of limiting the devastation caused when oil tankers shed their cargo.

The EPFL’s Hydraulic Construction Laboratory is developing a system able to recover, transport and store quantities of spilt hydrocarbons much larger than is possible at present.

It is estimated that a million tonnes of oil have been spilled into European waters in the past 40 years.

In the most vivid recent incident, the tanker Erika broke in two in the waters off Brittany, disgorging almost 20,000 tonnes of heavy fuel oil. Some 400 km of coastline and countless marine animals were affected.

Old methods

Yet despite the regularity with which such accidents occur, the methods of combating oil slicks have changed little. The main one consists of trapping the oil inside a rubber-coated membrane – or boom – suspended between two ships.

In view of its size, weight and inflexibility, such a barrier can only cope with a slick of up to 100 metres in length, and cannot be tightened. That means not only that the oil is more likely to reach the shore, but also that it is mixed with large quantities of sea water when it is recycled.

All too often, when this system fails, chemicals must be used to disperse the slick. In extreme cases, it must be burnt off.

“The methods currently being used are old. They have not been adapted to the development of new materials,” says Jean-Louis Boillat, head of the EPFL research team developing the new system.

Contain and recycle

This system is based on the same “contain and recycle” principle as the boom, but it employs a lighter, more flexible and more resistant material. The contractible reservoir consists of expanded polystyrene floats and a submerged skirt made from Kevlar.

The Lausanne researchers are confident that, given the lightness of the materials, their reservoir could contain a slick measuring at least 200 metres in diameter. This barrier can be contracted, making the trapped oil deeper and easier to pump.

The idea for the new system came from a retired Nyon-based engineer, Ugo Cavalli, who was prompted by the Erika disaster to come up with a more modern and efficient method of containing oil slicks.

Until a commercial name is coined, the project is being dubbed the “Ugo Cavalli system”

Experiments in wave-tanks at the EPFL and the Federal Office for Water and Geology have proven that the new system can cope with large waves and being towed.

“The results have been very positive,” Boillat says.

Tests at sea

The largest company dealing with international maritime pollution, the British-based Oil Spill Response Ltd., has suggested it is willing to use the new system once it is commercially available. All the EPFL needs now is to find a partner to develop a full-scale prototype to test at sea.

“The most important step now is to build a prototype with the right dimensions and the right materials and to put it to the test in nature,” Boillat says.

There is a possibility that, despite the lack of super-tankers plying its inland waters, Switzerland may benefit from a modified form of this new technology.

It’s is hoped that the reservoir might be used to collect not only pollution, but also the timber and debris that accumulate in Lake Geneva every time there is a flood in the upper reaches of the River Rhône.

by Roy Probert