A gigantic suction pipe is contributing to sustainable port construction in Esbjerg

The suction pipe mounted on the side of the good ship Sif R, which is a sand dredger, is not easy to miss. The pipe is 35 metres long, 60 centimetres in diameter and can suck up over 4,000 litres - every second.

Since the natural sand migration is continuously bringing new sand into the channel, Sif R helps to maintain the deep navigation channels at the entrance to Port Esbjerg. 

At the end of the suction pipe is a suction nozzle with a gaping breadth of one and half metres, that sucks up water and sand at top speed[MS1] . The load capacity is 1,700 cubic metres of sand, and it is usually filled up in less than an hour. 

On Sif R, skipper Christian Hansen sits like a king on his throne, surrounded by screens and several joysticks, and with a sweeping[MS2]  view of the ship and the sea. With the press of a button, the suction pipe starts up. It is no more noisy than a ferry’s engine as the pipe greedily sucks up and swallows 4,000 litres of water per second, which rushes down into the open hold.

The immense volumes of sand can be given back to the sea, as we saw during our visit. The sand can also serve as a natural building brick when reclaimed areas are backfilled. This is exactly how the eastern part of Port Esbjerg has been expanded by more than one million square metres.

Millions of cubic metres of sand in the eastern port

Sif R is owned by Rohde Nielsen A/S, a company that undertakes port expansion and land reclamation projects, excavation of deep channels in the seabed, coastal protection, sand deliveries, offshore excavation of trenches for gas cables, and many other activities.

“One of the great things about our activities is that we can give our customers new land without taking it from anyone else,” says Jeanette Rohde with a smile. She heads this[MS3]  family-owned company, which her father started up with his first ship in 1968.

Rohde Nielsen A/S also helped to move the several million cubic metres of sand used to expand the eastern port.

Jeanette Rohde believes that Port Esbjerg has put the sand spoil from the navigation channel to good use in the eastern port.

“This is a highly sustainable way of expanding a port, since it can hardly be any less invasive. One of the exciting aspects of the project was that we were building with nature, rather than against it,” says Jeanette Rohde.

“I think that Port Esbjerg has been ahead of its time by building in this way,” she says.

Danish Coastal Authority safeguards shipping lanes

The Danish Coastal Authority is responsible for safeguarding shipping lanes in Danish waters. Four times a year, the navigation channel off Port Esbjerg is charted, to find the places with new sand deposits, causing the depth to fall short of the required 10.5 metres. Then Sif R and other sand dredgers are sent in with their long suction pipes, to make sure that the channel stays deep enough.

The suction nozzle is lowered onto the seabed, where it functions like a super-size vacuum cleaner. If the sand is just to be moved and sent back into the sea, it is placed on a dredging spoil platform[MS4] , from where it is emptied out of the ship in an instant and carried out to sea by the current, rather than filling up the navigation channel.

“You can say that we’re helping the sand to move on,” says Nils Ladefoged, Site Manager at Rohde Nielsen A/S in Esbjerg.

A port built from sustainable materials

The sand used to expand the port is recovered from just outside the port, as in the case of the eastern port over the years. It is then sailed into the quayside and pumped directly into the area to be backfilled. The construction work in Port Esbjerg thus has a significantly lower environmental impact than in many other places where materials need to be excavated and transported over long distances.

“The alternative to using sand from the channel is to go out into the North Sea to dredge up sand. This is more expensive and also disrupts the North Sea’s natural environment. We have a constant need to keep the channel clear, so this is the optimum solution,” says Jesper Bank, Chief Commercial Officer at Port Esbjerg. 

“In both financial and environmental terms, this is an enormous advantage,” he says. 

Besides the sand, which lays the foundation, the quay areas are filled with Norwegian granite to a thickness of 30-50 centimetres. Granite is also a completely natural material and is transported by sea from Norway.

“Many areas of business have generally become more aware of sustainability in recent years, including here at Port Esbjerg. In terms of port construction, this is just business as usual for Port Esbjerg,” says Jesper Bank.

Greener ships

Yet sustainable port expansion is not just a question of using natural resources that are available from just around the corner. Rohde Nielsen A/S has also taken a number[MS5]  of measures to make ships greener.

Sif R is not powered by heavy fuel, but by marine gas, a gas oil that pollutes over 30 per cent less, with a significant sulphur reduction. The ship’s many hydraulic systems use a biodegradable hydraulic oil and soon, an SCR (Selective Catalytic Reduction) system will be installed on the exhaust. This is a catalytic converter that converts the nitrogen oxides contained in the ship’s exhaust gas into water vapour and nitrogen. The ship’s engines are also regularly replaced, to ensure optimum fuel utilisation.  

“Via our environmental profile, we’ve just won a project to create an artificial sandbank at the Great Barrier Reef in Australia . This is a major focus for us,” says Jeanette Rohde.

More sand for the eastern port

The construction of the eastern port comprises over a million square metres, requiring several million cubic metres of sand to backfill the land areas behind the quay. In the final phase, which is still to be completed, around 90,000 cubic metres of sand will become 500 metres of quay.

Future expansions will also use sand from the navigation channel as a natural resource.

“We’re doing this well today, with focus on sustainability. But we’re looking for new methods and new inputs, so that we can do this even better in the future, in more and more areas,” says Jesper Bank, Sales Director at Port Esbjerg. 

The sand is passed on

Back at sea, Sif R and the suction pipe have sucked up 1,700 cubic metres of sand in the course of an hour. The water is drained off before skipper Christian Hansen ships the sand out to a reef at the entrance to the port that surveys have shown to be the optimum spot. Then the sea current takes over, carrying the sand out on its natural journey.