The EU aims to reduce dependency on imports of raw materials. Large quantities of raw materials can be found in deep sea Polymetallic Nodules. Polymetallic Nodules contain relatively high concentrations of Nickel, Copper and Cobalt.
Cobalt is especially valuable to harvest since it is used in batteries for electric cars. Nodules occur at any depth, but the highest abundance has been found between 4,000 and 6,000m. How do you harvest these nodules at such a large depth?DeRegt was asked to join an EU funded consortium of 14 companies. Industry, research institutes and service companies across seven different countries joined hands to solve the question on how to harvest them, avoiding serious harm and minimizing the environmental risks.
DeRegt’s challenge, as a cable solutions company, was to develop and test a unique deep-water umbilical to link into pumps and the mining tool.
Peter Brussee explains more about this cutting-edge EU research project.
Power and communication over 5.5 km
The system can be best compared with a large vacuum cleaner with a 5.5 km long hose. The vacuum cleaner, called the harvesting system, collects the nodules from the seafloor. Six powerful pumps, called booster stations, transfer the nodules through a 5.5 km long vertical transport system to the surface vessel. The umbilicals connect the booster stations and the harvesting system to the vessel’s power supply and allow data transmission. It interacts with the system at many different points. We had to provide connectivity and an automated clamping system along the entire 5.5 km vertical transport system.
One of our main challenges for the sake of economic viability as well as sustainability was to ensure that we had a one-fits-all solution. The same design for each of the sections of the vertical transport system was selected. So that if a part needs to be replaced or you need to cut back, you can simply replace a single part, and shift the other components.
Automatic clamping system
We needed to develop a clamping system that allows the cables to be fixed to the vertical transport system. For safety reasons no human interference is allowed. Therefore we’ve developed a system that automatically clamps and de-clamps the umbilicals along the 5.5 km long hose during the launch and recovery of the system. An innovative method was used to minimize the mechanical loading onto the umbilicals and vertical transport system.
The umbilicals contain a double steel armour to transfer loads and to protect the electrical and optical components from crushing. Fragile components are placed towards the centre of the cable. For corrosion prevention we’ve jacketed every single steel wire. This means that if the cable is damaged and it’s water tightness is compromised it will have a minimal impact on its durability .
"The search for rare earth elements, whilst taking into account the environment, bring together the need to continue to grow technology and the method to do this in a responsible way. DEREGT are “technology partners” and fundamental to this ethos is their commitment to share lessons learned and exploit these new technologies and products across all subsea sectors, to the benefit of all DEREGT clients and its technology partners."