Dr. Henko de Stigter

Marine geologist Henko de Stigter investigates the possible effects of harvesting “manganese nodules” from the deep sea. ‘So far, the harvest of nodules is not yet economically viable. Extensive research into this has been done for years. A lot of thought has been given to the legal aspects of harvesting valuable minerals from the “no man's land” on the ocean floor that is effectively nobody’s property, but we still know little about the ecological impact. Therefore, the time is right to investigate the potential impact of that harvest and to limit this impact wherever possible by adapting the harvesting equipment of the future.’

Cobblestones on the ocean floor

‘Several kilometres below the surface, manganese nodules are spread out over millions of square kilometres of the ocean floor. They lie on the surface like Belgian cobblestones and are therefore – relatively! – easy to harvest. The main component of the nodules, which are several centimetres in diameter on average, is manganese, but there is far more economic interest in the fraction of a percent of cobalt that the nodules also contain. Cobalt is already a valuable metal for the production of batteries, and with the emergence of batteries for transport and industry, that interest will only grow. Now, most cobalt comes from conflict areas such as the Democratic Republic of Congo.’

Potato harvester

‘In all probability, the harvesting equipment of the future will be a kind of potato harvester that travels over the ocean floor on caterpillar tracks. Considering the rate at which these nodules develop, the damage caused by this will literally take thousands or even millions of years to restore. Furthermore, the harvesting equipment will unavoidably cause a plume of sediment in an environment where such “dust clouds” normally never occur. These dust clouds will have an enormous impact on the deep-sea life that has to filter the ever-scarce food from the water and already lives on the edge of existence. With our research, we will have to establish how great that impact will be and what can be done to mitigate this damage. If, over the next few decades, it actually comes to the nodules being harvested, then that can best be done in a manner which causes as little damage as possible to the environment.’