Science Matters: Mining the ocean floor, Richard Harwood

Mining the ocean floor

Richard Harwood looks into some of the complex issues around securing a sustainable future

Our demand for new technology seems to know few limits. Witness the queues for the latest smartphone when it came on sale. All this demand places a stress on the mining industry to find and exploit sources of the rare metals needed to support the technology. Often the mineral resources are located in environmentally sensitive areas, giving rise for instance to the past controversy over the possible mining of the pristine Bristol Bay area in Alaska. One further angle on this issue now arises as we become increasingly aware of the need to move our transport systems away from reliance on fossil fuels. The move to electric cars has placed a focus on improved battery technology. In particular, demand is soaring for the metal cobalt – an essential ingredient in the batteries needed to give such cars the requisite power and storage capacity. Currently most of the world’s cobalt is mined in the Democratic Republic of Congo, where for years there have been allegations of child labour, environmental damage and widespread corruption. Expanding production there is not straightforward, which is leading mining companies to weigh the potential advantages of mining cobalt from a different source.

The future of electric cars may depend on mining critically important metals on the ocean floor. For some time we have been aware of rocks rich in metals such as manganese and cobalt lying on the seabed, often in areas around hydrothermal vents. A ‘black smoker’ hydrothermal vent in the Pacific ocean floor Awareness of the presence of such mineral resources has increased in recent years. Billions of potato-sized rocks known as ‘nodules’ litter the abyssal plains of the Pacific and other oceans, and many are brimming with cobalt, suddenly highly sought-after as the boom in production of batteries gathers pace. The rocks of the seabed are far richer in valuable metals than those on land, and there is a growing incentive to get at them. We, as a society, may well face a choice. In future, alternative ways of making batteries for electric cars may be developed – and some manufacturers are exploring them – but the current technology requires cobalt, and there are limited land-based sources for this mineral. The need to expand battery production rapidly in the context of the demand for a carbon-neutral lifestyle brings the issue into sharp focus. For instance, it has been calculated recently that to meet the UK’s targets for electric cars by 2050 would require nearly twice the world’s current output of cobalt.

Manganese nodules taken from the bottom of the Pacific

But what is ‘deep sea mining’? It’s hard to visualise what would be involved. Imagine opencast mining taking place at the bottom of the ocean. Huge remote-controlled machines would excavate rocks from the seabed and pump them up to the surface. The concept has, in fact, been talked about for

several decades, but so far has been thought too difficult to

The future of electric cars may depend on mining critically important metals on the ocean floor.