Renewables’ deep-sea mining conundrum – by David Shukman (British Broadcasting Corporation – April 11, 2017)

http://www.bbc.com/

British scientists exploring an underwater mountain in the Atlantic Ocean have discovered a treasure trove of rare minerals. Their investigation of a seamount more than 500km (300 miles) from the Canary Islands has revealed a crust of “astonishingly rich” rock.

Samples brought back to the surface contain the scarce substance tellurium in concentrations 50,000 times higher than in deposits on land. Tellurium is used in a type of advanced solar panel, so the discovery raises a difficult question about whether the push for renewable energy may encourage mining of the seabed.

The rocks also contain what are called rare earth elements that are used in wind turbines and electronics. Known as Tropic Seamount, the mountain stands about 3,000m tall – about the size of one of the middle-ranging Alpine summits – with a large plateau at its top, lying about 1,000m below the ocean surface.

Using robotic submarines, researchers from the UK’s National Oceanography Centre found that the crust is dark and fine-grained and stretches in a layer roughly 4cm thick over the entire surface of the mountain.

Dr Bram Murton, the leader of the expedition, told the BBC that he had been expecting to find abundant minerals on the seamount but not in such concentrations. “These crusts are astonishingly rich and that’s what makes these rocks so incredibly special and valuable from a resource perspective.”

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