It is clear the world is facing a shortfall in the supply of critical elements to reach any meaningful target for net-zero carbon emissions this century.

With the recognition and acceptance that fossil carbon-based fuels are environmentally unsustainable sources of energy, causing uncontrolled and adverse effects on the global climate, the world is demanding their replacement with renewable energy sources to achieve a zero-net carbon future for humankind in the second half of the 21st Century [1].

The ambition to replace fossil carbon-based energy sources with renewables will be accompanied by a huge increase in demand for metals like copper, nickel, zinc, and elements critical to enabling renewable energy generation.

Many of these elements are relatively scarce or restricted to very few areas of the globe and include:

  • Cobalt and lithium – used in batteries for electric vehicles
  • Tellurium – used in cadmiumtelluride thin-film, photovoltaic electrical energy generation
  • Neodymium and dysprosium – used for permanent magnets in wind-turbines and electric motors
  • heavy rare earth elements – used in electronics
  • Platinum group elements – used in fuel cells and hydrogen catalysers.

This demand is illustrated by the resources needed to electrify the world’s estimated 2 billion private cars. Compared with today’s global metal production [2], the best-case scenario requires 126 years’ of cobalt, 62 years’ of neodymium, 45 years’ of lithium, and 31 years’ of copper. To power these by wind turbines requires 20 years of neodymium and dysprosium [3] or, using CdTe-type photovoltaic solar energy [4], 2,000 years’ of tellurium supply.

Potential of seafloor massive sulphides

Seafloor massive sulphides and their metalliferous sediments are the product of intense seafloor volcanic activity and form rapidly from high temperature (up to 415°C) hydrothermal fluids (black-smokers). They form 100–300 m diameter deposits, on and below the seafloor, at depths from 1,000 to 5,000m, in all oceans. They are primarily rich in iron (up to 32%), zinc (up to 17%), copper (up to 13%), gold (up to 13 ppm), silver (up to 2,000 ppm) and have elevated concentrations of selenium, cobalt, bismuth, cadmium, gallium, germanium, antimony, tellurium, thallium and indium [7]. While current estimates suggest about 600 million tonnes of accessible seafloor massive sulphide, hydrothermally inactive deposits may be 10 times more abundant than active ones with between three and five times more sulphide under the seafloor than above it [8], hosting 20 to 30 billion tonnes of ore worldwide.

Challenges

The role of Project Ultra is to better understand the resource potential of hydrothermally inactive SMS deposits, and especially those that were formed in ultramafic rocks on the flanks of mid-ocean ridges. It is likely that these types of deposit are very common at slow spreading ridges. Understanding their mode of formation, modification and preservation on and below the seafloor is essential if we are to assess the potential of seafloor minerals to help humanity achieve a low-carbon future society. As scientists, finding the right approach to solving society’s most pressing problems is our challenge, and we approach that with the utmost respect for the environment and responsibility for all our futures.

References

[1] The Paris Agreement, December 2015

[2] McKinsey & Co. Metals and Mining, June 2018

[3] Ayman Elshkaki and T.E. Graedel, 2014. Dysprosium, the balance problem, and wind power technology, Applied Energy, 136, 548–559

[4] Sarah M. Hayes, Erin A. McCullough, 2018. Criticalminerals:Areview of elemental trends in comprehensive criticality studies, Resources Policy, 59, 192–199

[5] WOR 3 Marine Resources – Opportunities and Risks. World Ocean Review, 2014

[6] Paul A.J. Lusty, James R. Hein, and Pierre Josso, 2018. Formation and Occurrence of Ferromanganese Crusts: Earth’s Storehouse for Critical Metals,Elements, 14, 313–318

[7] Sven Petersen, Berit Lehrmann, and Bramley J. Murton, 2018. Modern Seafloor Hydrothermal Systems: New Perspectives on Ancient Ore-Forming Processes,Elements, 14, 307–312

[8] Bramley J.Murton, Berit Lehrmann, Adeline M. Dutrieux, Sofia Martins, Alba Gil de la Iglesia, Iain J. Stobbs, Fernando J.A.S. Barriga, Jörg Bialas, Anke Dannowski, Mark E. Vardy, Laurence J. North, Isobel A.L.M. Yeo, Paul A.J. Lusty, Sven Petersen, 2019. Geological fate of seafloor massive sulphides at the TAG hydrothermal field (Mid-Atlantic Ridge). Ore Geology Reviews, 107. 903–925. https://doi.org/10.1016/j.oregeorev.2019.03.005