Deep-Sea Mining

Extraction via machines sweeping the ocean floor would reduce child labor and human rights violations currently occurring in land-based operations that collect the minerals needed for modern-day electronics. However, these sweeps may kill undiscovered organisms that possess biologies from which antibiotics could be derived and destabilize deep-sea ecosystems.

Polymetallic nodules are a source of manganese, cobalt, nickel, copper, molybdenum, and platinum, which are used in batteries, fuel cells, and metal alloys of electric vehicles. Seamount crusts contain rare-earth elements deemed essential to US national and economic security, including neodymium and dysprosium used to make permanent magnets.

The British HMS Challenger research vessel identified metal-rich seafloor rocks between Hawaii and Mexico in the 1870s, but rules governing what parts of the ocean are controlled by which nations were not created until 1958 by the UN. It later established the ISA to oversee mineral-related operations in international waters.

The International Seabed Authority—established by the 1982 United Nations Convention on the Law of the Sea—grants 15-year contracts for governments and private companies to legally search for minerals and test seabed mining technologies. China is already the global leader in the processing and refining of critical minerals.

The greatest interest is in polymetallic nodules—structures formed from metals in seawater collecting around a core of shell, bone, or rock. Cobalt-rich ferromanganese crusts cover underwater mountain ranges and form over millions of years of metal deposition. Polymetallic sulfide deposits accumulate when seawater seeps into volcanic rocks.

Polymetallic nodules are found in regions near the middle of the Pacific Ocean, along the eastern coast of South America, and along the western coast of Africa, while cobalt-rich crusts span significant portions of the Pacific tropics east of the Philippines. Polymetallic sulfide deposits occur at tectonic plate boundaries, including areas within national jurisdictions.

Located between Hawaii and Mexico and spanning an area larger than the European Union, the Clarion-Clipperton Zone is the world's region with the most contracts awarded to groups seeking to extract valuable metals by collecting polymetallic nodules. Conservative estimates suggest that 21.1 billion tons of polymetallic nodules exist in this abyssal plain, but about 90% of the species in the area are unknown to scientists.

This animation depicts the deployment of an extraction vehicle from a surface vessel and its descent to the ocean floor, where it collects polymetallic nodules containing useful minerals. The visualization also shows the transport of these nodules to the surface and the release of processing waste in a discharge plume.

Proposed solutions for collecting these potato-shaped rocks involve lifting a slurry composed of them, organic debris, and water through several kilometers of flexible tubing to a ship on the surface, a process that is more difficult than pumping crude oil. One method would use compressed air, but this method is only 15% energy-efficient.

While models suggest demand for crucial metals is expected to exceed supply through 2050, new battery technologies, such as those that require no nickel or cobalt, introduce uncertainty that opponents of deep-sea mining see as not worth the risk of certain environmental damage, which includes noise and light pollution and the release of toxic plumes from mining equipment.