Deep sea mining

Deep sea mining is the extraction of minerals from the seabed of the deep sea. The main ores of commercial interest are polymetallic nodules, which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain. The Clarion-Clipperton Zone (CCZ) alone contains over 21 billion metric tons of these nodules, with minerals such as copper, nickel, and cobalt making up 2.5% of their weight. It is estimated that the global ocean floor holds more than 120 million tons of cobalt, five times the amount found in terrestrial reserves.^[2]

As of July 2024^[update], only exploratory licenses have been issued, with no commercial-scale deep sea mining operations yet. The International Seabed Authority (ISA) regulates all mineral-related activities in international waters and has granted 31 exploration licenses so far: 19 for polymetallic nodules, mostly in the CCZ; 7 for polymetallic sulphides in mid-ocean ridges; and 5 for cobalt-rich crusts in the Western Pacific Ocean.^[3] There is a push for deep sea mining to commence by 2025, when regulations by the ISA are expected to be completed.^[4][5]

Deep sea mining is also possible in the exclusive economic zone (EEZ) of countries, such as Norway, where it has been approved.^[6] In 2022, the Cook Islands Seabed Minerals Authority (SBMA) granted three exploration licenses for cobalt-rich polymetallic nodules within their EEZ.^[7] Papua New Guinea was the first country to approve a deep sea mining permit for the Solwara 1 project, despite three independent reviews highlighting significant gaps and flaws in the environmental impact statement.^[8]

The most common commercial model of deep sea mining proposed involves a caterpillar-track hydraulic collector and a riser lift system bringing the harvested ore to a production support vessel with dynamic positioning, and then depositing extra discharge down the water column. Related technologies include robotic mining machines, as surface ships, and offshore and onshore metal refineries.^[9][10] Wind farms, solar energy, electric vehicles, and battery technologies use many of the deep-sea metals.^[9] Electric vehicle batteries are the main driver of the critical metals demand that incentivizes deep sea mining.^{[citation needed]}

The environmental impact of deep sea mining is controversial.^[11][12] Environmental advocacy groups such as Greenpeace and the Deep Sea Mining Campaign^[13] claimed that seabed mining has the potential to damage deep sea ecosystems and spread pollution from heavy metal-laden plumes.^[14] Critics have called for moratoria^[15][16] or permanent bans.^[17] Opposition campaigns enlisted the support of some industry figures, including firms reliant on the target metals. Individual countries with significant deposits within their exclusive economic zones (EEZ's) are exploring the subject.^[18][19]

As of 2021, the majority of marine mining used dredging operations at depths of about 200 m, where sand, silt and mud for construction purposes is abundant, along with mineral rich sands containing ilmenite and diamonds.^[20][21]