Mining of the Deep Sea is still under study but metals are abundant on the seafloor. Reserves are estimated to be worth anywhere from $8 trillion to more than $16 trillion.

This infographic from Prospector provides a visual overview of the seabed mining process.

Down in the Depths

The most prolific area for ocean mining is the Clarion Clipperton Zone (CCZ) in the Eastern Pacific Ocean, between Hawaii and Mexico. Almost 20 international mining companies have contracts to explore the region which spans over 5,000 kilometers.

Most of the metals are found in potato-sized rock-like polymetallic nodules. Millions of years old, the nodules grow by absorbing metals from the seawater, expanding slowly around the core of shell, bone, or rock.

It is estimated that there are 21 billion tonnes of polymetallic nodules resting on the ocean floor in the CCZ, containing an estimated:

• 6 billion tonnes of manganese
• 226 million tonnes of copper – about 25% of land-based reserves
• 94,000 tonnes of cobalt – about six times as much as current land-based reserves
• 270 million tonnes of nickel – 100 times the annual global nickel production in 2019

Cobalt-rich ferromanganese crusts are found on the sides of underwater mountain ranges and seamounts. Similar to nodules, these crusts form over millions of years as metal compounds in the water. Roughly 57% of them are located in the Pacific.

Polymetallic sulfide deposits formed after seawater seeps into volcanic rocks can be found along tectonic plate boundaries on the Pacific Ocean, Indian Ocean, and the Atlantic Ocean.

How Does Ocean Mining Work?

Extraction of minerals from the seafloor is planned to involve either modified dredging (for nodules), cutting (for massive sulphides and crusts), and transport of the material as a slurry in a riser or basket system to a surface support vessel.

The mineral-bearing material is then processed in a ship (cleaning and dewatering – with the wastewater and sediment being returned to the ocean) and then transferred to a barge for transport to shore where it will be further processed to extract the target metals.

Towards a Greener Future

Growing demand for batteries to power electric cars and store wind and solar energy has driven up the cost of many metals and bolstered the business case for seabed mining.

According to a study published in the Journal of Cleaner Production, producing battery metals from nodules could reduce emissions of CO² by 70-75%,  cut land use by 94% and eliminate 100% of solid waste.

Here is a look at how ocean and land mining compares:

The United Nations Convention on the Law of the Sea (UNCLOS) has so far approved 28 exploration contracts in the Pacific, Indian and Atlantic Oceans, covering 1.3 million square kilometers of the ocean floor.

With many companies turning their eyes to the unexplored riches of the ocean, seabed mining could offer a wealth of untapped minerals on the ocean floor.

(This article first appeared in the Visual Capitalist)