Deep sea mining: Exploring the Unknowns
Polymetallic nodules look like lumps of coal scattered across the seafloor. They have a similar purpose as coal as well, to provide energy. But they have many other reasons to exist, most of which we do not yet know or understand.
It takes millions of years for these potato sized rocks to form. The Cook Islands, and others, are wanting to mine them from our seabed 5000 m deep. Each nodule starts as a small piece of shell, a shark’s tooth or other hard fragment on the seafloor. Over time, layers of sediment, containing minerals and metals, build up around this small fragment, with most growing at a rate of a few millimetres every million years.
These potato-sized lumps may look like lifeless rocks, but they form the basis of deep sea ecosystems offering a rare, hard surfaced area which lifeforms such as sponges need to exist, and in turn offer octopuses a place to lay their eggs.
No one has yet mined the deep sea yet, but in recent years exploration has ramped up in deep national waters such as the Cook Islands and in international waters such as the Clarion Clipperton Zone (CCZ) in the North Pacific. These exploration prospectors have hoped to capitalise on the market for critical minerals said to aid the climate crisis, though this argument is weakening.
Global demand for lithium, copper and cobalt, which miners say can be sourced from the deep sea, was expected to spike, but projections have always been highly uncertain, and dependent on the shifting needs of a fast-changing technology sector.
In the past three years, the outlook for cobalt, as one example, has changed markedly. When the Cook Islands Government issued the three deep sea mining exploration licenses in 2022, the world price of cobalt was around US$80,000 per mt. Today it is only around 25% of that price, at US$21,550 per mt.
Tesla, currently the world’s second largest manufacturer of Electric Vehicles (EV), now uses cobalt-free batteries in half of its fleet. BYD, the Chinese-owned industry leader, has pioneer the use of sodium-ion batteries in its EVs, that is salt based batteries! If other car manufacturers follow this trend, future cobalt demand will likely drop further
Of course, cobalt is not only used in battery manufacturing. Cobalt also has many military applications, from military weapons to high-temperature aerospace alloys used in fighter jets. Will the Cook Islands find itself in the near future as a player in a future super power arms race?
The machinery needed to mine these nodules from the deep ocean is still only at a prototype stage. A lot of insurers are not willing to back the industry, making it very risky to go ahead. These prototypes are based on concept designs to use 27-tonne machines fitted with caterpillar tracks to suck nodules off the seafloor and send them to a surface vessel through a vertical pipe. By one estimate, a single mining machine would strip around 10,000 square kilometers (about 1.5 million rugby fields) of seafloor over a period of 25 to 30 years, the anticipated duration for a commercial mining contract. Bearing in mind this is one machine and each company will have multiple machines.
Some mining concepts have said they would pluck nodules from the seafloor surface without disturbing the sediment, even having AI power to determine which nodules have life on them, so they could avoid these rocks completely. A considerate concept design, but whether this could ever operate at a commercial scale, where time means money, is very doubtful.
Among other things we don't know is the extent of the impact that will occur. It is still going to take years if not decades to complete surveys to better make sense of the impacts. The knowledge gaps are actually quite massive. It is still way too early to predict what can happen with deep sea mining at many levels.
For the time being, the ocean’s abyss remains untouched—but would-be miners are still pushing hard to get started, all too aware that the tide may be going out.