Deep Blue Cobalt: Mining on the Ocean Floor

There is a need to transition energy, transportation and industrial infrastructure away from fossil fuels to meet the sustainable development goals laid out in the Paris Agreement. Accordingly, there has been an evident rise in the adoption of renewable energy sources worldwide. In the United States alone, renewable energy as an energy source has grown by 100 percent from 2000 to 2018.

This will require thousands of solar and wind farms, and billions of electric vehicles (EVs)—all of which will need batteries for electricity storage. According to the International Energy Agency (IEA), 10,000 gigawatt-hours of energy storage will be required worldwide by 2040, about 50 times more than current demand. An IDTechEx report estimates that demand for nickel, which is needed to make EV batteries, will increase 10 times by 2030 as compared to 2019. The demand for lithium is projected to increase by a whopping 650 percent by 2027. A 2020 report by the World Bank found that to meet this demand, production of minerals such as graphite, lithium and cobalt would need to increase by nearly 500 percent by 2050. 

The most vital elements for manufacturing lithium-ion batteries are nickel, manganese and cobalt (NMC), in addition to copper for the wiring. Most metals are currently obtained from conventional mining, which is not exactly environmentally friendly. Such methods can lead to issues such as soil and groundwater pollution, deforestation, biodiversity loss and an increasingly low yield of minerals—in addition to being detrimental to the physical and mental health of mine workers. 

On top of that, there are also supply issues. Cobalt is expensive and more than 70 percent of the cobalt in the world is found in the geopolitically unstable Democratic Republic of Congo, where mining occurs under the shadow of human rights abuses. Nickel ores usually contain only a very small percentage of useful Ni, indicating that the process is highly inefficient and results in a large amount of waste material. Elon Musk stated in August 2020 that Tesla needs more nickel and that there are not enough mines currently in operation to provide it. This could lead to a severe shortage of nickel right when the industry is poised to grow exponentially.

Is there an alternative method to obtaining the metals that can overcome all these problems?

Polymetallic nodules, also called manganese nodules, were first discovered in 1868 in the Kara Sea off the coast of Siberia. At the time, they were found in almost all the world’s oceans, with the highest concentrations between depths of 4,000 and 6,000 meters (on the abyssal plain). The nodules are potato-sized rocks formed of concentric layers of iron and manganese hydroxides around a core. There is still a lack of knowledge about how these nodules came to be sitting on the seabed, but two of the most popular theories are that:

• A hydrogenous process in which nodules are formed by slow precipitation of the metallic components from seawater. This is thought to produce nodules with similar iron and manganese content and a relatively high grade of nickel, copper and cobalt.
• A diagenetic process in which the manganese is remobilized in the sediment column and precipitates at the sediment/water interface. Such nodules are rich in manganese but poor in iron, nickel, copper and cobalt. 

In terms of the general chemical composition of the nodules, of particular interest are manganese (29 percent), nickel (1.4 percent), copper (1.3 percent) and cobalt (0.25 percent).

DeepGreen is a deep-sea mining company with an objective of reducing the adverse effects of mining on the environment. “Ocean nodules are a unique resource to consider at a time when society urgently needs a good solution for supplying new virgin metals for the green transition,” said DeepGreen CEO Gerard Barron. “Extraction of virgin metals—from any source—is, by definition, not sustainable and generates environmental damage. It’s our responsibility to understand the benefits—as well as the damages associated with sourcing base metals from nodules.”

The current system proposed to collect the nodules, the Patania II, is being tested by Global Sea Minerals Resources (GSR). It is a vacuum-type system that will suck up the top layer of the ocean floor, separate the nodules from the mud, pump them up using a giant flexible pipe to a surface collection vessel, and discharge seawater and sediment through another tube.

The nodules reportedly contain almost entirely useable minerals and have no toxic levels of deleterious elements. This would leave next to zero solid waste when processing the nodules, as compared to land ores, which generate inordinate amounts of solid wastes and toxic tailings.

The researchers also ascertain that nodule collection and processing could lead to a 70 percent reduction of carbon dioxide equivalent emissions, along with a 94 percent reduction in stored carbon at risk and a 90 percent reduction in SO_x and NO_x emissions. Additionally, nodule mining is at least 93 percent less damaging to flora, fauna and human health.

DeepGreen also has an interesting concept of “renting” the use of required metals to companies such as Tesla. EV batteries require the structural, electrical and chemical properties of the metals, rather than the metal itself. DeepGreen suggests collecting the battery cathodes at the end of an EV battery’s life and recycling the metals. In this way, future requirements of the metals can be partially but significantly covered by the recycled metals, thus eventually reducing the requirement of mining.

The Clarion-Clipperton Zone (CCZ) is a 4.5-million-square-kilometer abyssal plain between Hawaii and Mexico. It is the area where the highest density of nodules (27 billion metric tons) has been found. The CCZ is regulated by the International Seabed Authority (ISA) in international waters, which has granted contracts to 16 deep-sea mining contractors covering an area of 1 million square kilometers. DeepGreen holds the rights for three of those contracts: NORI, Marawa and TOML. It is estimated that the NORI contract area alone is potentially abundant enough to supply metals for 140 million EV batteries.

So, do these nodules provide the solution to all sustainable supply problems? It may seem to be the case based on the DeepGreen report, but there are some points of concern that should be considered.

DeepGreen itself concedes that one of the main assumptions of its life cycle assessment is that the deep-sea floor provides only scarce food resources to support limited biomass. However, that does not seem to be the case. The nodules are the only hard substrate on a seabed of soft clay, which makes them critical for myriad unique creatures in need of an anchor or habitat. The sediment surrounding the nodules also harbors remarkably high biodiversity. Biological surveys led by Craig Smith, a benthic ecologist at the University of Hawaii in Honolulu, revealed 330 mostly previously undiscovered species in an area measuring just 30 square kilometers.

According to a report by a group of researchers from James Cook University in Australia and the University of the South Pacific, scraping and vacuuming the seafloor can destroy habitats and release plumes of sediment that blanket or choke filter-feeding species on the seafloor and fish swimming in the water column. The report also highlights the potential impact of light and noise pollution, which could disrupt a multitude of species attuned to living in the dark and silent depths of the oceans.

These findings are further supported by another extensive study conducted over the last 30 years and whose findings were published in a July 2019 article in Nature. The researchers found that nodules are required to preserve the abyssal meiofauna—tiny creatures living on or around the nodules. In a test, Hjalmar Thiel used an eight-meter-wide rake in an 11-square-kilometer section of seafloor. The rake caused a cloud of sediment to descend onto the meiofauna. The test revealed that the deposit did bury and suffocate the tiny creatures beyond a scale that was previously anticipated. The site has been revisited four times over the last 30 years, but little recovery of life has been observed.

Another consideration is that the nodules are formed over millions of years and grow extremely slowly at a rate of only several millimeters to several centimeters per million years. For that reason, they are not exactly a renewable source.

Based on increasing evidence of undiscovered species at the bottom of the ocean, DeepGreen has promised that it will conduct a multiyear environmental and social impact assessment. This will consist of more than 100 separate studies carried out in partnership with the Republic of Nauru, the Republic of Kiribati, and the Kingdom of Tonga.

In the same vein, the International Seabed Authority has designated nine areas as Areas of Particular Environmental Interest (APEIs), which are currently protected from mining activities. These areas each cover approximately 160,000 square kilometers and are located around the exploration license areas (refer to the map of CCZ above). The APEIs were placed across the CCZ to protect and represent the full range of biodiversity and habitats in the region, including variations in nodule abundances, food availability, and seafloor topography (including the presence of seamounts).

There are also different varieties of mining robots in development that could potentially reduce the disturbance caused by mining activity on the seabed. One example is the C-Ray robot by Pliant Energy Systems, which is a maneuverable robot designed to move like a sea otter. It can be equipped with arms that can collect the nodules instead of vacuuming them, and it can even be programmed to replace the nodules with other rocks to ensure regrowth of sea life. 

There are still many gaps in our knowledge and understanding of the biodiversity and ecosystems of the deep sea, as well as our awareness of the long-terms effects of mining in that zone. These dangers are intensified by the relative difficulty of monitoring and managing ocean-based operations. In addition to the practical difficulties of monitoring mining work within the deep sea and dealing with setbacks such as equipment malfunctions or accidents, the recent safety history of the ocean-based industry in general has not been encouraging. 

Because of this, the Deep Sea Conservation Coalition, a group of more than 80 nongovernmental organizations (NGOs), is calling for a moratorium on deep-sea mining—including the issuance of licenses to explore the seabed for minerals—until several conditions have been met. These include acquiring a comprehensive understanding of the environmental, social and economic risks of nodule mining; demonstrating that deep-sea mining can be managed in a way that prevents damage to the marine environment and the loss of biodiversity; ensuring that mining companies receive consent to mine from indigenous peoples in affected communities; conducting exhaustive research into alternative sources of minerals for renewable energy; establishing public consultation mechanisms; and reforming the ISA to ensure that there is transparency and accountability.

However, the ISA is in the process of developing a framework to account for exactly these concerns, and actions by groups such as the Deep Sea Conservation Coalition are a positive indication of rising environmental awareness. This will hopefully lead to a positive outcome of sustainable economic growth.