To mine or not to mine deep sea to scale up marine renewables

The increase in metal mining needed to address the transition to renewable energy is drawing increasing attention and has led to a proposal to identify critical minerals for energy security options and identify sourcing challenges.

There is an elemental strain between the need to scale up ocean-based renewables and the resource and environmental implications related to metal demand, including current proposals to mine the deep seabed.

As accelerated transformation of our energy systems is mandatory, the ocean brings powerful potential for supporting this transition.

However, recent reports highlight that we must apply new technologies in a sustainable way in order to avoid unintended consequences that could undermine other aspects of ocean health.

Ocean-based renewable energy sources, or marine renewables, include offshore wind, floating solar, marine biomass and ocean energy, such as tidal, wave, ocean thermal energy conversion (OTEC) and others.

Offshore wind shows potential to become globally significant in the transition to a sustainable energy system, with other marine renewables contributing to the mix.

Construction of offshore wind turbines requires serious amounts of conventional materials, in particular steel.

However, this industry also stands in need of rare earth elements (REEs), particularly in the construction of the currently preferred direct-drive permanent magnet generators.

For offshore wind, reportedly the use of REEs in the generators appears to be the biggest potential challenge when it comes to supply of minerals.

Since most other marine renewable energy technologies are still in early phases of development with little deployment, few studies are out there on materials necessary to scale up the use of these technologies.

If these technologies have similar metal requirements to modern wind turbines, which is likely according to reports, implementation could quickly boost the demand for many metals, such as lithium, cobalt, copper, silver, zinc, nickel and manganese, and rare earth elements (REEs). 

In addition to these technologies, there is also general accord that electric car batteries will be the greatest source of increased metal demand.

Often, substitutes to specific metals can be found. The industry is continually working on solutions to use cheaper and more abundant resources avoiding specific costly metals.

The above mentioned metals and minerals are increasingly difficult to find in large quantities or high grades on land, but are present in higher concentrations in some parts of the deep seabed.

As such, the deep seabed resource potential has attracted interest in mining.

Nevertheless, the potential to mine the deep seabed raises various environmental, legal and governance challenges, as well as possible conflicts with the United Nations Sustainable Development Goals.

Greater knowledge of the potential environmental impacts and measures to mitigate them to levels acceptable to the global community will be crucial.

Recent papers stress that we require full analysis of the perceived positive and negative impacts before there can be confidence that engaging in industrial-scale deep-seabed mining would achieve a global net benefit.

In conclusion, there are large uncertainties about metal needs in long term. A hot topic for offshore wind is REEs for permanent magnets. However, this need should diminish as the industry transitions to even larger turbines with superconductors.

The energy sector as a whole has a wider set of mineral needs but also larger flexibility to switch between alternative technological solutions.

All things considered, the questions and concerns being raised are not new. It is not the first time we are looking to mine the seabed. But, since the idea is rapidly spreading globally let us take a closer look at what and how and risks and benefits.

Metals and minerals of interest on the deep seafloor include primarily copper, cobalt, nickel, zinc, silver, gold, lithium, REEs and phosphorites.

Many of the metals are found in polymetallic nodules on abyssal plains at water depths of 3,000 – 6,500 metres, on cobalt-rich crusts which occur on seamounts and in polymetallic sulphides near mid-ocean ridges.

Commercial mining of the deep seabed has not yet taken place.

Extraction of minerals from the seafloor is planned to involve either modified dredging (for nodules) or 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 will be processed on board a ship and transferred to a barge for transport to shore where it will be further processed to extract the target metals.

Relative to mining on land, there is less overburden to remove and no permanent mining infrastructure required for deep-seabed mining.

In partnership with DeepGreen Metals, Allseas is developing a deep-sea mineral collection system to recover polymetallic nodules from the ocean floor and transfer them to the surface for transportation to shore.

Allseas said in March, it had acquired the former 228 meters long ultra-deepwater drillship Vitoria 10000 for conversion to a polymetallic nodule collection vessel.

Still, reports indicate that there is likely to be solid waste material left after metal extraction, and disposal mechanisms for this waste could be comparable with those used for terrestrial mine tailings, some of which are introduced into the deep ocean via pipe.

The current governance structure under the UN Convention on the Law of the Sea gives the International Seabed Authority (ISA) regulatory responsibility for both the minerals on the seafloor in international waters and the protection of the marine environment from the effects of mining in this area.

Since 2001, 30 exploration contracts for deep-seabed minerals in the Area have been approved. Initially they were for 15 years each, and those contracts which have expired got renewed for another 5 years.

Seventeen of the ISA contracts are for polymetallic nodules in the Clarion-Clipperton Zone (CCZ) and two are for nodules elsewhere.

No contracts for mineral exploitation in this area exist.

Nevertheless, regulations for the exploitation of seabed minerals and for associated environmental management are currently under development by the ISA.

Mining deep-sea polymetallic nodules is said to release less CO2 per kilogram than mining on land.

Another report recently commissioned by a deep-seabed mining company involved with three exploration tenements in the CCZ suggests that extracting half of the CCZ nodules would provide the manganese, nickel, cobalt and copper needed to electrify 1 billion cars, while releasing only 30 per cent of the greenhouse gases of land mining.

Deep-seabed mining would bring increased metal supply to consumers globally and should benefit the exploitation company, shareholders and members of the supply chain through financial profits.

These projects within a state’s national jurisdiction or in the area under a state’s sponsorship have the potential to benefit that state by contributing to government revenues.

Further benefits may include creating jobs and training opportunities, strengthening the domestic private sector, encouraging foreign investment, funding public-service or infrastructure improvements, introducing a new supply of metals, and supporting other economic sectors.

Other benefits could involve technological innovation and the advancement of deep-sea science. Exploration and impact monitoring may expand scientific knowledge that is currently lacking.

The primary advantages of seabed mining are expected to be economic, and the primary costs ecological.

There may, however, also be economic costs to a state engaging in a deep-seabed mining operation, and in regulating it.

For example, if third-party harm or unforeseen damages occur, then either the mining company or the sponsoring state should cover the costs of compensation or remediation.

Environmental mysteries, vulnerabilities and costs are some of the most challenging aspects of deep-seabed mining.

The remoteness of most of the deep ocean combined with the harsh operating conditions, requiring expensive and highly technical equipment, have resulted in limited exploration and scientific research.

These constraints, and the expanse of the area in question, mean that the majority of the deep ocean, both within and beyond national jurisdictions, are not well characterised and understood, or still completely unexplored.

Several large programmes have addressed likely mining impacts, but in the absence of disturbance studies on appropriately large scales, the intensity, duration and consequences of the impacts of commercial mining remain speculative.

Regulators can set rules designed to minimise environmental impacts, such as requiring processed water and sediment to be returned to the ocean at certain depths in order to minimise the creation of a sediment plume in the water column.

To this end, High Level Panel for Sustainable Ocean Economy recently issued a Blue Paper, which finds that deep-seabed mining poses a risk for biodiversity loss, forced species migrations and loss of connectivity, potentially leading to species extinctions in the deep ocean.

Namely, this is of particular concern as many deep-sea species may have genetic compounds that could have biotechnical or pharmaceutical use in the future. There could also be impacts to ecosystem services, such as to fisheries, climate regulation, detoxification and nutrient cycling, but the potential risks have not yet been quantified, the paper shows. 

Another poorly understood issue is the length of time that biological communities affected by deep-seabed mining will take to recover.

There have been no tests undertaken on a scale that would replicate commercial mining and it is likely that recovery times will differ among ecosystems.

However, information gained from small-scale experiments, as well as from other industries such as deep-sea trawling, point to lengthy recovery times in each system.

Based on these studies the impacts of nodule mining may be greater than expected, and could lead to an irreversible loss of some ecosystem functions.

As nodule mining will remove the nodules, which take millions of years to form, full-scale recovery will likely take a period of time on that scale, authors of the paper believe.

Just as an example, Enshore Subsea, working in partnership with OSBIT, designed and fabricated its first seabed mineral collector and recently completed a first phase project in Pacific Ocean, recovering more than 75 tonnes of Polymetallic Nodules.

Enshore completed these trials also in partnership with DeepGreen Metals.

The company claims to have developed a method that both reduces the impact on the subsea environment and minimises plumes of seabed materials.

For the next stage a 50 per cent scale harvesting system will be built and then tested by 2022.

As mentioned above, the danger of biodiversity loss is of particular concern given the lack of baseline knowledge of the communities in habitats vulnerable to deep-seabed mining.

It is expected that there will be local extinctions, because many of the fauna inhabiting vents, nodule-rich abyssal plains and encrusted seamounts rely on the resources to be extracted as substrate.

If mining was to go ahead with the current state of knowledge, species and functions could be lost before they are known and understood.

A consideration of scale, placement and connectivity is key to prevention of biodiversity loss.

In vast, contiguous systems such as the CCZ, cumulative impacts from more than one mining operation may threaten species persistence, depending on their location or timing.

It is difficult to foresee how best to mitigate the potential impacts of deep-seabed mining because there have been so few studies investigating impacts that resemble those actually caused by mining activity, as well as none on the scale on which deep-seabed mining would take place.

It is likely that the mitigation ladder (avoid, minimise, remediate and offset) used in terrestrial and shallow-water extractive activities is not applicable in the deep ocean.

Challenges associated with restoration and recovery include the slow recruitment and growth of deep-sea species, the potentially vast scale of mining impacts, and the limited understanding of the requirements for proper ecosystem functions.

Additionally, the likely high cost of deploying assisted regeneration techniques, such as the use of artificial substrates, the transplantation or seeding of larvae and the artificial eutrophication of the ocean surface, may also be insurmountable.

Furthermore, no restoration strategies proposed have been tested, and even if benthic remediation were technically feasible, the financial commitment required may be extensive, Blue Paper says.

Most discussions of deep-seabed mining address where, when and how to conduct deep-seabed mining, as well as what the impacts might be, but no whether to mine.

Currently, opinions on whether it should proceed span a broad spectrum.

From one side, there is a firm opposition to any deep-seabed mining, with the claim that adverse effects on the environment will outweigh the benefit of additional metals.

This perspective argues that seabed minerals are not needed and suggests that “we should do more with less” via a circular economy that advances recycling, reuse and extended product lifetimes.

In the middle, there are calls for pilot testing and further scrutiny of the issue, as well as for a moratorium or precautionary pause to allow more scientific study and to see the highest environmental standards and the precautionary approach embodied in deep-seabed mining regulations and guidelines.

A pause may in practice prevent the issue of additional mining contracts unless and until there is scientifically supported evidence – not currently available – that the impacts will be outweighed by the benefits.

Concerns have been voiced that the process has gone too fast relative to the state of knowledge and the ISA’s capacity for environmental management.

Various bodies have proposed different forms of such a precautionary pause or moratorium on deep-seabed mining in international waters, including the European Parliament, and the UK House of Commons Environment Audit Committee.

In addition to environmental studies, the ISA recently commissioned a research to assesses the potential impact of polymetallic nodules production from the international deep seabed area on the economies of developing land-based producer States of metals, which would be most seriously affected.

The optimal option for the market to start offshore production will be the period of deficit, which will not be able to compensate for the landbased production, study finds.

The study also suggests approach to deep-seabed mining in a precautionary and adaptive manner in order to avoid and minimise harm to habitats, communities and ecosystems.

Additionally, it suggests more time to develop regulations and formulate regional environmental plans.

Bottom line is that most major and relevant studies agree that we need considerably better knowledge of the larger-scale environmental impacts as well as confirmation of the global benefit from mining activities before pursuing industrial-scale deep-seabed mining.