**Categories:** ONA Feature, Mining **Tags:** seabed, minerals, profitability, critical metals, regulation **Excerpt:** A scenario study of polymetallic nodule projects finds substantial financial risk, while companies in the sector argue for higher potential returns. The gap between these assessments depends on costs, prices, financing and rules still being developed. **Slug:** exploitation-miniere-fonds-marins-rentabilite-risques **Image alt:** Remotely operated vehicle observing the seabed during a deep-water scientific mission.
Deep-sea mining is often presented as a possible response to growing demand for metals used in batteries and energy technologies. Polymetallic nodules containing nickel, cobalt, copper and manganese, among other metals, lie on certain abyssal plains. But the gap between the presence of resources and a profitable industry remains considerable.
A recent financial analysis of two projects belonging to The Metals Company (TMC) highlights this uncertainty. It draws on thousands of simulations incorporating cost overruns typical of major industrial projects. Under its assumptions, a large majority of scenarios result in a negative net present value. Median results are unfavorable, and profitability deteriorates sharply when collection and processing expenditure increases.
These findings are not a certain forecast. The study was funded by organizations opposed to rapid commercialization of seabed mining, which must be considered when assessing its significance. TMC, for its part, argues for substantially higher potential returns. The debate therefore concerns the assumptions as much as the resources themselves.
Costs that remain difficult to establish
The main industrial challenge is to collect nodules at great depth, bring them to the surface, then transport and process them. Each stage requires specialized equipment and a logistics chain capable of operating in a remote, demanding and poorly documented environment. Collection systems, vessels, processing infrastructure and downtime can weigh heavily on expenditure.
The study’s simulations highlight the sensitivity of results to collection system costs. In some scenarios, capital expenditure substantially exceeds the company’s estimates. Uncertainty also concerns operating costs, schedules, equipment availability and the ability to maintain regular production.
Metal prices are another decisive factor. A decline in nickel or cobalt prices can erase expected margins, particularly if production begins when terrestrial supply is increasing or manufacturers are changing technologies. Future demand is not automatic: battery chemistries evolve, recycling rates rise and industrial policies can favor some materials over others.
Financing is also an obstacle. Banks, insurers and buyers have publicly expressed reservations about participating in the sector. If financiers demand high returns to compensate for technical, regulatory and environmental risks, the cost of capital can make projects less competitive. Profitability calculated before financing can therefore differ substantially from the return available to investors.
Two assessments, different assumptions
Mining companies highlight resource grades, long-term prices and potential economies of scale. They argue that offtake contracts and optimized industrial systems could improve margins. TMC has notably communicated after-tax return targets substantially above the independent study’s median results.
The divergence cannot be resolved simply by comparing two rates of return. The assumed costs, construction timelines, taxes, royalties, selling prices and possible interruptions must be examined. A project can appear profitable in a central scenario and become loss-making if investment costs rise, production is delayed or regulatory conditions change.
Public benefits also deserve attention. States and the International Seabed Authority could receive royalties, but these revenues would depend on production and sharing rules. Additional market volumes could also affect terrestrial producers, whose tax revenues and employment already contribute to national economies. Assessment must therefore extend beyond the company’s operating accounts.
Major environmental uncertainty
Profitability is not the only controversy. The deep sea contains poorly understood ecosystems, and the potential effects of collection, noise, sediment plumes and habitat disturbance remain central to scientific and regulatory debates. The scale and duration of some impacts cannot be confidently inferred from limited data.
This uncertainty can also become an economic risk. Stricter rules, monitoring requirements, restoration obligations or permitting delays can increase costs. Conversely, a lack of consensus on standards can discourage buyers and lenders. A project’s robustness therefore depends on its ability to demonstrate environmental performance, not just its cost per metric ton.
The decision will depend on verifiable evidence
For African countries with substantial terrestrial mineral resources, the debate calls for careful comparison of supply options. Undersea mining should not be considered an automatic solution to the energy transition’s needs. Investment in terrestrial exploration, local processing, recycling and material efficiency offers other paths, each with its own impacts and constraints.
Before any commitment, decision-makers and investors will need to compare economic models against operational data, independent tests and clear rules. Contracts will need to allocate risks from cost overruns, delays and falling prices. Environmental monitoring mechanisms will need to be accessible and credible.
At this stage, deep-sea profitability remains a hypothesis highly sensitive to the parameters chosen. Resources exist, but the ability to exploit them at scale with sufficient returns and robust environmental safeguards remains to be demonstrated. That demonstration—technical, financial and regulatory—will determine whether the sector can move from promise to sustainable activity.