Deep-sea mining: Superficial riches, deep hidden costs
Abstract
Deep-sea mining (DSM) is promoted as a solution to secure minerals critical for a rapid energy transition1,2, yet its full economic, environmental, and social implications remain poorly quantified3–5. Here, we conduct arguably the most comprehensive cost-benefit analysis (CBA) of DSM to date, compiling and using data from publicly available articles simply yet powerfully. We estimate the net present value (NPV) of extracting 3 million dry tonnes of polymetallic nodules annually6,7, over 50-years, applying both conventional and intergenerational discounting to capture long-term impacts8–10. Using the average of reported metal prices, our study suggests that DSM could generate direct financial gains of ~USD12 billion over 50 years (i.e., ~USD240 million a year), non-financial costs are significantly higher —reaching ~USD68 billion (i.e., trading off USD5.6 of non-financial losses for USD1 of financial gain), and ~USD105 billion (trading off USD8.7 for USD1 of financial gain) under conventional and intergenerational discounting, respectively. Sensitivity analysis reveals that a 42% fall in mineral prices or an 85% extraction costs overrun, both plausible, would wipe out all projected financial gains. Even if the cost of extracting deep-sea minerals was zero, the NPV would still be negative. These findings highlight the economic flimsiness of DSM, reinforcing ecological and social concerns11–13. Given that DSM’s net value is negative, policymakers should strengthen existing mining practices and prioritize circular economy strategies over high-risk exploitation14.
Abstract
Section titled “Abstract”Abstract Deep-sea mining (DSM) is promoted as a solution to secure minerals critical for a rapid energy transition1,2, yet its full economic, environmental, and social implications remain poorly quantified3–5. Here, we conduct arguably the most comprehensive cost-benefit analysis (CBA) of DSM to date, compiling and using data from publicly available articles simply yet powerfully. We estimate the net present value (NPV) of extracting 3 million dry tonnes of polymetallic nodules annually6,7, over 50-years, applying both conventional and intergenerational discounting to capture long-term impacts8–10. Using the average of reported metal prices, our study suggests that DSM could generate direct financial gains of ~USD12 billion over 50 years (i.e., ~USD240 million a year), non-financial costs are significantly higher —reaching ~USD68 billion (i.e., trading off USD5.6 of non-financial losses for USD1 of financial gain), and ~USD105 billion (trading off USD8.7 for USD1 of financial gain) under conventional and intergenerational discounting, respectively. Sensitivity analysis reveals that a 42% fall in mineral prices or an 85% extraction costs overrun, both plausible, would wipe out all projected financial gains. Even if the cost of extracting deep-sea minerals was zero, the NPV would still be negative. These findings highlight the economic flimsiness of DSM, reinforcing ecological and social concerns11–13. Given that DSM’s net value is negative, policymakers should strengthen existing mining practices and prioritize circular economy strategies over high-risk exploitation14.