Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific disturbance studies have been carried out. Here we evaluate changes in faunal densities and diversity of benthic communities measured in response to these 11 simulated or test nodule mining disturbances using meta-analysis techniques. We find that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys assessed recovery in fauna over periods of up to 26 years. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments, although there is variation in sensitivity amongst organisms of different sizes and functional groups, which have important implications for ecosystem responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future mining impact test studies. Further research to assess the effects of test-mining activities will inform ways to improve mining practices and guide effective environmental management of mining activities.

To meet UN Sustainable Development goals, a clean‐energy transition with minimal ecological impact from its raw‐material supply chain is essential. Polymetallic nodules lying unattached on the abyssal seafloor of the Pacific Ocean's Clarion Clipperton Zone contain four critical metals (nickel, cobalt, manganese, copper) in large quantities, and the International Seabed Authority may soon enact regulations to allow their commercial exploitation. There are complex global ecological implications of doing so. Nodule exploitation would damage abyssal habitats and may impact midwater‐column organisms; but in the absence of nodule exploitation, terrestrial mining's environmental and social impacts would intensify. This paper adds to the growing systems‐based literature on nodule collection by contributing a preliminary material flow analysis of global‐average cradle‐to‐gate waste streams using either nodules or terrestrial sources as part of a preliminary life cycle assessment, as well as integrated risk assessments of those waste streams. System endpoints are battery precursors (nickel sulfate, cobalt sulfate, manganese sulfate), copper cathode, and a 40% or 75% manganese product. Overburden, tailings, and processing and refining wastes from terrestrial mining are compared to the nodule industry's anticipated offshore and onshore wastes, including sediment disrupted by nodule‐collection machines. Robustness to offshore technology assumptions is tested using Monte Carlo simulation, while onshore mass‐flow scenarios incorporate a “negligible‐waste” flowsheet and high‐waste flowsheets where manganese is not recovered. A billion‐EV scenario incorporates the effects of declining terrestrial copper and nickel ore grades. Results imply that metal production from nodules may produce less waste of lower severities, caveated by uncertain impacts of disrupted sediment.

ABSTRACTLithium ion batteries (LIBs) have brought about a revolution in the electronics industry and are now almost a part of our everyday activities. They are on the verge of finding application in almost every electronic rechargeable device and have a bright future ahead. With the recent discovery of substantial reserves of lithium in India, along with the favourable government policies for the usage of electric vehicles (EVs), LIBs are expected to play a major role in meeting sustainable energy goals. Though LIBs have become a commercial success, they face many challenges, such as high cost of production, thermal runaway and overcharging, that might hamper their extensive use. Many research studies have been conducted regarding the operation of LIB, with safety being a concern. With rapid technology development, going nanoscale for LIB production has become achievable and valuable as it has been reported to increase the shelf life of the battery. In this review, recycling of spent LIBs is discussed, as the extraction of the leftover lithium and other minerals is possible through recycling process. The advantages and drawbacks of deep‐sea lithium mining have been discussed, as it is explored as an alternative to major lithium sources due to the rapid depletion of land mining sources. Its impact on the environment and the mineral market has been assessed. This review paper attempts to give an overview of all the vital characteristics of an LIB, such as life cycle, fast charging and overcharging, while covering strategies for overcoming challenges faced in the functioning of LIBs.

Infrastructure supporting the transition of human societies from fossil fuels to renewable energy will require hundreds of millions of tons of metals. Polymetallic nodules on the abyssal seabed of the Clarion-Clipperton Zone (CCZ), eastern North Pacific Ocean, could provide them. We focus on ethical considerations and opportunities available to the novel CCZ nodule-collection industry, integrating robust science with strong pillars of social and environmental responsibility. Ethical considerations include harm to sea life and recovery time, but also the value of human life, indigenous rights, rights of nature, animal rights, intrinsic values, and intangible ecosystem services. A "planetary perspective" considers the biosphere, hydrosphere, and atmosphere, extends beyond mineral extraction to a life-cycle view of impacts, and includes local, national, and global impacts and stakeholders. Stakeholders include direct nodule-collection actors, ocean conservationists, companies, communities, interest groups, nations, and citizens globally, plus counterfactual stakeholders involved with or affected by intensification of terrestrial mining if ocean metals are not used. Nodule collection would harm species and portions of ecosystems, but could have lower life-cycle impacts than terrestrial mining expansion, especially if nodule-metal producers explicitly design for it and stakeholders hold them accountable. Participants across the value chain can elevate the role of ethics in strategic objective setting, engineering design optimization, commitments to stakeholders, democratization of governance, and fostering of circular economies. The International Seabed Authority is called to establish equitable and transparent distribution of royalties and gains, and continue engaging scientists, economists, and experts from all spheres in optimizing deep-sea mineral extraction for humans and nature. Nodule collection presents a unique opportunity for an ambitious reset of ecological norms in a nascent industry. Embracing ethical opportunities can set an example for industrial-scale activities on land and sea, accelerate environmental gains through environmental competition with land ores, and hasten civilization's progress toward a sustainable future. Integr Environ Assess Manag 2022;18:634-654. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

To support the green energy transition, sustainable supplies of critical metals-60 million (metric) tons of copper, 10 million tons of nickel, and 1 million tons of cobalt-annually by 2050 are essential. These metals are currently sourced from declining terrestrial reserves, making deep-sea polymetallic nodules a promising alternative. However, current metal extraction methods are lengthy and energy and carbon intensive, emitting 45, 28, and 4 tons of carbon dioxide equivalent per ton of nickel, cobalt, and copper, respectively. We present a fossil-free hydrogen plasma-based reduction process, powered by green hydrogen and renewable energy, which condenses calcination, smelting, reduction, and refining into a single-step metal extraction, reducing direct carbon dioxide emissions by up to 90% and improving energy efficiency by up to 18%. In addition, we demonstrate selective copper recovery via a heat treatment requiring no acids or reducing agents, offering a more sustainable and cost-effective pathway for critical metal extraction from polymetallic nodules.

The growing importance of cobalt to the US economy has led to its categorisation as a critical mineral. Cobalt demand is increasing due to its requirement in lithium-ion batteries, which will significantly contribute to the energy transition. Supply is threatened for various reasons, primarily regarding supply chain concentrations, with the majority of the world’s cobalt originating in terrestrial deposits in the Democratic Republic of the Congo, and being refined in China. There remain environmental and ethical concerns over the present supply chain. Previous discussions around reducing cobalt’s criticality have suggested diversifying processing locations to reduce geographical and jurisdictional reliance where possible. This study assesses the viability of extracting cobalt from polymetallic nodules (PMNs) located on the deep-seabed in the Area, as an alternative strategy to reduce cobalt’s criticality. Assessments are made of the viability of PMN extraction considering ongoing barriers to introduction, contrasted with current arguments supporting PMN extraction. PMN mining offers a more stable and decentralised alternative to current cobalt supply. There exist impediments to its introduction, notably potential environmental impacts, which remain poorly understood. Technical and political restrictions must also be overcome. It is argued that the wider environmental benefits of increased cobalt supply from PMN mining may offset its detrimental environmental impacts. It is suggested that PMN mining be used in a wider strategy to improve supply security of cobalt to US markets. Cobalt demand is increasing due to its requirement in lithium-ion batteries, which will significantly contribute to the energy transition. Supply is threatened for various reasons, primarily regarding supply chain concentrations, with the majority of the world’s cobalt originating in terrestrial deposits in the Democratic Republic of the Congo, and being refined in China. There remain environmental and ethical concerns over the present supply chain. Previous discussions around reducing cobalt’s criticality have suggested diversifying processing locations to reduce geographical and jurisdictional reliance where possible. 2017 ). It is presently only extracted from terrestrial mining activities, with 131 cobalt-producing mines identified in 20 different countries as of 2020 (Brown et al. 2018 ; van den Brink et al. 2020 ). The vast majority of the global cobalt supply currently originates in the Democratic Republic of the Congo (DRC), which is Optimistic projections of global cobalt supply forecast a minimum annual deficit of 24,000 kt by 2030, potentially rising to as high as 342 kt in more pessimistic scenarios (Alves Dias et al. 2018 ). The electrification of currently fossil fuel-based energy sources is a major emerging trend worldwide (Mai et al. 2018 ). Resultantly, the storage requirement of lithium-ion batteries, of which cobalt is a key component, is causing increases in global demand for cobalt (Azevedo et al. 2018 ). The prospecting and exploration costs associated with PMNs derive from performing the detailed bathymetric surveys to determine suitability of the seafloor topography for mining, as well as nodule coverage. Sampling must then take place to determine metal grades and abundance, which allows for the market value of the deposit to be calculated (Cardno 2016 ). This calculation can include a wide margin of error, especially where a project relies on multiple metals for revenue, and even more so if prices of said metals are highly volatile, or there exists the prospect of wide-scale end-use substitution, i.e. cobalt, in the case of cobalt-free batteries. Prospecting and exploration aspects of DSM are currently governed by the Regulations for Prospecting and Exploration for Polymetallic Nodules in the Area (International Seabed Authority 2013 ), under which 18 contractors have been granted licences for PMN exploration so far (International Seabed Authority 2021 ). Despite this, though the ISA’s Draft Regulations on Exploitation of Mineral Resources in the Area (ISA 2018 ) have been developed by their Legal and Technical Commission, they are yet to be finalised and introduced (Shabahat 2021 ). This leaves the decision between allowing marine environments to suffer the effects of climate change globally, or sacrificing the stability of some local marine environments through DSM for the health of marine ecosystems worldwide, as well as the wider climate. In a broader context, a greater supply of cobalt to the world economy would theoretically reduce its price on global markets, or at the very least, stabilise it in the longer term. This would, in turn, provide more solid foundations for the energy transition, as well as reducing the unit cost of lithium-ion batteries (Alves Dias et al. Of course, the realities are much more complex, even when all factors other than the economic aspects are discarded. The backbone of the economic argument for cobalt recovery from PMNs is rooted in the economic concept of criticality, denoting demand inelasticity (vulnerability/importance to an economy) and capability of the market to ensure supply (supply risk). Despite attempts to decrease reliance on cobalt for battery technology, cobalt-bearing batteries are expected to continue to dominate the EV battery market (Ryu et al. 2021 ), maintaining demand inelasticity. When assessed as a method of alleviating supply-side issues for cobalt in terms of feasibility, it appears to stand up to scrutiny, though is far from a panacea. With the growing reliance on lithium-ion batteries, of which cobalt is and will likely remain a key component, for use in the energy transition, the question of cobalt’s correspondingly increasing criticality is becoming difficult to ignore. The Area as a jurisdiction and accompanying regulatory framework offer some respite to the tumultuous situation surrounding terrestrial cobalt mining.