By Maria Pleskach 

Although the deep sea remains primarily unexplored, deep-sea mining for critical minerals is an industry in the making. It targets critical minerals such as nickel, copper, cobalt and manganese, essential for various industrial applications and modern consumer electronics. These are found in three types of marine deposits in extreme deep-sea environments: polymetallic nodules spread along the abyssal plains, polymetallic sulphides formed around hydrothermal vents, and cobalt-rich ferromanganese crusts covering seamounts.

With exploration efforts ongoing since the 1960s, commercial-scale mining has yet to commence, despite increasing interest. As several mining enterprises race to obtain production licenses, an open debate between governments, environmental organizations and other mining stakeholders questions whether deep-sea mining should even go ahead at all. Amidst a regulatory limbo, deep-sea mining faces strong environmental concerns due to the potential ecological impacts on the affected ecosystems (Sea Technology, October 2024).

All existing and proposed regulations for deep-sea mining emphasize the requirements for comprehensive monitoring of the marine environment during any exploration and future extraction activities.

In an effort to step up marine research, Germany’s state-funded DeepSea Protection project targets the gaps in existing stationary monitoring technologies with the development of a mobile robotic deep-sea multi-sensor network for data collection and real-time assessment.

Legal Status of Deep-Sea Mining

The International Seabed Authority (ISA) is an autonomous organization established in 1982 under the United Nations Convention on the Law of the Sea (UNCLOS) and its subsequent 1994 Agreement on Implementation. ISA is responsible for managing the seabed, ocean floor and subsoil beyond the exclusive economic zones (EEZs) of sovereign nations: commonly referred to as the “Area.”

As of the writing of this article, the ISA is an intergovernmental body of 169 member states and the European Union, with the U.S. being a notable absence since the country never ratified the Law of the Sea.

The ISA’s dual mandate is to administer seabed mineral-related operations and ensure the effective protection of the Area’s marine environment. The ISA first prioritized developing comprehensive rules, regulations, and procedures for prospecting and exploration of mineral resources in the seabed Area. The ISA adopted exploration regulations for polymetallic nodules in 2000 (revised in 2013), polymetallic sulphides in 2010, and cobalt-rich ferromanganese crusts in 2012. These include guidelines to assess the environmental impacts of marine mineral exploration, including requirements for environmental impact assessments, baseline studies, monitoring and reporting.

So far, the ISA has issued 31 15-year exploration contracts in the deep seabed with 22 contractors. Despite years of exploration efforts for deep-sea minerals, commercial-scale seabed mining still lacks official regulation.

Since 2014, ISA has been working on rules for the exploitation phase in the Area, including standards and guidelines. The ISA Assembly meeting in July 2024 yielded no final decision on deep-sea mining, with more than 30 member states calling for a moratorium, so the debate continues.

Within the EEZs, deep-sea mining is governed by the corresponding nation’s state legislation. Several countries have enacted or proposed laws to allow these activities.

In 2022, the Cook Islands issued permits for exploration within its EEZ, which has significant and relatively well-studied cobalt deposits but has yet to permit extraction.

In January 2024, the Norwegian parliament approved exploratory deep-sea mining in a large part of the EEZ area between Jan Mayen Island and the Svalbard archipelago, opening a pathway for mining companies to apply for exploitation permits. The Norwegian parliament intends to grant these on a case-by-case basis. This decision opens a significant area of Norwegian waters to exploratory mining, pending further environmental research before commercial licenses are issued.

In June 2024, after a detailed survey earlier this spring, Japan’s Nippon Foundation and the University of Tokyo announced the discovery of over 200 million metric tons of manganese nodules on the seabed near Minamitorishima, an isolated Japanese coral atoll in the northwestern Pacific. Plans are made for a trial collection of the manganese nodules from the site as early as 2025, with a view toward commercialization.

It is crucial to note a growing number of nations opposing deep-sea mining activities. For example, France has enforced a ban, while Canada, New Zealand, Switzerland, Mexico, Peru and the United Kingdom have implemented moratoriums. An alliance of Palau, Fiji, Samoa and the Federated States of Micronesia advocates for a complete moratorium due to environmental concerns. Many other nations, including Germany, Spain, Brazil, Costa Rica and Chile, have chosen a precautionary pause approach, stressing the necessity for additional research and caution before permitting deep-sea mining activities. This growing consensus reflects apprehensions over environmental impacts and insufficient scientific understanding to ensure the safe exploitation of deep-sea resources.

For both opponents and supporters of deep-sea mining, environmental impact is a major consideration for any decision making on seabed activities.

Current Mining and Monitoring Equipment

In modern mining techniques, manganese nodules are collected by crawlers that scrape them from the seabed. These nodules are then transported to a production support vessel through a pump system connected to a pipe string, the so-called riser. On board the vessel, the nodules are separated from water and sediments and then transferred to transport ships for processing onshore. The mining of massive sulphides employs a similar system but requires crawlers not only to pick up material but also to break up seabed rock. This calls for grinding machines like those used in tunnel construction.

Recent years have seen significant advancements in the crawler-and-riser method. Modern trials of such equipment tend to have a scale of offshore drilling operations, so there is overlap between deep-sea mining and offshore oil and gas industry practices. Big offshore players such as Allseas and Transocean have entered the deep-sea mining sector, and the latest production support vessels, e.g., the Allseas Hidden Gem and Transocean’s Olympia, are converted from offshore drillships.

A recent example of exploratory crawler-and-riser nodule mining is the 2021 technical trials of the Patania II pre-prototype nodule collector vehicle in the GSR (Belgian-sponsored) and BGR (German-sponsored) contract areas of the Clarion-Clipperton Zone (CCZ) by Global Sea Mineral Resources (GSR), a subsidiary of DEME. Patania II was successfully operated at commercial driving speeds and nodule pickup rates.

In 2022, NORI, a subsidiary of The Metals Company (TMC), and Allseas concluded a large-scale, two-month deepwater pilot collection in the NORI-D area of the CCZ. Engineers drove the pilot collector vehicle over 80 km across the seafloor, collecting approximately 4,500 tonnes of seafloor polymetallic nodules and lifting over 3,000 tonnes of nodules up a 4.3-km riser system to the surface production vessel, the Hidden Gem.

It’s worth noting that autonomous harvester vehicle technology for hovering over the seafloor as opposed to tethered crawlers is also being developed, with U.S.-based Impossible Metals announcing a successful test of its Eureka II harvester AUV at a 1-mi. depth in May 2024, with plans for testing a production-scale Eureka III in 2025.

The much-needed monitoring of the environmental impact during deep-sea mining operations involves using advanced technologies to assess and mitigate potential damage to the marine ecosystem. Technological challenges are immense, given the extreme conditions of the deep ocean, including high pressure, low temperatures and total darkness.

For its 2021 trials, GSR collaborated with independent scientists aboard the chartered vessel Normand Energy to monitor the test mining. These trials were also independently monitored from the MV Island Pride by scientists from 29 European research institutes of the JPI-O MiningImpact consortium, invited by Germany’s Federal Institute for Geosciences and Natural Resources (BGR). The expedition members performed a series of experiments to advance the current understanding of both the extent of suspended sediment plumes and the ecological responses to nodule collection. An extensive array of environmental monitoring equipment was deployed, ranging from commercially available instrumentation to custom prototype sensors designed for these nodule collection trials. In total, around 200 individual monitoring instruments were hosted on 43 separate platforms, the majority of them being landers and moorings.

During its 2022 nodule collection trials, NORI worked with DHI Water & Environment, experts on sedimentation modeling, to implement a plume monitoring study. Over 50 assets and marine sensors were deployed to the test field to collect data on all aspects of plume dynamics, concentration, and dispersal. In 2023, NORI conducted additional research at the NORI-D trial site and reported gathering further environmental data. Scientists used an ROV, several seafloor sampling devices, and lander systems to assess impacts to biota, seafloor geochemistry, and ecosystem recovery on the seafloor.

Landers and moorings are the classic scientific tools for deep seafloor data collection, operating autonomously and hosting various sensors to measure environmental parameters over extended periods. Landers provide comprehensive data on physical, chemical and biological aspects of the seafloor, while moorings offer vertical profiles of the water column and continuous monitoring at fixed locations. Both are designed for long-term data collection, enabling the study of temporal changes and the impacts of human activities.

Modern trends in the blue economy include the increasing use of mobile robotic equipment for autonomous underwater exploration, enabling efficient mapping and monitoring of marine environments. Uncrewed underwater vehicles with advanced sensors and AI capabilities allow for real-time data collection and analysis. In addition, the deployment of mobile robotic systems enhances maritime safety and reduces operational costs by minimizing the need for human intervention. The dimensions of newly developed solutions are moving toward the extremes, with systems becoming either very large or increasingly smaller and smarter.

Deep-sea AUVs and ROVs have been adopted for mapping, surveying and monitoring seabed mining sites, while seabed landers and moorings are still a mostly stationary technology often lacking real-time data retrieval, and they require resurfacing to download the collected data and reposition the instruments.

 

The DeepSea Protection System

One of the ongoing research and development efforts for environmental monitoring during deep-sea mining activities is DeepSea Protection, a German consortium working on a mobile sensor system with flexible profiling and repositioning capabilities.

Funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK), the DeepSea Protection project runs until 2025, and the consortium comprises nine academic and industry partners: EvoLogics GmbH, Technical University of Berlin (TU Berlin) – Department of Design and Operation of Maritime Systems, Sea & Sun Technology GmbH, Sensorik-Bayern GmbH, PlascoTec GmbH, Plasma Parylene Systems GmbH, the Fraunhofer Institute for Reliability and Microintegration (IZM), the Fraunhofer Institute for Computer Graphics Research (IGD), and Aalen University – Laboratory for electric drives and power electronics.

The EEZ and ISA-licensed mining areas offer potential extraction opportunities for several decades. This implies that once a sub-area is harvested, the collectors move over to the next field, and the environmental monitoring system must follow along. The DeepSea Protection system will be fully mobile, following the collectors with relocatable ground stations and a swarm of autonomous UUVs—without the need to resurface.

The research objectives of the project include the development of the entire hardware and software of the system, rated for 4,000 to 6,000 m, including its communication, navigation and coordination, as well as data processing and visualization. To ensure the robustness required for deep-sea deployment, project partners are working on pressure-neutral motors for seafloor stations and underwater vehicles; custom application-specific sensors; miniaturized embedded power, control and evaluation electronics; and surface coatings for long-term protection against seawater.

Project partners aim to construct a demonstration setup comprising four seafloor stations and three UUVs, and to test and optimize their coordinated operation during a subsequent trial phase.

Repositionable Seafloor Stations

Commonly used lander and mooring systems are stationary and do not have a propulsion system. The few relocatable seafloor landers developed over recent years are not suitable for applications in deep-sea mining. They either lack functionality and depth rating, or have a size and weight calling for significant deployment, control and recovery efforts. Monitoring systems such as gliders and Argo floats do have a buoyancy system that enables moving up and down the water column, but these are not fit for precise positioning and repositioning due to their gliding/drifting design.

The novelty of the DeepSea Protection system is a network of repositionable seafloor and mobile benthic units, acting in a coordinated formation.

The seafloor units of the DeepSea Protection network are conceived as compact multifunctional stations positioned around the exploration/extraction area to be monitored. These units, dubbed the deep-sea “Kalmars” (German for “squids”), aim to combine the capabilities of landers, moorings, and acoustic network and positioning nodes for the mobile units of the monitoring system.

The Kalmars are developed at TU Berlin, with EvoLogics and Sea & Sun Technologies supporting the conceptual and component development, system integration, and open-water trials.

When anchored on the seafloor, the battery-powered Kalmar units with built-in EvoLogics acoustic modems serve as stationary nodes of the telemetry and positioning network, as well as sensor platforms for monitoring environmental parameters. Placed around the perimeter of the operations area, the Kalmars exchange acoustic signals to determine their positions relative to each other, thus establishing a local coordinate frame. Sent to the surface support vessel with a USBL transceiver and GNSS antenna, these positions are georeferenced and transferred back to the seafloor units, so the network can perform georeferenced LBL positioning of the mobile assets within the perimeter.

To sample environmental data, the engineers integrate a compact winch to periodically collect vertical profiles with a multiparameter probe, unwinding and rewinding it like a yo-yo.

The Kalmars are designed with a propulsion system and buoyancy control to move both vertically and horizontally within the water column, enabling autonomous deployment, repositioning, and resurfacing.

Mobile Units: Deep-Sea Poggy AUV

The mobile nodes of the DeepSea Protection system are the deepwater-rated evolution of the EvoLogics Poggy AUV, a biomimetic AUV initially developed as part of the Bonus Seamount project (2017 to 2020), aimed at studying submarine groundwater discharges in the Baltic.

Poggy’s distinctive design features dual propulsion thrusters and two flexible “tails.” Originating from EvoLogics’ Manta Ray AUV, Poggy’s “wingless” design is simplified and optimized to enhance maneuverability and reduce drag. The two mechatronic tails enable unique maneuvers and act like adjustable hydroplanes for precise control over roll and depth. With a payload capacity for multiple instruments, Poggy can demonstrate dynamic climbs and dives and glide very steadily at lower speeds to collect sensor data.

The tails are straight and symmetrical when propelling forward, and adjusting their geometry alters the drag profile and enables very accurate control of pitching and rolling. Poggy’s design also uses less energy than other methods because of less water disturbance. It is immune to the problem of clogging that can affect subsea thrusters near the seabed, which is important for surveys related to deep-sea mining where a steady, slow glide along the seafloor is required.

To adapt the Poggy design from coastal to deep-sea applications, EvoLogics collaborates with IZM on developing integrated pressure-neutral components and connectors to eliminate pressurized housings inside the vehicle’s hull. The vehicle is sized up from 1.3 m to approximately 2 m to increase the instrument payload.

For the next-generation depth-rated Poggy platform, EvoLogics is integrating a multiparameter probe, a CTD, side scan sonar, an underwater camera and a novel turbidity sensor developed by Sea & Sun Technology within the project framework. Poggy AUV’s measurement systems will supplement the Kalmars’ vertical profilers to form a 4D sensor network for collecting environmental data around the deep-sea sites.

Conclusion

Deep-sea mining for critical minerals is a disputed activity with strong opposition from environmental organizations worldwide. While an international “mining code” does not currently exist, several companies are trialing production-scale equipment. How and when to move forward must be supported by strong data on the environmental impacts of deep-sea mining.

Advancing existing technologies for comprehensive environmental monitoring is crucial to establish strict environmental regulations to minimize potential ecological disruption. Effective monitoring systems, such as DeepSea Protection, are key to balance resource extraction with conservation.

Maria Pleskach manages technical writing and communications for EvoLogics GmbH.