DeepGreen lifecycle analysis argues for sourcing EV battery materials from deep-sea polymetallic nodules
Canada-based DeepGreen Metals Inc., a company focused on sourcing metals with the least environmental and societal impact, has released the results of a year-long study it commissioned into the impacts of sourcing metals to produce battery cathodes and wiring for electric vehicles (EVs).
Demand for certain EV battery metals is projected to increase by 11 times the current level by 2050, according to the World Bank, and shortages in nickel, cobalt and copper have been predicted to emerge as soon as 2025.
An electric vehicle with a 75KWh battery and NMC 811 (nickel-manganese-cobalt) chemistry needs 56 kg of nickel, 7 kg of manganese, 7 kg of cobalt and 85 kg of copper for electric wiring. Taking that as a baseline, if 1 billion cars are replaced with EVs (the current global light-duty vehicle parc is soe 1.3 billion units), there would be a need for 85 million tonnes of copper (21Mt mined in 2019), 56 million tonnes of Ni (2.3Mt mined in 2019, only 50% suitable for batteries), 7 million tonnes of manganese (18Mt mined in 2019) and 7 million tonnes of cobalt (140Kt mined in 2019).
Using a lifecycle sustainability analysis (LCSA) framework and standard lifecycle analysis (LCA) methodology, the researchers compared two potential sources of minerals needed to manufacture electric vehicle batteries: ores mined from the land and polymetallic nodules collected from the deep seafloor of the Pacific Ocean.
At a high level, the findings suggest that, compared to mining the land for battery metals, sourcing the needed metals from ocean nodules can deliver:
- 70% less CO2e direct emissions
- 94% less stored carbon at risk
- 90% reduction in SOx and NOx emissions
- 100% reduction in solid waste
- 94% less land use
- 93% less wildlife at risk
The oceans are filled with metals, presenting as seafloor massive sulfides (SMS), cobalt crusts, polymetallic nodules and seabed sediments. They have never been mined on a commercial scale, and plans to develop these ocean resources have been met with opposition from ocean-conservation NGOs concerned about disruptions to seabed ecosystems and inhabitants. For the purposes of this report, we chose to focus on polymetallic nodules for several reasons: (1) nodules sit unattached on the ocean floor in the area of the South Pacific international waters known as the Clarion-Clipperton Zone (CCZ), which means they can be collected without the need for destructive rock cutting required for mining SMS and cobalt crusts; (2) nodules are high grade and do not contain toxic levels of heavy elements, and the metal contents of the nodules is uniquely aligned with the base metal needs of EV battery manufacturers; (3) the CCZ nodule resource alone contains enough metals to electrify the global EV fleet several times over.—“Where Should Metals For The Green Transition Come From”
Polymetallic nodules are hard, compact lumps of matter formed through precipitation and interactions of water contained in seafloor sediments (pore waters) and more oxidized seawaters. The process occurs over millions of years and is consistent over wide areas, with very large, high-grade deposits having been defined. Because of the consistency of the process, polymetallic nodules have remarkably consistent abundance and metal contents over large areas.
Because nodules sit unattached in the top layer of sediment on the seafloor, their removal does not require blasting, drilling, or excavating—they simply need to be collected from the seafloor.
The CCZ is one of the four deep-ocean seabed areas known to contain large quantities of nodules. The CCZ is an abyssal plain spanning 4.56 million square kilometers in the Pacific Ocean roughly 500 miles south of Hawaii. Polymetallic nodules found in the CCZ contain the four base metals critical for EV battery production in a single ore body.
To collect nodules, an offshore collection system with surface production vessels, a vertical lift system, and seabed collection machines. Compared to land mining, which requires construction of roads for transporting equipment, rock, and ore, as well as trenches, pits, and tunnels for mining, nodule collection requires no fixed infrastructure.
Nodule collection system including production vessel and riser
However, the authors note, nodule collection disturbs a large area of the deep seafloor ecosystem through three main mechanisms:
Removal of hard nodule surfaces. Nodules’ surfaces serve as attachment points for certain organisms and are used for laying eggs and other critical life functions. Their removal kills the attached organisms and reduces the surface area available for future attachments.
Suspension of sediment (plumes) at the seabed by nodule-collection machines. Plumes can settle over an area of several square kilometers and, depending on the thickness of the blanketing layer, risk smothering and killing marine life in those areas.
Reinjection of deep seawater used for vertical transport in the mid-water column. When deep seawater used in vertical lift transport is reinjected in the mid-water column, it can potentially disrupt the water column with turbidity and an altered temperature.
From: “Where Should Metals For The Green Transition Come From”
Ocean nodules are a unique resource to consider at a time when society urgently needs a good solution for supplying new virgin metals for the green transition. Extraction of virgin metals—from any source—is by definition not sustainable and generates environmental damage. It’s our responsibility to understand the benefits—as well as the damages associated with sourcing base metals from nodules.—Gerard Barron, DeepGreen Chairman and CEO
The study provides an in-depth comparison of the cradle-to-gate impacts of producing metals from land ores and polymetallic nodules, both sources of the nickel, cobalt, copper and manganese required to build one billion EV batteries. The researchers examine the relative impacts of the extraction, processing and refining of these key base metals on several impact categories, including: greenhouse gas emissions and carbon sequestration, ecosystem services, non-living resources and habitats, biodiversity, human health and economics.
In our opinion, the paper provides a comprehensive consideration of the environmental, social and economic impacts associated with land and deep-sea mining of metals used in electric vehicles.—Todd Cort, co-director of the Yale Center for Business and the Environment and Cary Krosinsky, lecturer in sustainable finance at the Yale School of Management
Polymetallic nodules are made of almost 100% usable minerals and contain no toxic levels of deleterious elements, compared to ores mined from the land which have increasingly low yields (often below 1%) and often do contain toxic levels of deleterious elements. This means that producing metals from nodules has the potential to generate almost zero solid waste and no toxic tailings, as opposed to terrestrial mining processes which produce billions of tonnes of waste and can leak deadly toxins into soil and water resources.
While the deep seabed is a food-poor environment with limited biomass, uncertainties remain over the nature as well as temporal and spatial scales of impacts from nodule collection on deep-sea wildlife. The study provides the broader context for a deeper, multi-year environmental and social impact assessment (ESIA) being conducted by DeepGreen, in what the company says will be the largest integrated seabed-to-surface deep-ocean science program ever conducted, with more than 100 separate studies being undertaken.
DeepGreen has partnered with three pacific island states for deep-sea environmental studies, mineral exploration and project development. Through these relationships with the Republic of Nauru, the Republic of Kiribati and the Kingdom of Tonga, DeepGreen has exclusive rights under the International Seabed Authority to explore for polymetallic nodules in regions of the Clarion Clipperton Zone of the Pacific Ocean.
In October DeepGreen derived its first metal from polymetallic nodules in a processing lab, and in March, the company’s partner Allseas acquired a former drill ship to convert to a polymetallic nodule collecting vessel. Earlier this month the company announced the acquisition of Tonga Offshore Mining Limited (TOML), giving DeepGreen access to a third seabed contract area in which to explore for battery metals with significantly lower environmental and social impact.