With the rush to build batteries for the incoming flood of electric cars, increasing attention is being paid to the resources used in those batteries, and from where they come. A team of Canadian scientists says that, instead of digging mines on land, we should instead be sourcing battery materials from the bottom of the sea...
Useful metals on the ocean floor
In a study published by the Journal of Cleaner Production, it's suggested that digging ever more mines on land, which can often disrupt animal habitats and actually release more carbon emissions because trees and forests need to be cleared, we can find all the battery components we need on the ocean floor. The paper, titled 'Life Cycle Climate Change Impacts of Producing Battery Metals from Land Ores versus Deep-Sea Polymetallic Nodules' says that the key components of battery production - nickel, manganese, cobalt, and copper - can helpfully and plentifully be found sitting on the ocean floor, just waiting to be picked up. The scientists behind the paper compared the manufacture of one-billion electric car batteries, with a capacity of 75kWh each, using either conventional mining or hoovering up sea-floor rocks, and found that there is a huge potential for carbon savings in the sea-bed technique.
"We wanted to assess how metal production using either land ores or polymetallic nodules can contribute to climate change. Looking from mining to processing and refining, we quantified three indicators for each ore type: direct and indirect carbon-dioxide-equivalent emissions, disturbance of existing sequestered-carbon stores, and disruption of future carbon-sequestration services. These three indicators directly impact the remaining global carbon budget to stay below 1.5C warming," said the study's lead author Daina Paulikas of the University of Delaware's Center for Minerals, Materials and Society.
Potential for massive carbon reductions
The study found that producing battery metals from nodules can reduce active human emissions of CO2 by 70-75 per cent, stored carbon at risk by 94 per cent and disruption of carbon sequestration services by 88 per cent. "Terrestrial miners are handicapped by challenges like falling ore grades, as lower concentrations of metal lead to greater requirements of energy, materials, and land area to produce the same amount of metal. Furthermore, the actual collection of nodules entails a relatively low energy, land, and waste footprint compared to a conventional mine. When it comes to emissions, even when we assume a complete phase-out of coal use from background electric grids for process inputs, our model shows that metal production from high-grade polymetallic nodules can still produce a 70 per cent advantage," said Paulikas.
"What happens to carbon sinks on land and on the seafloor used for metal production is another big part of the climate impact story," said Dr Steven Katona, marine biologist and co-founder of the Ocean Health Index who contributed to the study. "On land, carbon is stored in vegetation, soil and detritus. On the seafloor, carbon is stored in sediments and seawater. Producing metals for one billion EVs from land ores would disrupt 156,000 km2 of land and 2,100 km2 of seabed for deep-sea tailings disposal. Producing the same amount from nodules would disrupt 508,000 km2 of the seafloor during nodule collection and 9,800 km2 of land during metallurgical processing. Despite disturbing a larger area of the seafloor, metal production from nodules would cause much less carbon disruption. This is because seafloor sediments store 15 times less carbon per km2 than an average terrestrial biome and there is no known mechanism for disturbed seafloor sediment to rise to the surface and impact atmospheric carbon. In contrast, mining on land requires removal of forests, other vegetation and topsoil to access the ore, store waste and build infrastructure. In the process, we lose stored carbon and disrupt carbon sequestration services for as long as land remains in use, which can be as long as 30-100 years."
Huge increase in demand for minerals
In fact, according to the paper, this sea-floor mining could save as much as 11 gigatonnes of CO2 emissions compared to conventional mining and battery production. That's a colossal saving, 11 billion tonnes of CO2 that our atmosphere would not have to cope with. If the paper's findings are borne out, it could be a way of putting new electric cars into carbon credit, even before they're driven.
"We hope this work motivates others to dive deeper into supply chain analysis for the clean energy transition, and specifically to pay attention to the impacts of producing critical minerals like the ones we studied," said Paulikas. "Given the expected 500 per cent increase in mineral requirements for clean technologies, I think we have a shared responsibility to take a planetary view and think through all aspects of mineral production to ensure that this resource-intensive transition does not exacerbate climate change."
"This peer-reviewed study shows the intrinsic benefits of seafloor rocks when it comes to climate change impacts. The resource itself gives us a significant head start on land miners, but being low carbon is not enough. We are working on taking carbon out of the atmosphere, not adding it," said Gerard Barron, Chairman and CEO of DeepGreen Metals. "We'll use hydropower onshore; we are exploring electrofuels to power offshore operations and using electric equipment and carbon-negative reductants in metallurgical processing. Put it all together, and we have a shot at bringing carbon-negative metals to the market. We'll use hydropower onshore; we are exploring electrofuels to power offshore operations and using electric equipment and carbon-negative reductants in metallurgical processing. Put it all together, and we have a shot at bringing carbon-negative metals to the market."
While the idea of finding the minerals we need on the seafloor is a tempting one, there are those who are aghast at the prospect of it, saying that such schemes put deep-sea habitats at severe risk. The International Union for Conservation of Nature (IUCN) which says it 'harnesses the experience, resources and reach of its more than 1,400 member organisations and the input of more than 17,000 experts" says that deep-sea mining is very troublesome.
"A better understanding of the deep sea is necessary to guide mitigation strategies and proper enforcement of regulations in order to limit the environmental impacts of mining activities," said the IUCN. "Current technologies may not be sufficient to avoid serious and lasting harm to the environment, including the loss of biodiversity. Mining operations strategies will need to prioritise the avoidance of environmental impacts. The scraping of the ocean floor by machines can alter or destroy deep-sea habitats, leading to the loss of species and fragmentation or loss of ecosystem structure and function. Many species living in the deep sea are endemic - meaning they do not occur anywhere else on the planet - and physical disturbances in just one mining site can possibly wipe out an entire species. This is one of the biggest potential impacts from deep-sea mining."