Electric vehicle battery production is one of the most contentious subjects when it comes to their environmental friendliness. A new study, commissioned by underwater mining company DeepGreen, suggests that extracting the materials from the deep ocean could reduce their carbon footprint by 90 per cent compared to land-based mining.

The research, which has been peer-reviewed and published in the Journal of Cleaner Production, suggests that the hundreds of millions of tonnes of polymetallic rock (rocks containing the metals needed for EV batteries) required to produce batteries for EVs is far cleaner to get from the bottom of the deep ocean than from traditional land-based mines.

Researchers looked at a potential future scenario – demand for one billion 75kWh batteries with a cathode chemistry of 80 per cent nickel, 10 per cent manganese and 10 per cent cobalt, as well as the copper required for such a unit. It then compared the environmental impact of mining the four metals from traditional sources on land, and polymetallic rocks with high concentrations of the metals which are found on the ocean floor at between 4km and 6km.

It found that using the nodules, plucked from the sea floor, can reduce overall carbon dioxide emissions by around 80 per cent. This figure includes a variety of sources associated with mining that produce carbon dioxide.

The study’s lead author Daina Paulikas of the University of Delaware’s Center for Minerals, Materials and Society, said: “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. 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% advantage.”

Paulikas notes that the extraction process, despite the obvious complexities of picking up rocks from 6000 metres below the surface of the Pacific, is actually relatively low energy. The area of ocean, called the Clarion Clipperton Zone, between the USA and Hawaii in the Pacific, is rich in the required polymetallic nodules required.

According to the study, the benefits aren't just in plain CO2 savings from extraction and processing; mining the sea floor removes the need to cut down forest and other terrestrial habitats which are important carbon sinks. Furthermore, whilst there is obviously disruption to the sediments on the seabed – which do store carbon dioxide, albeit 15 times less than an equivalent area of land – there is no known mechanism for this CO2 to rise to the ocean surface and reach the atmosphere.

DeepGreen Metals' ultimate hope would be to power the mining using green power, and process it on land doing likewise. It also foresees a future of using blockchain to track its metals through their useful lifespan, and then through to recycling to be used again (almost 100 per cent of an EV battery is recyclable).

Gerard Barron, Chairman and CEO of DeepGreen Metals, said: “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.”

Impact and expense

Unfortunately, whilst the study looks at the impact on the atmosphere of mining the metals required for EV battery production, it covers neither the monetary cost, nor the impact on fragile underwater habitats. At present, it is well known that in all manner of industries extracting minerals from the ocean floor would yield far more than land-based mining using proportionally far less space. But how this disturbs habitats is far less known.

Robust studies would need to be undertaken to ensure that any undersea mining is only allowed on the basis that it doesn't detrimentally impact rare and important habitats.

Expense is also unknown. At present EVs cost around 45 per cent more to build than a regular ICE car, according to a study by management consulting firm, Oliver Wyman. It found that a regular C-segment car (i.e. a VW Golf) costs around 14,000 euros to build. However, whilst an EV is cheaper to assemble, the motors and battery pack bring the cost of an equivalent car to 20,000 euros. Electric drive components add 2000 euros to the cost, and at around 8000 euros, battery packs make up by far the biggest additional expense.

According to Oliver Wyman, the continuing development of EVs will see the build cost come down to just 9 per cent more by 2030. The availability of the metals needed for batteries and motors will be a huge factor in this, which is why DeepGreen's potential solution could be a golden bullet.