Mining companies and marine scientists want to know whether harvesting blobs of useful materials from the seafloor harms ocean life.

The push to build more electric vehicles to combat climate change rests on an inconvenient truth: The metals used in EV batteries are pretty dirty. From exploited child laborers digging cobalt in the Democratic Republic of Congo to toxic waste leaking from nickel mines in Indonesia, the sources of key ingredients to power climate-friendly transportation have been assailed by activists and led to lawsuits against the tech firms that use the metals.

US and European carmakers have been looking for alternative sources of these materials that would allow them to bypass some of these troublesome practices, while avoiding having to buy batteries produced by global competitor China. They also want a piece of President Joe Biden’s new plan to spend $174 billion to promote electric cars and build new charging stations.

Could materials mined from the deep sea be the answer? That’s what commercial mining firms and scientists are trying to determine this month during two separate expeditions to a remote part of the Pacific Ocean known as the Clarion-Clipperton Zone (CCZ). A potential treasure chest of metals waiting to be plucked is at stake: This region of water is the size of the continental US, and its floor is littered with potato-sized metallic nodules, each containing high concentrations of cobalt, nickel, copper, and manganese, which are used in EV batteries. (Lithium, another key component, is primarily mined from Australia.) These materials would all be harvested as minerals, then refined into metals that could be used in batteries, usually by adding an oxide. Of course, the trick is getting the nodules off the bottom, which is 12,000 to 18,000 feet deep, without killing the creatures that live there or the fish that swim above.

For the next few weeks, the two expeditions will be traversing the CCZ to test undersea mining technologies and how much damage they cause. A 295-foot supply ship called the Maersk Launcher is hosting Canada-based mining firm DeepGreen and a crew of independent scientists. Another expedition is operating in a separate section of the zone to test a bottom-crawling mechanical harvester called the Patania II operated by Global Sea Mineral Resource (GSR), a subsidiary of the Belgian dredging firm DEME Group. The harvester is designed to scoop up the precious minerals and is controlled from the surface vessel through a 3-mile-long tether that provides power and communication capabilities to it. The trial will test how well a smaller version of the robo-harvester can maneuver along the seafloor and pick up nodules. If successful, GSR will build a full-scale collector with a riser and lift system to bring the materials to the surface.

A view of the Normand Energy retrieving the Patania II nodule collector visible  seen from the Rainbow Warrior. The...
A view of the Normand Energy retrieving the Patania II nodule collector visible (green), seen from the Rainbow Warrior. The vessel is chartered by Global Sea Mineral Resources (GSR), a Belgian company researching deep sea mining in the Pacific. Photograph: Marten van Dijl/Greenpeace

Both expeditions will collect baseline environmental data on the kinds of marine organisms that live on the seafloor, the composition and chemistry of bottom sediments, and the flow of underwater currents at different depths. Knowing these control measurements will be important in determining whether such mining can be done without destroying the underwater habitat.

“Our goal is to find out how much sediment the harvester will take off along with the nodules,” says Matthias Haeckel, a marine biochemist at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, who is coordinating the environmental review of GSR’s activities for a project called MiningImpact. “That has never been done before.”

Plumes of sediment can harm bottom-dwelling creatures like sponges and corals that form the base of the food chain in the deep-sea ecosystem. If the grit remains suspended in the water, it can also affect fish and other marine life. Haeckel and his team have about 50 different types of sensors to measure the sediment in both the water and on the seafloor surface. This will provide the first quantitative scientific evidence on the environmental consequences of nodule extraction under real-world mining scenarios, according to Haeckel.

“We know that the sediment plume doesn’t rise very high, just 5 or 10 meters,” he says. “Now it’s basically to understand how far the particles settle. We want to measure how thick of a layer it is and how it thins out over distance, so we can determine its impact.”

DeepGreen and GSR have received exploration licenses from the International Seabed Authority, a UN-affiliated agency that controls access to the area’s mineral riches. Neither will be permitted to start actual mining until the authority adopts new environmental rules and issues extraction licenses. The agency has granted 30 exploration contracts involving 22 different countries and affiliated mining companies for deep-sea minerals.

Gerard Barron, the founder and CEO of DeepGreen, says he’s committed to operating in an environmentally responsible manner. Barron says ocean minerals are a better option than sourcing from China or from mines in politically troubled regions. “Everyone realizes that moving to electric vehicles is very metal-intensive, and the question is, where the hell are they going to come from?” says Barron. “We represent an opportunity for America to get some independence.”

Barron says it takes 64 metric tons of rock to produce enough of the four minerals—a total of about 341 pounds—needed to make an EV battery and its wiring from a mine on land. But it takes only 6 tons of the polymetallic seafloor nodules to make the same amount, because the metals are more concentrated.

The nodules formed over millions of years as naturally occuring minerals precipitated from both seawater and sediments and formed around cores that could have been microscopic bits of debris, rock, bone or even pieces of other nodules. They are more common in areas where there are low levels of dissolved oxygen, and under certain geological conditions, such as in the equatorial Pacific, which contains an estimated 21 billion tons of them.

According to a company spokesperson, DeepGreen currently has about $570 million available to fund mining. The firm is considering sites in Texas, Quebec, and Norway for a processing plant to turn the nodules into usable materials for batteries, sites that are close to renewable energy sources as well as markets for the minerals. Barron says the processing of the seafloor nodules would be pretty simple. They are first dried in a rotary kiln, which is a type of electric furnace. “It’s the first step to separate the manganese from the nickel, cobalt, and copper,” he says. “They form a mat-like material for the battery grade material, whether it’s powders or metallic sulfates.”

Of course, that processing is done on land. Operating a floating mining camp several days away from the nearest port has its own engineering uncertainties, such as bad weather that could shut down operations. And it raises several ecological questions. After the precious nodules are sucked from the harvester to the mining ship through a hose, leftover mud and sediments are released underwater. That could pose a risk to marine life, according to environmental groups. In addition, seafloor mining scars do not recover quickly. A 2019 study in the journal Nature found that seafloor tracks off the coast of Peru lasted 30 years, and that there were fewer species of plant and animal life in the disturbed areas. Another study published in 2016 found that one deep-sea octopus likes to lay its eggs on manganese nodules in that same region, a sign that mining could be a threat to those cephalopods.

These studies indicate that not enough is known about the bottom habitat and whether it can recover from large-scale mining with mechanical harvesters, says Douglas McCauley, a professor of ocean science at the University of California, Santa Barbara. “Deep ocean ecosystems are the least resilient ecosystems on the planet,” McCauley says. “It’s a weird place, biologically speaking. The pace of life moves more slowly in the deep ocean than any other place. Species live a long time, and ecosystems take a long time to recover.”

McCauley says the loss of habitat could destroy yet-unknown organisms that might provide new sources of biopharmaceuticals or disease-fighting compounds. “If you grind up the habitat, you are going to lose species—perhaps species we will never know,” he continues.

Last month, carmakers BMW and Volvo pledged not to use EV batteries that use metals sourced from the ocean, citing the potential environmental concerns from deep-sea mining.

DeepGreen’s Barron says the environmental monitoring tests will help guide development of harvesting technologies and will determine whether the effect is local or has a bigger footprint across the seafloor. He says DeepGreen will be testing its own harvesting device in 2022 with an eye to begin mining operations in 2024.

All the data collected on both the DeepGreen and GSR monitoring expeditions will be published and reviewed by independent scientists. The European “MiningImpact” environmental monitoring project is funded by various European universities and academic labs, according to GEOMAR’s Haeckel. Scientists monitoring DeepGreen’s efforts are not paid either, and both research data sets will be shared publicly.

GSR officials say they are devising ways to limit how far the sediment travels and will separate it from the nodules before they reach the surface. Commercial mining has to make both economic and environmental sense, says GSR’s head of sustainability, Samantha Smith. “If the science shows that deep-seabed mining has no advantages over the alternative, which is to rely solely on opening up new mines on land, then there won’t be any deep-sea mining industry, and we won’t submit an application,” she says.

Smith says that if all goes well, GSR won’t begin mining until 2028. It will take that long to do all the environmental tests as well as engineering trials. Technicians at GSR are considering varying the suction on the harvester to limit its effect on the seafloor, just as how turning down the power dial on a household vacuum cleaner changes how hard it sucks up dirt from different surfaces.

For his part, UC Santa Barbara’s McCauley says that if the studies show that the mining can take place without significant habitat destruction, he would support it. “I want good data to answer these questions,” he says. “If it turns out that there is no harm and it’s an innocuous activity, I would have no problem with it.” Still, McCauley cautions that long-term effects of deep-sea mining might not be understood for several decades. “We don’t have those answers, and we won’t get them in the time horizon that the mining companies have for their operations,” he says.

Update 4-14-2021 4:50 pm EST: This story was updated to correct information about how sediments collected by the underwater harvester would be released.


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