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DeepGreen, a private Canadian company based in Vancouver, is among companies looking to the bottom of the sea to mine metals. Its harvest of metal-laden nodules is focused on a 4,000-kilometre swath of the Pacific Ocean that stretches from Hawaii to Mexico.

Deep in the North Pacific Ocean, in an area as wide as the United States, billions of potato-sized rocks litter the ocean floor. These lumpy, black-brown balls are full of cobalt, nickel, copper and manganese – valuable minerals that are crucial for electronics and evolving green technologies, such as electric cars and solar panels.

As the world moves further away from fossil fuels, it needs metals to harness and store renewable energy. A Canadian company, among others around the world, is eyeing the vast, untapped minerals in the high seas as the way to a sustainable future, especially seabed rocks that require no drilling, blasting or digging.

DeepGreen Metals Inc. wouldn’t so much as mine the clumpy deposits, called polymetallic nodules, as scoop them up. The Vancouver-based company and its subsidiary, Nauru Ocean Resources Inc., are focused on the Clarion-Clipperton Zone (CCZ), a mineral-rich, 4,000-kilometre swath of the Pacific that stretches from Hawaii to Mexico. At depths of around 4,000 to 6,000 metres, the nodules lie in a shallow layer of mud on the seafloor.

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“Think of them like a pearl,” said Gregory Stone, DeepGreen’s chief ocean scientist and director. “There is something in the middle of every nodule that starts it off, like a grain of sand or a shark tooth, and then metals in the seawater slowly layer on over millions of years.”

The company plans to collect the fist-sized balls with remote-controlled harvesting vehicles that travel over the seabed and hoover up the nodules, transporting them to the ocean’s surface through kilometres-long riser pipes. Once the nodules are aboard the vessel, they will be transferred to land-based facilities where the company will dissolve the nodules and separate the metals.

“It’s like a battery in a rock,” said Gerard Barron, DeepGreen’s chairman and chief executive officer. “Every single part of the nodule is usable. That’s a really big change for the mining industry.”

The ocean minerals could be a sustainable alternative to metals mined on land, where environmental risks are well known, from erosion and water and soil contamination to deforestation and biodiversity loss, along with human displacement. As resources are depleted, some battery minerals are sourced from lower and lower grades of ore, which magnifies the ecological damage. According to research from Monash University in Melbourne, Australia, the average grade of today’s copper ore is below 0.6 percent: 1,000 tons of ore yield less than six tons of copper. Others are difficult to ethically source. Most of the world’s cobalt comes from mines in the Democratic Republic of the Congo that have been linked with child labour.

Deep-sea mining represents a new frontier. The shift to green energy sources, a growing need for metals in China and India and the rise of electric cars are fuelling growing demand for battery minerals, with 20 million electric cars predicted to be on the road worldwide by next year. While polymetallic nodules have never been commercially mined, they could be a multibillion dollar industry. In 2012, James Hein of the United States Geological Survey and colleagues estimated the CCZ holds more nickel, cobalt and manganese than all known land reserves of those metals combined.

Polymetallic nodule collection is less invasive than other forms of underwater mining, says DeepGreen.

“You need metals to build wind turbines, batteries and electric vehicles,” Dr. Stone said. “You can’t turn solar and wind energy off and on like you can with fossil fuels. We need storage, and we need a lot of it.”

Besides DeepGreen, the International Seabed Authority (ISA), a United Nations body that regulates mining in international waters, has issued 16 exploration licences in the CCZ to companies affiliated with nations that include China, Japan, Singapore and members of the European Union.

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For these entities and DeepGreen, commercial mining could soon be under way. Although the industry is still in the exploration phase, the ISA has set a target date of 2020 to adopt regulations for exploitation, which would allow companies to apply for a licence to start commercially mining metals from the ocean floor, according to Michael Lodge, the ISA’s secretary-general.

Mr. Barron said DeepGreen plans to start shipping product to manufacturers in 2025, and big names in the electric car business have expressed interest. With partners such as Glencore, a multinational commodity trader, and Maersk, the world’s largest shipping container company, DeepGreen plans to invest $200-million over the next three-and-a-half years to push the project through to final feasibility.

But challenges remain. Besides waiting for the ISA to pass regulations, DeepGreen has three more years of field studies to complete before it can finalize its environmental impact assessment, a report mandated by the ISA.

In the meantime, some environmentalists and scientists are raising questions about environmental consequences.

“We know more about the surface of the moon than we know about our deep sea,” said Steve Scott, a professor emeritus at the University of Toronto, who discovered the Solwara 1 seafloor massive sulfide deposit offshore Papua New Guinea in 1993. “But not knowing the whole deep sea in detail isn’t really the problem, it’s the area where you’re going to do the mining that’s the issue.”

One known side effect of mining nodules is mud plumes. Besides losing the nodules, which provide habitat and anchorage points for many species, some seafloor organisms, such as worms and sponges, can be smothered by shifting sediment clouds.

Deep-sea harvesters, specially designed to minimize impact, gather selected metal-rich nodules about four kilometres below the surface. Using a lift system, nodules are lifted to the surface ship, transferred to the trans-shipping fleet and shipped to the onshore plant.

“The thing about mining nodules is that you have to disturb a huge area of seafloor,” said John Jamieson, a Canada Research Chair in marine geology at Memorial University in Newfoundland and Labrador. “There’s a lot of organisms that live in that top layer of sediment, and that top layer takes a very long time to form. It’s not something that can recover quickly.”

Still, polymetallic nodule collection is less invasive than other forms of underwater mining, such as tearing apart cobalt crusts or removing mineralised chimneys formed by hydrothermal vents. Dr. Stone, who comes from the conservation world, said DeepGreen is committed to preserving biodiversity and minimizing the effects of the company’s activity. The harvesters will leave some nodules behind and large reference areas on the seafloor will remain untouched.

“The world is watching,” Dr. Jamieson said. “With any sort of new mining venture, there’s always people very much for it and very much against it. Until we do it, I don’t think we’ll really know whether or not it will work and what the environmental consequences will be.”

Harvesting nodules

Using offshore oil, gas and maritime technologies, DeepGreen employs remote-controlled harvesting vehicles to collect polymetallic nodules, sometimes called manganese nodules, from the ocean floor.

The machines are efficient, scooping up 85 to 90 per cent of the rocks. Once the nodules are brought onboard the production vessel, they are shipped to land-based processing facilities for further refinement and excess silt is pumped back down to the seabed, ensuring not to interfere with the water column. At the production facility, DeepGreen uses a process to dissolve the nodules and separate the metals which can be used to make electric car batteries, smartphones and other high-tech applications.

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Interest in the mineral-rich nodules isn’t new. It began in the 19th century, when the HMS Challenger, a British exploratory vessel, discovered nodules in 1868 in the Arctic Ocean. Since then they have been found in most of the world’s oceans.

The nodules first attracted commercial interest in the 1960s and 70s, but prospectors abandoned deep-sea extraction projects in the face of abundant, cheap metals from terrestrial mines and no legal framework governing the international seabed.

However, with global demand for battery minerals growing, countries and companies across the world are betting the next gold rush will be deep under water.

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