As deep as 1,600 meters under water and 1,500 km from Tokyo, work has begun on the new hunting ground for metals in Japan, a country so devoid of natural resources that most of what it needs has to be imported.

As the nation depleted most of its land-based minerals in the economic boom that followed World War II, scientists have identified swaths of the sea floor littered with nuggets containing everything from copper to gold left over from the volcanic activity that created the archipelago millions of years ago. The trick is extracting them at a profit, something a government consortium will start testing next year.

Ocean mining is not new — Japan began exploring in the 1970s. But new technologies make it easier for companies like Canada’s Nautilus Minerals Inc. to collect mineral-rich rock from the sea. With more than 50 million tons of ore estimated in Japanese waters, the government wants to revive home-grown supply and ease dependence on imports. By the time Tokyo hosts the 2020 Olympics, bullion for gold medals may come from the offshore sources.

“Disruption of metal supplies may occur in the near future,” said Tetsuro Urabe, a geologist who is director of the government’s Next-Generation Technology for Ocean Resources Exploration Program. “We don’t want to be in a panic when we are confronted with a copper crisis. Unless we develop various kinds of new technology in advance, we won’t be ready for launch when needed.”

It is not surprising that mineral resources sit untouched in deep waters around Japan. The country is nestled in the Pacific Basin along a line of volcanoes and fault lines known as the “Ring of Fire,” a region prone to earthquakes and eruptions. When that volcanic activity occurs in the sea, magma pushes up from the Earth’s crust. After it cools, the deposits contain minerals in far greater concentrations than those dug from the land. In the blackness of the deep ocean, engineers have used remote-controlled robots and special sensors to search the sea floor for the most promising deposits.

As the world’s third-biggest economy and a major importer of everything from iron ore to oil, the country wants to exploit its rights to access sea-based mineral ores that one domestic industry group estimates may be worth ¥80 trillion. Under international maritime law, Japan holds sway over the area 200 nautical miles from its shores, constituting the world’s sixth-largest exclusive economic zone.

Others also are trying to mine seabed ore in waters near China, South Korea and North America. So far, there is no commercial production, though Toronto-based Nautilus has a project underway off of Papua New Guinea, where the company plans to start mining gold and copper in the first quarter of 2018.

A Japanese consortium, led by Mitsubishi Heavy Industries Ltd. and Nippon Steel & Sumitomo Metal Corp.’s engineering unit, will conduct a pilot mining and lifting of ore at the Izena sea hole in the area off the southern island of Okinawa in the next financial year starting April 1. Japan has confirmed the deposit has about 7.4 million tons of ore, twice what was detected just three years ago.

“New deposits have begun to be found one after another,” said Mitsuya Hirokawa, deputy director-general at the metals mining technology department of Japan Oil, Gas & Metals National Corp. (JOGMEC), the state-run company that helps secure energy and mineral supplies and is providing support for the sea-bed venture. The area off Okinawa shows some of the “greatest potential,” Hirokawa said.

Extracting the ore is getting cheaper.

Nautilus Minerals, in a 2010 study, estimated it will cost about $480 million to build a seafloor production system at its Solwara 1 project in 1,600 meters of water off Papua New Guinea. That compares with about $1.5 billion-$2 billion for a similar project on land, the company said. It will cost about $70 a ton to extract the ore, which would contain on average 7 percent copper and 6 grams of gold, John Elias, a company spokesman, said in an email.

Even with higher costs associated with working on the water and transporting ore to shore for smelting, the expense is worth it because of the higher concentration of usable metal than what is found on land, said Yoshio Akiyama, chief research officer for the metals mining technology department at JOGMEC. Using the Nautilus report, he estimates cash costs at about 34 cents a pound for copper, compared with $1.60 for a land-based mine.

Such ventures are not without risk. Metals prices plunged last year, forcing mining companies to cut capital spending and close mines. Deep-sea projects raise environmental challenges that have to be resolved, according to Urabe. There is also politics. The site off Okinawa is near waters claimed by both Japan and China, which are feuding over a group of uninhabited islands, known as the Senkakus in Japan and the Diaoyus in China. Japan has protested China’s unilateral development of natural gas fields in the East China Sea.

Japan cannot afford to miss out on accessing sea-floor minerals, said Takashi Sakamoto, general manager of the submarine resource business department at Nippon Steel’s engineering unit.

“Japan is two laps behind overseas in the ocean oil market, so it would be very sad if the same thing happens when we try to work on undersea mineral resources,” Sakamoto said.

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