Underwater mining for rare earths, used in hybrid cars and plasma televisions, is economically and possibly environmentally not viable, an academic from the independent think tank Council on Foreign Relations said.
"To get these minerals out of the ocean in the foreseeable future and to be economically viable is still a long, long way off," David Abraham, an international affairs fellow at the New York-based CFR, said from Xian, China.
China, supplier of 95 percent of the 17 elements known as rare earths, has clamped down on the mining of rare earth minerals and has cut export quotas, boosting prices and sparking concern among overseas users such as Japan about access to supplies.