J-Power, Japan's biggest coal importer, has bought 60,000 metric tons of the fuel from Alaska and is evaluating reviving purchases from the U.S. after a six-year gap to reduce dependence on supplies from Australia, according to Executive Vice President Yoshihiko Sakanashi.

Electric Power Development Co., as J-Power is officially known, is considering a supply contract with an Alaskan producer after the trial, Sakanashi said. "Alaskan coal could increasingly be coming into Japan as long as it has price competitiveness."

Soaring prices and dwindling shipments from China are driving J-Power's search for alternative and diverse sources of coal. Australian mines operated by companies such as Xstrata PLC and Rio Tinto Group have gained a 70 percent share in Japan's ¥1.3 trillion power-station coal import market.