1. Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
2. Energy Business Unit, Japan Organization for Metals and Energy Security (JOGMEC), 1-2-2 Hamada, Mihama-ku, Chiba, Chiba 261-0025, Japan