Inpex announced the Ichthys liquefied natural gas project Friday, which will become one of the world's largest, producing 8.4 million tons of natural gas a year.
Inpex supplies Tokyo Electric Power Co., the utility whose gas needs are growing after reactors in northeastern Japan went into meltdown because of the March tsunami.
Inpex Chairman Naoki Kuroda said the deal will help provide clean energy and diversify Japan's energy sources while contributing to Australian economic growth.