The government said Tuesday that it has started a two-month survey of five areas mainly in the Sea of Japan to chart deposits of methane hydrate, a next-generation energy source that is drawing attention in the resource-poor country.
The research entered the second year of a three-year project through fiscal 2015. For the current fiscal year starting April, the Natural Resources and Energy Agency will study four areas in the Sea of Japan and one area in the Pacific Ocean near Hokkaido.
The agency said a survey ship, equipped with a device that uses sound waves to assess geological seabed formation, left a port in Sakaiminato, Tottori Prefecture, on Tuesday.
The agency also said it will conduct a drilling survey between June and July to take samples of geological layers that include methane hydrate, an ice-like substance that consists of methane gas and water. It is stable at low temperature and under high pressure.
An agency official said it is impossible at this point to estimate how much methane hydrate may exist in the Sea of Japan, where four of the five areas being surveyed are located.
Last year, the first of three years of research, the agency said it visually confirmed that methane hydrate exists at the seabed off Niigata Prefecture.
Methane hydrate around the Japanese archipelago is said to exist in two forms -- either near the seafloor surface, or hundreds of meters below the seafloor.
The former type is found mainly in the Sea of Japan, while deeper deposits have been found off the Pacific coast. Developing technology to extract the resource remains a challenge.