The power under the ocean

Japan is known to be a country with few natural energy resources. Her current energy self-sufficiency rate is only 4%, although it is normally closer to 20% if nuclear power stations, currently almost all off-line, are included. Japan depends on oil for more than 50% of the energy supply, importing about 90% of it from the Middle East with all the political and security risks to stability of supply involved.

Under these circumstances, Japan has been expanding her horizons in the search for sources of energy. Through marine research, the seabed around Japan has started to show the first glimmers of being an unopened treasure chest of potential energy.

Methane hydrate, otherwise known as ‘Burning Ice’, is the only energy resource mined in Japan apart from coal. Experimental drilling off the Atumi peninsula ran from February to March this year as part of a national research project. According to the published results, the volume of methane hydrate deposits is estimated to be the equivalent 90 to 100 years of Japan’s natural gas consumption.

There are substantial reserves of methane hydrate between 100 to 300 meters from the seabed in the sea off Niigata and around the East Nankai Trough. Developing this field would be the world’s first trial of offshore production of methane hydrate.

Japan Oil, Gas and Metals National Corporation (JOGMEC) research organisation under the Ministry of Economy, Trade and Industry has led this project, supported by the deep-sea scientific drilling vessel ‘Chikyu’, operated by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) under Ministry of Education, Culture, Sports, Science and Technology. There are still a lot of issues to be resolved before industrial production can begin, such reduction of mining costs, but the Government has high expectations.

The Chikyu research vessel has made a number of other significant discoveries recently, including a huge hot water mineral deposit lake (300 degree Celsius) located north west of Okinawa main island. Chikyu recovered minerals from this heated water lake with the same constituency of onshore black ore.

The mineral contains copper sulphate, zinc, gold and silver. This hot water lake could be the world’s largest blackore mineral deposit. Dr. Asahiko Taira, president of JAMSTEC said “It is the evolutional discovery in the study of mineral deposits.”

Chikyu has also successfully explored the inner structure of a submarine volcano off Kumano in Mie prefecture. It has found a 100 meter high sub-sea mountain which contains solidified methane hydrate cooled off around the seabed. The methane hydrate ice column contains a high concentration of lithium,
making it a potential mine for both energy and metals.

There are, however, skeptics about the potential usefulness of methane hydrate as an energy source. Dr. Yoshinori Ishii, former president of National Institute for Environmental Studies said that “Methane hydrate is not a real resource can be practically used. Quality is more important for energy than quantity”.

The difficulty is that methane hydrate has not been found in an incrassate form. A significant amount of energy is required to turn it into a useful form, which dramatically reduces the energy profit ration (EPR) of energy input against output that governs the commercial value of any energy resource.

For the moment, Japan looks set to continue with marine exploration and research into the use of methane hydrate. The message from the relevant agencies is that international partners are welcome to help develop technologies and processes that would make methane hydrate a commercially viable energy resource.

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