This NASA satellite image received on April 7, 2005 shows Shikoku island (bottom, left) western Japan. A huge layer of methane hydrate containing 1.1 trillion cubic metres in natural gas is believed to lie in the ocean floor off the coast of Shikoku, officials said.
apan said Tuesday it had successfully extracted methane hydrate, known as "fire ice", from its seabed, possibly unlocking many years' worth of gas for the resource-starved country.
In what they are claiming as a world first, a consortium is drilling for the hydrate, a fossil fuel that looks like ice but consists of very densely-packed methane surrounded by water molecules, one kilometre (3,300 feet) below sea level.
The solid white substance burns with a pale flame, leaving nothing but water. One of it is estimated to contain many times the equivalent volume of methane in gas form.
The consortium, led by Japan Oil, Gas and Metals National Corporation, began initial work in February last year and on Tuesday started a two-week experimental production, an economy, trade and industry ministry official said.
"It is the world's first offshore experiment producing gas from methane hydrate," the official said, adding that the team successfully collected methane gas extracted from the half-frozen substance.
Under the government-led project, the consortium is to separate methane -- the primary component of natural gas -- from the solid clathrate compound under the seabed using the high pressures available at depth, officials said.
A huge layer of methane hydrate containing 1.1 trillion cubic metres (38.5 trillion cubic feet) in natural gas -- equivalent to Japan's consumption of the gas for 11 years -- is believed to lie in the ocean floor off the coast of Shikoku island, western Japan, the officials said.
"We aim to establish methane hydrate production technologies for practical use by the fiscal 2018 year" ending March 2019, a consortium official said.
"We want to consolidate technologies for its commercialisation," economy, trade and industry minister Toshimitsu Motegi also told a news conference, according to Jiji Press.
"I hope we can make use of resources surrounding our country as soon as possible by clearing hurdles one by one," he added.
The move comes as resource-poor Japan has struck out in search of new energy supplies after it shut down its stable of nuclear reactors in the wake of 2011's tsunami-sparked nuclear crisis.
日本周二宣布，已经成功地从日本海底提取出甲烷水合物，俗称“可燃冰”，此举可能将给这个资源贫乏的国家开启可延续多年的燃气资源宝藏。
一个开采联盟从海平面下1公里处（3300英尺）钻探出这种甲烷水合物，这是一种外表像冰但含有被水分子包围的结构十分紧密的甲烷的一种矿物燃料。据称这是世界上首次提取出这种燃料。
这种白色固体物质燃烧时发出苍白色的火焰，燃尽后只留下水。据估计1立方米的可燃冰含有数倍于同体积甲烷气体的能量。
经济、贸易和工业部的一名官员称，由日本石油天然气金属矿产资源机构带领的这一联盟于去年二月份开始前期工作，本周二开始进行为期两周的试验性生产。
该官员称：“这是世界上首个从甲烷水合物中提取天然气的离岸实验。”他还说，该团队成功地收集了从这一半冰冻状态的物质中提取出的甲烷气体。
据官员称，在这一政府领头的工程中，该联盟将把甲烷（天然气的主要成分）通过在海洋深处才能达到的高压从海底的固体水合物中分离出来。
官员称，据认为日本西部四国岛海岸附近的大洋底部有一片面积巨大的甲烷水合物，这些甲烷水合物中含有1.1万亿立方米（38.5万亿立方英尺）天然气——相当于日本11年的天然气消费量。
联盟的一名官员说：“我们的目标是在2018财政年度结束前研发出可供实际应用的甲烷水合物生产技术。”2018财政年度截止于2019年3月。
时事通讯社的消息称，日本经济、贸易和工业部部长茂木敏充还在新闻发布会上表示：“我们要加强以商业化为目的的技术。”
他还说：“我希望我们能一个一个地扫清障碍，从而尽快实现对我国周边地区资源的利用。”
2011年海啸引发核危机之后日本就关闭了核电站，从那以后资源贫乏的日本就一直在奋力寻求新的能源供给来源。
methane hydrate: 甲烷水合物
consortium: 合伙，联合；社团，会社
clathrate: 笼形包合物