BEIJING • In the six weeks since China announced its first success in collecting samples of combustible ice in the South China Sea, it has extracted more than 235,000 cubic m of gas hydrate off the coast of Guangdong province, according to the China Geological Survey.
"China has beaten expectations in completing the trial explorations of combustible ice using local innovations in technology and engineering," said Mr Ye Jianliang, who heads the Guangzhou Marine Geology Survey. "It marks a historic breakthrough."
The mining operation deep into the ocean floor of the South China Sea took place at a trial site in the Shenhu area.
Technically known as methane hydrate, combustible ice is a frozen fossil fuel that energy-guzzling China hopes to exploit to meet growing demand.
Once extracted, 1 cubic m of gas hydrate releases 164 cubic m of conventional natural gas, according to the United States Department of Energy (DOE).
Methane is extracted by heating or reducing the pressure inside the well to break down the hydrates.
China discovered combustible ice in the South China Sea in 2007, reported the China Daily.
NOT SUSTAINABLE YET
We know where the resource is, the technology we need to apply, but the production rates out of the wells are not commercially sustainable at the current prices.
MR PAUL DUERLOO, partner and managing director at Boston Consulting Group in Tokyo. He says commercially viable production is "another 10 years" away.
What is combustible ice?
Combustible ice or methane hydrate is a frozen fossil fuel found under the seabed, buried inside Arctic permafrost or beneath Antarctic ice.
It can be ignited like solid ethanol, hence the name combustible or flammable ice.
Methane hydrate is said to be abundant enough to serve as a key energy source for up to hundreds of years.
Once extracted, 1 cubic m of gas hydrate releases 164 cubic m of conventional natural gas, said the United States Department of Energy.
But experts say extracting methane from the ice crystals is technologically challenging and expensive.
Estimates for the size of the planet's gas hydrate deposits vary widely, but the DOE said that they could exceed "the combined energy content of all other known fossil fuels".
Analysts said the substantial resource could be a game changer for countries that have limited access to conventional natural gas.
"The perfect example is Japan, because they don't have much conventional gas and, for them, it could be an important reserve," said senior lecturer Ingo Pecher from the science faculty at New Zealand's University of Auckland.
Japan is heavily reliant on imports of liquefied natural gas, with most of the country's fleet of nuclear reactors still offline more than six years after the tsunami disaster at Fukushima.
Even though known and presumed gas hydrate deposits have been identified from New Zealand to Alaska, the challenge is to find ones that are both highly concentrated and accessible.
Several countries are hoping to turn gas hydrate into a viable source of energy, including Japan, which has reported drilling success off its Pacific coast.
The US, which is also looking into the potential of gas hydrate, has obtained positive results from exploratory drilling carried out in the Gulf of Mexico.
However, commercially viable production is "another 10 years" away, according to Mr Paul Duerloo, who is a partner and managing director at Boston Consulting Group in Tokyo.
"We know where the resource is, the technology we need to apply, but the production rates out of the wells are not commercially sustainable at the current prices," he said.
He noted that shale gas, another unconventional energy source that faced similar challenges, took a long time to take off.
China expects to start commercial production of gas hydrate around 2030, according to the Ministry of Land and Resources.
Another concern surrounding gas hydrate extraction is the potential for methane - a greenhouse gas - to leak into the atmosphere and fuel global warming, said Associate Professor Xu Yuan, who is with the geography and resource management department of the Chinese University of Hong Kong.
Nevertheless, gas hydrates have "huge potential" if the cost and technological hurdles can be overcome, he noted.