(John Kemp is a Reuters market analyst. The views expressed are
By John Kemp
LONDON, March 13 There is enough gas locked in
ice-like crystals buried beneath the permafrost and trapped
under the oceans to guarantee the world will not run out of
fossil energy for centuries.
This potential energy source will be irrelevant, however, to
almost everyone for many decades to come, except perhaps Japan.
For decades, scientists have been trying to figure out
whether there is a commercial way to extract the gas from
methane hydrates, nicknamed flammable ice.
In an apparent breakthrough, state-owned Japan Oil, Gas and
Metals National Corporation (JOGMEC) has extracted natural gas
from hydrate accumulations hundreds of meters below the seabed
from a drill ship off the east coast of Japan.
JOGMEC estimates its test area contains enough hydrate to
cover 11 years worth of gas imports, according to an article
published in the New York Times on Tuesday ("An energy coup for
Japan: flammable ice" March 12).
Japan is a special case, because the country has almost no
hydrocarbon resources of its own and relies almost entirely on
The National Institute of Advanced Industrial Science and
Technology puts the total hydrate in the waters around Japan at
enough to cover nearer 100 years of the country's needs.
For most other countries and companies, developing hydrates
comes at the bottom of the list of commercial priorities behind
easier and proven forms of fossil energy including conventional
and unconventional oil and gas, coal-bed methane, gas-to-liquids
and coal-to-liquids technology.
Methane hydrates are the reason the world will never run out
of fossil fuels over any reasonable timeframe. But their
uncontrolled release has also been identified by climate
scientists as one of the biggest long-term dangers for the
"Gas hydrate is a solid crystalline substance composed of
water and natural gas (primarily methane) in which water
molecules form a cage-like structure around the gas molecules,"
according to the authors of the 2012 Global Energy Assessment
(GEA), a landmark study commissioned by the International
Institute for Applied Systems Analysis.
"The cage structure of the hydrate molecule concentrates the
component gas so that a single cubic metre of gas hydrate will
yield approximately 160 cubic metres of gas and 0.8 cubic metres
of water," if it is brought to atmospheric pressure and room
temperature (20 degrees Centigrade).
USGS photo of hydrate recovered from the Mississippi Canyon
in the Gulf of Mexico:
For methane to become trapped in a hydrate structure,
temperatures must be moderately cool and pressures moderately
"Gas hydrates are widespread in marine sediments beneath the
ocean floor and in sediments within and beneath permafrost
areas," according to USGS. "There pressure-temperature
conditions keep the gas hydrate 'stable', meaning it is intact
and gases are contained in its solid form."
Under the oceans, the conditions for hydrate stability are
usually found at water depths of more than 150 to 200 metres
near the poles and 500 metres towards the equator. The zone of
hydrate stability may extend several hundred meters down into
the sediments on the sea floor.
Beneath that level, rising temperatures as a result of the
greater depth make it impossible for gas to remain trapped. "At
some depth beneath the sea floor, the temperature increases to
the point where the hydrate is no longer stable," according to
The same boundary conditions govern the presence of methane
hydrates in and beneath the Arctic permafrost. The methane must
be buried far enough north and deep enough to meet the
pressure-temperature requirements for hydrates to form, but not
so deep that the geothermal gradient makes them unstable.
AN ENORMOUS RESOURCE
Methane hydrates are found in most offshore areas around the
world, as well as across the Arctic, and contain enormous
amounts of energy, but no one really knows how much there is or
how much might be technically and economically recoverable.
"The volume of natural gas contained in the world's gas
hydrate accumulations greatly exceeds that of known gas
reserves, although a substantial proportion of that gas hydrate
is in low-grade accumulations that are unlikely to be developed
commercially," the GEA concluded last year.
Theoretically, hydrate accumulations could contain between
2,500 and 2.8 million exajoules (EJ) of energy, according to the
GEA. An exajoule is equivalent to 1 joule followed by 18 zeroes.
For comparison, global conventional gas resources are put at
12,200 EJ, and unconventional gas resources (tight gas, shale
gas, deep gas and coal-bed methane) are estimated at 40,000 EJ,
according to the United States Geological Survey (USGS).
Conventional and unconventional oil resources are put at around
12,000 and 56,000 EJ, respectively.
World hydrocarbon resources
Chart 1: link.reuters.com/qyk66t
Chart 2: link.reuters.com/syk66t
In 2010, the International Energy Agency's World Energy
Outlook (WEO) estimated that methane hydrates contained almost
twice as much energy as all the world's resources of gas, oil
and coal combined.
But it is anyone's guess how much could actually be
recovered. Ten to 50 percent might be technically recoverable,
according to the GEA. The amount that could be economically
recoverable might range from 12,000 EJ down to zero.
Hydrates can make up as much as 85 percent of the bulk
volume of porous and permeable sands and gravel formations,
falling away to less than 10 percent of fine-grained sediments
Unfortunately, most of the gas hydrate appears to be trapped
in fine-grained sediment. "The prospects for commercial
development of natural gas from such a highly disseminated
resource are very poor without a paradigm shift in technology,"
the GEA concluded.
Because hydrates are only stable under specific temperature
and pressure conditions, the obvious way to disassociate them
(converting the hydrate into its separate gas and water
components) is either to raise the temperature or lower the
Other options include injecting the accumulation with an
antifreeze chemical such as methanol or ethylene glycol to melt
the crystals, or injecting it with carbon dioxide to displace
the methane (pushing carbon dioxide into the crystalline
lattices and methane out). CO2 injection has the added advantage
that it could be part of a carbon capture and storage (CCS)
In onshore tests, Japan's researchers explored using hot
water to warm the hydrate. But the offshore test relied on
depressurisation; pumping warm water under the seabed would have
required an enormous amount of energy and been prohibitively
expensive, according to the New York Times.
ENOUGH TO COOK THE PLANET
Climate researchers worry that as global temperatures rise,
the hydrates will become unstable, releasing thousands of
billions of tonnes of methane into the atmosphere. Methane is 21
times more potent as a greenhouse gas than carbon dioxide.
Mass release of methane hydrates from the ocean floor
"appears to have occurred in connection with rapid warming
episodes in the Earth's history", according to the
Intergovernmental Panel on Climate Change's Third Assessment
Report published in 2007.
IPCC estimated 4,000 billion tonnes of methane are locked
away in ocean hydrates, with a global warming potential
equivalent to 84,000 billion tonnes of carbon dioxide. Annual
emissions from burning fossil fuels currently amount to 34
billion tonnes of CO2. Releasing all that methane, or burning
it, would have substantial climate consequences.
Environmentalists want the hydrates to remain locked away
forever, and they are likely to get their wish for now.
Outside of Japan, where hydrates have the potential to
provde energy security, flammable ice will remain an interesting
curiosity - a last reserve of fossil fuels if humanity should
ever need them in centuries to come when other, far easier
hydrocarbon resources are nearing exhaustion.
(editing by Jane Baird)