Methane Release From the Gulf Oil Spill: What Does It Mean? How Bad Could It Get?
Tremendous quantities of methane are being emitted by the Gulf oil
The methane could kill all life in large areas of the Gulf.
rumors being spread widely around the Web claiming that the methane
could bring on a doomsday catastrophe are not credible.
essay will attempt to clear up the confusion and convey the facts
regarding methane and the oil spill.
Thank Uncle Sam
a preface, I want to touch on the government's role in this mess.
people know that the government has encouraged deepwater drilling for
oil by giving huge tax
subsidies for deepwater drilling.
As the Los Angeles Times writes:
say the Gulf of Mexico catastrophe can be linked to Congress' policy of
oil-friendly tax breaks and financial benefits.
issue was the 2005 Energy Policy Act — the largest energy bill in years.
The committee chairman, Rep. Joe L. Barton (R- Texas), a friend of the
industry, had saved some big issues for the end: billions of dollars in
tax and royalty relief to encourage drilling for oil and gas in the Gulf
of Mexico and other offshore areas. There was even a $50-million annual
earmark to support technical research for the industry.
royalty waiver program was established by Congress in 1995, when oil
was selling for about $18 a barrel and drilling in deep water was seen
as unprofitable without a subsidy. Today, oil sells for about $70 a
barrel, but the subsidy continues.
The Government Accountability
Office estimates that the deep-water waiver program could cost the
Treasury $55 billion or more in lost revenue over the life of the
leases, depending on the price of oil and gas and the performances of
Oil companies won a lawsuit last year
requiring the government to pay back $2.1 billion in royalties from
previous years, including about $240 million to BP.
number of analysts say the waiver program has pushed drilling into
fragile and remote areas where emergency response plans were inadequate.
"If it wasn't profitable for them to do it, then that's a good argument
for leaving the oil in the ground," said Robert Gramling, who studies
the history of the oil industry at the University of Louisiana,
Lafayette. The government-subsidized rush to deep-water exploration led
to a situation where the industry was doing "things that were
technically possible but were beyond our ability to undo them if we find
out we have a problem."
But most people don't know that
the government has actively encouraged drilling for methane in the Gulf
of Mexico as well.
For example, Congress passed
the Methane Hydrate Research and Development Act
of 2000 "to promote the research, identification, assessment, exploration, and development of
methane hydrate resources...."
The Energy Policy Act of 2005 also
support for methane hydrate research, exploration and development -
including in deep water.
fact, the government,
oil industry and academia have been exploring
the high methane content in the Mississippi
Canyon area of the Gulf of Mexico - where the spill is occurring -
Unprecedented Release of Methane
As CBS notes:
The oil emanating from the seafloor contains about 40 percent methane, compared with
about 5 percent found in
typical oil deposits, said John Kessler, a Texas A&M University
oceanographer who is studying the impact of methane from the spill.
Kessler also points
This is the most vigorous methane eruption in
modern human history.
A U.S. scientist says
that methane levels in the Gulf are "astonishingly high", that 1 million
times the normal level of methane gas has been found in some regions
near the oil spill, high enough to create "dead zones" devoid of life.
Methane depletes oxygen, and the scientist noted:
locations, we saw depletions of up to 30
percent of oxygen based on its natural concentration in the waters.
studying the [plumes] have found concentrations of methane up to
10,000 times greater than normal and oxygen levels depleted by 40 percent below normal.
unprecedented release of methane into the ocean kill all life within
large swaths of the Gulf of Mexico.
has found that methane is 33
times more potent than carbon dioxide in causing global warming.
Many scientists have said that methane releases have caused past warming
spells. See this,
Indeed, methane has such a powerful effect on climate that scientists
believe that woolly
mammoth farts gaseous emissions are responsible
for warming the Earth 13,000 years ago.
As Nature wrote
The Siberian Shelf alone harbours an
estimated 1,400 billion tonnes
of methane in gas hydrates, about twice as much carbon as is contained
in all the trees, grasses and flowers on the planet. If just one per
cent of this escaped into the atmosphere within a few decades, it would
be enough to cause abrupt climate change, says [Natalia Shakhova, a
biogeochemist at the University of Alaska, Fairbanks, and one of the
leaders of the Siberian Shelf study].
Associated Press points
Estimates from the U.S. Geological Survey's
"flow team" [are] that 2,900 cubic feet of natural gas are escaping for
every barrel of oil.
That's 105 billion cubic feet
a year. That's a very large number.
However, as the Guardian notes:
new study, published
in the journal Science, shows that methane emissions from the
Arctic increased by 31% from 2003-07. The increase represents about 1 [million] extra
tonnes of methane each year. Palmer cautioned that the five-year
increase was too short to call a definitive trend.
found that just over half of all methane emissions came from the
tropics, with some 20
[million] tonnes released from the Amazon river basin each
year, and 26
[million] tonnes from the Congo basin. Rice paddy fields across
China and south and south-east Asia produced just under one-third of
global methane, some 33 [million] tonnes.
million metric tons of methane [are] emitted worldwide each year from a
combination of human activities and natural sources like rotting
plants in wetlands, termites and wildfires.
1 ton of
liquefied methane equals
approximately 16 barrels or 50,000 cubic feet of natural gas, depending
on methane content (Natural gas contains between 75
percent methane by volume. Natural gas used by consumers is composed
almost entirely of methane. However,
natural gas found at the wellhead, although
still composed primarily of methane, is not
as pure. )
So using a rough calculation, 440 million metric tons
equals approximately 2.2
× 1013 or 22,000,000,000,000 cubic feet.
22 trillion cubic
feet a year ... 210
times bigger than the amount of methane being released from the
Gulf oil spill.
So the bottom line is that the methane gushing
out from the broken oil equipment is adding to the worldwide methane
output, but constitutes less
than one-half of one percent ... which would normally be considered
a statistical rounding error.
Remember, these are very rough
estimates which are certain to be somewhat off. I hope that an expert
can provide better estimates, and correct any erroneous assumptions
which I made. But the estimates still provide some sense of scale and
(Note also that Iceland's volcanoes are probably going
to throw a
lot of ash into the air. This could have a cooling effect which
offsets any warming from the Gulf methane release.)
Methane released deep underwater might not even make it to the atmosphere.
The latest science suggests that relatively
little, if any, methane hydrate is currently degassing, amounting to at
most 2 percent of global methane emissions, and much of that may not
even be entering the atmosphere. Most
of the degassing hydrate would be deep underwater, so the methane
that’s released can get dissolved in the water or chewed up by certain
microbes before it reaches the surface.
Valentine of the University of California, Santa Barbara, agrees:
methane from surface-vessel spills or shallow-water blowouts escapes
into the air, I expect that the vast majority of methane making the
long trip to the sea surface from a deep water spill would dissolve,"
Valentine wrote. "Unlike oil, methane dissolves uniformly in seawater.
And the tools are available to measure it accurately and
As Alexander Higgins points
[A] study called Project “Deep Spill”
... debunks the lie that the methane gas being released from the well
is floating to the surface and not being absorbed into the sea.
study analyzed a wide range of controlled releases at different depths
below the sea surface of different types of oil found all over world
to help better understand the flow of hydrocarbons released from a
One of the studies, called DeepBlow, released
10,000 barrels of oil per day at a depth of 800 meters which is less
than half of the depth of the Deepwater Horizon blowout.
basic findings of that study has been recreated by scientists from the
University of North Carolina.
In their research the scientists simulated of the formation of the underwater oil plumes
that are created during deepwater blowouts.
University of North Caroline Simulation Shows How Oil Released
Underwater Forms Plumes
the University of North Carolina simulation gives you a basic
understanding of how deepwater blowouts create oil plumes it does not
fully account for all the findings of Project “Deep Spill”.
particular the final report of Project “Deep Spill” found: ound:
- Only 2% of the oil released in a
deepwater blowout may actually make it to the surface.
That’s as little as 2% naturally without the use of dispersants. Add
dispersants into the equation and it could be less then one percent of
oil that makes it to the surface.
- None of the methane
released from the deepwater blowout made it to the surface. The
study found that released natural gas may dissolve completely within
the water column if it is released from a deep enough depth relative to
the gas flow rate.
From the study of the 800 meter release:
sounders provided efficient tracking of oil and gas releases in the
field and showed that the gas was completely dissolved before it could
DeepBlow does not include hydrate kinetics, and hence,
under hydrate forming conditions, the model predicts solid hydrate
particles. Not only is the mass transfer from such particles slower than
from gas bubbles, but also hydrate density is closer to that of water
than that of natural gas, substantially reducing plume buoyancy.
- The buoyant parts of the oil released in a deepwater blowout
split from the main plume within the first 200 meters of release. Those
buoyant parts, which represent only a small portion of the total amount
of oil, turn into small droplets that float to the surface.
Here is a
graph from the study showing this process.
oil release – Buoyancy particle separation graph
an image that captures the separation process
oil release – Buoyancy particle separation simulation
- Within the first 100 to 200 meters from the source of the release the
the majority of the oil loses its buoyancy and stops rising. This
majority of the oil remains submerged in an underwater plume that is
then carried away by subsurface currents.
fact that much of the methane released from the Gulf oil spill won't
make it to the surface is good for those worried about global warming,
but bad for the marine life. Remember as discussed above, methane
depletes oxygen, and thus kills everything in the ocean.
It is true that one scientist speculates
that methane bubbles released from the seafloor have caused
extinction-level events in the past.
But the odds that the release of methane from
the leaking oil will cause a tidal wave or a firestorm are infinitesimally
There are many real things to worry about -
such as the destruction of the Gulf ecosystem, and the threat to human
health from toxic chemicals in the oil and dispersants.
waves and firestorms are not worth worrying about. And - unlike the
destruction of the ecosystems and the threat to human health which we
can do something about (by stopping the use of Corexit dispersant and
using proven clean-up and containment methods) - there's nothing much we
can do about such low-probability Armageddon scenarios.
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