News

Jun 18, 2010 11:25 AM by Melissa Canone

Natural gas: An overlooked danger in the oil spill

NEW ORLEANS (AP) - It is an overlooked danger in the oil spill
crisis: The crude gushing from the well contains vast amounts of
natural gas that could pose a serious threat to the Gulf of
Mexico's fragile ecosystem.
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.
That means huge quantities of methane have entered the Gulf,
scientists say, potentially suffocating marine life and creating
"dead zones" where oxygen is so depleted that nothing lives.
"This is the most vigorous methane eruption in modern human
history," Kessler said.
Methane is a colorless, odorless and flammable substance that is
a major component in the natural gas used to heat people's homes.
Petroleum engineers typically burn off excess gas attached to crude
before the oil is shipped off to the refinery. That's exactly what
BP has done as it has captured more than 7.5 million gallons of
crude from the breached well.
A BP spokesman said the company was burning about 30 million
cubic feet of natural gas daily from the source of the leak, adding
up to about 450 million cubic feet since the containment effort
started 15 days ago. That's enough gas to heat about 450,000 homes
for four days.
But that figure does not account for gas that eluded containment
efforts and wound up in the water, leaving behind huge amounts of
methane. Scientists are still trying to measure how much has
escaped into the water and how it may damage the Gulf and it
creatures.
The dangerous gas has played an important role throughout the
disaster and response. A bubble of methane is believed to have
burst up from the seafloor and ignited the rig explosion. Methane
crystals also clogged a four-story containment box that engineers
earlier tried to place on top of the breached well.
Now it is being looked at as an environmental concern.
The small microbes that live in the sea have been feeding on the
oil and natural gas in the water and are consuming larger
quantities of oxygen, which they need to digest food. As they draw
more oxygen from the water, it creates two problems. When oxygen
levels drop low enough, the breakdown of oil grinds to a halt; and
as it is depleted in the water, most life can't be sustained.
The National Science Foundation funded research on methane in
the Gulf amid concerns about the depths of the oil plume and
questions what role natural gas was playing in keeping the oil
below the surface, said David Garrison, a program director in the
federal agency who specializes in biological oceanography.
"This has the potential to harm the ecosystem in ways that we
don't know," Garrison said. "It's a complex problem."
BP CEO Tony Hayward on Thursday told Congress members that he
was "so devastated with this accident," "deeply sorry" and "so
distraught."
But he also testified that he was out of the loop on decisions
at the well and disclaimed knowledge of any of the myriad problems
on and under the Deepwater Horizon rig before the deadly explosion.
BP was leasing the rig the Deepwater Horizon that exploded April
20, killing 11 workers and triggering the environmental disaster.
"BP blew it," said Rep. Bart Stupak, D-Mich., chairman of the
House investigations panel that held the hearing. "You cut corners
to save money and time."
In early June, a research team led by Samantha Joye of the
Institute of Undersea Research and Technology at the University of
Georgia investigated a 15-mile-long plume drifting southwest from
the leak site. They said they found methane concentrations up to
10,000 times higher than normal, and oxygen levels depleted by 40
percent or more.
The scientists found that some parts of the plume had oxygen
concentrations just shy of the level that tips ocean waters into
the category of "dead zone" - a region uninhabitable to fish,
crabs, shrimp and other marine creatures.
Kessler has encountered similar findings. Since he began his
on-site research on Saturday, he said he has already found oxygen
depletions of between 2 percent and 30 percent in waters 1,000 feet
deep.
Shallow waters are normally more susceptible to oxygen
depletion. Because it is being found in such deep waters, both
Kessler and Joye do not know what is causing the depletion and what
the impact could be in the long- or short-term.
In an e-mail, Joye called her findings "the most bizarre
looking oxygen profiles I have ever seen anywhere."
Representatives of the National Oceanic and Atmospheric
Administration acknowledged that so much methane in the water could
draw down oxygen levels and slow the breakdown of oil in the Gulf,
but cautioned that research was still under way to understand the
ramifications.
"We haven't seen any long-term changes or trends at this
point," said Robert Haddad, chief of the agency's assessment and
restoration division.
Haddad said early efforts to monitor the spill had focused
largely on the more toxic components of oil. However, as new data
comes in, he said NOAA and other federal agencies will get a more
accurate read on methane concentrations and the effects.
"The question is what's going on in the deeper, colder parts of
the ocean," he said. "Are the (methane) concentrations going to
overcome the amount of available oxygen? We want to make sure we're
not overloading the system."
BP spokesman Mark Proegler disputed Joye's suggestion that the
Gulf's deep waters contain large amounts of methane, noting that
water samples taken by BP and federal agencies have shown minimal
underwater oil outside the spill's vicinity.
"The gas that escapes, what we don't flare, goes up to the
surface and is gone," he said.
Steven DiMarco, an oceanographer at Texas A&M University who has
studied a long-known "dead zone" in the Gulf, said one example of
marine life that could be affected by low oxygen levels in deeper
waters would be giant squid - the food of choice for the endangered
sperm whale population. Squid live primarily in deep water, and
would be disrupted by lower oxygen levels, DiMarco said.
Meanwhile, the Coast Guard signaled a shift in strategy Friday
to fight the oil, saying it was ramping up efforts to capture the
crude closer to shore.
Coast Guard Adm. Thad Allen said an estimated 2,000 private
boats in the so-called "vessels of opportunity" program will be
more closely linked through a tighter command and control structure
to direct them to locations less than 50 miles offshore to skim the
oil. Allen, the point man for the federal response to the spill,
previously had said surface containment efforts would be
concentrated much farther offshore.

»Comments

»Topics in this article

Top Videos

1 2 3 4

Most Popular