NOx and VOCs in the troposphere are bad news. When blest by solar radiation, the pair begets
ozone and smog.
VOC to the future
We are accustomed to freighting the air we breathe with few sequents, but now the ante is upped. Apart from abundant NOx
emitted from drilling rigs and the trucks that serve them, fracked wells leak
between 40 and 60 percent more
methane than do conventional natural-gas wells; this has been confirmed by
Petron's employer. After drilling, methane entwined with chemically
loaded water from below escapes at the wellhead; escapes continue all along the
matrix. Although the
atmosphere holds more carbon dioxide--200 times more than methane--infrared-absorbing
methane is the more insidious greenhouse gas.
The fracking craze is not confined to gas. Bakken
shale beneath North Dakota, Montana, and Saskatchewan harbors oil, a
high-quality light crude that gushes fewer carbon-dioxide emissions than the
thick stuff from Canadian tar sands or even Venezuela. Pursuit of this crude is full-throttled. To the dismay of the drillers, however, their oil is often encumbered by natural gas.
Some of this raw natural gas is being sold to Canada to dilute raw bitumen from Alberta
tar sands, but supply is greater than demand.
So, as making full use of such gas requires both pipelines and
processing that are nonexistent, it is being burned off--flared. In 2011, oil producers in North Dakota flared
nearly 32 percent--one third--of all gas produced in the state, and the next year they flared more. This strikes me as ironic.
Back in the fields where natural gas is feted, how much slips through the cracks? Initial estimates from Colorado tallied around 4 percent of all produced escaped, but another team measuring methane in Utah's Uinta Basin, where over the past decade fracking has flourished, assay leakage as high as 9 percent. The methodology for calculating leakage is disputed in a peer-reviewed comment presenting an alternate interpretation of the data that aligns leakage with industry estimates. But a more recent study using carbon isotopes to distinguish industrial emissions from bovine-generated methane reinforces earlier findings. These findings are for wellheads only and exclude losses occurring elsewhere in the matrix.
Erie, a town of 18,000 straddling Weld and Boulder counties,
has spikes in
methane and butane that exceed by a factor of nine those of the Los Angeles
suburb Pasadena and of Dallas, Texas, two cities with the most health-impinging
air in the land.
How critical are the numbers? One study reports that, as long as the cumulative
methane leakage from natural-gas production remains below 3.2%, shifting
from coal-fired to natural-gas generators will have immediate climatic benefits
and those benefits will accrue over time as gas plants replace coal
plants.
We're well beyond that benchmark.
***
[1] Jana Milford carries a master of science in engineering
and a Ph.D. in engineering and public policy from Carnegie Mellon University
and a J.D. from the University of Colorado School of Law. With a primary technical focus in modeling
the chemistry and transport of ozone, secondary organic aerosols, and other
photochemical air pollutants, she researches legal, technical, and policy
aspects of air pollution.
[2] Gabrielle Petron
is a Research Laboratory Associate Scientist with the National Oceanic and
Atmospheric Administration. The title of
their talk was Atmospheric Perspectives on
Oil and Gas Operations.
[3] The Environmental Protection Agency recognizes two
general kinds of pollutants. Of the six criteria
air pollutants it defines, nitrogen dioxide, ozone, and particulate
matter concern us. (The others are lead, carbon monoxide, and sulfur dioxide.) To be exposed to these substances is to risk
health, environment, and property. EPA
also recognizes 189 Hazardous Air Pollutants that increase the risk of
developing health issues when levels of the substances are high enough and
exposure is long enough. Criteria
pollutants are more common and more potent and were written into 1970's Clean
Air Act while hazardous pollutants were named in an expansion to that list in
1990. Better late than never.
[4] EPA's new
rules for fracking, at last released in 2012 although the industry has
until 2015 to comply, require that levels of benzene and other toxic pollutants be reduced by 30 percent and VOCs by 25 percent, while methane is to be more
adequately recovered and its emissions reduced.
While the ruling was celebrated, some were dismayed that it addressed
only air pollution while ignoring water, public health, and other vexations
related to fracking. Of course, EPA is
rather feckless in the face of the Halliburton Loophole, which exempts water infected
by fracking from EPA oversight.
***
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