Howarth's testimony urges further research on the numerous environmental and human health risks associated with the very recent mix of technolological advances in modern hydraulic fracturing before continuing development.
Among the concens Howarth raises:
Surface water pollution: Shale gas development has already caused significant surface
water pollution. The additives used in hydraulic fracturing include toxic and
carcinogenic substances, such as formaldehyde, benzene, xylene, and
monoethanolamine. As importantly, frac fluids extract chemical substances from shales,
including toxic and carcinogenic aromatic hydrocarbons, toxic metals, and radioactive
materials such as uranium, thorium, and radium. Some of these materials are released
to the environment when blowouts and other accidents occur. A greater route of
release and exposure comes from disposal of frac-return fluids. Approximately 20%, or
1 million gallons or so, of the material used in hydraulic fracturing flows back to the
surface in the first few weeks after fracturing, with all of the added and extracted
chemical substances. In Texas, where most high-volume hydraulic fracturing has
occurred so far, these wastes are disposed of by injection into old, abandoned
conventional gas wells. In the Marcellus formation in Pennsylvania, some waste has
been injected in such disposal wells, but suitable disposal wells are rare in the northeast,
and much more has been disposed of in municipal sewage treatment plants. Such
treatment plants simply are not designed to handle these toxic wastes. A significant
amount of the wastes flow through the plants and are released into rivers. Public
drinking water supplies in the Pittsburg area have already been affected, with elevated
bromides from the waste interacting with chlorination in public drinking water systems
to produce highly dangerous brominated organic compounds. As a result, the PA DEP
and US EPA have put a stop to using sewage plants to dispose of frac wastes, as of the
summer of 2011. But suitable alternative disposal methods have yet to be developed.
Groundwater contamination: There are several reports of contamination of drinking
water wells and surface aquifers by fracking fluids, particularly in Pennsylvania and in
Colorado. The extent of such contamination, and the mechanisms which might lead to
such contamination, remain poorly studied. Most scientists familiar with the existing,
public data (note that a lot of information is not publicly available) believe the
contamination is likely caused by well and cementing failures. A recently published
model suggests there may also be a threat of migration of contaminated fracking fluids
from depth to surface drinking water aquifers over time through fissures and cracks.
The US EPA is currently pursuing a comprehensive study of groundwater contamination
from hydraulic fracturing, and intends to release a preliminary report later this year and
a final report in 2014.
Shale gas development also leads to contamination of drinking water wells, as
indicated by a May 2011 study published by Duke University scientists in the
Proceedings of the National Academy of Sciences. Methane concentrations were
frequently elevated in drinking water wells within 1 km of shale gas operations,
sometimes at levels great enough to pose a significant risk of explosion.
Local air pollution: The development of shale gas and other unconventional forms of
natural gas (from coal-bed seams and tight-sand formations) results in significant local
air pollution. One concern is the release of benzene and other aromatic hydrocarbons
to the atmosphere from routine operations. State officials in Texas have reported
benzene concentrations in the air near gas operations that sometimes exceed acute
toxicity standards. In Pennsylvania, reported benzene concentrations are so far lower,
quite likely because the rate of gas development has been much lower. Nonetheless,
reported atmospheric benzene levels near some drilling operations in Pennsylvania are
high enough to pose risk of cancer from chronic exposure.
Ozone pollution: Ozone is created in the atmosphere
when nitrogen pollution and organic compounds react under strong sunlight. Current
ozone pollution in the US is estimated to cause 30,000 premature deaths each year,
almost the same death rate as from automobile accidents. Unconventional natural gas
development from hydraulic fracturing increases ozone pollution due to leakage of
organic compounds to the air. The problem has been particularly acute in Wyoming,
Utah, and Colorado in recent years, with ozone concentrations in the winter due to
natural gas development being higher than observed in New York City.
Methane and global warming: Methane is released to the atmosphere during
development, transport, storage, and use of natural gas. Methane is an incredibly
powerful greenhouse gas, and as a result of methane emissions, both shale gas and
conventional natural gas have larger greenhouse gas footprints than other fossil fuels
such as oil and coal (when viewed over an integrated 20-year time frame after
emission). Recent climate models point to the urgency in reducing methane emissions:
without immediate global reductions in methane pollution, these models indicate that
the Earth will warm to 1.5 degrees C above the long-term average within 15 years or so,
and to 2 degrees C within 35 to 40 years. This is a dangerous level of warming, a level
that greatly increases the likelihood of positive feedbacks in the climate system, leading
to an acceleration of further warming. Reducing emissions of methane and other shortlived
radiatively active materials such as black carbon is the best way to reduce this
dangerous warming. Currently, almost 40% of all atmospheric methane released by
human activity in the US comes from the natural gas industry. Most studies indicate
that shale gas development releases 40% to 60% more methane than does conventional
natural gas. To address the huge threat posed by global warming, I believe it is essential
to move as quickly as possible away from natural gas towards renewable energy
resources, and to not further develop shale gas unless major (and expensive) steps are
taken to greatly reduce methane emissions.
Radon in natural gas supplies: Radon gas is a carcinogen, and exposure to radon is the
largest source of public exposure to ionizing radiation in the US. Currently, radon in
homes in the US results in an estimated 20,000 deaths per year. Natural gas contains
radon, and using natural gas for home cooking is one route of home exposure. Shale
gas from the Marcellus formation, and perhaps from other formations as well, has much
greater levels of radon than does conventional natural gas. This is because the
Marcellus shale is particularly rich in uranium and thorium, and radon is formed from
the decay of these radioactive materials. Radon has a half life of 3.8 days, so with
sufficiently long storage, the radon decays away and poses less public health risk.
However, the rapid movement of natural gas from the Marcellus shale to northeastern
cities would seem to pose a major public health risk, one that certainly deserves much
greater study and scrutiny.
Michael Brune (Sierra Club): Statement before the Committee
Howarth et al. 2012. Methane Emissions from Natural Gas Systems.
Background Paper Prepared for the National Climate Assessment Reference number 2011-0003