Marvin Chan
Bio: I am an undergraduate studying electrical engineering with a concentration in circuit
design. I have always been interested in natural gas because I believe it is a stepping-stone
from coal and petroleum to renewable energy sources.
Keywords: Energy, Power, Sustainability, Water Conservation, Natural Gas
Multimedia Suggestions: http://www.youtube.com/watch?v=VY34PQUiwOQ
Abstract:
Hydraulic fracturing dramatically increases the yield of natural gas, which is a cleaner fuel
compared to coal and petroleum. However, this technique has recently been a topic of
national debate because of environmental controversies. High levels of water consumption
and groundwater contamination are two issues that are constantly brought up for
discussion when talking about hydraulic fracturing. This paper will specifically tackle to see
whether hydraulic fracturing is responsible for these two issues. To figure out whether
hydraulic fracturing uses high volumes of water, an estimate was made using reasonable
assumptions and government data. The estimate is then put into context by comparing it to
water consumption in the United States. As for groundwater contamination, reported cases
of groundwater contamination were examined and studied. The results were that hydraulic
fracturing consumes 100-250 billion gallons of water per year, which is only a fraction of
the United States annual consumption of 43,800 billion gallons of water. After examining
different cases of groundwater contamination, hydraulic fracturing is not the culprit for
contamination, but the poor design and construction of wells and the careless treatment of
fracturing that causes groundwater contamination. In terms of water consumption and
groundwater contamination, hydraulic fracturing does neither, so it should be continually
used to extract natural gas.
The Waters of Hydraulic Fracturing
Natural Gas, a mixture made of primarily methane, is one of the most commonly
used energy resources in the United States. It is used to generate electricity in power
plants, heat up entire buildings, and fuel simple domestic stovetops. Studies conducted by
the United States Department of Energy (DOE) conclude that burning natural gas is cleaner
than burning petroleum and coal by releasing 30% and 45% less carbon dioxide,
respectively [1]. According to the Energy Information Administration (EIA), natural gas
currently supplies 24% of total energy consumption in the United States, and it is expected
to supply 50% of total energy consumption in the U.S. in 2030 [2]. In addition, data from
the EIA shows that the price of natural gas has substantially decreased from 2008 till now
[3]. These two statistics were made possible because of a technique called hydraulic
fracturing, which increases the yield of natural gas. Hydraulic fracturing, commonly known
as fracking, has dramatically driven up the supply of natural gas, but not without
controversy and debate. Reports of hydraulic fracturing consuming large volumes of water
and contaminating groundwater have called for the banning of hydraulic fracturing.
Without the proper knowledge of fracking, it is easy to quickly jump to negative
conclusions that could result in the banning of a technique essential to lessening carbon
emissions. In order to phase out the use of petroleum and coal for a cleaner future, the
process of hydraulic fracturing must be continually used in the extraction of natural gas
and must become correctly and properly understood.
In order to discuss the effects of hydraulic fracturing, it is essential to understand
the process itself. Contrary to popular belief, hydraulic fracturing is not a new technique,
and has been around for decades. Hydraulic fracturing is technique in which fracturing
fluid, which is typically 90% water, 9.5% sand and .5% of chemicals, is injected at high
pressure into a well to cause small fractures in a gas reservoir, a layer of rock formation
with an abundance of natural gas [4]. This is similar to the usage of jackhammers, but while
jackhammers cause fractures on the surface of pavements, hydraulic fracturing causes
fractures deep down in the earth. Natural gas within the rocks of the gas reservoir flow into
these fractures, up the well, and are captured on the surface. More fractures mean that
there is more space for natural gas to flow into, which means a greater yield in natural gas.
Hence, hydraulic fracture is a stimulation process that is done to new wells, or wells that
have experienced a decrease in yield. There is an additional natural process after hydraulic
fracturing called flowback, which can return about 20% of the fracturing fluid back up to
the surface for recycle or disposal [5].
For decades, hydraulic fracturing has been used to stimulate natural gas wells
connected to “conventional” gas reservoirs such as limestone and sandstone formations,
which have relatively high permeability compared to other rock formations [5].
Permeability is the capacity for a material, in this case rock, to transmit a fluid.
Conventional gas reservoirs are permeable enough to yield enough natural gas to make it
profitable to drill more wells in them, as opposed to “unconventional” gas reservoirs like
shale formations, which have a lower permeability than conventional gas reservoirs and
therefore don’t yield enough natural gas to make it profitable to drill more wells [5].
It was not until recently
that a new technique called
horizontal drilling (which is
exactly what it sounds like)
coupled with hydraulic
fracturing made wells in shale
formation permeable enough to
make them profitable [5].
Horizontal drilling occurs once
the desired depth is reached, in
this case, once the well reaches
the shale formation. After
horizontal drilling, hydraulic
Figure1: Diagram of the use of hydraulic fracturing and
horizontal drilling in retrieving natural gas in shale formation.
Source: American Petroleum Institute [4]
fracture is performed to
stimulate the well. Figure 1 on
the side shows an example of hydraulic fracturing and horizontal drilling used together in
shale formation, which is a topic of constant debate due to its high consumptions of water
and reports of groundwater contamination.
There is no denying that hydraulic fracturing in shale formation consumes a
substantial amount of water, but the volume of water consumed is normally reported
without supporting evidence and context. For example, “Fracking Water Use Draining
Resources, Especially in Western U.S., New Studies Find” by Huffington Post states that
North Dakota, Wyoming, Montana and Colorado use 7 billion gallons of water without
proper evidence and context [6]. Another example would be the website
dangersoffracking.com, which states that fracking will use 72 trillion gallons of water [7].
This website uses extreme assumptions that are impossible. The truth is that nobody really
knows how much water fracking uses annually, but there are articles like “Energy Facts:
How Much Water Does Fracking for Shale Gas Consume?” by Jesse Jenkins that try to
estimate the amount. Jesse Jenkins calculated that hydraulic fracturing used around 135
billion gallons of water in 2011 from the 27,000 shale gas wells that were drilled in 2011
and the average use of 5 million gallons of water per well. To put this number into
perspective, the U.S. consumed 43,800 billion gallons of water in 2005 (consumption of
water in this case refers to water that cannot be recaptured because it is assumed that
water injected into the wells cannot be retrieved) [8]. In the U.S., agriculture is the biggest
consumer of water consuming 32,850 billion gallons of water, while shale gas fracking
consumes .3% of total U.S. water consumption [8]. Jenkins uses his own assumptions to
estimate the water consumption of hydraulic fracturing, but there are many additional
assumptions that can be made when calculating annual water consumption of hydraulic
fracturing, which include reusing water captured from flowback or using higher average
use of water per well. In the hydraulic fracturing community, the general consensus is that
fracking uses around 100-250 billion gallons of water annually. Although it may seem like
fracking uses a large volume of water, in reality, it only uses a fraction of the total U.S.
water consumption. Hence, the issue of water consumption should not be blown out of
proportion when debating the banning of hydraulic fracturing.
Aside from water consumption, another concern about hydraulic fracturing is
groundwater contamination. Though there is truth in reports of groundwater
contamination near hydraulically fractured wells, contaminated waters are not necessarily
due to the process of hydraulic fracturing itself. In the study “Methane contamination of
drinking water accompanying gas-well drilling and hydraulic fracturing”, methane
contamination was reported near hydraulically fractured wells connected to the Marcellus
and Utica shale formation in Pennsylvania and New York. The study sampled 68 private
drinking wells, and found that methane contamination was more severe with proximity to
the wells. The average methane concentration of the sample was 19.2 mg/L, which is
within the recommended level for action (>10mg/L but < 28mg/L) to mitigate hazard
defined by the U.S. Department of the Interior, with the highest recorded methane
contamination to be 64mg/L [9]. Ingestion of dissolved methane in water is currently not
classified as a health hazard, but is known to be explosive and deadly at high
concentrations. Figure 2 shows an example of methane-contaminated water taken from a
resident’s well in Pennsylvania [10].
Many articles try to connect
fracking with methane contamination,
such as “Pennsylvania Drinking Water
Study Shows Methane Might
Contaminate Some Wells Near Fracking
Sites” by Kevin Begos from the
Figure 2: Photograph of methane-contamined water
found in a resident’s well in Pennsylvania. Source:
IBT [10]
Huffington Post [11]. However, fracking
may not be the cause for methane
contamination. When wells are drilled into the ground, there are additional layers of casing
and cement in the first 500 – 1,000 feet where aquifers exist are meant to prevent methane
from leaking out of the well as seen in figure 1 [4]. Even though additional layers were
designed to prevent methane from leaving, there weren’t any strict standards for design
and construction [12]. John Hanger, former head of Pennsylvania Department of
Environmental Protection (DEP), blames poorly designed and constructed wells for
methane leakage. He stated that after repairing and plugging gas wells in Pennsylvania,
contaminations decreased to negligible levels in 14 of 19 previously contaminated wells
tested in 2010 by the DEP [12]. Even though not all contamination in wells was eliminated,
it is obvious that the major players in methane groundwater contamination were poor
design and construction. Without full and complete studies on the effects of fracking on
methane contamination in ground water, it is impossible to make any final conclusion, but
elementary studies have falsified the reports that try to connect fracking with methane
contamination.
Hydraulic fracturing is also constantly accused of contaminating groundwater with
fracturing fluid. A study by the Environmental Protection Agency (EPA) in 2011 found 10
compounds used in fracturing fluid in Wyoming’s groundwater [13]. Many quickly
conclude that fracturing fluid deep down in the earth flowed through rock formations and
reached groundwater. However, that is simply not true, shale formation and groundwater
is separated by at least 4,000 feet of impervious solid rock formation, which makes
contamination from fracking practically impossible [14]. “The Hydraulic Fracturing Water
Cycle” by EPA suggests that there are many possibilities for fracturing fluid to get into the
groundwater that is not in the specific process of injecting fracturing fluid in hydraulic
fracturing [15]. These possibilities include spillage of chemical during delivery, flowback,
and waste disposal and leakage in well casing and abandoned waste pits. In the case of
Wyoming, EPA identified 33 abandoned oil and gas waste pits that are to some degree
contributing to groundwater contamination. It is again obvious that the process of
hydraulic fracturing does not contaminate groundwater, but that it is the careless and
negligent treatment of chemicals and waste that is used and produced in hydraulic
fracturing that causes the pollution of groundwater.
In conclusion, even though the process of hydraulic fracturing consumes negligible
amounts of water and doesn’t cause groundwater contamination, there are many
improvements and provisions that can be made to reduce water consumption and prevent
groundwater contamination. In terms of decreasing water consumption, flowback fluid is
filtered to extract water for reuse. This advance has made it possible to reuse up to 70100% of flowback fluid [16]. As for preventing methane contamination in groundwater,
Pennsylvania enacted stricter regulations for the design and construction of gas wells to
prevent leaking in February 2011. This new regulation also requires test, monitor and
disclose the chemicals used in hydraulic fracturing [12]. In addition, companies are
retrieving and recycling wastewater previously dumped in waste pits as an effort to
prevent wastewater from leaking into groundwater [15]. Hydraulic fracturing is safe
process for groundwater and is key to extracting natural gas for a cleaner future.
References
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