Environmental Engineering Reference
In-Depth Information
year in 2011, only one fourth of the world average.
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China's severe water
shortages have already constrained economic growth during the last dec-
ade.
4
Hydraulic fracturing, however, is highly water intensive. The problems
are made even worse by the fact that water resources are unevenly distrib-
uted spatially and temporally. Except for the Sichuan basin, the other major
shale gas basins in China are located in the arid and water-scarce north and
northwest. Therefore, the development of shale in China may be severely
hampered by lack of water resources.
7.5 Environmental Issues
Hydraulic fracturing is a technology that involves injecting water, chemicals
and proppants to break shale rock and release the gas locked in it. Hydraulic
fracturing is controversial due to the environmental risks involved in the
fracturing or 'fracking' process, which can result in issues of landscape and
land usage, ground water contamination, minor earthquakes, waste water
disposal and greenhouse gas emissions after fracturing.
7.5.1 Land Consumption. During the construction phase for a well
pad and associated infrastructure, such as unimproved or gravel roads
for trucks, water storage, gas processing and transporting facilities, etc.,
land is needed. China has only 7% of the world's farmland and per
capita farmland occupation is only about half of the world average rate.
In the last several decades, remarkable economic success in China has
caused rapid loss of farmland to residential, industrial and commercial
uses. This further restricts access to land for large-scale shale gas drilling.
7.5.2 Aquifer Water Contamination and Waste Water Disposal. The con-
tamination of aquifer water and wastewater from hydraulic fracturing has
been one of the most prominent areas of debate. This is due, in part, to
the success of the 2010 documentary, Gas land, which largely focused on
the issue of water contamination from fracturing fluids containing hazard-
ous substances such as benzene, toluene, formaldehyde or hydrochloric
acid and methane. Fracturing fluids, methane and H
2
S from fracked shale
formation in China could get into the aquifer water and cause serious con-
tamination if a well is not properly cemented. Flow-back wastewater may
contain salt, chemicals, heavy metals and radioactive materials, which
could be problem if not properly processed.
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7.5.3 Greenhouse Gas and H
2
S Emissions. Compared with conventional
gas, the development of shale gas has a higher risk of greenhouse gas (me-
thane and CO
2
) release. Some shale gas reserves in China also potentially
contain hazardous levels (41%) of H
2
S. Inappropriate collection and treat-
ment of these air pollutants will affect the local air quality. Given the high
population density in China, the impacts of air pollution and climate
change should not be neglected.
