Environmental Engineering Reference
In-Depth Information
Figure 6.8.
A tar sand mine in Alberta (Canada) in 2006. The extraction site is to the
left of the image, the plant to the right, and the sulphur stockpiles in the middle.
Source:
TastyCakes/Jamitzky at Wikimedia Commons.
Shale gas is equally, if not more, contentious than tar sand oil extraction. Up to now the
most commercially viable method of extracting this natural gas trapped in shale rock has
been to inject water under high pressure, combined with sand and a cocktail of chemical
agents, thereby blasting pathways into the shale, allowing the gas to escape. This method,
known as hydraulic fracturing or 'fracking' has only been widely applied in the last ten
years, but it has already transformed the U.S. natural gas market. The main environmental
problem with fracking is the risk of groundwater contamination. This can happen if the
water-chemical mixture or the released gas finds a way through the well into aquifers (and
since many aquifers are connected, the contamination is likely to spread), or if the pools
containing the contaminated water that flows back out of the well leak or overflow.
