Hydraulic fracturing is a technique used in one step of the extraction of energy resources. Sometimes referred to as "fracking," its wide application over the last decade has led to debate over its risks and benefits.
Hydraulic fracturing opens narrow cracks in rock layers in order to allow oil, gas, or water to flow through the rock. During hydraulic fracturing, pressurized fluid is injected through a well into a subsurface rock layer in order to open the fractures. Hydraulic fracturing requires large volumes of water mixed with chemicals and proppants (often sand, used to "prop" open the fractures). These fluids must be recycled or disposed of in deep wells, separate from local water tables. Read more