Also called hydraulic fracturing, fracking is the process to extract natural gas by pumping chemically treated water and sand into a drilled well to crack shale rock, releasing natural gas trapped underground. Fracking is an important technology because it promises a significant new source of natural gas output from deposits that were previously impossible or too expense to extract. Both the U.S. and China have discovered significant shale gas deposits that are sufficient to supply enough natural gas for the world’s top two energy consumer markets for decades.

However, fracking has been highly controversial due to popular fears that the chemically treated liquid can cause ground water contamination leading to health issues. On the other hand, supporters of the technology state that the chemicals used for fracking are derived from food ingredients and that the liquid is pumped into the ground at a depth well below the drinking water table.