But, until the practice became the mainstay of new shale gas production hydraulic fracturing was about as uncontroversial as drilling itself. (Yes, there are deliberate ironies in that statement.)
Geologically speaking (roughly), a gas or oil "play" involves source rocks (which are the locations where the hydrocarbons were deposited and matured) and traps (which are locations where the oil and gas migrated to in economically recoverable quantities). Oil and gas, being less dense than water, migrate upwards as buoyant fluids in the overlying rocks until they are trapped by impermeable layers. There are other styles of trap, but that gives you the gist of it.
Old style oil and gas plays exploited the traps. Fracking plays now exploit the (mostly shale) source rocks.
In my opinion, what caused the recent controversies are the sheer numbers of wells being drilled for fracking. In addition to the new locations where development takes place -- at least in recent memory in places like Pennsylvania -- there were also a larger number of accidents per unit time. Perhaps there was an element of less-experienced operators drilling and fracking wells that also increased the rate of accidents.
EGS geothermal plays fracture rocks, yes. (Heck, so do quarries for things like road metal.) But the resource value proposition is so weak compared to hydrocarbons that geothermal people realize they MUST do things right or they will be shut down. Hence, better casing designs -- leading to far fewer leaks -- and a reluctance to use nasty chemicals.
Everything is a tradeoff. Geothermal is not a fossil fuel. But it is not a panacea either.
But, until the practice became the mainstay of new shale gas production hydraulic fracturing was about as uncontroversial as drilling itself. (Yes, there are deliberate ironies in that statement.)
Geologically speaking (roughly), a gas or oil "play" involves source rocks (which are the locations where the hydrocarbons were deposited and matured) and traps (which are locations where the oil and gas migrated to in economically recoverable quantities). Oil and gas, being less dense than water, migrate upwards as buoyant fluids in the overlying rocks until they are trapped by impermeable layers. There are other styles of trap, but that gives you the gist of it.
Old style oil and gas plays exploited the traps. Fracking plays now exploit the (mostly shale) source rocks.
In my opinion, what caused the recent controversies are the sheer numbers of wells being drilled for fracking. In addition to the new locations where development takes place -- at least in recent memory in places like Pennsylvania -- there were also a larger number of accidents per unit time. Perhaps there was an element of less-experienced operators drilling and fracking wells that also increased the rate of accidents.
EGS geothermal plays fracture rocks, yes. (Heck, so do quarries for things like road metal.) But the resource value proposition is so weak compared to hydrocarbons that geothermal people realize they MUST do things right or they will be shut down. Hence, better casing designs -- leading to far fewer leaks -- and a reluctance to use nasty chemicals.
Everything is a tradeoff. Geothermal is not a fossil fuel. But it is not a panacea either.