If fracking has a disadvantage, though, it's not the famous problems with burning water, (methane has been found in water for centuries so it's not from the fracking) it's that it uses a lot of water. It is hydraulic fracturing after all In case you haven't noticed it, there have been articles appearing for years saying the next big shortage that's going to affect us all is drinkable water. (for example)
In the current copy of trade magazine Machine Design, I noticed an interesting article by writer Elisabeth Eitel which takes on the subject and reveals a very clever idea.
One Canadian company goes even further with a waterless process. GasFrac Energy Services Inc., Calgary, makes equipment that fracks wells with liquid petroleum gas (propane) infused with viscosifying additives. It doesn’t muck up millions of gallons of water. It pulls more fuel out of wells. All the propane is reclaimed.Frankly, I think this is really ingenious. The benefits are all enormous there. No water to recover, or abandon underground; the process extracts more gas with propane than water; plus propane is chemically very similar to the gas being extracted and the gas refinement process undoubtedly can remove it. That suggests it's reusable. It simply has everything going for it. I assume there must be some drawbacks, but I don't see what they might be.
Water is [a] polar [molecule], so it has a notoriously high surface tension of 72 dyn/cm and tends to get stuck in the capillaries of fracks. In contrast, propane (C3H8) has a surface tension of just 7 dyn/cm, so it easily slips into shale’s nooks and crannies. That helps rig pressure reach deeper into well formations and crack open more recesses. Low surface tension also helps when the process is reversed and pressure is released: Water tends to plug formations, but propane lets more gas flow out for collection. Propane has half the specific gravity of water and small volumes do the job, so tanking sufficient supplies to wells takes fewer trips. After a well tap, propane doesn’t necessitate separate transport back out of the site like water, because it mixes with natural gas and trucks out with the fuel. [portions in brackets added - link added - SiG]