In the U.S., 4% of all electricity used is to transport and treat water. In California, where dense population and scant water resources prevail, that number jumps to 19%, with 31% of the state's natural gas use also going to the ongoing supply of freshwater.

And the nexus works conversely.

It can take up to 168 gallons of water to get one barrel of oil from oil sands. And 800 gallons are required to generate one megawatt-hour of electricity from traditional resources.