Producing more power means using more water

This problem with the so-far embryonic industry is what regulators and industry experts call an “energy-water nexus” issue: Just as water needs energy to travel from source to tap, nearly every form of energy needs water throughout its lifecycle, from mining to generation to reclamation.

Most of the country’s electricity, for example, comes from coal, gas or nuclear plants that heat water until it flashes to steam and spins a turbine; that steam then has to be cooled back into water — using yet more water.

Biofuels use water, from cultivation to distillation, and some forms of geothermal production consume as much as 800 gallons per megawatt-hour of electricity, the amount of power the average home uses in a month.

Energy, says the Congressional Research Service, outpaces municipal use in its water demands; it’s second only to agriculture. And while farms and cities have begun to conserve water, energy — thanks to biofuels and shale gas — is increasingly voracious.

Nor is consumption the only issue: Electricity plants return almost all that cooling water to the source, but they return it at a higher temperature, altering riparian or marine ecosystems.

The Government Accountability Office has published five reports over the last three years on energy-water nexus issues, analyzing oil shale’s water needs, the interdependency between electrical plants and their water supplies, and the hydrologic impacts of hydraulic fracturing.

But the GAO’s sixth and latest report, published in September, argues that the most crucial component of the nexus is information sharing — between state and local governments, industry and science, and even across federal agencies.

“People have been aware of these issues from their individual viewpoints at various agencies,” says Frank Rusco, the GAO’s director of water and energy issues.

The Energy Department might understand that hydrofracturing for natural gas could contaminate local water supplies, for instance, but the Environmental Protection Agency may lack baseline studies showing the water’s condition before industry got there.

Interior officials might suspect that developing oil shale in Colorado could exhaust local water supplies, but not have accurate data to prove it.