Energy or water?

Energy return of energy invested is a concept well known in the industry. An equally important concept is that of Energy return on water invested (EROWI).

Water is needed for irrigation of plants and in large power plants for cooling. Nuclear plants are especially vulnerable to water scarcity. Many drain water into rivers at higher temperatures than considered safe. But nuclear power plants built next to the ocean use salt water for cooling. The resulting steam is cooled down and turned into fresh water. But of course, energy is spent for that.

Thermal plants are no exception; coal plants for instance. A "closed loop" cooling system would save water but at the expense of energy. The U.S. for example generates about 13.1 MWh per person per year. The total water consumption/person/yr there is a colossal 121,000 gallons!

In the final analysis, what should we concentrate on – saving energy at expense of water, or save water at expense of energy? Which can we live without?!