Which is more important: Meeting energy demand, lowering carbon emissions, or conserving water? How about all three?

The U.S. electric power industry has huge challenges to meet in the coming decades.

First and foremost it has to meet growing demand for electricity. By 2050 it is estimated that U.S. demand will grow by about 37 percent*.

And then there’s climate. In 2012 the U.S. electric industry emitted 2,039 million metric tons of carbon dioxide (CO2) — that’s almost 40 percent of all U.S. energy-related emissions. To meet the climate commitments made in the Copenhagen Accord, U.S. emissions will almost certainly have to come down substantially even while total power generation goes up.

And finally there’s water. The electric industry uses