One is that without a large dam or reservoir, there is no way to store energy and adjust power output according to peak periods of consumer demand.

FORBES: Hydroelectric Revolution: A River Runs Through It

We trade or invest our surplus output using dollars to measure transactions today or to store value for future enjoyment.

FORBES: Why The Recession Recovery Remains Anemic

Geological surveys show America has enough saline rock formations to store three trillion tons of carbon dioxide enough for the next 500 years at the country's current output from human activities.

ECONOMIST: Tech.view