Primer

The Water-Energy Connection

The farther we have to pump water, the greater the energy use—especially if we have to pump it over mountain ranges, like in California. For many cities and towns in the U.S., water pumping and sewage treatment use more electricity than anything else. On a per-capita basis, this energy use for water pumping and treatment varies from about 350 kWh/year in the South Atlantic states to over 750 kWh/year in the Mountain states, according to a 2002 Electric Power Research Institute report—about as much annual use as a refrigerator.

Just as it takes energy to provide water, it also takes water to provide energy. Roughly 89% of U.S. electricity is produced in thermoelectric plants—plants that use a heat source such as coal or nuclear fission to produce steam, which spins a turbine that generates electricity. Water is used to create the steam, and then more water is used to cool that steam and condense it back into water. Averaged nationally, thermoelectric plants use 0.47 gallons of water for each kWh of electricity produced, according to a 2003 National Renewable Energy Laboratory (NREL) paper (see “Save Energy to Save Water,”

Published September 29, 2010