Water and Energy Interactions

Human habitations require energy and water, which are increasingly interdependent. Energy systems have changed from using water for mechanical energy to building dams to provide irrigation water for agriculture and hydroelectricity. Large volumes of water are required to cool thermal electricity-generating stations—whether coal, natural gas, nuclear, or solar powered. Changes in cooling technology are reducing water withdrawals while increasing water consumption. Water produced from fossil fuel production represents environmental challenges and supply opportunities. Some renewable energy sources, such as wind turbines and photovoltaics, have far lower water requirements. Increasing development of biofuels creates a direct connection between water and energy systems. Energy, mostly for pumps, is necessary for supplying potable water and treating wastewater. Pumping from deeper underground as well as removing more contaminants (e.g., medicines, agricultural chemicals) and salt requires more energy. Water and wastewater treatment can dominate electricity demand in municipalities. Water reuse requires energy for treatment and pumping. Life cycle assessments and integrated resource planning strive to account for the total impacts.