The water-energy nexus is the relationship between how much water is evaporated to generate and transmit energy, and how much energy it takes to collect, clean, move, store, and dispose of water. The energy sector may be the largest water consumer among all industrial sectors. As long as there is a surplus of both water and energy, we do not realize the close relationship between them. When any of them gets limited, it becomes necessary to consider their interdependence. Most of us realize intuitively that all water operations will require energy. It is less obvious that all energy production and generation also require a lot of water; for the extraction, refining, and electric power generation. As a consequence, water and energy systems and operations have to be planned together. Already there have been many negative consequences of water or energy systems being planned separated from each other.
Some examples of the water and energy interdependence can be mentioned: Between 1% and 18% of the electrical energy in urban areas is used to treat and transport water and wastewater. Furthermore, the energy related to water use – mostly heating the water in households and industries – requires about ten times more energy compared to the energy needed to deliver the clean and cold water and to treat the wastewater. To treat water to drinking standards requires energy. As the raw water source becomes more contaminated traditional methods are no longer sufficient. More energy will be required to treat the water to drinking standards, using for example membrane technology. Hydropower generation obviously depends on water. The dam itself often resembles a gigantic sedimentation basin, and the silt brought by the river flow and that earlier served as fertilizers downstream now are trapped in the dam. Obviously the water flow downstream is affected. Increasing water shortage in combination with increased water use in many regions is now causing lack of water in the dams. With lower water levels the generation of electricity is decreasing.
Projects under Water-Energy Symbiosis:
Assessment of Expert Appraisal of Land Use Impacts in the Brazilian Sugarcane Bagasse Life Cycle
The Regional Energy & Water Supply Scenarios (REWSS) Model
Use of Treated Municipal Wastewater as Power Plant Cooling System Makeup Water
Process Based Life-Cycle Assessment of Natural Gas from the Marcellus Shale
Modeling Future Life-Cycle Greenhouse Gas Emissions and Environmental Impacts of Electricity Supplies in Brazil