by Iliana Sepulveda*
Water is essential for human life. It is also very useful for transportation, and agricultural and industrial production. Energy is also an essential ingredient. The relationship between these two resources has become an important topic for national security and for human development worldwide. With current available technology, vast quantities of water are required to produce energy (thermoelectric production as an example). Moreover, due to the geographical mismatch of water supply and demand, a significant amount of energy is needed to transport water where it is consumed, and to ensure that it has the proper quality for its different end uses (human consumption, agricultural uses, industrial production, and ecosystems protection).
Since the amount of fresh water that can be accessed by humans is only 0.3169 percent of the earth’s total, there is direct competition for its use.[i] The decision of how much water to allocate for human consumption, food production, energy generation, industrial output or environmental needs is not an easy one. Furthermore, in each category, many alternatives for the use of water arise. For example, in the energy sector, the amount or quality of the water required depends on the energy source and the technology used to convert it into a productive resource (like electricity or gasoline).
Fossil fuels such as oil and natural gas require vast amounts of water in their extraction process, as does coal mining. This quantity becomes even higher when accounting for the refining or the electricity generation processes in thermoelectric plants. In fact, electricity generation has some of the largest water needs in the United States and worldwide.[ii] In thermoelectric plants, water is used to generate electricity with steam-driven turbine generators and for cooling processes.[iii] Nuclear power generation uses a similar cooling technology. Nuclear power is the thirstiest energy source, using about 2.5 times the water per unit of electricity produced than natural gas.[iv] In 2005, almost 50 percent of total withdrawal of water in the US was allocated to thermoelectric power generation.[v] However, not all the water reserved for electricity generation is actually consumed. The term withdrawal refers to the amount of water removed from the local water source -that may or may not get returned to the same source after the process-, while consumption defines the amount of water that will definitely not return to the its source because it has been lost in the production process, usually through evaporation.[vi] However, water returned can contain traces of chemicals or have a significantly higher temperature, a pollution known as thermal intrusion. Water pollution is especially controversial in shale gas development, as regulation over this practice remains too lax and the related environmental impacts have yet to be fully understood.
In the renewable energy sector, the panorama is just as dire. Hydroelectric power generation utilizes large quantities of water to generate electricity in a non-consumptive way. However, evaporation rates derived from large reservoirs represent a challenge. First generation biofuels also require large quantities of water for growing corn, sugar cane or any other fiber used as biomass. While solar and wind require far less amounts of water during the electricity generation phase, much water is consumed in the infrastructure’s upstream production processes manufacturing solar panels and wind mills.
To meet growing urban centers’ energy demand, the decision on how much energy should be produced and from what sources is of fundamental importance. Moreover, as water resources are often shared between states or countries, competition increases as different stakeholders hope to use the same resource for economic prosperity, human development and environmental conservation. For this reason, fairness and economic issues arise. For example, is it better to produce the energy needed locally or would the region benefit from importing it from other states? Furthermore, as new issues arise, such as too lax regulation surrounding shale gas development, more layers of complexity are added to the water-energy nexus.