Water and energy are fundamental to life on Earth. Water, which covers most of the planet, is essential to both basic biological processes and advanced economic systems. Energy empowers living organisms and makes our modern life possible. Most people, however, don’t fully recognize the connection between water and energy. Water is used in the production of energy. Energy is used to process and distribute clean water. This interrelationship is known as the Water-Energy Nexus and is important to understand when considering critical systems infrastructure. Water in Energy
Water is used in various fashions in the production of energy. On one far side of the nexus, energy is produced in the absence of water. Technologies such as wind turbines and photovoltaic cells don’t require water as they are generating power. However, a comprehensive lifecycle analysis would show that the manufacturing process of solar panels and the steel and concrete used in the construction of wind turbines do require water. The next step along the nexus shows water use in conventional energy. It is used extensively in fossil fuel extraction as well as a coolant in thermoelectric power generation. Major considerations here include water quantity and quality. While evaporated water isn’t “wasted” from the point of view of the closed system of the planet, regional supply and demand are major factors. The middle of the nexus shows water as an energy source such as through the use of hydroelectric dams. Todd Loar and Robyn McGuckin with MWH Global, a leader in “wet infrastructure”, presented at the recent Energy Africa Conference held at the Colorado School of Mines. They raised the audience’s awareness of the Water-Energy Nexus through sharing experiences and perspectives from their company’s expertise in engineering, construction, and consulting for infrastructure projects involving both energy and water.
Energy for Water
Purifying and transporting water requires energy. In nature, this is known as the hydrological cycle. Energy from the sun heats water into evaporation and it later precipitates once it cools. Cities are dense areas of water consumption. This demand often exceeds the natural supply in the area. The physical and chemical processes used in municipal and industrial sized water treatment plants require significant amounts of energy. According to a 2007 state assembly committee report, "In California, water related energy use, which includes the conveyance, storage, treatment, distribution, wastewater collection, treatment, and discharge sectors of the water use cycle, consumes about 19 percent of the state’s electricity, 30 percent of its natural gas, and 88 billion US gallons (330,000,000 m3) of diesel fuel every year–and this demand is growing." Part of this energy demand stems from the fact that ⅔ of California’s precipitation falls in the north, while ⅔ of the state’s population lives in the south. On the far side of the nexus, “water without energy” represents the billions of people who don’t have energy to clean and distribute their water for them. For many around the world, several hours a day must be spent carrying water. Though not exclusively a female problem, much of this responsibility falls to women and can limit their ability to gain an education or a job outside the home. According to the U.N., diarrhea is the leading cause of illness and death globally. Lack of access to pure drinking water and sanitation is responsible.
The Water-Energy Nexus is a broadly encompassing concept that ranges from solar panels on one side, to a child dying every 20 seconds from lack of sanitation and the resulting dehydration. The purpose of MWH Global’s presentation as well as this ICOSA article and accompanying online video is to raise awareness. Water and energy are critically interrelated and this relationship has implications for the environment, the economy, for business, and for human lives. As humanity faces unprecedented challenges, comprehensive understanding is necessary for improving designs of our planet’s systems.