State legislatures and natural resource managers have traditionally addressed water and energy as two separate issues. However, water and energy are deeply connected and sustainable management of either resource requires consideration of the other. Thus, resource managers and lawmakers across the country are beginning to take a comprehensive and interdisciplinary approach to the management of water and energy. This report provides overview information about the nexus between water and energy and provides a summary of state legislation addressing this issue.
Water Energy Nexus Overview
Water and energy are critical, mutually dependent resources- the production of energy requires large volumes of water and water infrastructure requires large amounts of energy.
Water is required to generate energy. Thermoelectric cooling, hydropower, energy mineral extraction and mining, fuel production (including fossil fuels, biofuels, and other non-conventional fuels), and emission controls all rely on large amounts of water. In the United States, the electricity industry is second only to agriculture as the largest user of water. According to the National Renewable Energy Lab, electricity production from fossil fuels and nuclear energy requires 190,000 million gallons of water per day, accounting for 39% of all freshwater withdraws in the nation. Remarkably, in many regions of the country, we use as much water turning on the lights and running electric appliances in our homes, as we use in taking showers and watering lawns.
On the other hand, water supply also requires energy use. A large amount of energy is needed to extract, convey, treat, and deliver potable water. Additionally, energy is required to collect, treat, and dispose of wastewater. Approximately 4 percent of U.S. power generation is used for water supply and treatment and about 75 percent of the cost of municipal water processing and distribution is electricity, according to the Department of Energy.
Water and energy are both multifaceted issues with many variables impacting their supply, demand, and management. Lawmakers should consider the following variables which add complexity to the management of water and energy:
Growing population: According to the 2001 National Energy Policy, our growing population and economy will require an additional 393,000 MW of new generating capacity. This generating capacity equates to 1,300 to 1,900 new power plants by 2020 that will require additional water withdraws.
Agriculture: Water demands will increase as agricultural demands increase with the need to feed a growing population. In 2000 irrigation accounted for about 40 percent of fresh water withdraws in the U.S., according the U.S. Geological Society.
Geographical water demand: Water supply and demand are not geographically linked. During the 1990's, the largest regional population growth, 25%, occurred in the mountain West, one of the most water deficient regions in the United States. In comparison to the Southeast, where population increased by 14% and the Northeast which only experienced a 2% growth in population. Additionally, water consumption in the western U.S. is much higher than other regions due to agricultural demands. It is estimated that it takes over 1 million gallons of water a year to irrigate one acre of farmland in arid conditions. In other words about 86 percent of irrigation water withdrawals were in western states in 2000.
Climate Change: The impacts of climate change may also impact water supply and availably. It is predicted that the timing of spring rains and winter snows may change in many regions, impacting stored water, agricultural production, and water supply. For instance, in the northwest climate change may cause more winter precipitation to fall as rain instead of snow, increasing streamflow and decreasing the winter snowpack, in turn impacting hydro-ecltrcity capacity and water supply.
As water and energy demand and supply shift, managing the two resources in tandem will help states maintain reliable and sustainable supplies of both energy and water. To sustain energy production and a dependable water supply, the U.S. must gain a detailed understanding of the interdependencies of water and energy systems, balance the needs of all users, and develop technologies to reduce water use and loss (i.e. water conservation and efficiency). These goals can be achieved through advancing water and energy system prediction and forecasting, scientific and technological innovation, and the implementation of technologies and management systems. State lawmakers and constituents will be critical in this process given their responsibility formulating policy, convening stakeholders, facilitating negotiations, and ratifying reached agreements.
