Vincent Tidwell
Sandia National Laboratories

The Energy-Water Nexus:  Report to Congress and National Roadmapping Exercise

Water and energy are inherently linked. Water is used directly in hydroelectric power generation and is used extensively for thermoelectric power plant cooling and air emissions control. Water is also needed for energy-resource extraction, refining, and processing, as well as for energy resource transportation. Altogether, the energy sector accounts for approximately 39 percent of daily fresh water withdrawals and 48 percent of total overall daily water withdrawals in the U.S. Likewise, significant energy is expended to extract, convey, treat and deliver water and waste water. While the total energy requirement by water utilities is highly location-specific, the California Energy Commission has estimated that almost 20 percent of California’s electricity demand, and over 30 percent of California’s natural gas demand, are associated with water use.

The Energy Information Administration projects the U.S. population will grow by 70 million people by the year 2030, increasing electric power demand by 50 percent and transportation fuel demand by 30 percent. The emerging electric power generation and transportation fuel needs will require more water—the extent depending on the type and number of power plants built, cooling technologies used, air and carbon emission requirements, and the type and quantity of transportation fuels used. This growth in water demand will occur at a time when the nation’s fresh water supplies are seeing increasing stress from limitations of surface-water storage capacity, increasing depletion and degradation of ground water supplies, increasing demands for the use of surface water for in-stream ecological and environmental uses, and the uncertainty about the impact of climate variability on future water fresh surface and ground water resources.

To address this emerging energy and water interdependency challenge, Congress directed the DOE in 2005 to “initiate planning and creation of a water-for-energy roadmap”. This roadmapping process relied heavily on stakeholder input gathered through three regional needs workshops and two technology identification workshops. Almost 500 stakeholders from over 40 states participated in the five Energy-Water workshops representing a broad range of energy and water agencies, developers, regulators, users, managers, utilities, industry, and academia. Participant input and suggestions were used to define the future research, development, demonstration, and commercialization efforts needed to adequately address emerging water-related challenges to future, cost-effective, reliable, and sustainable energy generation and production.

This presentation will convey results of the recent Report to Congress (DOE 2006), which provides the basic context for the emerging energy and water resource issues and challenges as they relate to water demands and water impacts on future energy production and generation. Additionally, results of the roadmapping exercise will be presented and discussed in efforts to better understand the broader energy-water-policy-technology nexus.