Specific Connection in Energy-Water Nexus

Growing urban communities and industrial facilities increasingly require water supplies that already are stretched by demands from other sectors. Seasonal droughts and protracted water shortages are ubiquitous in many areas, particularly in developing countries. Increasing contamination of groundwater and surface water due to rapid urbanization and economic development has further reduced available water sources. As freshwater sources become depleted, it becomes more difficult and expensive to pump, transport, and treat water from original sources for portable use. In addition, the processes required to supply potable water often consume energy.

Resource Significance

Urban water usage has increased steadily to reflect more concentrated populations and intensified economic activities around urban areas. Although the volume of water dedicated to urban use is less than that used by agriculture and other sectors, its social and economic importance is enormous. And urban water has a high embedded energy content, between 1,100 and 20,100 kilowatt-hours per million gallons (California Energy Commission, 6/2005).)

Sector Challenges and WETT Solutions

Urban water usage is unique in its fragmentation, in terms of both physical utilization of the resource and the institutional structures that govern its use. Municipal uses usually include residential plus industrial, commercial, and institutional (ICI). Each end use has distinct quality requirements, usage processes, disposal methods, and jurisdictional oversight and responsibilities. As a result, there is no cohesive approach to planning and policy that can formulate consistent and effective responses to urban water issues, in particular protracted droughts.

This fragmentation has increased the attention paid to demand-side management in both the residential and ICI municipal sectors. Programs are designed to modify the level and/or timing of consumers’ demands for water by encouraging changes in either consumer behavior or the efficiency of water-using appliances or equipment.

Water-related technologies also help determine the amount of water needed to meet demands. Water-efficient technologies range from low-flow toilets to electronic controllers on irrigation equipment and sophisticated innovations in industrial processes. Other technologies are being developed to improve the efficiency of existing plumbing fixtures and fittings, appliances, and drip irrigation, as well as to modify people’s habits regarding how and when they use water (e.g., programmable electronic controllers for landscape watering). The Water and Energy Technology Team (WETT) at Lawrence Berkeley National Laboratory has investigated topics ranging from options for distributing residential hot water to the economic effects of efficiency standards for clothes washers. Our goal is to save both water and energy through innovative engineering designs, rigorous testing procedures, and information dissemination.