Research

California’s water system, which transports water hundreds of miles and thousands of feet over mountain ranges, is very energy-intensive. Conventional energy production is highly water-intensive. Despite the inextricable interdependence of power and water systems, these systems and the bodies that regulate them stand apart from each other.

The Center for Water–Energy Efficiency is working to accomplish sustainable results in the water and energy sectors by breaking down the divide between them, giving consumers, engineers, and policy-makers new ways to conserve energy by saving water and conserve water by saving energy. We are investigating and advancing the state of knowledge at the home, neighborhood, utility, and global scales to enable everyone—from homeowners to heads of state—to make the connection between water and energy and to use and allocate both more efficiently.

CWEE is working to accomplish sustainable results… giving consumers, engineers, and policy-makers new ways to conserve energy by saving water and conserve water by saving energy.

Our portfolio of research reflects this broad focus. At the residential level, in collaboration with our colleagues at the Western Cooling Efficiency Center, we worked to establish the baseline water–energy consumption values for evaporative cooling systems used with fresh and recycled “gray” water. We scoped the possibility of achieving zero-net water use at UC Davis’s new West Village multi-use neighborhood development, determining what conservation techniques and energy accounting practices would enable practical zero-net water at the household, multifamily, and neighborhood scales.

Our explorations revealed a problem at the urban scale: though water utilities are essential agents for change in water–energy conservation, their efforts to conserve are stymied by rate structures with built-in structural deficits. The more customers save, the harder a hit water utilities take to their bottom line. Existing rate structures offer solutions to this problem that ratepayers perceive as unfair, or even punitive. To address this, CWEE Director Frank Loge co-authored the consumption-based fixed-rate (CBFR) water rate structure now adopted by the City of Davis, which we hope will be a model structure for water utilities around the state and beyond. With conservation-related deficits eliminated, water utilities will be able to pursue novel and aggressive conservation schemes without fear of “rewarding” ratepayer conservation with higher rates.

With a rate structure that assures revenue stability, cities and utilities can tackle new water–energy savings. One such method involves giving water customers detailed information about their water use and how to conserve using sophisticated analytics as part of their water bill information. Beyond the easy and obvious immediate savings of water, we’re further helping define the energy savings from water conservation and water heating that accompany the overall water savings claimed by conservation software vendors.

We’re also engaging with water and energy utilities around California, starting with East Bay Municipal Utility District and PG&E to establish the energy intensity of water at the tap. While every water district’s unique terrain precludes a one-size-fits-all energy intensity per gallon, our advanced techniques can use water utility system control data to provide a close approximation of the energy intensity of water for any given water system. Overlaid with Geographic Information System (GIS) and other geospatial technologies, these data offer utilities extremely detailed, rich information about where and when to target conservation measures to maximize energy efficiency and target maintenance and upgrades.

While we can accurately approximate a water utility’s energy intensity using such simple data streams as energy utility billing and the ubiquitous and venerable SCADA (supervisory control and data acquisition) data, water systems remain “black boxes”—we can measure inputs and outputs, but what goes on in between is often a mystery. New technologies promise new capabilities, if we seize the opportunity to develop them. Streams of “big data” from a new generation of cheap, ubiquitous, intelligent sensors, yielding rich streams of data on water pressure, temperature, volume, leakage, and quality will enable future decision-makers to target repairs and adjust pressures more effectively and efficiently, taking energy intensity (and economies of conservation) into account. Working with leaders in cloud computing, CWEE is laying the groundwork to realize this cloud data-based utility-scale water–energy efficiency revolution.

At the global scale, CWEE Program Manager Ned Spang reviewed all the world’s non-hydroelectric power and industry-standard water consumption statistics to document the water intensity of energy production in “A thirst for power: A global analysis of water consumption for energy production.” This paper won First Prize in the 2012 UNESCO Global Water Forum Emerging Scholars Award paper competition. In addition to breaking down water consumption by power type (i.e., nuclear, coal, natural gas, etc.), Spang described the energy portfolios and water intensity of each of the world’s reporting nations, per capita, by financial productivity, and in the context of local water stress. We hope that this first-order research will inform planning and policy decisions concerning the water intensity of future national energy systems.