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WATER ENERGY

Opportunities

The California Aqueduct transports water from Northern to Southern California.
The California Aqueduct transports water from Northern to Southern California.

Approximately 65% of the California’s water supply is in Northern California while 65% of water demand is in Southern California.  California’s water conveyance system requires an enormous amount of energy to transport water through hundreds of miles of canals and pipelines and dozens of pump stations from the north to the south.   Water treatment, distribution and wastewater treatment also require significant energy. A set of studies recently completed for the California Public Utilities Commission estimated that about 7.7% of the state’s total electricity requirements are used every year by the water infrastructure. 

A simple diagram of the water use cycle is used as a framework for identifying and qualifying opportunities to optimize the net resource, economic and environmental benefits of the state’s water and energy resources and infrastructure. Opportunities to optimize water and energy in combination exist in all segments of the water use cycle.

California's Water Cycle

To help quantify the opportunities for energy savings in the water sector, the CEC introduced the concept of energy intensity as a means of expressing the relative magnitude of water-energy relationships.

“Energy intensity is defined as the amount of energy consumed per unit of water to perform water management-related actions such as desalting, pumping, pressurizing, groundwater extraction, conveyance, and treatment - for example, the number of kilowatt-hours consumed per million gallons (kWh/MG) of water. This concept is applied to water supplies, to components of the water use cycle, and to the total energy intensity of a unit of water throughout the entire water use cycle.1”

The energy intensity of future water supplies (marginal supplies) is expected to increase dramatically due to increased pumping requirements, higher treatment energy use by brackish and seawater desalination, and more stringent treatment requirements for discharge of wastewater.  For example, the average energy intensity of untreated water supplied to Southern California is approximately 3,500 kWh/MG; however, the energy intensity of marginal supplies ranges from 3,500 to 12,200 kWh/MG.  

Key strategies to keep energy costs from sharply increasing as a result of increased reliance on marginal water supplies include: conserving water, investing in energy efficient water infrastructure, new technologies to reduce energy use by marginal supplies, and expanding the use of recycled water (a less energy intensive supply).  Additional actions are detailed in the next section: Measures.

 

1California Energy Commission. California’s Water-Energy Relationship. CEC-700-2005-011-SF. November 2005.

The life cycle of water; from collection and production, to treatment, delivery to end uses, consumption, and for treatment of wastewater that is either recycled or discharged.
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Water Treatment Plant Operator holding a sample of recycled water
Water Treatment Plant Operator holding a sample of recycled water
Recycled Water Study

In the U.S., many non-potable uses are served by potable water that has been treated to safe drinking water standards established by the federal Environmental Protection Agency and state and local agencies charged with protecting public health and safety.  Recycled water can be used to safely displace use of potable water for these types of non-potable uses such as toilet flushing, landscape irrigation, commercial car washing, and fire protection. 

Recycled water is produced by treating municipal wastewater.  California treated about 5 million acre-feet of municipal wastewater in 2002.  About half of that amount was recoverable as recycled water.  However, as much as 70% is discharged without beneficial use to natural waterways and to the ocean every year, representing a viable, untapped resource – a lost opportunity.

Recycled water could be used to enhance potable supplies after undergoing highly advanced treatment. Several water agencies in Southern California are taking advantage of advanced technologies to produce recycled water that exceeds California drinking water standards.  These agencies are using this recycled water to protect and replenish groundwater aquifers that serve as a major potable supply to the region. 

In May 2008, the Alliance released a study titled The Role of Recycled Water in Energy Efficiency and Greenhouse Gas Reduction that estimated the potential energy and carbon benefits of accelerating and increasing the development and use of recycled water in Southern California.

Results of the study show up to 580,000 acre-feet of existing recycled water supply in Southern California is currently being released to streams and the ocean without benefit.  This supply could meet all of Southern California’s projected increase in water use through 20301 . According to the study, every gallon of recycled water that is not used to offset potable water use is a missed opportunity for California to increase water and energy supplies and to reduce carbon emissions.

Download the full report for more information.  See the appendices for profiles of each of the participating water agencies.

1As projected by the Department of Water Resources under a Business As Usual scenario

Agencies include:

Appendices include:

Water Energy Video

Water-Energy Nexus

Water related energy use accounts for nearly 20% of all electricity consumed in California. Below, Cynthia Truelove, Senior Water Policy Analyst, California Public Utilities Commission, discusses the water-energy nexus and how water can be conserved and used more efficiently to decrease energy usage. As part of California's Climate Action Team focused on water and energy, Cynthia discusses six measures identified as principle targets to reduce GHGs in addition to those required under AB32.

Showcase Water Agencies

In the last two years, the Alliance recognized two water agencies as leaders in sustainability: Inland Empire Utilities Agency and Sonoma County Water Authority. The Alliance celebrates their success and the excellent work they are doing to improve sustainability and provides important information to other organizations about the strategies that these water agencies have used to achieve their goals.

Inland Empire Utilities Agency is a leader in best-in-class projects and initiatives that range from green buildings and energy efficient systems and operations, to innovative environmental and resource management strategies. The Agency has become the leader in recycled water production in California as it accelerated development of its infrastructure so that all recycled water produced through its wastewater treatment activities can be beneficially used.

IEUA Headquarters
Inland Empire Utilities Agency's LEED headquarters.

Sonoma County Water Agency pledged to eliminate its carbon footprint by 2015 through its Carbon Free Water effort. The Agency has taken several steps towards its goal including: improving energy efficiency, using hybrid vehicles into its fleet, installing three solar projects, conducting ongoing studies of alternative energy generation options, and co-founding a county-wide financing mechanism to spur investment in efficiency and renewable energy for existing homes and buildings.

SCWA Solar
Sonoma County Water Agency’s solar panels.