Reliable access to adequate water supplies is critical in electric power generation. As an energy company located in the desert Southwest, APS understands that responsible management of this vital resource can have a positive impact on the communities we serve and the environment. To help ensure regional water resources are responsibly managed, we take a leadership role in Arizona’s water policy. We are committed to preserving the long-term quality and availability of our water resources, and we are guided by a water resource strategic plan that ensures sufficient long-term water resources for our generating resources, promotes effective, sustainable water supplies, and minimizes water-related operational costs.

Water conservation efforts include retiring older, water-intensive units, upgrading to more water-efficient technologies at existing plants, increasing renewable energy and supporting energy efficiency among our customers. By 2032, our goal is to reduce water intensity (gallons per MWh) company-wide by 30% compared to a 2014 baseline.

Our commitment to water management is demonstrated by our actions. CDP, which evaluates the environmental impact of major corporations, recognizes companies that are taking coordinated action on water issues. In 2019, our CDP reporting for water management received a “Leadership” score (letter grade A). This score is above the electric utility sector average score of B- and higher than the North America regional average of C. In fact, CDP awarded us a spot on both their Water & Climate A Lists for 2019 – one of just 10 U.S. companies with A’s in both categories. Our water withdrawal data reported to CDP is third-party verified.

Learn more about our CDP responses and documents.

APS also works with Arizona’s two other largest energy companies, Salt River Project and Tucson Electric Power, to collect data on the total water used for all power generation statewide. Currently less than 3% of the Arizona water budget is used for power generation, which is below the national average.

APS has a long history of being a leader in Arizona with respect to the management and conservation of water resources. To ensure we maintain focused on water resources and our leader position in this area, APS developed a set of Water Resource Principles to direct and guide our future water resource actions.

APS Water Resources Principles

Ensuring Adequate Water Resources

az water for generation

APS has secured adequate water contracts and water rights to allow us to meet the future energy needs of our customers even if water supplies are negatively affected by environmental changes. Contracts vary by type and duration for each plant, but most last 25 or 50 years or have no expiration date. Maintaining long-term water contracts or contracts without expiration dates not only ensures adequate water supplies, but it also allows us to maintain strategic cost management of our water needs. As an example, the water contract for the Palo Verde cooling water supply from 2025 to 2050, which accounts for more than 70% of APS’s fleet water consumption, has a price increase ceiling that will assure long-term affordable water supplies.

The APS Water Resource Management Strategic Plan provides a blueprint to efficiently manage our water resources portfolio. It ensures long-term water supplies are available, even in times of extended drought, and water contingency plans are in place for each of our facilities. Each APS power plant has a unique water strategy, developed to promote efficient and sustainable use of water. This plan was revised in 2018 to encompass the period from 2019-2023. The revised plan includes new sections on water investment, including potential new business initiatives that will improve water infrastructure and be financially beneficial to APS and Pinnacle West. Specific new research has been targeted at developing alternative water supplies, including brackish water recovery, aquifer storage and recovery, and brine disposal through deep well injection.

Water is an important factor in assessing risk for all utilities, regardless of location. However, those operating in water constrained areas—such as the desert Southwest—face greater challenges that can be further exacerbated when coupled with anticipated load growth. To meet those challenges while maximizing the use of renewable water resources and minimizing the use of non-renewable resources, it is important to consistently monitor water use, both in terms of the amount of water used and the water intensity (gallons per MWh). The focus is on non-renewable water (i.e., groundwater) because this supply is at the greatest risk of depletion and is a significant source of supply at seven of nine APS power plants.

Water Overview by Facility (go to p. 93)

Water Usage and Metrics

Every APS power plant has specific strategies in place to ensure efficient water use. Examples include the use of zero liquid discharge blowdown/recovery systems at the Redhawk and West Phoenix power plants, which maximize reclamation and on-site water reuse. Zero liquid discharge means no wastewater is discharged to rivers, streams or oceans. At the Cholla Power Plant, a site with a large and complex well field, APS has performed groundwater modeling to prioritize withdrawal from wells with the highest water quality. This results in increased efficiency of the cooling towers and ultimately conserves water.

In 2016, APS implemented a Tier 1 water metric designed to reduce consumption of non-renewable groundwater supplies—those most at-risk in Arizona. Tier 1 metrics are the highest company metrics and the status of these metrics is reported to senior management on a monthly basis. We reduced non-renewable water use in 2018 by 13.4% compared to a 2014 baseline—exceeding our goal of a 12% reduction. Our Tier 1 metric will be reduced by an additional 2% per year in 2019 and 2020. This water-use reduction will be accomplished by retiring older, water-intensive units and replacing them with new units that employ water-efficient technologies; shifting loads from water-intensive power plants to more water-efficient plants; implementing water conservation strategies developed during water efficiency audits at each power plant; implementing leak-reduction programs; and expanding reliance upon renewable generation that requires little or no water. Expanding energy efficiency programs that reduce the need for new, potentially water-intensive generation will lead to further reductions. Through these measures, long-range projections indicate continued reductions in non-renewable water use. We project to achieve a 45% reduction in the use of non-renewable water from the 2014 baseline by 2020, and a 60% reduction by 2026.

Water Usage for Generation Table

Water is growing in importance as a factor in assessing the viability of new energy projects for all utilities. Utilities operating in water constrained areas—such as APS’s service territory—face greater challenges. To meet those challenges while maximizing the use of renewable water resources and minimizing the use of non-renewable resources, it is important to consistently monitor water use, both in terms of the amount of water used and the water intensity (gallons per MWh).

Even though energy consumption is forecast to increase significantly in the next 15 years, water consumption will see a minimal increase due to energy efficiency and renewable energy resources envisioned in the 2017 Integrated Resource Plan. The rate of water usage declines dramatically over the course of the planning period (2017-2032), which shows a decline in water intensity from 430 gallons/MWh in 2018 to 338 gallons/MWh in 2032. Demand-side management programs and renewable energy resources generally consume little or no water. The expansion of these programs in the 2017 Integrated Resource Plan contributes to a reduction in water consumption per MWh over the planning period.

Read more about improving efficiency of water use. (go to p. 184)

Reclaimed Water

water for power generation

Our usage of reclaimed water exemplifies our awareness of the water-energy nexus. Reclaimed water accounted for about three-quarters of the water used in our generating facilities in 2018. Use of reclaimed water is crucial in Arizona, where a non-renewable water resource like groundwater accounts for 40 percent of statewide water use.

A critical asset in our water resource strategy is Palo Verde Generating Station, an internationally recognized leader in the use of reclaimed water for power generation. Palo Verde is the only nuclear plant in the world that is not located next to a large body of water. Instead it uses treated effluent, or wastewater, for plant cooling. No other nuclear power plant exclusively utilizes wastewater for cooling water.

Wastewater is transported to Palo Verde through 36 miles of underground pipe from treatment facilities in Phoenix and Tolleson. More than 20 billion gallons of municipal effluent are recycled each year to meet the plant’s cooling needs, making limited surface water and groundwater supplies available for other uses, such as municipal drinking water. Effluent undergoes treatment at Palo Verde’s water reclamation facility, one of the world’s largest advanced water treatment facilities. Treated water is stored in the plant’s 85-acre and 45-acre reservoirs for use in the cooling towers.

Zero Liquid Discharge

Water is an essential resource for most power generating facilities, as water is heated and converted into steam to drive steam turbine-generators and it is used for cooling plant equipment. Consistent with our strategy to conserve water, we look for ways to reuse water whenever possible. In addition to the reclaimed effluent use at Palo Verde, our water conservation measures include ensuring our power plants produce little, if any, wastewater. These power plants are known as zero liquid discharge (ZLD) plants and have systems to collect and treat the wastewater for reuse at the plant.

Three APS power plants utilize ZLD operating strategies:  Palo Verde, Redhawk and West Phoenix. These plants are all located in the Phoenix Active Management Area and are subject to Arizona Department of Water Resources (ADWR) groundwater regulations.

  • Palo Verde. The most cost-effective zero liquid discharge practice at Palo Verde is through the use of evaporation ponds. Palo Verde has multiple evaporation ponds totaling 650 surface acres to hold wastewater. Collectively, the evaporation ponds have a capacity of about 5,500 million gallons. Palo Verde is the only nuclear power plant in the world that operates with a zero liquid discharge, which ensures no wastewater is discharged to the environment.
  • Palo VerdeEvaporation ponds (left) and water storage reservoirs (right) at Palo Verde Generating Station

  • Redhawk. The plant uses treated effluent water from the City of Phoenix to make steam and cool plant equipment. The heat recovery steam generation boilers use waste heat from the combustion turbines to produce steam for power generation and thereby increase generation efficiency. The plant cooling towers use evaporative cooling to provide cooling water for plant equipment. The wastewater blowdown from the cooling towers is discharged to the zero liquid discharge system for processing, where more than 95 percent of the water is captured and reused in the plant.
  • West Phoenix. The plant has many generating units that use waste heat from combustion turbines to produce steam for power generation. The plant also uses a brine concentrator to capture and treat wastewater for reuse. The zero liquid discharge system at West Phoenix is an effective water management tool that significantly reduces the plant's water use.

Applied Technology

Although we have secured long-term water resources and maximized our water efficiency, we continue to explore methods to reduce our water use. Technological advances such as alternative cooling and water treatment may potentially improve water use efficiency. We participate in the EPRI Water Research Center’s membrane treatment and cooling tower technology research, which includes cooling tower studies and evaluation of the potential use of alternative technology.

Steam Units. We analyzed alternative cooling strategies and selected a state-of-the-art hybrid cooling technology for new units nearing completion as part of our Ocotillo Power Plant modernization project. The modernization project, which will go online in summer 2019, will replace two 1960s-era steam units with five new quick-start combustion turbines equipped with hybrid wet/dry cooling towers. Hybrid cooling will decrease water use from 900 gallons per MWh to 160 gallons per MWh, a reduction of more than 80%.

Well and Pumping Equipment. To ensure the operating areas have reliable water resources when needed, we operate a well and pumping equipment maintenance program. Currently, there are approximately 47 wells in the APS fleet. In 2014, the well and pumping equipment reliability rate was 90%. We set a goal to increase the reliability rate by 2% per year through 2019, when the rate is projected to be 98%.

Strategies to meet this goal include drilling new wells, replacing old equipment, testing and evaluating each well for efficiency, and monitoring performance trends in order to respond before failure occurs. Typical planned well repairs can cost tens of thousands of dollars. However, if a well fails and then requires repair, costs are typically two to three times higher because damage may extend to multiple well components, plus emergency repairs and expedited parts delivery add cost. Many well failures were caused by lubrication problems. To address this issue, we installed automatic lubrication systems on our wells that detect low lubrication and prevent potential damage. In addition, we spend approximately up to $1 million annually on a capital replacement program to identify wells most likely to fail and prioritize replacement. As a result of these measures, in 2018 we achieved a 98% reliability rating for well pumping equipment, exceeding our target of 96%.

We also have developed well field operation plans for our larger power plants, which achieve increased efficiency in the use of higher quality groundwater, decreased water consumption and more strategic use of water. Plans are in place for the Cholla, Redhawk and West Phoenix power plants.

Groundwater Well at Cholla Power plant Groundwater well at Cholla Power Plant

Community Support and Collaboration

APS works closely on water issues with federal and state agencies and governments, local community members and Native American tribes. We collaborate with organizations including Sandia National Laboratories, EPRI, the U.S. Department of Energy and Idaho National Laboratory.

  • Research Partnerships. We participate in a critical watersheds project with four national laboratories and the U.S. Bureau of Reclamation to evaluate possible impacts of climate change on water supply demands and energy operations in the Colorado River Basin.
  • Policy and Stewardship. We have committed financial support to the Kyl Center for Water Policy, a research, analysis and collaboration entity at the Morrison Institute for Public Policy at Arizona State University. The Kyl Center works to promote sound water policy and stewardship in Arizona. Through the Kyl Center, we actively engage in discussion of the water economy, water-energy nexus, water rights, drought, water costs and policy solutions that are important to our customers, our company and our state.
  • Regional Partnerships. APS maintains a shortage sharing agreement with all San Juan River water users. This multilateral agreement includes our Four Corners Power Plant, the Navajo Nation, municipalities, industrial operations and agricultural irrigators. It assures that all parties will share equally in any water shortages on the river.
  • US Bureau of Reclamation. We also work with the U.S. Bureau of Reclamation, providing data and projections of future use that enable the agency to create models that project shortages.
  • Colorado River. The State of Arizona worked in 2018 to develop a Lower Basin Drought Contingency Plan to establish guidelines for Arizona’s contribution to sharing shortages on the Colorado River. The shortages could affect the Yucca and Sundance power plants. APS was a part of the plan’s development process and has established contingencies to avoid cuts to water needed to operate our plants.

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