Water Conservation and Management

Water is a critical resource that helps power California and PG&E is taking steps to conserve and protect water in our facilities and operations. As climate scientists continue to raise concerns about the impacts of climate change to global freshwater resources, there is a growing public concern and focus on management of precious water resources. In California, increased pressure on the state’s limited water resources adds an impetus for PG&E to identify and implement water use reduction strategies.

In 2010, PG&E made solid progress toward our five-year water use-reduction goal of 20 percent for our offices and service yards, compared to a 2009 baseline. We also took important steps to quantify our “water footprint,” including voluntarily responding to the Carbon Disclosure Project’s (CDP) first information request on water. This request was made on behalf of 137 investors around the world representing $16 trillion. The CDP recognized PG&E for demonstrating best practice among major companies worldwide.

Taking a Sustainable Approach

PG&E is taking a sustainable approach to using water in our facilities and operations. Doing so allows us to ensure we meet our future business needs, while also focusing on near-term opportunities for efficiency and cost savings.

PG&E’s water conservation and management efforts span a range of areas:

  1. Reducing water consumption at company offices and service yards.
  2. Using air for cooling (versus once-through “wet” cooling) at repowered and new generation facilities.
  3. Developing plans to manage the potential future impacts of climate change on our hydroelectric system.
  4. Considering freshwater usage when evaluating potential third-party suppliers of electricity.
  5. Working with non-electricity generation suppliers to reduce their water use.
  6. Helping customers reduce their water use.
  7. Using best management practices in maintenance and construction projects to protect water quality.

Water Use Statistics

PG&E has no power plants that use freshwater for once-through cooling; however, we have one power plant with a once-through cooling system that uses saltwater. PG&E does use freshwater to support the internal operations of our plants, but this, by comparison, represents a much smaller volume of water. As discussed more fully below, PG&E’s largest use of freshwater is the generation of hydroelectricity; this is not considered a consumptive use of water because the water runs through the turbines and returns to the river or stream.

Moving forward, we will continue to expand the scope of water use included in our water footprint. For example, we are expanding the metering and tracking of our facility water use and plan to include this usage in our 2011 summary of water use statistics.

Water Use Statistics

  2008 2009 2010
Water Withdrawal (Saltwater and Freshwater) (thousand gallons)
Once-Through Cooling (Saltwater)
Diablo Canyon Power Plant1 830,631,000 802,067,000 856,154,000
Humboldt Bay Power Plant1,2 25,369,000 24,365,000 18,145,000
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant 134,610 134,440 138,093
Freshwater3 8,810 14,640 17,650
Seawater Reverse Osmosis Product Water 125,800 119,800 120,443
Humboldt Bay Power Plant 10,940 7,195 5,808
Humboldt Bay Generating Station1,2 N/A N/A 39
Gateway Generating Station1,4 N/A 17,615 16,769
Colusa Generating Station1,5 N/A N/A 2,063
Corporate Real Estate Facilities (Freshwater)
Offices and Service Yards6 101,300 133,400 123,900
Wastewater Discharged (Saltwater and Freshwater) (thousand gallons)
Once-Through Cooling (Saltwater)7
Diablo Canyon Power Plant 830,631,000 802,067,000 856,154,000
Humboldt Bay Power Plant 25,369,000 24,365,000 18,145,000
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant      
Permitted Discharge 124,950 124,385 123,498
Humboldt Bay Power Plant 20,980 15,685 11,793
Sanitary Sewer 3,740 3,595 3,108
Permitted Discharge 17,240 12,090 8,685
Humboldt Bay Generating Station
Sanitary Sewer N/A N/A 39
Gateway Generating Station
Sanitary Sewer N/A 7,552 7,452
Colusa Generating Station8
  N/A N/A N/A

1 Net operating capacity on December 31, 2010: Diablo Canyon: 2,240 MW; Humboldt Bay Generating Station: 146 MW; Gateway Generating Station: 580 MW; Colusa Generating Station: 657 MW.

2 The Humboldt Bay Power Plant (Humboldt Bay) facilities, two operating fossil fuel-fired plants and two mobile turbines, were retired at the end of September 2010. The new Humboldt Bay Generating Station, which does not use once-through cooling, became operational in September 2010.

3 Freshwater sources were groundwater and creek water through June 2008 and are now solely groundwater for back-up and emergency purposes.

4 The Gateway Generating Station, which does not use once-through cooling, became operational in January 2009.

5 The Colusa Generating Station, which does not use once-through cooling, became operational in December 2010.

6 This figure represents the water supplied to 91 of the 194 offices and service yards managed by PG&E's Corporate Real Estate Department for the 12 month period from October to September. These facilities represent the scope of operations covered by PG&E’s water reduction target in 2010. Water usage reported for 2008 and 2009 has been adjusted to reflect an increase in the number of sites measured from 78 sites in the 2009 report, and, for 2008, additional data gathered. We expect to report water consumption from additional facilities in subsequent sustainability reports, consistent with our plan to encompass more facilities in our water reduction target.

7 These are estimated figures as PG&E only measures water withdrawal associated with once-through cooling.

8 Colusa Generating Station uses a zero liquid discharge system. A septic system is used to manage sanitary waste.

Use of Saltwater for Once-Through Cooling

PG&E owns and operates one power plant that uses saltwater for once-through cooling to condense steam to water in the electricity generating process. Diablo Canyon is a 2,240 MW nuclear power plant with a maximum discharge limit of 2.5 billion gallons per day. The water discharge limit is set by the facility’s Clean Water Act permit.

In 2010, PG&E replaced its aging 105 MW Humboldt Bay Power Plant with a high-efficiency plant at the same site that does not use once-through cooling, leaving the Diablo Canyon Power Plant as PG&E’s only once-through cooled plant.

Because once-through cooling systems can adversely affect aquatic organisms in some circumstances, steps must be taken to ensure the protection of the surrounding aquatic ecosystem. PG&E closely monitors the marine environment at its Diablo Canyon Power Plant by conducting regular studies and sampling required under the plant’s Clean Water Act permit. The marine studies at Diablo Canyon, ongoing since the mid-1970s, represent one of the largest databases of intertidal marine data in the United States.

In May 2010, California’s State Water Resources Control Board adopted a new policy regulating the use of once-through cooling at existing power plants and establishing a compliance schedule to phase out once-through cooling at most facilities. The policy acknowledges the unique contributions of nuclear plants to both baseload power and meeting the state’s greenhouse gas reduction goals, and allows for alternative compliance requirements for these facilities after a review of compliance costs and factors such as engineering and permitting constraints, as well as any adverse environmental impacts of a cooling tower installation. If the State Board allows a nuclear plant to comply through alternative requirements, the policy requires that the impacts of the plant be mitigated through projects that increase marine life near the facility.

For new generation projects, PG&E supports efforts to transition away from once-through cooling and is using alternative technologies that rely on air for cooling at its repowered and new facilities. For example, we are using new advanced reciprocating engine technology at the repowered 163 MW Humboldt Bay Generating Station. Because this plant is cooled with air radiators using a closed loop liquid coolant, it requires minimal water use.

PG&E is using another dry cooling technology, an air-cooled condenser, at the Gateway and Colusa Generating Stations. The Gateway Generating Station went online in early 2009 and is a state-of-the-art 530 MW combined-cycle natural gas power plant with 50 MW peaking capacity that uses approximately 97 percent less water and discharges 98 percent less wastewater than a traditional “wet” cooled plant. The similarly designed 530 MW Colusa Generating Station with 127 MW peaking capacity also uses dry cooling and was completed in 2010; it uses a zero liquid discharge system that recycles wastewater.

Freshwater Consumptive Uses

PG&E consumes some freshwater for the internal operations at the four power plants we own and operate. These operations are largely closed-loop systems, which minimize the amount of water consumed. The systems draw from on-site groundwater, irrigation canal water and/or municipal water. Additionally, the Diablo Canyon Power Plant uses freshwater generated through seawater reverse osmosis. The freshwater is used to generate steam, cool auxiliary equipment, support fire water systems and supply drinking water at the power plants, among other uses. To ensure operational efficiency and maintain plant chemistry, we closely monitor these internal systems to ensure they are watertight, thus reducing consumptive use.

PG&E also purchases a significant portion of its delivered electricity from third-party suppliers. Some of this purchased electricity comes from conventional power generation facilities that use freshwater for once-through or other wet cooling technologies.

We also consume freshwater in our office buildings for kitchens and bathrooms, landscape irrigation and cooling towers associated with heating, ventilation and air conditioning systems. Our gas and electric transmission and distribution facilities consume freshwater as well for operation, maintenance and construction activities. These include washing electric circuit insulators, cleaning vehicles, controlling dust, conducting pipeline and other underground drilling operations, as well as natural gas pipeline hydrostatic testing.

Freshwater Non-Consumptive Uses

PG&E’s hydroelectric power plants are largely non-consumptive. After water passes through turbines to produce electricity, it is returned to the river.

Of PG&E’s 68 hydroelectric power houses, 24 are classified as “run-of-the-river.” This refers to hydroelectric plants that operate on water as it is available from the natural flow of a stream without the need for storing the water. The other units draw water from reservoirs. Some experts have begun to characterize the evaporation that naturally occurs from reservoirs as water consumption. PG&E will continue to monitor such reporting developments as we further quantify our water conservation and management efforts. Evaporation represents a small percentage of the total water that flows in the watersheds where PG&E operates hydroelectric facilities.

PG&E also uses water for energy storage to help balance daily variations in electric demand. The Helms Pumped Storage Project is located in Fresno County at a site more than 1,000 feet inside a solid granite mountain. With a total output of 1,212 MW, the facility alternately draws water from an upper reservoir to produce electricity when demand is high, and pumps it back when demand is low for reuse during the next high demand period.

Water Conservation in Our Facilities

Demonstrating a long-term commitment, PG&E set a five-year goal to reduce water usage in offices and service yards by 20 percent by the end of 2014, with 2009 as the baseline year.

In 2010, we reduced water use by 7.1 percent—or 9.5 million gallons—from the prior year at more than 90 offices and service yards, exceeding the 4 percent target. To achieve these reductions, we reduced landscape water use through increased attentiveness to repairs and the timing of when sprinklers are turned on and off, installing “smart” irrigation controllers and replacing irrigation systems. We also modified a high water use electron microscope and the water treatment of mechanical systems at selected buildings. PG&E uses the electron microscope for analysis of material, equipment and chemicals, and we eliminated water use by replacing the once-through water cooling system with a closed circuit cooling loop.

In 2011, we aim to achieve an additional 5.7 percent reduction at an expanded set of sites by continuing to install smart controllers for irrigation, adopting drought resistant landscaping and upgrading plumbing fixtures at selected buildings.

Helping Customers Reduce Water Use

It takes large amounts of energy to extract, treat and deliver water—and still more energy to use, collect and treat it after use. The CEC estimates that almost 20 percent of California’s electricity demand is related to the use of water.

Photo: Joseph Dannels

Since 2004, PG&E has hosted an annual Water Conservation Showcase in San Francisco that features innovative new policies, strategies and technologies to conserve water. At the event, industry experts cover a wide range of topics related to building and landscape water savings for both residential and commercial building projects. The event is held in collaboration with the U.S. Green Building Council’s Northern California Chapter and the East Bay Municipal Utility District. The attendees—which include architects, engineers, building owners and operators, manufacturers and government employees—see new technologies first-hand through a range of exhibits.

PG&E’s Pacific Energy Center also provides workshops and classes during the year on various topics related to water conservation and energy efficiency.

PG&E enables our customers to reduce water use by encouraging energy efficiency. For example, we offer rebates for commercial customers to retrofit commercial laundry equipment with a system that uses ozone as a cleaning agent; the ozone equipment uses less water at a lower temperature, achieving gas and water savings. Business customers can also receive rebates for energy- and water-efficient dishwashers and water heaters, while agricultural customers can earn rebates for retrofitting irrigation systems with low pressure nozzles and drip irrigation.

Residential customers can earn rebates for purchasing energy- and water-efficient dishwashers, clothes washers and water heaters. In fact, PG&E has a collaborative program with 30 local water agencies to provide incentives for high-efficiency clothes washers, where customers receive a combined rebate from PG&E and the local water agency.

In late 2007, the CPUC established a “Water-Energy Pilot Program” for PG&E and the state’s other investor-owned gas and electric utilities to save energy by saving water. The program investigated the idea of offering incentives for achieving energy savings “embedded” in water. It also included several studies that investigated the relationship between water and energy in California.

As a major focus of the program, PG&E collaborated with several water agencies during 2008 and 2009 to provide incentives to 11 high-use commercial customers—K-12 schools, universities, hotels, detention centers and commercial buildings—for projects that saved nearly 34 million gallons of potable water each year, equivalent to more than 55,000 kWh in annual energy savings. Customers earned rebates from both PG&E and their local water agency by conducting water audits and then retrofitting laundry equipment, replacing commercial dishwashers, upgrading toilets and sinks and switching from potable water to recycled water for cooling towers and landscaping.

Working in partnership with the Santa Clara Valley Water District, PG&E also installed nearly 500 high-efficiency toilets in the homes of low-income customers, which saved more than five million gallons and 14,000 kWh per year. The pilot program also explored ways that new and emerging technologies can yield water savings at water utilities and assessed opportunities for investor-owned water utilities to adopt system-wide energy efficiency improvements.

As a next step, the CPUC is conducting studies to better understand how much energy is used to treat water before and after use, which will help assess potential new embedded energy programs for California’s electric utilities.

The CPUC has issued its final evaluation, measurement and verification analysis on the water-energy pilot. The analysis indicated that among the projects with the most cost-effective energy savings potential were PG&E’s project with high efficiency toilets at detention facilities and our recycled water retrofit projects. However, the report stated that additional research is needed to fill data gaps to fully evaluate the potential for the programs.

Managing Storm Water Run-Off and Protecting Species

In California, storm water run-off poses potentially significant environmental threats, with precipitation transporting pollutants into nearby lakes, rivers, wetlands and coastal water. Some of these sites are also home to sensitive plants and animals.

PG&E has taken necessary steps to comply with new state requirements for storm water management associated with construction projects, which went into effect in July 2010. The new, more stringent requirements call for PG&E to implement minimum best management practices commensurate with a project’s risk level to minimize potential impacts to water quality.

PG&E implemented a number of process improvements to ensure we use a consistent approach to complying with the new storm water construction permit. These included working to clearly define roles and responsibilities for compliance, centralize our permitting activities and develop an enhanced system to track and monitor compliance.

We are also implementing best management practices at construction sites to protect water quality, plants and animals. This includes using reusable fencing to prevent sediment from entering streams and waterways, setting up portable vehicle wash stations to prevent the spread of plant diseases and invasive weeds and installing biological exclusion fences to prevent sensitive species—such as the California red-legged frog and the California tiger salamander—from entering construction sites.

Last year, PG&E reused approximately 70 percent of the fencing purchased the prior year. We made sure to clean the fencing between uses to avoid spreading plant diseases. PG&E also continued to use portable vehicle wash stations at targeted projects where it was especially important to control noxious weeds and the spread of plant pathogens. Because the fencing can be moved and reused, it also gives PG&E more flexibility. For example, at the Moss Landing-Salinas-Soledad reconductoring project, the fencing helped enable PG&E to stay on schedule, while also protecting sensitive species in the area.

PG&E is also focused on best practices for managing storm water at its power plants. For example, at our Humboldt Bay Generating Station, storm water is managed through a process on-site that takes advantage of plants and microbes to filter and clean the storm water, thereby protecting water quality.

Learn more about how we are minimizing our impacts to natural resources.


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