Water Conservation and Management
Estimated gallons of water saved by customers who adopted energy efficient measures that also save water
Water is an important resource for the utility industry and is in increasing demand by a wide range of stakeholders. PG&E is taking numerous steps to conserve water in our facilities and protect the watersheds where we operate. We met our annual water reduction goal in 2012, staying on track toward our five-year goal of a 20 percent reduction in water use for our offices and service yards. We also employ air-cooled technology at all but one of our thermal power plants and offer incentives to help customers conserve water.
Taking a Sustainable Approach
At PG&E, we are working to use water more sustainably in our facilities and operations. Taking a sustainable approach allows us to ensure we meet our future business needs, while also addressing near-term opportunities for efficiency and cost savings.
PG&E’s water conservation and management efforts span a range of areas:
- Reducing water consumption at PG&E offices and service yards
- Using air for cooling (versus once-through “wet” cooling) at our generation facilities
- Developing plans to manage the potential future impacts of climate change on our hydroelectric system
- Working with suppliers to reduce their water use
- Helping customers reduce their water use
- 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. (The Diablo Canyon Power Plant uses a once-through cooling system that relies on saltwater.) Although freshwater is used to support the internal operations of our plants, this, by comparison, represents a much smaller volume than required for plant cooling. 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.
We will continue to expand the scope of water use tracked and reported in our water footprint. For example, as we expand the metering and tracking of our facility water use, we will include this usage in our summary of water use statistics.
|Water Withdrawal (Saltwater and Freshwater) (thousand gallons)|
|Once-Through Cooling (Saltwater)|
|Diablo Canyon Power Plant1||856,154,000||863,753,000||833,390,000|
|Humboldt Bay Power Plant2||18,145,000||N/A||N/A|
|Domestic and Process Water (Freshwater)|
|Diablo Canyon Power Plant||138,093||145,546||149,705|
|Seawater Reverse Osmosis Product Water||120,443||132,136||128,605|
|Humboldt Bay Power Plant||5,808||N/A||N/A|
|Humboldt Bay Generating Station1,2||39||231||131|
|Gateway Generating Station1,4||16,769||20,339||20,012|
|Colusa Generating Station1,5||2,063||2,810||4,086|
|California State University, East Bay Fuel Cell1,6||N/A||699||1,940|
|San Francisco State University Fuel Cell1,6||N/A||419||N/A|
|Corporate Real Estate Facilities (Freshwater)|
|Offices and Service Yards7||129,200||121,400||127,358|
|Wastewater Discharged (Saltwater and Freshwater) (thousand gallons)|
|Once-Through Cooling (Saltwater)8|
|Diablo Canyon Power Plant||856,154,000||863,753,000||833,390,000|
|Humboldt Bay Power Plant||18,145,000||N/A||N/A|
|Domestic and Process Water (Freshwater)|
|Diablo Canyon Power Plant|
|Humboldt Bay Power Plant||11,793||N/A||N/A|
|Humboldt Bay Generating Station|
|Gateway Generating Station|
|Colusa Generating Station9||0||0||0|
1 Net operating capacity on December 31, 2012: Diablo Canyon: 2,240 MW; Humboldt Bay Generating Station: 163 MW; Gateway Generating Station: 530 MW of base capacity and 50 MW of enhanced capability; Colusa Generating Station: 530 MW of base capacity and 127 MW of enhanced capability; CSU-East Bay Fuel Cell: 1.4 MW; San Francisco State Fuel Cell: 1.6 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 Humboldt Bay Generating Station, which does not use once-through cooling, became operational in September 2010.
3 Freshwater sources are well water 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 The Utility owns and operates fuel cell sites in the Bay Area that became operational in September 2011 and have a combined capacity of 3 MW. Water meter data was only collected for the California State University, East Bay Fuel Cell facility in 2012.
7 This figure represents the water supplied to 135 of the 194 offices and service yards managed by the Utility’s Corporate Real Estate Strategy and Services 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 2012. 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.
8 These are estimated figures as PG&E only measures water withdrawal associated with once-through cooling.
9 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 currently 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 of 2.5 billion gallons per day, set by the facility’s Clean Water Act permit.
PG&E closely monitors the marine environment at the 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.
The Clean Water Act requires that cooling water intake structures at electric power plants, such as Diablo Canyon, reflect the best technology available to minimize adverse environmental impacts. U.S. EPA regulations are expected in 2013 that will include specific compliance requirements for impingement (when organisms are caught on water filter screens) and entrainment (when organisms are drawn in through the cooling system).
On the state level, the California State Water Resource Control Board has a policy regulating the use of once-through cooling at existing power plants and establishing a schedule to phase out once-through cooling at most facilities. The policy acknowledges the unique contributions of nuclear plants to baseload power and to meeting the state’s greenhouse gas reduction goals, and allows for alternative compliance requirements at these facilities.
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 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 uses approximately 97 percent less water and discharges 98 percent less wastewater than a traditional “wet” cooled plant, and the similarly designed Colusa Generating Station also uses dry cooling—a zero liquid discharge system that recycles wastewater. Fluctuations in water use at these facilities are largely attributable to plant maintenance activities.
In addition, PG&E owns and operates fuel cell sites that have a combined capacity of 3 MW and require freshwater for the electrochemical energy generation process.
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 that minimize the amount of water consumed. 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.
In 2012, PG&E used a significant amount of water to perform hydrostatic testing on more than 175 miles of its gas transmission pipelines to verify the safety and reliability of its natural gas transmission system. Hydrostatic pressure testing involves filling a section of pipe with water, pressurizing it to a much higher level than the pipe operates with natural gas, then monitoring the pipe for at least eight hours. Any pipe sections that do not pass are repaired and retested. Following a completed test, the water is sampled and analyzed to verify that applicable discharge limits are met. Water is then discharged either under permit from a Regional Water Quality Control Board or the local sanitary sewer agency.
We also consume freshwater in our office buildings and gas and electric transmission and distribution facilities for purposes such as sanitation, landscaping, cooling and cleaning vehicles. Water is also used as part of environmental remediation of our historic impacts.
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,” with no need for storing water. The other units draw water from reservoirs.
PG&E also uses water for energy storage to help balance daily variations in electric demand at the Helms Pumped Storage Project, 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
PG&E remains on track to meet our 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 2012, we reduced water use by 2.3 percent—or 3.1 million gallons—at 135 offices and service yards, exceeding our 2.0 percent target. To achieve these reductions, we reduced landscape water use through enhanced maintenance and operations, and by installing “smart” irrigation controllers at 11 sites to govern the use of sprinkler systems. In 2013, our goal is to achieve an additional 2.0 percent reduction at the 135 sites.
Helping Customers Reduce Water Use
By encouraging energy efficiency, PG&E also enables our customers to reduce their water use. PG&E analyzed 12 of the more common water-saving technologies promoted through our energy efficiency incentives and estimated the savings to be more than 1.3 billion gallons of water savings per year, equivalent to the annual water consumption of nearly 8,000 California households.
Since 2004, PG&E has hosted an annual Water Conservation Showcase in San Francisco that brings together experts and innovative products and services to explore 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.
Forty-nine percent of these water savings came from programs for residential customers in 2012, where we directly installed the water-saving devices and provided rebates to lower their cost. Through PG&E’s Energy Savings Assistance Program, we installed hundreds of thousands of low-flow showerheads and faucet aerators at no cost to low-income homeowners and renters. In addition, PG&E issued more than $4.3 million in residential rebates for dishwashers and clothes washers. For the clothes washers, customers received a combined rebate through a partnership between PG&E and 30 local water agencies.
The remaining 51 percent of water savings resulted from commercial, agricultural and industrial customers. For agricultural customers, we helped convert high-pressure sprinklers to low-energy drip irrigation, which alone saved more than 280 million gallons of water. Other technologies include steam traps, low-flow showerheads, faucet aerators, air-cooled ice machines and ozone laundry equipment, which uses ozone as a cleaning agent in lieu of hot water.
Managing Storm Water Run-Off and Protecting Species
In California, storm water run-off can pose an environmental threat, with precipitation transporting pollutants into nearby lakes, rivers, wetlands and coastal waters.
PG&E has a comprehensive program to comply with state permitting requirements for storm water management associated with construction projects. The stringent requirements call for PG&E to implement pollution prevention plans and best management practices. Examples include reusable fencing to prevent sediment from entering waterways and active treatment systems that remove sediments from collected storm water at construction sites.
PG&E continues to expand its program by proactively including projects that do not trigger state permitting requirements.