Climate Change

APS was one of the first electric utilities to sign the Climate Challenge Participation Accord to reduce greenhouse gas emissions to 1990 levels. APS met its year 2000 commitment.

The APS service territory, however, has experienced tremendous growth over the past decade as illustrated in the electric customer table included in this report. Meeting this growth and its associated electricity demand has required APS to augment its existing energy generation capacity. This demand has been met through more efficient use of existing sources, such as the up-rating of the Palo Verde Nuclear Generating Station, improving the availability of existing fossil plants and the addition of state-of-the-art gas-fired generators. Over time, the net effect of this demand has been an increase in the overall company CO₂ emissions, but with a corresponding reduction in CO₂ intensity in (lbs/MWH). (See graph).

Note that this trend is projected to continue through 2012. APS’ strategy is to provide a diverse mix of energy sources to ensure reliable and stable cost energy to its customers while meeting their growing demand. In addition, APS is actively involved in several leading-edge projects and research into other potential energy options for the future. See also Renewable Technologies Section.

Here are a few of our greenhouse gas offset projects: 

Solar
With a natural abundant resource in the sun, Arizona produces the most solar power per capita in the U.S. For more than 30 years, APS has been a leader in solar energy and research. APS operates or supports numerous solar electric facilities across the state, with a total installed capacity of 4.9 megawatts. Use of our current solar plants generated 6.6 million megawatt hours and avoided the emission of more than 5,365 tons of greenhouse gas in 2003.

Ash Sales
Coal combustion fly ash is a powdery material that is a byproduct of burning coal at electric utility plants. U.S. power plants produce millions of tons of coal fly ash annually. APS is using its fly ash to help reduce greenhouse gases while adding to its bottom line. APS sells much of its fly ash to Phoenix Cement for use in concrete production. This offsets energy used for cement production and reduces greenhouse gas emissions. The company sells bottom ash and cenospheres in addition to fly ash.

Fly Ash:
Total sales = 317,9394 tons of CO₂ reduced
APS Share = 99,855 tons of CO₂ reduced

Bottom Ash:
Total = 1,142 tons of CO₂ reduced
APS Share = 787 tons of CO₂ reduced

Cenospheres:
Total = 143,767 tons of CO₂ reduced
APS Share = 143,767 tons of CO₂ reduced

New Fuels
In 2002, APS opened its hydrogen/compressed natural gas fueling station at one of its downtown facilities. The fueling station, originally constructed in 1920 for the City of Phoenix to illuminate its streetlights, has been reconfigured to supply hydrogen, compressed natural gas or a combination of the two for vehicles capable of operating on such fuels.

This station will enable APS to gain experience handling these fuels on a small scale, before seeking larger applications. In the meantime, company vehicles that use hydrogen have a place to refuel, and they emit nothing but water vapor from the exhaust.

Wind
In 2003, APS and Western Wind Energy Corp. (WND) agreed to build a 15-megawatt wind turbine generating facility to be constructed approximately 200 miles northeast of Phoenix, near St. John’s. Construction of the plant is scheduled to begin in late 2004, and is expect to offset 34,525 tons of CO₂ annually.

Biomass
APS is involved in a biomass project in northeastern Arizona that, in addition to reducing the amount of forest waste and providing jobs, will provide electricity, reduce future forest fire threats and greenhouse gases by approximately 15,000 tons annually.

Other projects:

• Trip reduction: Company employees voluntarily telecommute, carpool and use other means to travel to and from work. In 2003, more than 8,236 tons of greenhouse gas was reduced through these means.
• Algae: APS is supporting efforts to grow algae in ponds, which is fed with an enriched source of carbon dioxide emitted from APS’ plants. The algae is grown in ponds, then is used as a nutrient for plants as well as other applications.
• Off-grid solar: Customers who live off the grid use APS-maintained solar energy as their primary energy source. In 2003, this resulted in a reduction of more than 779 tons of greenhouse gas.
• PowerTree: To achieve additional CO₂ reductions, APS joined 24 other electric utilities in the PowerTree Carbon Company, which plants trees in ecologically sensitive areas of the lower Mississippi Valley in cooperation with local and national, governmental and conservation organizations. Planting began in 2003 and 2.0 million tons of CO₂ are expected to be sequestered over the 100-year life of the project.
• APS also joined Trees for the Rim, an organization dedicated to replanting trees on residential, commercial and community lands damaged by the Rodeo-Chedeski fires of June, 2002. APS donated $25,000 and transported trees, provided volunteers, dug holes for the trees and will continue to be involved as the project unfolds. This benefits both the environment and the community.

Changes to Generation Mix
In addition to our other greenhouse gas-reducing projects, changes to APS’ generation mix have helped reduce the intensity of CO₂ emissions measured in pounds per megawatt hour of energy. From 1999 to 2001, APS reduced CO₂/MWh by more than 12.7 percent. Based on energy demand and dispatch projections, this intensity will continue to decline. Through 2012, cumulative reductions of more than 24 percent are expected.

The addition of natural gas capacity and the continual improvements at the Palo Verde Nuclear Power Plant have been key to these reductions. Each year since 1990, Palo Verde has avoided more than 20 million tons of CO₂ emissions annually (more than six million tons of that attributed to APS’ ownership share of Palo Verde) and efficiency improvements have raised this amount to nearly 30 million tons per year since 1997.