Ash Sales to reduce GHG
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 Salt River Materials Group for use in concrete production. This allows them to use the coal ash as a base product in cement production, eliminating their need to produce this material and significantly reducing their energy consumption in cement production. In 2007, APS recycled 943,814 tons of coal ash for cement production or other use, reducing overall greenhouse gas emissions by over 200,000 tons of carbon dioxide.

Ownership of GHG reductions from activities such as ash recycling are current established by APS in contractual language with the other parties involved, in order to prevent "double reporting" of reduction numbers and to establish potential ownership of future emission credits.

PowerTree Carbon Company
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 over two million tons of CO2 are expected to be sequestered over the 100-year life of the project. In 2007, APS' share of PowerTree Carbon Company sequestration results was the equivalent of a reduction of over 60 short tons of carbon dioxide.

Emission Reduction/Sequestration
APS has an active technology research and development program which is exploring new ways to reduce or sequester carbon dioxide emissions from existing and future electric generation. This includes the development of renewal energy sources, innovate pollution reduction technologies for fossil fuel power plants and other clean energy strategies. 

In addition, we are looking at other types of innovative (and sometimes unusual) technologies that can help create a sustainable energy future and reduce greenhouse gases (See Technology Innovation section for details).  An example of this effort is our Emissions to Fuel project in which APS is evaluating the possibility of using carbon dioxide in stack emissions to grow algae, which will then be used for bio-fuel.   Another example is  West Coast Regional Carbon Sequestration Partnership (WESTCARB), a research project evaluating whether storing carbon dioxide underground may be a viable option for reducing greenhouse gas emissions into the atmosphere.