Arizona Public Service, the Salt River Project and Tucson Electric Power have joined a coalition to test the viability of storing CO2 underground to manage greenhouse gas emissions. All three utilities have joined the West Coast Regional Carbon Sequestration Partnership (WESTCARB), which will test the safety, feasibility and efficiency of carbon sequestration.

The project site is located one mile east of Joseph City in Navajo County, Arizona, and was chosen for deep geologic formations containing salty water. The carbon dioxide will be transported to the site by truck and injected into underground formations about 3/4 of a mile down. While WESTCARB will monitor the CO2 storage, it will not test capture technologies. The project is expected to last two years, including the permitting process.