Facts & Figures - the U.S. Department of Energy reported

The Department of Energy’s Carbon Sequestration Atlas of the United States and Canada has identified more than 3,500 billion metric tons of carbon dioxide (CO2) storage potential capable of approximately 1,100 years of CO2 storage. http://www.netl.doe.gov/publications/press/2008/08060-DOE_Releases_Sequestration_Atlas.html