Abstract: There is an international effort to test the feasibility of injecting compressed carbon dioxide into gas-permeable geological formations as a technique to reduce the pace of global climate change. The Sleipner Project in Norway is one example; about one million tons of CO2 are injected each year. In about 2003, carbon sequestration became a national priority in the U.S., and the U.S. Department of Energy established seven regional partnerships for field-scale demonstrations including the Illinois Basin-Decatur Project. Lessons learned from Enhanced Oil Recovery projects are being applied to investigate the long-term behavior of the supercritical gas after injection which includes potential mineral sequestration reactions between the gas, brines and injection rocks. The future of carbon sequestration may depend on economics.