Carbon dioxide from a power plant or refinery could be piped underground and sequestered beneath a dome of rock in a geological basin formation. But because the CO2 is buoyant, some scientists worry that the gas will leak back into the atmosphere. There are also problems of scale: in the long run, the amount of space in oil wells is tiny compared to the amount of gas that needs to be stored.
According to Daniel Schrag, Professor of earth and planetary sciences at Harvard, a potentially permanent solution, well-suited to coastal areas, would involve transporting the CO2 to tanker ships that would carry it to offshore platforms, where it would be injected into deep-ocean sediments. Under high pressure and low temperature, the CO2 becomes a liquid that is heavier than water, and slowly dissolves. Tests indicate the CO2 will remain there permanently.
Source: Harvard Magazine, 05-06/06
