Carbon dioxide can in some situations be sequestered, or trapped, in geological sinks such as depleted oil and gas reservoirs, unminable coal seams and in deep saline formations. Taken together, these sinks could potentially hold hundreds to thousands of gigatons (billions of tons) of carbon. Moreover, the technology to inject carbon dioxide into the ground is developing rapidly.
Ocean sequestration represents the largest potential sink for human-produced carbon dioxide. Already the ocean contains approximately 40,000 gigatons of CO2, as compared to 750 gigatons in the atmosphere and 2200 gigatons in the terrestrial biosphere. As a result, the amount of carbon that would double the atmospheric concentration would change the ocean’s concentration by less than 2%.
However, it must still be demonstrated that these storage options are effective and safe (for both people and the environment). Initial research suggests that this may be the case, but some concerns still need to be addressed. The long-term cost-effectiveness of geological sequestration also remains questionable at this point in time. Demonstration projects are already underway, and may provide insights into the characteristics of good storage reservoirs, the long-term effectiveness of geological sequestration, environmental impacts and cost-effectiveness.
Return to: How Offsets are Created
