The concept of carbon sequestration is to put carbon dioxide, the leading global warming pollutant, somewhere other than into the atmosphere. There are two basic methods of sequestering carbon: geologic sequestration and terrestrial sequestration.
Geologic CO2 sequestration takes carbon dioxide from large emissions sources, such as coal-fired power plants, and pumps it in a nearly liquid state deep into the earth. The geologic formation then traps the carbon dioxide. As stated by the Intergovernmental Panel on Climate Change: “For well-selected, designed and managed geological storage sites, the vast majority of the CO2 will gradually be immobilized by various trapping mechanisms and, in that case, could be retained for up to millions of years.”
Geological CO2 sequestration has the potential to help stabilize the concentration of global warming pollutants in the atmosphere, but it comes with certain hazards:
- Fractured rock formations, faults, and seismic activity could provide an avenue for CO2 leakage.
- Pressure from CO2 injection could trigger small earthquakes.
- The cement caps usually placed on the wells could deteriorate when exposed to carbonic acid, which can form when CO2 interacts with saline formations.
- Abandoned oil and gas wells that were not sealed to today’s standards could leak. A sudden and large release of CO2 could pose immediate dangers to people in the vicinity.
- Elevated CO2 concentrations in the shallow subsurface could have lethal effects on plants and subsoil animals, and could contaminate groundwater.
- Carbon-laden liquids could mobilize toxic metals and organics and contaminate groundwater.
Despite these hazards, and despite substantial talk on the part of the coal and electric utility industry on wanting to start pumping carbon dioxide into geologic formations, there are no regulations defining geologic CO2 sequestration, and no guarantee that carbon dioxide will be pumped into the earth in a safe and effective manner. Carbon capture has also proven to be too prohibitively expensive for coal and electrical utility companies to implement. Carbon capture and sequestration in Montana has not yet proven to be a viable, cost effective way for controlling our emissions.