Carbon capture and storage (CCS) is a developing approach to offsetting global warming by capturing carbon dioxide (CO2) and storing it rather than allowing it to be released into the atmosphere. The carbon dioxide would be removed from sources such as power plants that use fossil fuel as their source of power. Storage would take place either within geological formations, oceans or in the form of mineral carbonates. The technology for this process is already commercially available and is being used in some parts of the world. At present time, no large-scale power plant is using CCS to fully capture and store all of it’s carbon dioxide emissions.
The process of carbon capture and storage requires that the carbon dioxide be captured and compressed in order for storage. This is where things get interesting. The process requires an increase in fuel needs of the power plant by around 11-40%. So, not only is more fuel used, but also the cost to the end user will increase. However, the reduction in CO2 released into the atmosphere could be as much as 90%.
Storage is another concern. CO2 can’t just be stored in containers. It’s been established that the best ways to store carbon dioxide are in old and empty oil and natural gas fields such as those found in the North Sea, or deep coal seams and saline formations. Other options are in forming mineral carbonates with the CO2 to produce what is basically a very stable rock, or storage within the ocean. All are actually considered to be safe ways to store carbon dioxide, with mineral carbonates being the most stable and leakage from geological formations or oceans at extremely low levels, but the cost of transportation is high and in the case of forming mineral carbonates, the cost of the actual process is an increase of anywhere from 60-180% energy usage by the capturing plant. Ocean storage is probably the least desirable form of storage, as large deposits of CO2 in the ocean are known to be quite hazardous to the ocean ecosystem.
Currently, there are a handful of carbon capture and storage programs in use:
- The oldest is the Sleipner project and is located in the North Sea. Norway’s StatoilHydro strips CO2 from natural gas as it is piped out of a field deep below the sea. The carbon dioxide is then disposed of in a saline formation. By storing the CO2 in this way, Statoil saves itself hundreds of millions of euro in avoided carbon taxes.
- The Weyburn project in located in an old oil reservoir in Southeastern Saskatchewan, Canada. The CO2 that is capture at Great Plains Coal Gasification plant in Beulah, North Dakota is injected in to the oil reservoir at the rate of around 1.5 million tons per year.
- The third site is located in Salah, Algeria, where there is a natural gas reservoir like Sleipner. As the CO2 is separated from the natural gas, it is re-injected into the subsurface.
The technology is already in place, or near in place, for capturing CO2 before, during or after it becomes a by-product of the energy producing process, but the questions regarding the viability of CCS versus costs in terms of money and energy have yet to be answered.