If you are looking for information previously contained on the CCCSTN website it has been incorporated into a Federal and Provincial Collaborative website as a part of the Canadian CCS Network, at www.ccs101.ca.
What is CO2 Capture & Storage (CCS)?
Geologic storage of carbon dioxide (CO2) is the underground storage of CO2 from large industrial sources such as power plants and other industrial sources.
Carbon Capture and Storage (CCS), also known as Carbon Capture and Sequestration, includes geologic storage as one of its components.
Carbon capture and storage is a process for reducing GHG emissions into the atmosphere by first extracting CO2 from gas streams typically emitted during electricity production, fuel processing and other industrial process. Once captured and compressed, the CO2 is transported by pipeline or tanker to a storage site, often to be injected into an underground storage site (or geological formation), where it will be safely stored for the long-term.
What is CO2?
CO2 is a natural substance in the air that is essential to life. As part of the natural carbon cycle, people and animals inhale oxygen from the air and exhale CO2. Meanwhile, green plants absorb CO2 for photosynthesis and emit oxygen back into the atmosphere. CO2 is also widely used for many purposes such as carbonating drinks and filling fire extinguishers.
As a greenhouse gas, its presence in the atmosphere traps heat from the sun. Normally, this keeps the climate warm enough for life to continue. However, the burning of fossil fuels is increasing CO2 levels in the atmosphere above naturally-occurring levels, contributing to global climate change.
Is CO2 Storage Safe?
Injection of CO2 is a technology that has been in use since the 1960's, therefore, scientists have decades’ worth of data to guide present day storage projects.
The subsurface naturally stores a myriad of naturally occurring gases, including naturally occurring CO2, so the concept is to use the natural barriers that have held other gases for millions of years. Through decades of injecting and storing other gases in the subsurface, like natural gas, researchers are very confident that CO2 storage is safe.
How does the CO2 stay underground?
First of all, the CO2 must only be injected into storage sites that have been well characterized and classified as safe prior to the injection of CO2.
A safe storage site means that the CO2 will be injected into a layer deep underground with porous rocks where CO2 can be stored in the pores. There must be a solid rock (cap rock) on top of the porous layer to prevent the CO2 from moving upwards.
This way of storing CO2 is the same mechanism that has stored oil and natural gas below the ground for millions of years. The fact that oil and natural gas have been trapped underground for millions of years is a very good indication that CO2 will remain safely stored.
There can never be a guarantee that CO2 will not leak, but it is possible to store CO2 at locations where the risk of leakage is very low, and in formations where the CO2 itself converts on a broad scale into a form that is no longer susceptible to gaseous release. In the unlikely case of leakage we will have the mechanisms in place to detect the leak and initiate remediation actions.
According to experts the risk of leakage is very low. If proper characterization of the storage location is performed prior to CO2 injection, the probability is that less than 1 percent CO2 can leak within 1000 years.
The injected CO2 will after hundreds or thousands of years start to react with other minerals and form limestone (a solid rock), which is the safest form of CO2 storage. That means that as time goes by the CO2 storage will become even safer.
What can be done if CO2 leaks?
If CO2 should leak there are ways to stop the leak. The highest risk for leakage is that CO2 will come out again through cracks in the injection well. If that happens the well must be closed down and sealed with cement. Leakage in such situations is unlikely to be at levels that would be toxic. Detection devices would catch such leaks at a very early stage.
Leakages can also be stopped if the injection of CO2 is stopped and the pressure is reduced. Again, remember that CO2 in formations often changes state into solid forms, or mixes with water, resulting in smaller likelihoods that gases would escape in large quanities.
Can earthquakes result in CO2 leakage?
CO2 will not be stored in areas where earthquakes are likely to occur. But even if an earthquake should occur at a CO2 storage site, research projects have shown that the CO2 will most likely not leak. There are many underground geological formations near earthquake zones that have experienced countless, large earthquakes over many thousands of years and not released oil or gas from these areas in any capacity.
Remember that oil and natural gas do not necessarily leak out of their reservoirs if there is an earthquake.
How much CO2 can be stored?
The U.S. Department of Energy (DOE) has made an assessment of the potential sequestration capacity across the United States and parts of Canada and has determined that there exists sufficient volume to store approximately 600 years of CO2 produced from total U.S. fossil fuel emissions (at current rates).
Why is CCS such an important technology?
Renewable energy, energy efficiency, and other tools will all be needed to find solutions for climate change. CCS can play an important role in mitigating the CO2 that contributes to climate change because CCS is the most immediate solution existing for large point emitters of CO2.
With estimates ranging between 40 to 60 per cent, much of the world’s CO2 comes from these large stationary sources. When increasing demand for energy from these sources is considered, CCS represents a practical approach to keep this climate-altering gas from even entering the atmosphere.
As our social and economic success is dependent on access to energy, CCS has the potential to mitigate existing CO2 production necessary for our shared quality of life. CCS has vast potential to buy us more time in bringing other energy solutions on line.
Where is CCS currently in use?
CCS has been in use by the oil and gas industries as a means to enhance the production of oil and gas for over 40 years. Projects such as Sleipner in Norway (since 1996), Weyburn in Saskatchewan, Canada (since 2000) and Salah in Algeria (since 2004) have permanently been sequestering CO2 with no incidents.
For more information on CCS please visit Canada's CO2 Capture & Storage Information Source, www.CCS101.ca
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