Global warming has become an accepted phenomenon in the scientific community. The consensus is that anthropogenic activities are dominant factors in this rapid climate change. An increase in violent storms and severe droughts are becoming a normal occurrence on a global scale. The impacts of one species have never before induced global changes in climate. Limiting global temperature rise to 2 °C above preindustrial temperatures has become an accepted broad political consensus worldwide (1, 3). The combustion of fossil fuels has been identified as the major contributor to climate change (1, 5, and 7). Climate change predictions set a deadline of 2020 to significantly reduce greenhouse gases in order to mitigate anthropogenic effects on global warming (3). Urgent action is needed.
Carbon capture and storage (CCS) has the potential to play a significant role in limiting climate change. Future global emissions from the combustion of fossil fuels can potentially be reduced by 20% with the implementation of CCS (4). Currently 3 megatons of CO2 (MtCO2) per year by pilot plants is already being captured from the emissions caused by natural gas cleanup and power plants. The CO2 is then being stored in geologic formations (3). Unfortunately, at the present there is a serious lack of funding to provide for new construction of CCS. This fact will push the learning from these first pilot projects well beyond the year 2020 (3). Additionally, another drawback to CCS will be the inevitable incremental costs incurred. For example in the U.K., additional costs per year per household may be increased as much as 10% as a result of CCS implementation (3).
There are three methods of CCS currently under investigation. Pre combustion capture is a process that chemically strips off the carbon leaving only hydrogen to burn. Oxyfuel combustion burns coal or gas in the presence of denitrified air to yield only CO2 and water. Post combustion uses chemical solvents to capture the CO2 from the flue gases (1, 2, and 3). Captured CO2 is then fluidized by pressurizing to 70 bars. This liquefied CO2 is next transported to a storage site where it can be injected to depths greater than 800m (2, 3). The selection of storage sites is critical and will require monitoring for leakage for many decades to come. Additionally, methods to re-mediate deficient storage will need to be readily put into place (1, 2, and 3). Many of the techniques already being practiced by the oil and gas industry will function quite well as modeling and monitoring tools for CO2 storage. However, as learning progresses these techniques will need to be evaluated for strengths and weaknesses. Some examples of these techniques are: horizontal drilling to provide for cost effective storage, modeling techniques to predict groundwater displacement, CO2 migration, CO2 distribution and immobilization, seismic monitoring to image location of underground CO2, and borehole monitoring to heed early warnings of seepage (2, 3). Teng et. al (2005) have analyzed some theoretical outcomes to physical and economic outcomes of carbon storage with leaking. Their research highlights the need for critically essential decisions in reservoir selection, project design, and plant operation to avoid project failure (6).
At the moment the largest barrier to deployment of more CCS pilot plants is not a technological barrier but a market barrier. Current demonstration coal plants have required additional capital in the range of $1.5 billion to complete construction. Demonstration plants also have the barrier of recovering the operational costs of producing decarbonized electricity (3). Critical commercial help and subsidies are needed for large scale up of CCS. Haszeldine (2009) points out that price supports currently used to support renewables are actually supporting a more expensive option per energy unit than it would if it supported the deployment of CCS. Rapid deployment of CCS is needed to promote learning. Additionally, the sharing of detailed commercial information instead of tightly controlled company secrets commonly associated with competitive development will be help to straighten the learning curve of a much needed technology (3).
My colleagues seem to have mixed views on the practice of CCS. The reliability of CO2 available to inject for enhanced oil recovery is a serious dilemma. How can we implement CCS on a grand scale without the Co2 delivery infrastructure in place? It is my opinion that this is only a reality because we have not been able to convince investors or the public that CCS is a reliable and safe science for us to be practicing. It is true. Until a CO2 distribution network is constructed, a reliable source of CO2 will be a pressing concern. The practice of CO2 injection for enhanced oil recovery (EOR) has been going on for decades. EOR is being practiced in areas where we have already disturbed the natural development of the earth. It seems to me that one of the biggest fears for my colleagues is what will be the consequences of this CO2 injection? This is also a concern of mine. It perplexes me that some are so willing to accept similar risks with hydraulic fracturing, but they are not willing to trust the science behind CCS.
Another fascinating topic raised by one of my colleagues was the idea of pore space ownership. Just like many battles have been fought over the ownership of groundwater, I foresee the same thing happening with CO2 sequestration. Who will really own the pore space underground? On the borders of conflicting countries it’s not so simple. If you use Texas as an example, the wise governing bodies of Texas legislature have given the landowners the right to the resources below them, unless they have sold them off.
1Environmental Non-Government Organisation (ENGO) perspectives on Carbon Capture and Storage (CCS)., 2012. http://cdn.globalccsinstitute.com/sites/default/files/publications/55041/engo-perspectives-carbon-capture-storage.pdf
2Gibbins, J., and Chalmers, H., 2008, Carbon capture and storage: Energy Policy, v. 36, p. 4317–4322.
3Haszeldine, S.R., 2009, Carbon capture and storage: how green can black be?: Science, v. 325, p. 1647–1652.
4International Energy Agency, 2010, Energy Technology Perspectives: , p. 458.
5Metz, B., Davidson, O., Coninck, H. de, Loos, M., and Meyer Leo, 2005, IPCC special report on carbon capture and storage: Cambridge University Press,, p. 443.
6Teng, F., and Tondeur, D., 2007, Efficiency of carbon storage with leakage: physical and economical approaches: Energy, v. 32, p. 540–548.
7U.S. Energy Information Administration; International Energy Outlook, 2011. Pg. 6