“Quo Vadis Anthropogenic CO2?” Part 3: Uses of CO2
So far I have discussed the problems that CO2 can pose and methods at hand to capture CO2 emissions. The next question is, what are the potential applications of the CO2 after it has been captured? Well, in the oil industry for instance, CO2 represents a desirable product. Instead of ‘simply’ storing the CO2 underground, it could be used for enhanced oil recovery (EOR). In simple terms, EOR refers to a number of technologies that allow increased recovery of oil in depleted or high viscosity oil fields. EOR is also sometimes referred to as tertiary oil recovery because it usually represents the third step in the oil production chain. CO2-based EOR belongs to the miscible displacement methods, that means it is injected into an oil field at a sufficiently high pressure at which the CO2 and oil mix together to form a liquid that can be more easily recovered [Shah2010]. This method has been applied by the oil industry since the 1970s and this repertoire of experience is one of the arguments to pursue this route. According to studies from the National Energy Technology Laboratory (NETL), CO2-EOR can potentially add another 5-15% of the original oil in place to the ultimate recovery [NETL2010]. There are currently 129 CO2-EOR projects operating around the world, 114 of those are located in the US [Dooley2010]. But is the available volume sufficient to have a positive effect on the global CO2 emissions? Estimates released by the US Department of Energy (DOE) show that depleted oil and gas wells in the US and Canada alone have the potential to sequester more than 82 billion tons of carbon, i.e. after oil has been produced. Remember, we emit over 7 billion tons of CO2 every year. I leave it to you to do the math.
About 20% of the CO2 used in EOR is produced in natural gas processing plants. The majority, however, comes from natural underground sources. Consequently, the use of natural CO2 does not lead to a net reduction of emissions. The cost for CO2 from natural sources is roughly US$ 10-15 per metric ton. This is a critical parameter because the total cost of CO2 (including purchase price and recycle costs) can amount to 25-50% of the cost per barrel of oil produced. The DOE’s Energy Information Administration (EIA) estimates that in 2030 CO2 will be available at a cost between US$ 20 to US$ 60 per ton [NETL2010].
We already learned that it is not all roses with reducing CO2 emissions by CO2-EOR. The situation gets even more difficult. For instance, after EOR methods have been employed and a depleted oil field is used for CO2 sequestration, there could be a significant quantity of oil remaining in the reservoir which may be extracted in future and the injected CO2 in the reservoir could help to recover some of it. Apart from the fact that the CO2 in the reservoir may be released to the atmosphere, the question of ownership of the reservoir/sequestration site needs to be clarified. Besides, there are also some non-trivial differences between injecting CO2 to increase oil recovery and injecting it with the purpose of ‘simply’ reducing GHG emissions. The latter one requires a set of measures that would not be undertaken on a business-as-usual CO2-EOR project [Dooley2010], in other words, who takes care of the reservoir? But even if the CO2 is not stored in depleted oil fields, it is not clear whether the CO2 will really stay there long enough to have a positive effect on the climate. If it happens to leak out too early, all the effort would not just be wasted, but man-made CO2 emissions would be accelerated. And, at the scale of billions of tons of available CO2, it becomes a waste product with a zero market value [Dooley2010].
To sum up, there are plenty of challenges to be solved before global CO2 emissions can be curbed by employing technology and I encourage you to reduce your own energy needs as much as possible. With such a consensus in place I am very optimistic that we can solve this challenge!
Please post your comments and questions and let the lively discussion begin!
References
[Dooley2010] Dooley et al.; Pacific Northwest National Laboratory; CO2-driven Enhanced Oil Recovery as a Stepping Stone to What?; 2010.
[NETL2010] National Energy Technology Laboratory; Carbon Dioxide Enhanced Oil Recovery; 2010
[Shah2010] Shah et al.; A review of novel techniques for heavy oil and bitumen extraction and upgrading; Energy & Environmental Science; 2010
- “Quo Vadis Anthropogenic CO2?” Part 2: Carbon capture and storage techniques
- Quo Vadis Anthropogenic CO2? Part 1: Greenhouse gas emissions and global warming
- Nanotechnology meets CO2 capture
- Beschleunigung der Effizienz und Umweltfreundlichkeit von GE Jenbacher Gasmotoren
- GE’s ORegen system has roots in Munich
