1.1 Depleted oil and gas reservoirs – Enhanced Oil Recovery (EOR)Depleted oil or gas reservoirs can be used to store CO2. During the process, not only the injected CO2 remains stored permanently, but also residual oil and gases can be extracted by increasing the pressure and providing the driving forces.
Technologies for injection of CO2 for EOR are mature and it is indicated that up to 40% of residual oil left in an active reservoir can be extracted. 52.1.
2 Unmineable coal bed storage – CO2 Enhanced Coal Bed Methane (CO2- ECBM)CO2 can be injected into deep coal beds and store methane which is trapped in the porous structure of coal seams, which can be defined as CO2 Enhanced Coal Bed Methane (CO2- ECBM). This technology makes it possible to remove the trapped methane in the coal seams as well as to store CO2 in the void fraction. Considering the advantages, it is high economic beneficial, since there are large methane resources worldwide. 33Figure 1. List of current and planned CO2-ECBM projects 33 CCS potential in ChinaCCS has high potential to achieve significant reductions in CO2 emissions from fossil fuel–based systems. This is very suitable for the Chinese situation, since in 2009 70% of the energy came from coal, which still plays a dominant role now 48. China’s current energy consumption pattern shows that only 12% comes from renewable sources while over 90% of the total emissions from China come from fossil fuels 6.
This upper hand of fossil fuels over renewables makes it harder for countries to make a transition. The object of CCS is not only to allow the continued use of fossil fuels, but also to improve Chinese energy security while decreasing the impacts on climate change. EOR, on one hand, can be used to store more CO2, thus decreasing CO2 emission. On the other hand, it can be used to increase oil field production as well as prolong oil field production.
For now, to achieve a significant drop in CO2 emission from usage of fossil fuels, CCS is the only available way out 24.One of the main components of CCS is storage. The estimation of the total geological storage capacity in China was around 196.2 GT CO2 35. Furthermore, China has in total 23 onshore and 9 offshore basins to store the CO2 safely in 2. Already in 2013 there were 72 large scale integrated CCS demonstration projects in the world, of which 11 were located in China 18. China has a sufficient space to store CO2 safely which might help China to reduce emissions and also ensure economic growth to its people.
This technology might prove to be a win-win situation for both the environment and economy as it will control the emission levels while buying the economy some time to make the change towards renewable energy.