99 學年度第一學期專題討論 99 學年度第一學期專題討論 Sorption of methane and CO 2 for enhanced coalbed methane recovery and carbon dioxide sequestration Prusty, B. K., Sorption of methane and CO 2 for enhanced coalbed methane recovery and carbon dioxide sequestration. Journal of Natural Gas Chemistry, 17, Adviser ： Loung-Yie Tsai Presenter ： Ling-Szu Wang Date ： 2010/12/30 1

Outline Introduction Objectives Methods of Study Results and Discussion Conclusions 2

Introduction 3

4 溫室效應示意圖 co 2 N2OCH4O3O3 H2OCFCs Greenhouse gases causing global warming with their increasing concentration in the atmosphere are H2O, CO2, CH4, N2O, O3, and CFCs. (Mavor, M.J. et al., 2002; Orr, F. M., 2004.)

Diagram of CBM recovery. ( 5 Clean Energy ： Coalbed Methane (CBM) CBM

Injection of CO2 in coal seams may help in enhancing the recovery of coalbed methane. (Gunter, W. D. et al., 1997) 6 CO2 CH4

Objectives 7

To investigate whether recovery of methane could be enhanced by injecting CO2 after partial desorption of methane by pressure depletion. To assess the ability of coal to sequester CO2. 8

Methods of Study 9

Figure 1. Schematic of the experimental set up. FV ： fixed volume cylinder SC ： sample container PT ： pressure transducer GC ： Gas Chromatograph 10 CO2 CH4 1. adsorption experiment

Figure 1. Schematic of the experimental set up. FV ： fixed volume cylinder SC ： sample container PT ： pressure transducer GC ： Gas Chromatograph (ad/de)sorption and injection experiment CO2 CH4

Peng-Robinson equation ( Peng, D. Y., and Robinson, D. B., 1976 ) Vads = Volume of gas adsorbed R = Universal gas constant for real gas T = Temperature P1 = Pressure of FV before opening the valve P2 = Pressure of FV after opening the valve VR = Volume of FV Vv = Void volume in SC Z= Compressibility factor of the adsorbate gas at the corresponding P and T 12

Results and Discussion 13

Table 1. Overview of the coal samples. Adsorption capacity of coals Figure 2. CO2 and CH4 adsorption isotherm for the coal samples. 14 Coal Sample Ash content (%) Moisture content (%) Seam Seam Seam

CO2 injection and release of methane sample 1 ： Desorption pressure (MPa) InjectionCO2 injection pressure (MPa) CH4 partial pressure (MPa) Sorbed CH4 (ml/g) 3.4 pre- injection st nd Figure 3. Results of (ad/de)sorption and injection experiment on Seam 1.

CO2 injection and release of methane sample 2 ： Desorptio n pressure (MPa) InjectionCO2 injection pressure (MPa) CH4 partial pressure (MPa) Sorbed CH4 (ml/g) 3.4 pre- injection st nd rd Figure 4. Results of (ad/de)sorption and injection experiment on Seam 2.

CO2 injection and release of methane sample 3 ： Desorption pressure (MPa) InjectionCO2 injection pressure (MPa) CH4 partial pressure (MPa) Sorbed CH4 (ml/g) 3.7 pre- injection st nd rd Figure 5. Results of (ad/de)sorption and injection experiment on Seam 3.

18 Figure 6. Methane released as percentage of gas-in-place after CO2 injections. Enhanced methane recovery behavior of coals is not uniform and varied for different coals.

CO2 sequestration capacity Figure 7. Volume of CO2 adsorbed with different CO2 injections. 19

Conclusions 20

It is possible to enhance the recovery of methane by injecting CO2. Enhanced methane recovery behavior of coals is not uniform and varied for different coals. 21

It is possible to sequester a large quantity of CO2 in all the coals tested. More studies need to be undertaken to understand the enhanced methane recovery process and preferential sorption behavior of various coals. 22

Thanks For Your Attention. 23