1. Energy Analysis of Underground Coal Gasification with Simultaneous Storage of Carbon Dioxide Ali Akbar Eftekhari Hans Bruining x

2. (Enriched) Air Water (Steam) CO, CO 2, H 2, H 2 O, CH 4, N 2 C + 2 H 2 O + CaO  CaCO 3 + 2 H 2 + 87.9 kJ/mol

3. Exergy Analysis of Energy Recovery Processes Recovery Process Energy Consumption CO 2 Capture and Storage Energy Source CO 2 Capture and Storage Recovery Process Energy Consumption CO 2 Capture and Storage Energy

4. Zero-emission recovery factor Coal (56%) Natural Gas (62%) Ref: Dellucci, 2003; Except the CCS data

5. UCG with mineral injection 5 High Temperature: CaCO3  CaO + CO 2 Volume Constraint:

6. Independent reactions Combustion  C + O 2  CO 2 + 393.77 kJ/mol Gasification  Global reaction C + 2 H 2 O + CaO  CaCO 3 + 2 H 2 + 87.9 kJ/mol  Boudouard reaction C + CO 2  2 CO – 172.58 kJ/mol  Shift reaction CO + H 2 O  CO 2 + H 2 – 41.98 kJ/mol  Methanation C + 2 H 2  CH 4 + 74.90 kJ/mol

7. Equilibrium relations y i : gas phase mole fraction P 0 : standard pressure (1 bar) P: system pressure K j : equilibrium constant of reaction j v i,j : stoichiometric coefficient of component i in reaction j Φ i : fugacity coefficient of component i in a gas mixture

8. Temperature constraint at P=80 bar Volume constraint

9. Optimum composition (O 2 injection) Composition (dry basis) H20.46 CO20.08 CO0.32 CH40.14 Higher heating value (MJ/m 3 )14.679 Lower heating value (MJ/m 3 )13.286

10. Process flow diagram (1) E gain E1E1 E2E2 E4E4 E3E3 E5E5 E CCS η = (E gain - (∑E i +E CCS ))/E Res E Res

11. From theory to practice Theoretical Practical Zero-emission (Sustainable)

12. Results of PFD (1) Theoretical, practical, and zero-emission recovery of coal energy (water to oxygen molar ratio of 3.2) Recovery factor (%)

13. Process flow diagram (2)

14. Sustainable recovery for other energy conversion processes

15. Conclusion In situ introduction of absorbent e.g. CaO is energetically expensive and with the current state of technology is not feasible Using naturally abundant minerals can improve the exergetic recovery of UCG process

16. Coal Zero-emission Recovery

17. Natural gas sustainable recovery

18. Formulation

20. Exergy? Energy = Exergy + Anergy Exergy is a portion of energy that potentially can be converted to mechanical work 1 kJ of Electricity = 1 kJ of Exergy + 0 kJ of Anergy 1 kJ of energy in hot water at 70 o C = 0.13 kJ Exergy + 0.87 Anergy Energy is conserved; Exergy is consumed