1. 1 Iron Fertilization, Air Capture, and Geoengineering Woods Hole, MA 26 September 2007 David Keith (keith@ucalgary.ca; www.ucalgary.ca/~keith) Director, Energy and Environmental Systems Group Institute for Sustainable Energy, Environment and Economy University of Calgary

2. 2 New York Times May 24th 1953

3. Emissions are rising faster than expected 3 Skeptics argued that this “unrealistic” scenario was included only to make the problem look worse This is where we need to be heading

4. And, it’s melting quicker than models predict 4 Ice cover on 16 September 2007 minimum ice cover 1979-2000

8. Carbon Management: Location vs Mechanism 8

9. 9 Biomass Energy with Capture

10. 10 Biomass with Capture

11. 11 Electricity for free… … at a ~300 $/tC carbon price

12. 12 Air Capture

13. 13 Thermodynamics of CO 2 capture Free energy of mixing: To get 1 bar it takes: ~ 6 kJ/mol starting at 10% CO 2 in a power plant exhaust, and ~ 20 kJ/mol starting at the 380 ppm ambient atmospheric concentration It takes ~13 kJ/mol to compress from 1 to 100 bar C + 2 O 2  CO 2 394 kJ/mol Power plants are ~35% efficient (~160 kJe/mol-C from coal) min loss of electric output should be ~12% ((6+13)/160). Current designs are at least twice as bad.

14. 14 Direct Air Capture

15. 15 A A

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19. Cost and energy use vs flow rate 19

20. 20 Negative emissions change long-run climate policy Keith, D. W., Ha-Duong, M. & Stolaroff, J. K. Climate strategy with CO 2 capture from the air. Climatic Change (2005).

21. 21 Air Capture Summary 1.Three uses Long run negative emissions (2100?). Acting in a rush, AC along while we do Coal CCS (2030?) Low Carbon Fuels and remote EOR (2015?) 2.NaOH contactor ETH/Rome group using commercial data on packed towers. Calgary/CMU using spray tower Less than $50/tCO 2 3.NaOH regen Nuclear heat Electrochemical Borates/Titenates No good end-to-end costing.

22. 22 Other Methods

23. 23 Increasing ocean alkalinity Motivation: 2×[CO 3 -2 ] + [HCO 3 - ]  [A] Mg-silicates –Olivine (Mg 2 SiO 4 ) and serpentine (Mg 3 Si 2 O 5 (OH) 4 ) are the most abundant Mg-silicates MgO CaCO 3 CaO

24. 24 Comparisons

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