Options for Capturing Carbon Dioxide from the Air

1. Options for CapturingCarbon Dioxide from the Air Klaus S. Lackner Columbia University May, 2008

2. The Challenge: Holding the Stock of CO2 constant Extension of Historic Growth Rates Constant emissions at 2010 rate 560 ppm 33% of 2010 rate 10% of 2010 rate 0% of 2010 rate 280 ppm

3. Comparison With Keeling’s Data

4. Lifting Cost Carbon as a Low-Cost Source of Energy US1990$ per barrel of oil equivalent Cumulative Carbon Consumption as of1997 Cumulative Gt of Carbon Consumed H.H. Rogner, 1997

5. A Triad of Large Scale Options • Solar • Cost reduction and mass-manufacture • Nuclear • Cost, waste, safety and security • Fossil Energy • Zero emission, carbon storage and interconvertibility Efficiency, conservation and alternative energy will help, but not solve the problem

6. Net Zero Carbon Economy • Closing the carbon cycle CO2 extraction from air CO2 emissions power consumption • CO2 collection CO2 handling refining energy carrier FOSSIL FUEL CYCLE oxidized carbon disposal fossil carbon extraction

7. Net Zero Carbon Economy CO2 extraction from air CO2 from concentrated sources Permanent & safe disposal

8. Initially Air Capture is tied to Carbon Dioxide Storage Mg3Si2O5(OH)4 + 3CO2(g)  3MgCO3 + 2SiO2 +2H2O(l) +63kJ/mol CO2

9. Air Capture • Takes CO2 from the atmosphere to offset CO2 emissions • Can compensate for all and any emissions • Aims at distributed, small and mobile sources • Preserves access to hydrocarbon fuels

10. The Substitution Principle • All CO2 is equal • Combustion and capture cancel out • No need to co-locate • Air is a perfect transport system • Mixing times are fast, weeks to months • Air is an excellent storage buffer • Annual emissions are 1% of stored CO2

11. Air Capture: A Different Paradigm • Leave existing infrastructure intact • Retain quality transportation fuels • Eliminate shipping of CO2 • Open remote sites for CO2 disposal • Enable fuel recycling with low cost electricity Separate sources from sinks in space and time

12. Air CaptureIs it Geo-Engineering? • Con • Air capture simply separates sources and sinks in space and time • Air capture matches emissions one for one • Air capture provides a source of CO2 • Pro • Air capture makes it possible to control the CO2 level in the atmosphere Air capture directly counters an emission, it does not fight one change with another

13. Natural Air Extraction • Ocean Uptake • 30% of anthropogenic CO2 emission • Trees • Biomass absorbs 100 GtC annually • Capture cost ~ $27/ton of CO2 • Land demand too large • Leaves are underutilized for CO2 extraction

14. Air Capture: Many Options • Growing biomass • Terrestrial biomass: Biofuels • Carbon is delivered as bio-based fuel • Combustion at a power plant with CCS leads to a net carbon reduction • Marine biomass: Ocean fertilization • Carbon is never collected but some is removed from the surface carbon cycle • Raising the alkalinity of the ocean • Adding base • E.g. dissolving CaCO3 into the ocean • Removing acid from ocean water • Removing HCl via electro-dialysis and disposing of it through neutralization

15. Air Capture: Collection & Regeneration Synthetic Tree Courtesy GRT

16. Challenge: CO2 in air is dilute • Energetics limits options • Work done on air must be small • compared to heat content of carbon • 10,000 J/m3 of air • No heating, no compression, no cooling • Low velocity 10m/s (60 J/m3) Solution: Sorbents remove CO2 from air flow

17. Air CO2 CO2 Capture from Air 1 m3of Air 40 moles of gas, 1.16 kg wind speed 6 m/s 0.015 moles of CO2 produced by 10,000 J of gasoline Volumes are drawn to scale

18. How much wind?(6m/sec) Wind area that carries 10 kW of wind power 0.2 m2 for CO2 Wind area that carries 22 tons of CO2 per year 80 m 2 for Wind Energy 50 cents/ton of CO2 for contacting

19. Air Flow CO2 diffusion Ca(OH)2 as an absorbent Ca(OH)2 solution CaCO3 precipitate CO2 mass transfer is limited by diffusion in air boundary layer

20. Ion exchanger: Na2CO3 + Ca(OH)2 2Na(OH) + CaCO3 A First Attempt Calciner: CaCO3CaO+CO2 Air contactor: 2Na(OH) + CO2 Na2 CO3

21. ProcessReactions Hydroxylation Reactor CO2 (4) Fluidized Bed (1) (2) (3) (6) Membrane Capture Device Trona Process Limestone Precipitate Dryer (5) Depleted Air Air Membrane Device (1) 2NaOH + CO2 Na2CO3 + H2O Ho = - 171.8 kJ/mol (2) Na2CO3 + Ca(OH)2 2NaOH + CaCO3 Ho = 57.1 kJ/mol (3) CaCO3 CaO + CO2 Ho = 179.2 kJ/mol (4) CaO + H2O  Ca(OH)2 Ho = - 64.5 kJ/mol (5) CH4 + 2O2 CO2 + 2H2O  Ho = -890.5 kJ/mol (6) H2O (l) H2O (g) Ho = 41. kJ/mol Source: Frank Zeman

22. Lime Based Air Capture • Is feasible • Carbon Neutral • < 250 kJ/mole of CO2

23. Need Better Sorbents • Fast Reaction Kinetics • Limited by air side transport • Low binding energy • Comparable to flue gas capture • Small environmental footprint • Failsafe designs Sorbents designed for flue gas scrubbing are strong enough to capture CO2 from air

24. Sorbent Choices 350K 300K Air Power plant

25. Cost of Contacting the Air Unit Cost 1/

26. Cost of CO2 from Air Unit Cost 1/

27. Cost of CO2 from Air(rescaled) Unit Cost Fixed Cost 1/

28. Comparison to Flue Stack Scrubbing • Much larger collector • Similar sorbent recovery • Cost is in the sorbent recovery

29. Sketching out a design • Compare to windmills in 1960 • Cost goal • $30/ton of CO2 • Motivated by cost of fuel, oxygen, electricity, raw materials

30. 115m 15 km3/day of air 15 km3/day of air 9,500t of CO2 pass through the tower daily. Half of it could be collected 450 MWe NGCC plant Water sprayed into the air at the top of the tower cools the air and generates a downdraft. 300m As electricity producer the tower generates 3-4MWe Cross section 10,000 m2 air fall velocity ~15m/s

31. 60m by 50m 3kg of CO2 per second 90,000 tons per year 4,000 people or 15,000 cars Would feed EOR for 800 barrels a day. 250,000 units for worldwide CO2 emissions

32. Air Extraction can compensate for CO2 emissions anywhere 2NaOH + CO2 Na2CO3 Art Courtesy Stonehaven CCS, Montreal

33. GRT’s approachto air capture • GRT in Tucson has developed a sorbent process that is energetically efficient, always carbon positive • GRT plans to provide small factory produced units • Begin with the physical CO2 market Together with Allen Wright & Gary Comer, I helped found a company to develop air capture technology. I am now a member

34. Small factory produced units can be packed into a standard 40 foot shipping container GRT’s Vision

35. The first of a kind

36. Collection and Regeneration • Collection • Natural wind carries CO2 to collector • CO2 binds to surface on ion exchange sorbent materials • Regeneration • CO2 is recovered with: • liquid water wash • or carbonate solution wash • or low-temperature water vapor • plus optional low grade heat • Regenerated sorbent is reused many times over Courtesy GRT

37. Options for Regeneration • Pressure Swing • Thermal Swing • Water Swing • Liquid water – wet water swing • Water vapor – humidity swing • Carbonate wash is a water swing • With CO2 transfer • Salt splitter for CO2 recovery

38. Na+ Na+ Na+ Cl- Cl- Cl- Electrodialysis Bipolar membrane Bipolar membrane H+ OH- H+ OH- salt H+ OH- salt salt acid acid base acid base anionic membrane cationic anionic membrane cationic anionic membrane

39. Air Capture: Collection & Regeneration Courtesy GRT

40. GRT’s Carbon, Energy and Water Balance • Production costs are negligible compared to lifetime capture • Energy consumption is small • Low grade heat • Electric power • Ambient energy • Water consumption can substitute for energy • Water consumption can be 5 to 15 times CO2 collection • Water can be salty or dirty • Some fresh water can be produced • Indirect emissions depend on energy sources • Worst case is still carbon positive

41. Four Stages of Air Capture • Industrial and commercial CO2 • CO2 capture compensating for emissions • CO2 capture for reducing CO2 concentrations in the air • CO2 capture for fuel recycling

42. Hydrogen or Air Extraction? Coal,Gas Fossil Fuel Oil Hydrogen Gasoline Distribution Distribution Cost comparisons Consumption Consumption CO2 Transport Air Extraction CO2 Disposal

43. Carbon Capture and StorageforCarbon Neutral World • CCS simplifies Carbon Accounting • Ultimate Cap is Zero • Finite amount of carbon left

44. Air Capture Supports Underground Injection • Safety Valve • Unpredicted changes in the underground reservoir should trigger a safe release of CO2 • Compensated for by air capture • Carbon Accounting • Losses can be made up by air capture • Air capture can introduce C-14 tracking

45. Stabilizing CO2 in the atmosphere • CO2 capture can exceed emissions • CO2 capture can aim for design point

46. CO2 CO2 H2 H2 CH2 Materially Closed Energy Cycles O2 O2 Energy Source Energy Consumer H2O H2O

47. O Oxygen Oxidizer Free O2 CO2 H2O Combustion products Increasing Oxidation State Free C- H CO Town Gas Methanol Fischer Tropsch Synthesis Gas Fuels Biomass Ethanol Coal Petroleum Natural Gas H C Carbon Benzene Methane Hydrogen Gasoline Increasing Hydrogen Content

48. O Oxygen Oxidizer Free O2 CO2 H2O Combustion products Increasing Oxidation State Free C- H CO Town Gas Methanol Fischer Tropsch Synthesis Gas Fuels Biomass Ethanol Coal Petroleum Natural Gas H C Carbon Benzene Methane Hydrogen Gasoline Increasing Hydrogen Content

49. O Oxygen Oxidizer Free O2 CO2 H2O Combustion products Increasing Oxidation State Free C- H CO Town Gas Methanol Fischer Tropsch Synthesis Gas Fuels Biomass Ethanol Coal Petroleum Natural Gas H C Carbon Benzene Methane Hydrogen Gasoline Increasing Hydrogen Content

50. Private Sector Carbon Extraction Farming, Manufacturing, Service, etc. Carbon Sequestration Certified Carbon Accounting Public Institutions and Government guidance Carbon Board certification Permits & Credits certificates