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Air Capture and the Need for Negative Emissions


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Presentation by Klaus Lackner (Arizona State University) at the ORAU 74th Annual Meeting of the Council of Sponsoring Institutions

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Air Capture and the Need for Negative Emissions

  1. 1. Air Capture and the Need for Negative Emissions Klaus S Lackner March, 2019
  2. 2. 200 300 400 500 600 700 800 1900 2000 2100 2200 Continued Exponential Growth Constant Emissions after 2010 100% of 2010 rate 33% 10% 0% Preindustrial Level 280 ppm Hazardous Level 450 ppm Hazardous Level 450 ppm IPCC calls for negative emissions CO2(ppm) year
  3. 3. Economymust decarbonizefast ReducingCarbonIntensity to zero Overcoming 3% growth (economic + population) Required annual reduction in carbon intensity to limit CO2 levels to 𝒙𝒙 Required annual reduction in carbon intensity to limit CO2 levels to 450 ppm starting in year 𝒙𝒙
  4. 4. Rapid Reductions IPCC, 2018: Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson- Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. World Meteorological Organization, Geneva, Switzerland, 32 pp.
  5. 5. Need for carbon removal Drawdown Negative Emissions • Compensating for continued use of fossil fuels • Will take decades to stop emissions and phase out fossil fuels • We act too slowly, but we can’t go too fast either • Recovering from an overshoot • Return to prior values 350 ppm, 400 ppm, 450 ppm? • Prepare for recovering 1 to 2 trillion tons of CO2 • 1500 Gt CO2 ~ 100 ppm (40 years of current emissions) • More than 20th century emissions • Carbon Storage has become unavoidable
  6. 6. Removing carbon from the environment • Collection from the biosphere • Collection from the ocean • Collection from the air – Direct Air Capture
  7. 7. Air Capture of CO2 is an enabling technology • Air capture eliminates all exceptions • Air capture can draw down CO2 • Air capture enables non-fossil liquid fuels • Air capture enables fossil liquid fuels
  8. 8. Feasibility & Affordability? CO2 in air is dilute and air is full of water • Sherwood’s Rule suggests that costs scale linearly in dilution • The air carries 10 to 100 times as much H2O as CO2 • First-of-a-kind apparatus is expensive (APS study: $600/t) Wikipedia picture Not a conventional separation technology
  9. 9. CO2 in the air is not too dilute! • One cubic kilometer of air • Passes through a wind mill in the course of an afternoon • Carries $300 of kinetic energy • assuming a wind speed of 6m/s and an energy value of 5¢/kWh • Carries $21,000 of CO2 • assuming a CO2 tipping fee or commodity value of $30/ton As a source of CO2,the air is 70 times more valuable than as a source for wind energy. Wind energy is routinely harvested
  10. 10. Thermodynamics is not limiting Separation Process involving Sorbents Membranes etc. Air (P0, P1) CO2 (P0, P0) CO2 depleted air Theoretical minimum free energy requirement for the regeneration is the free energy of mixing (Specific irreversible processes have higher free energy demands) (P0, P2) Gas pressure P0 CO2 partial pressure Px Denoted as (P0, Px) ∆𝐺𝐺 = 𝑅𝑅𝑅𝑅 �� 𝑃𝑃0 − 𝑃𝑃2 𝑃𝑃1 − 𝑃𝑃2 � 𝑃𝑃1 𝑃𝑃0 ln 𝑃𝑃1 𝑃𝑃0 − � 𝑃𝑃0 − 𝑃𝑃1 𝑃𝑃1 − 𝑃𝑃2 � 𝑃𝑃2 𝑃𝑃0 ln 𝑃𝑃2 𝑃𝑃0 + � 𝑃𝑃0 − 𝑃𝑃1 𝑃𝑃0 � � 𝑃𝑃0 − 𝑃𝑃2 𝑃𝑃0 � 𝑃𝑃0 𝑃𝑃1 − 𝑃𝑃2 ln 𝑃𝑃0 − 𝑃𝑃1 𝑃𝑃0 − 𝑃𝑃2 � 22 kJ/mol of CO2 vs. 700 kJ of energy extracted
  11. 11. Sherwood’s Rule can be avoided Sherwood’s Rule • The cost of the first step in the separation dominates • 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 = 𝑎𝑎𝑎𝑎 + 𝑏𝑏 + 𝑐𝑐 log 𝐷𝐷 SOURCE: National Research Council (1987) U from seawater Air Capture Aspiration Bulk processing Thermodynamic separation Sherwood’s Rule for minerals ~ $10/ton of ore Cost of separation scales linearly with dilution D
  12. 12. Mass production lowers costs • Car engines are 100 times cheaper than power plants on a kilowatt basis • Mass production wins out over the economy of scales • Short life times reduce risks specifically risks of obsolescence • Small scales shorten time to deployment • Automation addresses cost of operation and maintenance 𝟏𝟏 + log𝟐𝟐 𝜺𝜺 ≈ 𝜶𝜶 Same Power Law! Photovoltaic learning curve from “Photovoltaics Report,” Fraunhofer Institute for Solar Energy, Freiburg July 2017 • Economies of scale: 𝐶𝐶 = 𝐶𝐶0 𝑠𝑠 𝑠𝑠0 𝛼𝛼 , α~ 2 3 • Economies of numbers: 𝑐𝑐 2𝑛𝑛 = 𝜀𝜀𝜀𝜀(𝑛𝑛), 𝜀𝜀~0. 8 • Cost of N small units: C = 𝑐𝑐(1) 1+log2 𝜖𝜖 𝑁𝑁1+log2 𝜖𝜖
  13. 13. wikipedia pictures 10 year life time implies a production capacity of 10 million per year Shanghai harbor processes 30 million full containers a year World car and light truck production: 80 million per year 100million container-sizedunits balancecurrent world emissions (or eliminatea 100 ppm overshoot in 40 years) (Containersizedunitscapture1tonCO2/day)
  14. 14. Lowcost comes with experience price dropped fortyfold price dropped hundredfold cost of lighting fell 7000 fold in the 20th century Wikipedia pictures Ingredient costs are already small – small units: low startup cost $600 $500 $400 $300 $200 $100 $0 APS (low tech, first-of-a-kind) Early implementations Practical interest Per ton CO2 Raw material and energy limit (frictionless cost) Cost ratio to navigate is much smaller than for renewable energy
  15. 15. Research is proceeding at a number of universities ASU, Georgia Tech, Columbia University, ETH Zurich, Sheffield University, Zhejiang University, … • Several start-ups have working prototypes • Different approaches, different markets • Gaining experience, demonstrating costs • Establishing a new technology …. Commercial Interest is stirring, carbon price incentives are starting, 45Q Tax Credit in the US is worth $50/ton Air Capture is Real
  16. 16. ASU’s Direct Air Capture • Passive System • Moisture Swing Sorbent • Mass Manufacturing Design • Two Stage Concentrator
  17. 17. MoistureSwingSorbentforLowEnergyAirCapture • Positive ions fixed to polymer matrix – Negative ions are free to move – Negative ions are hydroxides, OH- • Dry resin loads up to bicarbonate – OH- + CO2  HCO3 - (hydroxide  bicarbonate) • Wet resin releases CO2 and unloads to carbonate – 2HCO3 -  CO3 -- + CO2 + H2O Anionic Exchange Resin: Solid carbonate “solution” Quaternary ammonium ions form strong-base resin 2 to 2.5 mol/kg of charge 1 to 1.25 mol/kg of CO2 capacity Durable: life time 10 to 20 years
  18. 18. ASU’s air capture design  Passive wind-driven design avoids Sherwood’s objection  Moisture controlled sorbent reduces energy consumption  Mass production of small units drives costs down Lessons are applied in a DOE project to feed CO2 to algaePrototype tested on the roof
  19. 19. No significant limits on the global scale of operation  Local and global air transport constraints are understood and similar in nature to those of wind farms  Volume of air processed in CO2 capture is orders of magnitude smaller than for comparable wind energy extraction  DAC installation for the same carbon reduction are much smaller than wind farms  Mass manufactured products penetrate markets in decade or two
  20. 20. Timescales of technology change Large technology driven infrastructure change • Automobile 1880 – 1900 – 1925 • Jet planes 1940 – 1950 – 1960 • Television 1900 – 1941 – 1955 • Internet 1960 – 1984 – 2000 • Cell Phones 1947 – 1978 – 2000
  21. 21. A Vision of the Future: Renewable Electricity and Liquid Fuels • Balance the carbon budget • Pay back the carbon debt • Move to renewable energy • Close the carbon cycle with liquid fuels Batteriesvs. liquidfuels
  22. 22. How to get started: Engage Volunteers GovernmentSupport,StrategicInterest,EnvironmentalAdvocacy • Oil companies should offer carbon neutral gasoline • Assume initial removal cost: $100/ton of CO2 • Reachable with current development efforts • $50 covered by US Tax Credit (45Q) • Passed into law in the spring of 2018 • $25 taken on by the oil company • Based on interest to establish the technology • $25 offered by volunteer = 22 cents/gallon • Like green electricity premium Demonstrate the policy, build support, and learn down costs CO2 recapture +$0.22 per gallon