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Explore the pressing issue of rising CO2 levels from fossil fuel use and the need for carbon mitigation strategies like large-scale capture and sequestration. Learn about energy demand growth, potential solutions, and the cost implications of implementing carbon capture technologies.
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CO2 Capture and Fossil Energy Christopher W. Jones Georgia Institute of Technology School of Chemical & Biomolecular Engineering Atlanta, GA 30332 Thursday, March 29, 2012
Climate and Fossil Fuel Use: • The earth is warming (about 0.6 ˚C in last 100 years). • Intergovernmental Panel on Climate Change (IPCC): 90% probability that increase in CO2 concentration in the air is main culprit. • Major source of CO2 concentration increase is fossil fuel combustion. • Future increases could have catastrophic consequences… or not. • Need carbon mitigation options.
A Problem Created by Chemists & Chemical Engineers: A chemist and chemical reaction engineer who produced the most important scientific discovery1 of the 20th century? Who are these people? What was the discovery? 1. V. Smil Nature1999, 400, 415.
A Problem Created by Chemists & Chemical Engineers: • A chemist and chemical reaction engineer who • produced the most important scientific discovery1 of the • 20th century? • Who are these people? • What was the discovery? • Fritz Haber • Nobel Prize, Chemistry, 1918 • Carl Bosch • Nobel Prize, Chemistry, 1931 N2 + 3 H2 -> 2 NH3. Nitrate minerals for fertilizer (Chile): $45/tonne in 1925 $19/tonne in 1937 1. V. Smil Nature1999, 400, 415.
Energy Demand Growth Dominated by Developing Countries: Source: ExxonMobil
Energy Demand Growth Dominated by Developing Countries: Year Population 1650 0.5 Billion 1900 1.6 Billion 2011 7.0 Billion Source: ExxonMobil • Population growth in (relatively) poor zones will drive increased use of • cheap (fossil) energy.
How the Energy Demand Will be Met: Message: Advances in wind and solar energy are desperately needed, but even with tremendous growth….. Source: ExxonMobil
How the Energy Demand Will be Met: Message: Advances in wind and solar energy are desperately needed, but even with tremendous growth, society will continue to rely heavily on fossil energy for the next several decades. Source: ExxonMobil
Energy Outlook and CO2 Capture: • Continued use of fossil fuel in a carbon constrained world will require all of the following: • Moderating demand (e.g., by improving energy efficiency). • Developing low/no-carbon energy sources. • Implementing large scale CO2 capture and sequestration?
Envisioning Widespread Carbon Capture and Sequestration: Source: IPCC, 2005
Base Case Scenario of Energy Cost: • Separation and concentration require work (energy). • Capture and sequestration will cost us energy and money. • What is the best we can do? The thermodynamic limit. Post-Combustion Capture from Power Plant Flue Gas: Pumping underground and water displacement Pressurized CO2 at 140 atm Pipeline ready Dilute CO2 mixed in N2 Separated CO2 at 1 atm ~9kJ/mol ~5% of the output ~13kJ/mol ~7% of the output ~2kJ/mol ~1% of the output House et al., Energy Env. Sci. 2009, 2, 193.
The Bruce Mansfield Power Plant: • 2360 MW electric power generation capacity. • 7 million tons coal burned/year. • ~41% efficiency. • 17.5 million tonnes CO2 generated per year. • 47,800 tonnes/day CO2 formed (at ~15% vol concentration). • 220,000 tonnes flue gas processed per day. • The yearly output fits in a 400m cube at sequestration pressures (140 atm). Slide courtesy of Prof. John Kitchin, Carnegie Mellon University.
Post-Combustion Capture Conditions Separation of CO2: • Flue gas composition after sulfur scrubbing • 13-16% CO2 • 4-5% O2 • 6-7% H2O • Minor impurities • Balance N2 • Flue gas conditions • 60-80°C • 10-15 psi • Flue gas production rate • A 2500 MW coal plant produces ~550 kg CO2/s • ~240,000 tons/day of flue gas must be treated • Capture goal • 1200-2000 psi, dry CO2 for pipeline ready transport
CO2 emission sources in the US: Global CO2 emissions • The US has 1493 coal-fired units (400+ plants) • 336,000 MW of power generation capacity. • Burn 930 million tonnes of coal/year. • ~50% of total US electricity production. • Produced ~2Gt of CO2 emissions. • Power generation is ~1/3 of the total CO2 emissions --Transportation ~1/3, -- Industrial sources ~1/3. http://cdiac.ornl.gov/ftp/ndp030/global.1751_2004.ems http://cdiac.ornl.gov/ftp/ndp030/CSV-FILES/nation.1751_2003.csv Slide courtesy of Prof. John Kitchin, Carnegie Mellon University.
What Would Capture and Sequestration Cost? • ~$300 billion dollars/year in electricity sold from coal. • At 2 Gt CO2/year, if we can manage CO2 at $30/tonne ~ $60 billion/year in the US. • The $30/tonne has to include all the operating and capital costs associated with CCS. • ~$1 trillion/year globally to deal with 30 Gt/year (1-2% GDP). • Replacing power capacity with CO2-free energy also very $$$.
Envisioning Widespread Carbon Capture and Sequestration: Source: IPCC, 2005
Schematic of a CO2 Capture Process Key: Amine adsorbent Non-CO2 flue gas CO2 Exhaust from combustion.
Schematic of a CO2 Capture Process 75˚C Key: Amine adsorbent Non-CO2 flue gas CO2 Exhaust from combustion.
Schematic of a CO2 Capture Process Exhaust with 90% CO2 removed 75˚C Key: Amine adsorbent Non-CO2 flue gas CO2 Exhaust from combustion.
Schematic of a CO2 Capture Process Exhaust with 90% CO2 removed 75˚C Key: Amine adsorbent Non-CO2 flue gas CO2 Exhaust from combustion.
Schematic of a CO2 Capture Process Exhaust with 90% CO2 removed 125˚C 75˚C Key: Amine adsorbent Non-CO2 flue gas CO2 Exhaust from combustion.
Schematic of a CO2 Capture Process Exhaust with 90% CO2 removed 125˚C 75˚C Key: Amine adsorbent Non-CO2 flue gas CO2 CO2 for sequestration or conversion Exhaust from combustion.
Questions for Discussion: • If CCS costs 1-4% of GDP? Will we do this? Should we do this? What would you do as a policy-maker? • Why can’t we simply turn the CO2 into something useful, on a practical scale? • What country should take the lead in implementing CCS? What country do you think is most likely to take the lead in using this technology?
Point Source Capture vs. “Air Capture”: CO2 Source Properties: Air/Flue Two motivations: (i) environmental and (ii) CO2 source
Base Case Scenario of Energy Cost: Post-Combustion Capture from Power Plant Flue Gas: • What is the best we can do? The thermodynamic limit. Pumping underground and water displacement Pressurized CO2 at 140 atm Pipeline ready Dilute CO2 mixed in N2 Separated CO2 at 1 atm ~9kJ/mol ~5% of the output ~13kJ/mol ~7% of the output ~2kJ/mol ~1% of the output House et al., Energy Env. Sci. 2009, 2, 193. CO2 Capture from Ambient Air: -- first step is thermodynamically more expensive, the rest is the same. -- for 25-90% CO2 capture from air, the minimum energy required is 2.6 – 2.9 times more expensive than flue gas capture at 90% capture. -- actual cost = how close to perfect thermodynamic efficiency can be achieved. M. Ranjan, M.S. Thesis, MIT 2010
Air Capture Conclusions: • A review of approaches to extract CO2 from the ambient air has been written. • Supported amine adsorbents are promising materials for the extraction of CO2 from the ambient air; IF it can be done economically: • -- air capture may allow for a “carbon-negative technology” • -- account for CO2 from all emissions sources, including cars, planes • -- economics for “environmental applications” currently unknown • -- may allow for on-site generation of CO2 – business development • Supported amines offer the advantage of high capacities (1.5-2.5 mol CO2/kg sorbent) and operation in all humidity levels. C. W. Jones Ann. Rev. Chem. Biomol. Eng. 2011, 2, 31-52.
Air Capture Conclusions: • Air capture may allow for feeding CO2 to biomass for biofuel production (low concentration) or eventually, CO2 production for sale (EOR) or sequestration. • Air capture should • NOT be considered • as an alternative to • CO2 capture from • flue gas – these are • complimentary • approaches. Photo: NY Times
Global Thermostat: Conflict-of-Interest Statement: Georgia Tech receives research funding from Global Thermostat, LLC, and Jones has a financial interest in Global Thermostat Operations, LLC.
Questions for Discussion: • If post-combustion CCS costs ½ of what “air capture” costs, should we pursue CCS? Or air capture? Or both? At what cost should priorities shift to air capture?