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Grantham Institute for Climate Change
Carbon Capture and Storage – The Way Ahead Geoffrey Maitland FREng Professor of Energy Engineering Department of Chemical Engineering Imperial College London
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Current world consumption 15 TW
The Energy Landscape Current world consumption 15 TW Hydroelectric: 4.6 TW gross, 1.6 TW feasible technically, 0.6 TW installed capacity Tidal/Wave/Ocean Currents: 2 TW gross Fossil Fuels: Current 12.5 TW Potential 25 TW Geothermal: 9.7 TW gross (small % technically feasible) Wind 2-4 TW extractable Solar: 1.2 x 105 TW on earth’s surface, ,000 TW on land Biomass/fuels: 5-7 TW, 0.3% efficiency for non-food cultivatable land
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The Driver for Carbon Mitigation
CO2 emissions from the combustion of fossil fuels, excluding use in cement industry Boden T, Marland G Andres RJ. Carbon Dioxide Information Analysis Centre Oak Ridge National Laboratory, Oak Ridge, Tennessee Total emissions from the combustion of solid, liquid and gaseous f/fs, excluding use in cement All major economies underpinned by f/f usage, energy sector accounts for most emissions There needs to be an energy system transformation but this means there must be a transition towards a sustainable energy future CCS is critical/least cost technology option underpinning this transition which will allow meaning emission reductions
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Sources of Greenhouse Gases
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Future Energy Mix… the growth of renewables but the continued importance of hydrocarbons
Source: International Energy Agency World Energy Outlook 2009
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CO2 Emissions Scenarios
16 4-6 oC 3-4 oC 2 oC DT 1000 ppm 12 Global Carbon EmissionsGT 550 ppm 8 4 450 ppm 375 ppm [CO2] 2000 2010 2020 2030 2040 2050 2060 Year
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Carbon capture and storage must play a role...
In Carbon Capture and Storage (CCS) CO2 is captured at a point source such as a power station Transported to a storage site, usually via a pipeline Injected deep into the subsurface as a supercritical fluid ICCT August 2010
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Carbon dioxide properties
Critical point of CO2 is 31oC and 72 atm (7.2 MPa). CO2 will be injected deep underground at supercritical conditions (depths greater than around 800 m). CO2 is relatively compressible; density less than water, similar to oil. Low viscosity – around10% of water. ICCT August 2010
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Some numbers... Current emissions are around 30 Gt CO2 per year (8.5 Gt carbon). Say inject at 10 MPa and 40oC – density is kgm-3. This is about 108 m3/day or around 700 million barrels per day. Current oil production is around 85 million barrels per day. Huge volumes – so not likely to be the whole story but could contribute 1-3 Gt carbon/yr… or ~ 10 Gt CO2 pa Costs: 2-3 cents/KWh for electricity for capture and storage; $ per tonne CO2 removed – Shackley and Gough, 2006
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World abatement of energy-related CO2 emissions in the 450 ppm Scenario
ICCT August 2010
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Carbon capture and storage
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The main Carbon Storage options
IEA: 40Gt CO2 <2% emissions to 2050 P&K: Gt CO2 IEA: 920 Gt CO2 45% emissions to 2050 P&K: Gt CO2 IEA: ,000 Gt CO2 20-500% emissions to 2050 P&K: Gt CO2 Estimated worldwide geological storage capacity > 2000 Gte CO2 IEA: Freund, Comparative potentials at storage costs up to $20/t CO P&K: Parson and Keith, Science 282, , 1998
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Injection into a depleted oil field - EOR + CCS if below MMP
ICCT August 2010
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Components and Costs of CCS
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Major Classes of Carbon Capture Processes
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Post-combustion capture – amine scrubbing
‘End of pipe technology’, can be retrofitted CO2–rich gas is exposed to MEA (15 – 30 wt. %) in a scrubbing column, at around 55oC, at a pressure of 1 bar. The loading of CO2 at the exit of the column is around 0.4 mol CO2/mol MEA. The CO2 is then removed from the MEA by boiling (at a pressure of ~ 2 bar and a temperature of ~120oC). Loading = Heat input for regeneration of solvent accounts for decrease in process /cost efficiency
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Amine Scrubbing Cost When talking about large-scale implementation, cost is always an important issue. According a study carried out by the US Department of Energy on a 450 MW coal-fired power plant. The largest proportion of the overall cost comes from the energy consumption, of which about half is as low-temperature steam, while the other half is for the compressor work. Other proportions include capital cost and O&M cost. Figures from: DOE/NETL (2007) ‘Carbon Dioxide Capture from Existing Coal-Fired Power Plants’.
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Improved solvent processes
Key parameters Rate of reactive absorption Loading capacity Energy of regeneration Standard solvent: monoethanolamine, MEA Possible alternatives Alkylamines Ammonia (chilled) Energy of reaction for MEA + CO2 = 82 kJ/mol Energy of reaction for NH3 + CO2 = 55 kJ/mol
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Calcium Looping CaO + CO2 CaCO3 DH = -179 kJ/mol
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Post-combustion carbonate looping
Advantages (i) sorbent derived from cheap and abundant natural limestone (ii) relatively low efficiency penalty (iii) synergy with cement production (iv) technology proven on medium scale plant Disadvantages (i) deactivation, particularly in the presence of sulphur, (ii) produces hot CO2 – wastes energy unless the system is pressurized (iii) particle attrition
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ICCT August 2010
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Oxy-fuel combustion O2 burn the fuel in a mixture of pure O2 and recycled flue gas (the later to moderate the temperature) ‘bolt-on’ technology suitable for retrofit Major energy penalty associated with separating O2 from N2 in air + O2
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Oxy-fuel Advantages (i) Technology suitable for retrofit (burners)
(ii) Comparatively simple Disadvantages/ technical challenges (i) Leaks (air inwards reduce purity) (ii) Pure O2 (pneumatic conveying difficult) (iii) Burner redesign (high CO2 makes flame properties different) (iv) Safety concerns (v) CO2 purity (vi) O2 produced using air liquefaction is energy intensive and extremely costly
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Reducing the efficiency penalty
Efficiency estimates for capture and compression (published by IEA)
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Other developing CO2 capture methods
Chemical Looping Adsorption on active solids, waste minerals, zeolitic materials, MOFs... Ceramic gas membranes and membrane reactors Gas hydrates Cryogenic separation
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Chemical Looping Chemical Looping Combustion – Richter and Knoche (1983), Ishida et al (1987) Thermal efficiency (Power stations) Advantages: Efficient and low cost fuel combustion Facilitates CO2 Separation (H2O (l)↓) Fuel Reactor (Mainly Endothermic) (2n+m)MeO + CnH2m ⇒ (2n+m)Me + mH2O + nCO2 (Complete oxidation) (n)MeO + CnH2m ⇒ (n)Me + ((½)m)H2 + nCO (Partial oxidation) Air Reactor (Exothermic) Me + ½O2 ⇔MeO (CO, H2) N2, Unreacted O2 CO2, H2O (H2) MeO Air reactor Fuel reactor Qo Heat (Re- Generator) (Reformer) Me PSA: molecular sieves Working principle of the process. Thermal efficiency: due to the enhanced reversibility of the two redox reaction. Air Fossil Fuel (H2O) (H2O) (Me + H2O ⇔ MeO + H2)
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Gas Separation Membranes
H2 Porous tubular membrane CO2 + H2 CO2 From IGCC power plant Pressure differential drives H2 through the selective membrane
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Ionic Liquids
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Gas Hydrates
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CO2 Capture Challenges Lower Capex and Opex costs
Higher pressure processes – lower compression costs Sorbents with high sorption and low regeneration energy Smaller and more efficient contacters Low cost air separation (oxyfuel) Exploit membranes – lower energy separation
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Electricity from Gas and Coal with CCS
Gas Price, $/MBtu Kheshgi, et al., 2010
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Likely technology adoption trajectory after Figueroa et al (2008)
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Long-term fate of ‘buried’ CO2
How can we be sure that the CO2 stays underground? Caprock seals Dissolution CO2 dissolves in water – 1,000-year timescales Chemical reaction forming acid carbonate precipitation – 103 – 109 years Capillary Trapping rapid (decades): CO2 as pore-scale bubbles surrounded by water we can design this process Host rock
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What is the ultimate fate of the CO2?
CO2 dissolves into the water and sinks over 103 years CO2 can combine with minerals in the water and form calcium carbonate (limestone) over years CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+ Ca2+ + 2HCO3- ↔ CO2 + H2O + CaCO3 Riaz et al., J Fluid Mech, 2006 ICCT August 2010
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Eight integrated CCS projects (LSIPs) in operation in the oil and gas industry
LSIP defined as >0.8 Mtpa for coal and >0.4 Mtpa captured-and-stored for coal and gas/industry, respectively (Global CCS Institute 2011, The global status of CCS: 2010) LSIPs is defi ned as:14 • not less than 80 per cent of 1 million tonnes per annum (Mtpa) of CO2 captured and stored annually for coal-fi red power generation; and • not less than 80 per cent of 0.5Mtpa of CO2 captured and stored annually for other emission intensive industrial facilities (including natural gas-fi red power generation).
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Current CCS projects – planned or underway
ICCT August 2010
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Sleipner Project 1 million tonnes CO2 injected per year
CO2 separated from produced gas Avoids Norwegian CO2 tax (~$55 per te) Gravity segregation and flow under shale layers controls CO2 movement ICCT August 2010
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In Salah project, Algeria
10% CO2 is produced with natural gas CO2 cannot be put in commercial pipeline Injected into deep saline formation in Krechba reservoir, at a depth of 2km One million tonnes of CO2 stored each year Operational since 2004 Surface has been uplifted by increased pressure
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Lacq project, France- Total
Natural gas production from Lacq Emissions captured from oxyfuel combustion unit in steam generating plant 40 tonnes of steam per hour Emits up to 120,000 tonnes of CO2 over a two-year period 27km pipeline to storage reservoir Injected at a depth of 4500m into Rousse natural gas reservoir
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FutureGen – $ 1.5 billion US clean coal concept
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Global deployment of CCS...?
100 projects by 2020 3400 by 2050 Still a lot of work to do, these targets include industry applications and today there is a very limited focus on CCS in industry, the next years up to 2020 will be critical IEA, Technology Roadmap, CCS, 2010 A lot of progress has to be made… av. 100 projects per year after 2020
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Downhole or In-Reservoir Hydrocarbon Processing + in situ CCS?
Fuel H2, Methanol… Electricity Chemicals, Feedstocks CO2 CO2
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