CO 2 Capture John Davison IEA Greenhouse Gas R&D Programme
Overview of this Presentation Leading CO 2 capture technologies for power generation Descriptions Main advantages and disadvantages Examples of existing and future plants Recent IEA GHG studies on CO 2 capture Thermal efficiencies Costs
CO 2 Capture Technologies Capture of CO 2 from flue gases Post-combustion capture Burning fuel in pure oxygen instead of air Oxy-combustion Conversion of fuel to H 2 and CO 2 before combustion Pre-combustion capture
Post-Combustion Capture Power generation Capture Air N 2, O 2, H 2 O to atmosphere Fuel Boiler or gas turbine (FGD) Solvent scrubbing Steam Steam turbine Power CO 2 compression CO 2 to storage
Liquid Solvent Scrubbing Absorber Reduced-CO 2 flue gas CO 2 -lean solvent Stripper CO 2 Condenser Flue gas CO 2 -rich solvent Steam Reboiler
Liquid Solvent Scrubbing Widely used for reducing gases, e.g. natural gas Less widely used for oxidising flue gases MEA 1 used in post-combustion capture plants CO 2 is used mainly for chemicals and food and drink New solvents being developed and used e.g. hindered amines Lower energy consumption, solvent losses, corrosion Low SO X (<10 ppm) and NO 2 (<20ppm) is needed Possible with limestone-gypsum FGD and SCR 1. MEA: mono-ethanolamine
Post-Combustion CO 2 Capture Warrior Run power plant, USA 180 MW e coal fired circulating fluidised bed combustor 150 t/d of CO 2 captured from a slipstream About 5% of the total
Advantages Post-Combustion Capture Existing combustion technology can be used Retrofit to existing plants is possible But retrofit to old inefficient plants is not attractive Demonstrated at some small power plants Disadvantages Energy penalty has been relatively high Penalty is being reduced by process developments Solvents are degraded by oxygen and impurities Need to dispose of degraded solvent
Oxy-Combustion Air Air separation Oxygen Recycled flue gas Vent Fuel Boiler or gas turbine Cooling (+FGD) Purification/ compression CO 2 Steam Steam turbine Power
Oxy-Combustion Advantages Combustors could be fairly conventional Possibility of compact boilers with lower quantities of flue gas recycle Possibility of avoiding FGD Disadvantages Only tested at a small scale High cost of oxygen production Advanced oxygen separation membranes with lower energy consumptions are at pilot plant scale New gas turbines designs are needed Will only be developed if there is a large market
Oxy-Combustion Pilot Plant 5 MW e CES water cycle plant at Kimberlina, California
Pre-Combustion Capture Natural gas fired plant CO 2 compression CO 2 Natural gas Partial Oxidation CO+H 2 O H 2 +CO 2 Shift conversion Acid gas removal Fuel gas (mainly H 2 ) Air Combined cycle Power
Pre-combustion Project DF1 Project by BP and Scottish and Southern Energy CO 2 capture at Peterhead power station, UK 350 MW e gas turbine combined cycle plant CO 2 used for EOR at the Miller Field in the North Sea Plant scheduled to start in 2009 Go-ahead decision depends on financial arrangements
Pre-Combustion Capture IGCC without CO 2 capture Sulphur recovery Sulphur H 2 S Coal Gasification CO, H 2 O H 2, CO 2 etc Acid gas removal Oxygen Fuel gas Air Air separation Nitrogen Combined cycle Power Air Air
Pre-Combustion Capture IGCC with CO 2 capture Coal Gasification CO+H 2 O H 2 +CO 2 Shift conversion CO 2 compression Acid gas removal H 2 S CO 2 Sulphur Sulphur recovery Oxygen Fuel gas (mainly H 2 ) Air Air separation Nitrogen Combined cycle Power Air Air
IGCC Without CO 2 Capture 4 coal-based IGCC demonstration plant in the USA, Netherlands and Spain Availability has been poor but is improving IGCC is not at present the preferred technology for new coal-fired power plants Main commercial interest in IGCC is for use of petroleum residues Several plants built and planned at refineries
IGCC without CO 2 Capture Shell gasifier IGCC plant, Buggenum, Netherlands
CO 2 Capture in IGCC Advantages of IGCC for CO 2 capture High CO 2 concentration and high overall pressure Lower energy consumption for CO 2 separation Compact equipment Proven CO 2 separation technology can be used Possibility of co-production of hydrogen Disadvantages IGCC is unfamiliar technology for power generators Existing coal fired plants have low availability IGCC without CO 2 capture has generally higher costs than pulverised coal combustion
Gasification with CO 2 Capture Dakota Gasification Plant, North Dakota, USA Synthetic natural gas plant with CO 2 capture for enhanced oil recovery
Demonstration of IGCC with CO 2 Capture Future Gen plant, USA 275 MW e plant with hydrogen co-production Site selection mid/late 2007 Start up scheduled for 2012
Recent IEA GHG Studies on CO 2 Capture Plants Post combustion capture Fluor MHI IGCC Foster Wheeler Oxy combustion Mitsui Babcock, Air Products and Alstom
Power Generation Efficiency Efficiency, % LHV 60 50 40 30 20 10 0 Postcomb IGCC slurry IGCC dry Oxyfuel Postcomb Oxyfuel Coal Natural gas Without capture With capture Source: IEA GHG studies
Efficiency Decrease due to for Capture Percentage points 12 10 8 6 4 2 CO2 compression and purification O2 production and power cycle impacts Shift conversion and related impacts Power for CO2 separation Steam for CO2 separation 0 IGCC slurry Coal IGCC dry Oxyfuel Postcomb Postcomb Oxyfuel Natural gas
US $/kw Capital Cost 2000 1800 1600 1400 1200 1000 800 600 400 200 0 Post Fluor Post MHI IGCC slurry IGCC dry Oxyfuel Post Fluor Post MHI Oxyfuel Based on 1 US $/Euro Coal Without capture With capture Natural gas Source: IEA GHG studies
10 Cost of Capture and Storage Electricity cost, US c/kwh 8 6 4 2 PF-CCS IGCC-CCS NGCC-CCS PF IGCC NGCC 0 0 1 2 3 4 5 6 Fuel cost, $/GJ (LHV) Basis: 10% DCF, 25 year life, 85% load factor, $8/t CO 2 stored
Cost per Tonne of CO 2 Avoided $/t CO 2 = increase in generation cost ($/MWh) quantity of CO 2 avoided (t/mwh) Cost per tonne of CO 2 depends on the baseline plant without CO 2 capture
CO 2 Produced and Avoided Coal no capture Coal capture CO 2 avoided CO 2 avoided CO2 emissions CO2 captured Gas no capture 0 200 400 600 800 1000 CO 2 kg/mwh
160 140 120 100 80 60 40 20 Cost per Tonne of CO 2 $ per tonne of CO 2 emissions avoided 0 Coal-capture coal baseline Gas-capture, gas baseline Coal-capture, gas baseline Gas-capture, coal baseline Basis: Post combustion capture, 10% DCF, Coal $1.5/GJ, Gas $3/GJ, $8/t CO 2 stored
Summary CO 2 can be captured using existing technology Capture technology needs to be demonstrated at larger scales CO 2 capture reduces power plant efficiency by about 6-11 percentage points Cost of capture is about 1-3 USc/kWh, excluding storage $20-60/t CO 2 -avoided CO 2 capture and storage can have an important role in a mix of CO 2 abatement options