PRECOMBUSTION CAPTURE OF CO 2 Opportunities and Challenges. Kristin Jordal, SINTEF Energy Research Marie Anheden, Vattenfall Utveckling

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1 PRECOMBUSTION CAPTURE OF CO 2 Opportunities and Challenges Kristin Jordal, SINTEF Energy Research Marie Anheden, Vattenfall Utveckling 1

2 Three Main Routes to CO 2 Capture Pre-combustion decarbonisation Precombustion denitrogenation (Oxyfuel) 2

3 Pre-combustion capture Pre-combustion technologies either carbon or nitrogen is removed from the process BEFORE the combustion Pre-combustion denitrogenation, often referred to as oxyfuel: Nitrogen is removed from the air before combustion with fossil fuel Pre-combustion decarbonisation: Carbon is removed (in the form of CO 2 ). The remaining fuel is hydrogen N.B!!! Hydrogen is not an energy source, it is an energy carrier. Hydrogen must always be produced 3

4 ENCAP enhanced capture of CO 2 Integrated Project within the FP 6, budget 22.2 MEUR Coordinated by Vattenfall Project management by SINTEF Six sub- projects dealing with different aspects of pre-combustion capture technologies of CO 2 Target: 90% CO 2 capture with 50% capture cost reduction Commercial exploitation of results beyond year Project partners: Vattenfall SINTEF Energi E2 PPC RWE Statoil Air Liquide Alstom BOC Linde Lurgi Mitsui Babcock Siemens ISFTA Chalmers DLR IFP TNO NTNU U Stuttgart U Twente U Ulster U Paderborn 4

5 Pre-combustion technologies many pieces of the puzzle are already there Pre-combustion capture technology development is based on existing commercial technologies in other applications Main challenges: decrease energy demand and equipment cost for the capture process by finding the best technology integration opportunities finding innovative solutions to combine with the existing pieces of the pre-combustion puzzle Previous work in FP 5: Grace, AZEP projects Joule II programme!! 5

6 Pre-combustion capture I: decarbonisation Chemical transformation of the fuel into a CO 2 /H 2 mixture Known technologies: Coal gasification/natural gas reforming, cryogenic air separation, CO 2 capture through the use of absorption/desorption, gas turbine combined cycles, IGCC Innovative work is required for processing of the gas from gasification/reforming, for gas turbine combustion and for the design of the overall power process Opportunity for co-production of H 2 for use for other purposes than in the power plant where it is produced (DYNAMIS project proposal) 6

7 Natural gas reforming at Tjelbergodden methanol plant Source: Natural gas reforming: the gas is converted into CO and H 2 Tjelbergodden reforming of natural gas for methanol production Reforming and removal of CO 2 done today in ammonia manufacturing H 2 manufacturing 7

8 IGCC and CO2 capture from coal syngas IGCC plant in Puertollano, Spain North Dacota synfuel plant: CO 2 capture from coal gasification 8

9 Gas turbine combined cycles Existing combined cycle technology has high efficiency for natural gas (over 58% without CO 2 capture) Combined cycles integrated with coal gasification (IGCC) has a potential to give high efficiency for coal (over 50% without CO 2 capture) 9

10 Challenges in pre-combustion decarbonisation Optimisation and integration of process steps to reach: High energy conversion efficiency High CO 2 separation rate Simplified process flow diagram to reduce investment Acceptable reliability and availability Gas treatment to reach demands on CO 2 and H 2 purity Demands on CO 2 largely unspecified Combustion of H 2 -rich fuel in gas turbine power plants!! 10

11 ENCAP activities ENCAP SP2: Development of power plants with precombustion decarbonisation (for bituminous coal, lignite and natural gas) Process outline Optimised gas processing H 2 -rich combustion in gas turbines (Siemens, Alstom) Integration of cryogenic oxygen production, CO 2 capture, gas and steam turbines into functioning power plants ENCAP SP5: High-temperature oxygen generation ENCAP SP6: Novel concepts SP5 and SP6 investigate pieces that can be inserted in the SP2 plant beyond year

12 Hydrogen combustion Hydrogen as fuel behaves very different from natural gas Hydrogen is extremely reactive, a safe design of the combustion chamber for a stable flame with low nitrogen oxide emissions is a genuine challenge Hydrogen is known as gas turbine fuel in cases without severe restrictions on nitrogen oxide emissions or high demands on power plant efficiency Simulation of temperature in combustion chamber Temperature (K) Temperature (K) Natural gas Hydrogen 12

13 Pre-combustion capture II: Denitrogenation (oxyfuel) Combustion of fuel with O 2 instead of air results in a flue gas consisting of mainly CO 2 (about 90%(v) on dry basis) and minor amounts of non-condensable gases Flue gas is recycled to control the combustion temperature Can be applied to both natural gas and coal but have different implications depending on the preferred technology for energy conversion (boiler with steam turbine vs. GTCC) Experience: oxygen enriched combustion Experience from glas- and metal industry Tests in small-scale rigs (few kw up to 3 MWth) 13

14 Oxyfuel combustion for coal Based on existing boiler and steam turbine technology Can take advantage of ongoing development to increase efficiency of conventional steam power plants Opportunity to reach high CO 2 capture rate and near zero emission Co-capture of other pollutants? Reduced investment in flue gas cleaning equipment? Reduced boiler heat losses and compact boiler design No bulk N 2 in flue gas gives reduced heat loss Reduced recycle rate gives reduced boiler size and cost Availability of almost pure oxygen enables enhanced combustion control 14

15 Oxyfuel combustion for natural gas Based on gas turbine technology for energy conversion Possible to recycle either CO 2 or water to control combustion temperature Redesign of compressor, combustor and turbine is necessary to compensate for the new environment (CO 2 and water vapour) 15

16 !! Challenges: oxyfuel technologies Energy efficient integration and optimisation of the process Recovery of low temperature heat in flue gas and CO 2 compression train Reduced energy consumption for air separation More experimental and modelling work needed to increase the knowledge of combustion fundamentals Optimisation of flue gas treatment and CO 2 processing to balance Investment cost Operational issues CO 2 product requirements CO 2 recovery Oxyfuel coal: Adjustment of boiler design to accommodate for changes in combustion characteristics and heat transfer Oxyfuel natural gas: Completely new design of gas turbine cycle for CO 2 /H 2 O mixture 16

17 N2 + H20 N2 + H20 ENCAP activities on oxyfuel combustion Coal Boiler technologies Oxyfuel combustion for bituminous coal and lignite plant PF and CFB combustion technology Integration and optimisation in combination with economic evaluation Operational characteristics, risk analysis Natural gas combined cycle technologies Novel process concept for increased efficiency Lignite Vapour condensate Condensate to steam cycle Air Stream s Unit 100 Coal Ash Handling (VAB/RW E) Mill Molecular sieves Steam Water Lignite Ash N2, NOx, O2, Ar O2 + Ar N2 N2+H20 TEG recirculation Dried lignite Pneumatic fuel transport Ash Handling O2 + Ar Flyash Dest. Preheated N2 to molecular sieves Bottom Ash O2 + Ar DCAC Unit 500 ESP + FG Clean-up (VAB) ESP TRIFLUX heat exchanger DCWC Flue gas fan Primary recycle Secondary recycle Unit 200 Boiler Island (Alstom) Unit 1100 Cryogenic ASU (Air Liquide) Flue gas condenser IP steam To R/H HP steam Feed water Wet ESP IP steam to coal dryer Unit 700 Steam Turbine Island (Alstom) Water to DCWC Feed water preheating Unit Unit 1300 Inerts removal(vab)+ CO2 compression(air Liquide) G Dehydration H20 Condensed water Inerts vent CO2 XX% Flue gas condensate FIGURE 3.1: High Level Conceptual PFD, 1000 MWe Lignite Fired Oxy-Combustion Power Plant Make-up water 17

18 ENCAP experimental work and pilot testing coal + primary air coal mill, primary gas/ O 2 Experimental investigation of combustion fundamentals in kw th test rigs Phase 2 pilot testing decision: PF oxyfuel plant in size range of MW th vertical furnace reduction zone burnout zone video control burner slag and ash > 100 µm additional fuel + conveyor air secondary air, flue gas recirculation reburning fuel burnout air fly ash samples : in-flame measurement : O 2, CO 2, CO, NO X, C mh n, temperature flue gas emissions : O 2, CO 2, CO, NO X, C m H n, temperature - particle size - burnout - ash analysis - trace element analysis - melting behaviour SCR Catalyst = 400 C secondary, main combustion gas staging gas ESP = 200 C Centerline temperature profiles = 150 C re-circulated part-stream of flue-gas bag filter Test case Air OF 21 OF 27 oxygen supply ` to stack O 2 CFB 1 MW th Gas temperature [ o C] Axial distance from burner inlet [mm] 18

19 New developments Air separation Important part of pre-combustion technologies Presently cryogenic air separation is the main technology choice Stands for a large part of the auxiliary energy consumption Opportunity to use emerging technologies (with reduced energy requirement?) 19

20 Air separation: Development within the ENCAP project High temperature oxygen separation with ceramic materials oxygen transfer membranes high temperature oxygen adsorbent (CAR) Development of materials, cost, integration into power plant AIR BED A O 2 STORED N 2-RICH WASTE GAS O 2 -RICH STREAM BED B O 2 RELEASED PURGE GAS 20

21 New Developments Chemical Looping Combustion Combustion with a solid oxygen carrier avoids energy penalty of air separation Developments within the ENCAP project Chemical looping combustion for solid fuels Evaluation of oxygen carrier materials Novel reactor concepts Process design, integration optimisation and economics Phase 2 decision on pilot testing Ni + O 2 => NiO Air reactor Cyclone Fuel reactor CH 4 + 4NiO => 4Ni + CO 2 + 2H 2 O Courtesy Jens Wolf, Vattenfall Utveckling AB 21

22 Economical evaluation Cost of capturing CO 2 from the power plant is currently the dominating cost in the CO 2 capture -transport and storage chain Capture has the largest potential to improve Energy demand from the capture process has to decrease. Today, capture can reduce the power plant efficiency with 20 per cent More efficient power plants are needed for lower capture cost penalties Equipment costs need to decrease 22

23 Cost aspects Variable COE including CO2 emissions penalty 20 EUR/ton CO2 Lignite Hard coal CO2 penalty 20EUR/T Variable COE with capture Variable COE, no capture Natural gas It is not enough to develop and build power plants with CO 2 capture they must also operate many hours to make a difference! Capture technology should be included in plants for base load power production The option with lowest estimated total costs will be built Capital costs O&M costs Fuel costs Cost of CO 2 emission rights Variable COE [EUR/MWh] Lippendorf 2001 O2/CO2 Lippendorf 2001 IEA GHG 2000, PC IEA GHG 2000, PC+postcomb IEA GHG 2003, IGCC IEA GHG 2003, IGCC+pr ecomb IEA GHG 2020, IGCC IEA GHG 2020, IGCC+precomb IEA GHG 2000, NGCC IEA GHG 2000, NGCC+postcomb IEA GHG 2000, IRCC+precomb Variable costs will decide how much a plant will actually operate once it is built Cost of CO 2 emission rights will be included in the variable cost mainly as emission penalty for power plants without CO 2 capture 23

24 Framework for benchmarking established in ENCAP COE [EUR/MWh] EUR/ton CO Lippendorf O2/CO2 Lippendorf 2001 IEA GHG 2000, PC Total COE with CO2 emission penalty 20 EUR/ton CO2 IEA GHG 2000, PC+postcomb IEA GHG 2003, IGCC IEA GHG 2003, IGCC+precomb IEA GHG 2020, IGCC IEA GHG 2020, IGCC+precomb IEA GHG 2000, NGCC IEA GHG 2000, NGCC+postcomb CO2 penalty 20EUR/T Total COE with capture Total COE, no capture Lignite Hard coal Natural gas IEA GHG 2000, IRCC+precomb Lignite Hard coal Natural gas O2/CO2 Lippendorf 2001 IEA GHG 2000, PC+postcomb IEA GHG 2003, IGCC+precomb IEA GHG 2020, IGCC+precomb IEA GHG 2000, NGCC+postcomb IEA GHG 2000, IRCC+precomb A common framework is established to define: State of the art reference power plants without CO 2 capture Boundaries for economic analysis Procedure to evaluate power plants with CO 2 capture Design scenarios for CO 2 purity This will enable consistency in the benchmarking of CO 2 capture alternatives Coordinated with CASTOR 24

25 Concluding remarks Pre-combustion capture technologies involve a combination of existing and new technologies to create low CO 2 emission power plants Some parts of the technologies are mature, some are under development Time frame (rough estimates) demo commercial plant ~ emerging technologies with higher performance after 2020 Accurate view of full potential of pre-combustion capture technologies will not be available until we have experience from pilot-, demo- and full scale plants important to support these activities! 25