Introduction

1. Routen der CO2-Abscheidungin KraftwerkenE. Riensche, J. Nazarko, S. Schiebahn, M. Weber, L. Zhao, D. StoltenForschungszentrum Jülich GmbH, D-52425 JülichInstitut für Energie- und Klimaforschung – IEK-3: BrennstoffzellenJahreshaupttagung der DPG - Arbeitskreis Energie (AKE)Dresden, 13.-16. März 2011

2. Introduction • Three phases of power production from coal occur: • 20th century: Continually increasing efficiency up to ……………..….… ~45 % • Ending with: Flue gas cleaning (DeNOx, Dedust, DeSOx) ……….....… 1-2 %-points loss • 21th century: Necessity for CCS (Carbon Capture and Storage) … ~8-14 %-points loss • Challenge of CCS: • Collecting CO2 as pure as possible • High efficiency of power production • Current efficiency penalties of 12-14 %-points • CO2 separation degrees ~90% and • CO2 purities between ~90 and 99 mol% • R&D: • Gas separation • Integrated CCS systems

3. 1 CO2 separation CO2 transport and storage 2 3 4 5 6 Further compression Potential further compression Potential power plant modifications Gas/gas separation Potential subsequent CO2 cleaning CO2 com- pression 1  100 bar liquefaction Up to 1000 bar Injection at significant depth e.g. aquifers in Germany 1 – 10 km Pipeline e.g. 500 km pressure drop 200  100 bar Exceptions: e.g. post comb. chilled ammonia 15-20  100 bar • Further flue gas cleaning • CO shift • Recirculation • CO2/N2 • O2/N2, CO2/H2O • CO2/H2 Power plant CCS Process Steps • Up to 6 processes contribute to CCS energy demand •  Accumulated losses to be minimized

4. Data Base of Energy Content for Fossil Fuels 20 CH4 10 203% Typical Coal LHV / MJ/kgCO2 LHV / kWhth/Nm³CO2 C 10 117% 5 100% 0 0 Source:Reference power plant NRW, VGB 2004 • Typical coal: LHV = 2910 kWhth/tCO2 produced Efficiency loss = 1 %-point for CCS energy demand of 29 kWhe/tCO2 (100% separated)

5. Separation Routes, Tasks and Methods

6. Prevalent Gas Separation Methods Materials Sep. gas Separation principles Separation methods CO2 Amines Chemical Amino salts Ammonia Absorption with liquids “Rectisol” Physical “Selexol” “Purisol” Cryogenic air separation O2 Condensation & Rectification Me <–> MeO Ni, Cu, Fe Reaction with solids (Chemical Looping) CO2 AO <–> ACO3 CaO, MgO, FeO CO2 or H2 Polymer Molecular transport Microporous Membranes O2 MIEC for O2 sep. Ionic / atomic transport H2 MPEC for H2 sep. Metallic MIEC: Mixed Ionic-Electronic Conductor MPEC: Mixed Protonic-Electronic Conductor

7. Absorption with Liquids Purified Gas CO2 Henry´s law IGCC Flue gas Solvent Solventmake-up CO2Cap- ture SolventRegene- ration Solvent+ CO2 pCO2~5-10 bar Spentsolvent Energy Gas with CO2 • Chemical absorption for low CO2 partial pressures, e.g. flue gases • Physical absorption for high CO2 partial pressures, e.g. coal gas (IGCC, pressurized)

8. Reaction with Solids CO2-freeflue gas CO2for compression CO2 + H2O Make-upCaCO3 CaCO3 NiO Oxidationunit(Air reactor) Reductionunit(Fuel reactor) Absorption(Carbo-nizing)T = 650 °C Regene-ration(Calcining)T = 900 °C Fuel Ni CaO AshCaO CaCO3 Oxygen Coal gas or flue gaswith CO2 Fuel Air Oxyfuel via Chemical Looping Combustion Carbonate Looping • CLC: applicable for coal gas & natural gas • CLC: direct oxygen transport via a metal carrier • CLC promises energy saving oxygen delivery for oxyfuel

9. p~100 bar p~100 bar pCO2~10 bar Natural gas p~1 bar CO2 pCO2~1 bar Polymer Membranes:CO2 Separation from Natural Gas Example for a natural gas field • Transport: solution diffusion mechanism • Driving force: partial pressure difference • Compressors: not required in natural gas fields • Integration in coal power plants: • - Limitation in operating temperature • - Compression energy to be considered

10. Inorganic Membranes Inorganic Membranes Metallic Ceramic Microporous Dense Dense MPEC: Mixed Protonic-Electronic ConductorsH+/e- MIEC: MixedIonic-Electronic ConductorsO2-/e- Diffusion of H-atoms Amorphous:e.g. Sol-gel membranes Crystalline:e.g. Zeolites Up to 600 °C 150 - 400 °C 150 - 400 °C 800 - 1000 °C 500 - 800 °C H2/CO2 – Pre(H2) O2/N2 – Oxy CO2/N2 – PostH2/CO2 – Pre(H2) CO2/N2 – PostH2/CO2 – Pre(H2) H2/CO2 – Pre(H2)

11. Résumé: CCS Power Plant Classes * Flue gas recycle for higher CO2 concentration ** Flue gas recycle for membrane sweep with a large O2-poor N2 gas stream • Today: two power plant technologies: Steam Power Plant (SPP)andIGCC • Identified:32 CCS power plant classes

12. Increase of CO2 Concentrations through Flue Gas Recycling CO2~6% CO2~13-15% CO2~90% λ~1 λ~1 λ~2.5 SG CO2 Coal gas CO2 CO2 Coal gas Coal gas GT GT GT IGCC ST ST ST ASU O2 Air Air Air H2O N2~70% N2~5% O2~0% O2~10% CO2~12-14% CO2~90% λ~1 λ~1 CO2 CO2 Coal Coal Steam power plant ST ST ASU N2, (H2O) O2 H2O Air Air l: air ratio, ASU: air separation unit, GT: gas turbine, SG: steam generator, ST: steam turbine

13. CO2-freeflue gas CO2+H2O 40°C 60°C 90°C Absorber Desorber Heatexchanger Flue gas 100°C 55°C Heat supply Post-combustion: Amine Scrubbing • Absorption heat is released at low temperature • Desorption requires heat at higher temperature • Heat supplied by steam condensation at the desorber

14. Final Compression of Captured CO2 to 120 bar 120 For compression to 120 barCO2 captured at 1 bartakes from efficiency 4 %-points(100% CO2 separation, 5 mol% N2) 4 100 3 Source: after Göttlicher 2004 80 Plant efficiency loss / %-points 60 2 Compression energy / kWh/tCO2 40 1 20 0 0 0 20 40 60 80 100 120 CO pressure after capture / bar 2  CO2 released at 10 bar takes 2 %-points (e.g. Post-combustion/Chilled ammonia) CO2 released at 30 bar takes 1 %-point (e.g. Pre-combustion/H2 membrane)

15. CO2 Phase Diagram for Pure CO2 and CO2-N2 Mixtures Pipeline Source: Goos, Riedel, Zhao, Blum, GHGT-10, Amsterdam 2010 • Pure CO2: Two-phase behaviour only at the saturation line • Impure CO2: Two-phase regions occur - exceeding 100 bar •  Work hypothesis for pipeline transport: 5 mol% N2 tolerable

16. Conclusions • CCS concepts encompass a broad variety of solutions • Post-combustion, Oxyfuel, Pre-combustion • Gas separation: Absorption, Adsorption, Reaction with solids, Rectification, Membranes. • All concepts show potentials for further improvement • Materials´ and componenent development • Integration of components and “CCS waste heat” (from capture and compression). • The minimum efficiency penalty for CCS is estimated to be • 4 %-points for CO2 capture from flue gas (90% separation) and • Even potentially lower, if separation of pure gases is avoided, e.g. by • - Membrane sweep (permeation - dilution) and • - Chemical looping (e.g. reaction of O2 with a metal carrier – directly in air). Successful development of CCS concepts will require in-depth dialogue between process engineers and material scientists.

17. Thank You for Your Attention! June 20-22-2011, Frankfurt am Main Efficient Carbon Capture for Coal Power Plants www.icepe2011.de

18. Thank You for Your Attention! 2nd International Conference on Process Engineering Efficient Carbon Capture for Coal Power Plants June 20-22, 2011 Frankfurt am Main/ Germany Registration: www.icepe2011.de