MOLTEN CARBONATE FUEL CELLS ANSALDO FUEL CELLS: Experience & Experimental results

1. MOLTEN CARBONATE FUEL CELLSANSALDO FUEL CELLS: Experience & Experimental results Filippo Parodi /Paolo Capobianco (Ansaldo Fuel Cells S.p.A.) Roma , 14th & 29th March 2007

2. MOLTEN CARBONATE FUEL CELLSANSALDO FUEL CELLS EXPERIENCE MOLTEN CARBONATE FUEL CELLSANSALDO FUEL CELLS EXPERIENCE Elements of Fuel Cell TheoryEvaluation of the characteristic parametersFlow diagram of a typical MCFC plantANSALDO Fuel Cells experienceExperimental results Filippo Parodi (Ansaldo Fuel Cells S.p.A. - Italy) Roma , 14th March 2007

3. Electrical Energy - e H - AFC OH 100 °C 2 O H O 2 2 O + H PEFC 80 °C 2 H H O 2 2 CH OH O + DMFC H 80 °C 3 2 CO H O 2 2 O + PAFC H 200 °C 2 H H O 2 2 H O = MCFC CO 650 °C 2 2 H O 3 CO 2 2 H SOFC = O 1000 °C 2 O 2 H O 2 Oxygen Air Fuel H2 Cathode Anode Electrolyte FUEL CELL IS A DEVICE ... DIRECTLY TRANSFORMS THE CHEMICAL ENERGY OF THE FUEL INTO ELECTRICAL ENERGY BY ELECTROCHEMICAL REACTIONS

4. CO2, NOx, SOx, particulate, ash Heat losses Mechanical losses THERMAL TO MECHANIC CONVERSION MECHANIC TO ELECTRICAL CONVERSION COMBUSTION ELECTRIC ENERGY Steam/Gas Turbine Alternator CO2 H2O FUEL H2 FUEL PROCESSING FUEL CELL ELECTRIC ENERGY OXYGEN HEAT FUEL CELLS BASED vs. CONVENTIONAL ENERGY PRODUCTION PROCESS FUEL OXYGEN

5. Fuel Cells based vs. conventional power systems • Direct energy conversion (no combustion) • Less conversion steps / Lower energy losses • Higher efficiency • Environmental benefit • No moving parts in the energy converter, Low maintenance , Low noise • Low exhaust emissions, • Modularity • Modular installations to match load and increase reliability • Size flexibility • Good performance at off-design load operation • Fuel flexibility • hydrogen, Natural Gas, biogas, biomass gasification, landfill gas, reformed heavy fuels • Possibility of remote/unattended operation

6. Fuel Cells Technologies

7. AFCo selects as most promising FC technology: MCFC Operating temperature about 650°C No noble metal catalysts are used into the stack Uses carbon monoxide as fuel and carbon dioxide as cathode reactant Allows much simpler reforming section Allows coupling to gas turbine hybrid cycles (higher efficiencies) Plants up to 1- 2 MW size, for stationary applications, demonstrated in USA & Japan

8. Ansaldo Fuel Cells Labs MCFC single cells Electrochemical Reactions: CO2 + ½ O2 +2e- CO3- - cathode H2 + CO3- - H2O + CO2 + 2e- anode ---------------------------------------------------- H2 + ½ O2 H2O overall reaction Materials: anode: Ni / Cr cathode: Li x Ni 1-x O matrix: LiAlO2 electrolyte: K2CO3 e Li2CO3

9. To obtain the required electrical voltage and power, many cells are connected in series to build the MCFC Stack MCFC STACKS single cell voltage= 0.6 - 1 V current = up to 1000A DC

10. MCFC stack components and manufacturing • These aspects will be shown on the next lesson Working principles of Fuel CellsMCFC technologyKey materials and componentsTechnological developmentLAB level tests 29/03/07 Paolo Capobianco Ansaldo Fuel Cells S.p.A. Responsible for laboratories

11. Elements of Fuel Cell theory Characteristic parameters • Reversible cell potential • temperature effects • operating pressure effects • reversible cell potential calculation • cell voltage out of reversibility • polarisation effects: activation, ohmic, concentration • experimental data on MCFC • thermal management and operating ranges • MCFC based power plants • fuel reforming + MCFC • mass balance • performance • experimental results

12. RL e- - + A C H+ H2 O2 reversible cell potential • The Fuel Cell is a device that directly transforms chemical energy of the fuel into electric energy by mean of electrochemical reactions. From the thermodynamic point of view: • From the thermodynamic point of view: • at constant pressure: • 1st Principle of Thermodynamics: • for reversible transformations: • for electro-chemical reactions

13. reversibie cell potential definition

14. Temperature effects on Erev

15. Temperature effects on Erev

16. Operating pressure effects on Erev

17. Operating pressure effects on Erev

18. Erev : study case calculation for MCFC

19. Erev: pressure effects on MCFC

20. Elements of Fuel Cell theory Characteristic parameters • Reversible cell potential • temperature effects • operating pressure effects • reversible cell potential calculation • cell voltage out of reversibility • polarisation effects: activation, ohmic, concentration • experimental data on MCFC • thermal management and operating ranges • MCFC based power plants • fuel reforming + MCFC • mass balance • performance • experimental results

21. fuel oxidant RL ne- I - + A C H+ combustibile ossidante cell voltage on load

22. out of reversibility conditions cell voltage on load 1.5 1.4 Erev-OCV: parasitical reactions 1.3 Erev OCV-A: polarization for activation 1.2 OCV 1.1 A-B: linear voltage drop - ohmic behaviour 1 B-C: polarization for concentration 0.9 A 0.8 V 0.7 B 0.6 0.5 C 0.4 0.3 0.2 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 i

23. Elements of Fuel Cell theory Characteristic parameters • Reversible cell potential • temperature effects • operating pressure effects • reversible cell potential calculation • cell voltage out of reversibility • polarisation effects: activation, ohmic, concentration • experimental data on MCFC • thermal management and operating ranges • MCFC based power plants • fuel reforming + MCFC • mass balance • performance • experimental results

24. Experimental results on a MCFC stack By courtesy of Ansaldo Fuel Cells SpA Voltage vs current characteristic curve is linear: V = Erev - Rpol • I Negligible activation and parasitic voltage loss High current density design condition is possible

25. Concentration effectsexperimental results on MCFC single cell can be measured only for gas compositions very poor in H2 or at very high current densities good agreement with simulated values By courtesy of Ansaldo Fuel Cells SpA

26. Elements of Fuel Cell theory Characteristic parameters • Reversible cell potential • temperature effects • operating pressure effects • reversible cell potential calculation • cell voltage out of reversibility • polarisation effects: activation, ohmic, concentration • experimental data on MCFC • thermal management and operating ranges • MCFC based power plants • fuel reforming + MCFC • mass balance • performance • experimental results

27. Thermalmanagement on MCFC results from detailed simulation code (*) exothermal electrochemical reaction power generation produces heat excess in the cell thermal management need to avoid high temperature damaging of components high gas flow rate is used to cool down the stack (*) By courtesy of Ansaldo Fuel Cells SpA and PERT group of Genoa University

28. Thermal management on real MCFC STACK MCFC - experimental data temperature distribution on the cell plane 700-710 690-700 680-690 670-680 660-670 650-660 640-650 630-640 620-630 610-620 600-610 By courtesy of Ansaldo Fuel Cells SpA

29. typical operating ranges

30. Fuel Cells Plant Concept to accomplish with proper operating ranges the fuel cell need of a Balance of Plant tailored on the application

31. MOLTEN CARBONATE FUEL CELLSANSALDO FUEL CELLS EXPERIENCE Elements of Fuel Cell Theory Evaluation of the characteristic parameters Flow diagram of a typical MCFC plant ANSALDO Fuel Cells experience Experimental results