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

MOLTEN CARBONATE FUEL CELLS ANSALDO 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 Filippo Parodi (Ansaldo Fuel Cells S.p.A. - Italy) Roma, 14 th March 2007 MOLTEN CARBONATE FUEL CELLS ANSALDO FUEL CELLS EXPERIENCE

FUEL CELL IS A DEVICE... DIRECTLY TRANSFORMS THE CHEMICAL ENERGY OF THE FUEL INTO ELECTRICAL ENERGY BY ELECTROCHEMICAL REACTIONS Anode Cathode Electrolyte e - Electrical Energy O 2 O 2 O 2 O 2 O 2 O 2 H 2 O H 2 O H 2 O CO °C 80 °C 200 °C 650 °C 1000 °C Fuel H 2 Oxygen Air

FUEL PROCESSING CO 2 H2OH2O FUEL FUEL CELL OXYGEN H2H2 ELECTRIC ENERGY HEAT FUEL OXYGEN CO 2, NO x, SO x, particulate, ash ELECTRIC ENERGY COMBUSTION THERMAL TO MECHANIC CONVERSION Heat losses MECHANIC TO ELECTRICAL CONVERSION Mechanical losses Steam/Gas TurbineAlternator FUEL CELLS BASED vs. CONVENTIONAL ENERGY PRODUCTION PROCESS

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 Fuel Cells based vs. conventional power systems

Fuel Cells Technologies

AFCo selects as most promising FC technology: 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 MCFC

Ansaldo Fuel Cells Labs MCFC single cells Electrochemical Reactions: CO 2 + ½ O 2 +2e -  CO cathode H 2 + CO  H 2 O + CO 2 + 2e - anode H 2 + ½ O 2  H 2 O overall reaction Materials: anode: Ni / Cr cathode: Li x Ni 1-x O matrix:  LiAlO 2 electrolyte: K 2 CO 3 e Li 2 CO 3

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

MCFC stack components and manufacturing These aspects will be shown on the next lesson Working principles of Fuel Cells MCFC technology Key materials and components Technological development LAB level tests 29/03/07 Paolo Capobianco Ansaldo Fuel Cells S.p.A. Responsible for laboratories

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

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: for electro-chemical reactions AC +- H2H2 O2O2 H+H+ RLRL e-e- at constant pressure: 1 st Principle of Thermodynamics: for reversible transformations: From the thermodynamic point of view:

reversibie cell potential definition

Temperature effects on Erev

Operating pressure effects on Erev

Erev : study case calculation for MCFC

Erev: pressure effects on MCFC

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

cell voltage on load AC +- combustibile H+H+ RLRL ne - ossidante I fueloxidant

out of reversibility conditions cell voltage on load i V Erev OCV A B C OCV-A: polarization for activation Erev-OCV: parasitical reactions A-B: linear voltage drop - ohmic behaviour B-C: polarization for concentration

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

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

Concentration effects experimental results on MCFC single cell By courtesy of Ansaldo Fuel Cells SpA can be measured only for gas compositions very poor in H 2 or at very high current densities good agreement with simulated values

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

Thermal management on MCFC results from detailed simulation code (*) (*) By courtesy of Ansaldo Fuel Cells SpA and PERT group of Genoa University 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

Thermal management on real MCFC STACK MCFC - experimental data temperature distribution on the cell plane By courtesy of Ansaldo Fuel Cells SpA

typical operating ranges

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

MOLTEN CARBONATE FUEL CELLS ANSALDO 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