UNESCO Desire – Net project Molten Carbonate Fuel Cells State of the Art & Perspectives State of the Art & Perspectives Angelo Moreno, Stephen McPhail ENEA – Hydrogen and Fuel Cell Project Rome, 13 th March 2007

Summary Fuel cell lessons programmeFuel cell lessons programme Hydrogen and fuel cellsHydrogen and fuel cells MCFC: cell, stack, system, plantMCFC: cell, stack, system, plant Difficulties, solutions, perspectivesDifficulties, solutions, perspectives

FC lessons programme 13 MarchMCFCENEA Moreno, McPhail 14 MarchMCFCAnsaldoParodi 29 MarchMCFCAnsaldoCapobianco 12 April MCFC System configurations ENEA Moreno, Cigolotti PEM/SOFC lessons in planning

H 2 production plant Fuel cell plant H2H2H2H2 Natural gas Filling station Depleted gas well Deep saline aquifer Power generation plant CO 2 CO 2 H2H2H2H2 Thermal solar Wind turbines Biomass PV plant Hydropower

Turbine avanzate Efficiency, % Plant size, MW SOFC-GT Steam turbines Diesel Gas engines Combined cycle turbines Internal combustion engines PAFC PEFC MCFC, SOFC 0, Microturbines Advanced turbines Fuel cells & competing technologies

Hydrogen and Fuel Cells

Hydrogen and Fuel Cells – Roadmap

Why Fuel Cells?

Chemical Energy Thermal conversion Work q loss CO 2 CO NO x SO x PM q loss H 2 O (CO 2 ) FUEL CELL CONVENTIONAL SYSTEM Fuel Cells – principle

Electric power Hydrogen (Fuel) Oxygen (air - oxidant) + heat water No thermal cycles Fuel Cells – principle No thermodynamic limitations (Carnot)

Electric power Hydrogen (Fuel) Oxygen (air - oxidant) + heat water Thermal efficiency Fuel Cells – principle for H 2 /O 2 reaction:  H = kJ/mole  G = kJ/mole With pure H 2 /O 2 : η = 0.83

 Temperature: °C  Efficiency: 60%  State of the art technology: kW  Market: Special applications (military, space) transportation Alkaline, AFC  Temperature: °C  Efficiency: 40-50%  State of the art technology: 50 kW -1 MW plants up to 11 MW  Applications: CHP, distributed generation  Temperature: °C  Efficiency: 40%  State of the art technology: kW  Applications:Transport Residential Premium power Remote generation Polymer elctrolyte, PEFC  Temperature: °C  Efficiency: 45-55%  State of the art technology: 100 kW - 3 MW  Applications: CHP, distributed generation (plants up to 20 MW) Molten carbonate, MCFC  Temperature: °C  Efficiency: %  State of the art technology: 50 kW- 1 MW  Applications: CHP, distributed generation (plants up to 20 MW, transport (APU) Solid oxide, SOFC  Temperature: °C  Efficiency: 30-40%  State of the art technology: : < 1kW  Applications:portable, electronics Direct methanol, DMFC Phosphoric acid, PAFC Fuel Cells – types

Anode H 2 + CO 3 = → H 2 O + CO e - Cathode 1/2 O 2 + CO e - → CO 3 = Water is produced at the anode side CO 2 is needed at the cathode side Temperature 650 °C ELECTROCHEMICAL REACTIONS MCFC – characteristics Electrolyte: combination of alkali carbonates – Li, K, Na

Anode H 2 + CO 3 = → H 2 O + CO e - Cathode 1/2 O 2 + CO e - → CO 3 = CO 2 is needed at the cathode side: Temperature 650 °C ELECTROCHEMICAL REACTIONS MCFC – characteristics Supply CO 2 from alternate source Produce CO 2 by combustion anode off-gas Transfer CO 2 fm anode exit to cathode inlet

Anode H 2 + CO 3 = → H 2 O + CO e - Cathode 1/2 O 2 + CO e - → CO 3 = Temperature 650 °C ELECTROCHEMICAL REACTIONS MCFC – characteristics CO is a fuel: through combination with water to H 2 : CO + H 2 O → H 2 + CO 2 (water-gas-shift) through direct electrochemical oxidation: CO + CO 3 = → 2 CO e -

MCFC – stack

With sealing & manifolds

MCFC – stack Manifolds: Sealing: Ensure leak-tight closing in highly corrosive atmosphere Between cells Between stack & manifolds Gas flow distribution Homogeneous reactant distribution to the cell Lower pressure drops Uniform fuel utilisation

MCFC – stack Fuel and oxidant feed

MCFC – Fuelling Fuel: H 2 CO Oxidant: O 2 CO 2 Possible sources: Natural gas Syngas (coal gasification) HC-rich fuel (butane, methanol…) Biomass (gasification, digestion…) Chemical production (electrolysis…) Possible sources: Air Reaction products (recirculation)

MCFC – Fuelling Fuel: H 2 CO Possible sources: Natural gas Light hydrocarbons (butane, methanol, …) C x H y + x H 2 O (g) → x CO + (½y+x) H 2 (Endothermic reaction → heat required) Yield: H 2 75% CO 10% CO 2 15% Traces of NH 3, CH 4, SO x …

MCFC – Fuelling Reforming External Heat provided by burn-up of anode exit gas + HX Internal Heat provided by cell reaction + Simplicity inside cell Separation of functions - Complexity in system Large coolant flow required + Cell cooling provided System simplicity & lightness (= cost) - Reforming catalyst required in cell Not ideal for high P

MCFC – Fuelling Fuel: H 2 CO Possible sources: Biomass, coal (gasification) Heavy hydrocarbons (distillate, oil) C x H y + ½x O 2 → x CO + ½y H 2 (Exothermic reaction → heat released) Yield: H 2 20% CO 25% CO 2 10% N 2 40% CH 4, NH 3, SO x, H 2 S, HCl, …

MCFC – Fuelling Partial oxidation (gasification) + High-T heat produced Quick start & reaction Works on many fuels - Low H 2 yield High emission of pollutants (upgrading, clean-up required) Complex external components

MCFC – stack 300 W, 10-cell stack (MTU) With fuel & oxidant inlets & CO 2 recirculation 125 kW, 150-cell (Ansaldo, Italy)

MCFC – Heat Recovery Thermal management of cell: Optimum temperature for cell & system ≈ 650°C Fuel cell reactions generate heat T cell ↓ Open circuit potential ↑ Available heat quantity ↑ Electrolyte loss ↓ Corrosion effects ↓ T cell ↑ Polarization ↓ Reaction kinetics ↑ Reforming conditions ↑ Available heat quality ↑

MCFC – stack With heat recovery 250 kW, HotModule (MTU, Germany) 100 kW (KEPCO, Korea)

MCFC – Power conditioning Power consolidation Current control Invert DC to AC Voltage increase Efficiency of power conditioning between 94-97%

MCFC – system Fuel Treatment Heat Recovery MCFC Stack System Control Fuel Heat H2OH2O H 2, CO DC AC Air Power Cond.

MCFC – Balance of Plant (BoP) Balance of Plant components: Pumps and fans Heat exchangers Spray nozzles Piping Filters Seals Gaskets Valves Regulators

MCFC – Balance of Plant (BoP) 500 kW Joint effort (Ansaldo, Iberinco, Balke, ENEA, AMG – Madrid)

AFCO: 500 kW system ConfigurationConfiguration Cell Size Operating Pressure Operating Temperature Modular Integrated Reformer TWINSTACK ® 0.81 m² Rectangular shape 0.81 m² Rectangular shape 3.5 bar 650°C MCFC – Plant

Modular build-up to MMW units!