UNESCO Desire – Net project Molten Carbonate Fuel Cells State of the Art & Perspectives State...

UNESCO UNESCO Desire – Net projectDesire – Net project

Molten Carbonate Fuel CellsMolten Carbonate Fuel Cells State of the Art & PerspectivesState of the Art & Perspectives

Angelo Moreno, Stephen McPhail Angelo Moreno, Stephen McPhail ENEA – Hydrogen and Fuel Cell ProjectENEA – Hydrogen and Fuel Cell Project

moreno@casaccia.enea.itmoreno@casaccia.enea.itstephen.mcphail@casaccia.enea.itstephen.mcphail@casaccia.enea.it

UNESCOUNESCORome , 13Rome , 13thth March 2007 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 March MCFC ENEAMoreno, McPhail

14 March MCFC Ansaldo Parodi

29 March MCFC Ansaldo Capobianco

12 AprilMCFC System configurations

ENEAMoreno, Cigolotti

PEM/SOFC lessons in planning

H2 production plant

Fuel cell plant

HH22

Natural gas

Filling station

Depleted gas well Deep saline aquifer

Power generation plant

COCO22

HH22

Thermal solar Wind turbines

Biomass

PV plant

Hydropower

Turbine avanzate

Efficiency, %

Plant size, MW

SOFC-GT

Steam turbinesDiesel

Gas engines

Combined cycle turbines

Internal combustion engines

PAFCPEFC

MCFC, SOFC

0,1 1 10 100 1000

80

60

70

50

40

30

20

10

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

qloss

CO2 CO NOx SOx PM

qlossqloss

H2O (CO2)

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

H

G

available

usefulT

for H2/O2 reaction: H = 285.8 kJ/mole G = 237.1 kJ/mole

With pure H2/O2: η = 0.83

Temperature: 60-120 °C Efficiency: 60% State of the art technology: 5-150 kW Market: Special applications

(military, space) transportation

Alkaline, AFCAlkaline, AFC

Temperature: 160-220 °C Efficiency: 40-50% State of the art technology: 50 kW -1 MW

plants up to 11 MW Applications: CHP, distributed generation

Temperature: 70-100 °C Efficiency: 40% State of the art technology: 1-250 kW Applications: Transport

ResidentialPremium powerRemote generation

Polymer elctrolyte, PEFCPolymer elctrolyte, PEFC

Temperature: 600-650 °C Efficiency: 45-55% State of the art technology: 100 kW - 3 MW Applications: CHP, distributed generation

(plants up to 20 MW)

Molten carbonate, MCFCMolten carbonate, MCFC

Temperature: 800-1000°C Efficiency: 45 - 60% State of the art technology: 50 kW- 1 MW Applications: CHP, distributed

generation (plants up to 20 MW, transport (APU)

Solid oxide, SOFCSolid oxide, SOFC

Temperature: 50-100 °C Efficiency: 30-40% State of the art technology: : < 1kW Applications: portable, electronics

Direct methanol, DMFCDirect methanol, DMFCPhosphoric acid , PAFCPhosphoric acid , PAFC

Fuel Cells – types

Anode H2 + CO3

= → H2O + CO2 + 2 e-

Cathode 1/2 O2 + CO2 + 2 e- → CO3

=

Water is produced at the anode side

CO2 is needed at the cathode side

Temperature 650 °C ELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONS

MCFC – characteristics

Electrolyte: combination of alkali carbonates – Li, K, Na

Anode H2 + CO3

= → H2O + CO2 + 2 e-

Cathode 1/2 O2 + CO2 + 2 e- → CO3

=

CO2 is needed at the cathode side:

Temperature 650 °C ELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONS

MCFC – characteristics

• Supply CO2 from alternate source

• Produce CO2 by combustion anode off-gas

• Transfer CO2 fm anode exit to cathode inlet

Anode H2 + CO3

= → H2O + CO2 + 2 e-

Cathode 1/2 O2 + CO2 + 2 e- → CO3

=

Temperature 650 °C ELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONSELECTROCHEMICAL REACTIONS

MCFC – characteristics

CO is a fuel:

through combination with water to H2: CO + H2O → H2 + CO2 (water-gas-shift)

through direct electrochemical oxidation: CO + CO3

= → 2 CO2 + 2 e-

MCFC – stack

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 – stackFuel and oxidant feed

MCFC – Fuelling

Fuel:

• H2

• CO

Oxidant:

• O2

• CO2

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:

• H2

• CO

Possible sources:

• Natural gas• Light hydrocarbons (butane, methanol, …)

CxHy + x H2O (g) → x CO + (½y+x) H2

(Endothermic reaction → heat required)

Yield: • H2 75%• CO 10%• CO2 15%

Traces of NH3, CH4, SOx…

MCFC – Fuelling

ReformingExternal

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:

• H2

• CO

Possible sources:

• Biomass, coal (gasification)• Heavy hydrocarbons (distillate, oil)

CxHy + ½x O2 → x CO + ½y H2

(Exothermic reaction → heat released)

Yield: • H2 20%• CO 25%• CO2 10%• N2 40%

CH4, NH3, SOx, H2S, HCl, …

MCFC – Fuelling

Partial oxidation (gasification)

+High-T heat produced

Quick start & reaction

Works on many fuels

-Low H2 yield

High emission of pollutants (upgrading,

clean-up required)

Complex external components

MCFC – stack

300 W, 10-cell stack (MTU)

With fuel & oxidant inlets & CO2 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

Tcell ↓

• Open circuit potential ↑• Available heat quantity ↑• Electrolyte loss ↓• Corrosion effects ↓

Tcell ↑

• 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

Heat

Heat

H2O

H2, 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 ConfigurationConfigurationConfigurationConfiguration

Cell SizeCell Size

Operating Pressure

Operating Pressure

Operating TemperatureOperating

Temperature

Modular Integrated Reformer

Modular Integrated Reformer

TWINSTACK®TWINSTACK®

0.81 m²Rectangular

shape

0.81 m²Rectangular

shape

3.5 bar3.5 bar

650°C650°C

MCFC – Plant

MCFC – Plant

Modular build-up to MMW units!