Fuel Specification for fuel cells

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					Fuel Specification for fuel cells
  EU workshop on Regulations, codes and
     standards for H2/FC technologies
            February 25, 2005



       Paul van den Oosterkamp
            Frank de Bruijn


      ECN-Fuel Cell Technology
                       Outline

• Fuel Cell Applications and Fuels
• Fuel diversity and Fuel Cells
• Production of Fuels for Fuel Cells
      • Centralised
      • Decentralised
• Impurities for PEMFC
• Impurities in Fuel Processing
• Conclusions
                       Fuel Cell Applications and Fuels
                           Natural Gas      Natural Gas
                           Propane
              Hydrogen
              Methanol



                                            Stationary Power (< 250 kW)

Portable Power (1-200 W)    Micro CHP          Marine oil
                                               Hydrogen
                             (1-5 kW)
                                               Gasoline
                         Hydrogen
                         Gasoline
            Hydrogen
            Gasoline

                                            Ships APU and propulsion
                                                  (10-10000 kW)

Transport (50-200 kW)
                                                                   Kerosine
                         City Transport (2-5 kW)             Airplane APU (100-500 kW)
                                  Fuel specifications and
                              reformate/hydrogen production
                                        Hydrogen         Established tolerance levels
                                                         H2S,CO,CO2,NH3,H2S
                                        storage
Centralised production
    of Hydrogen
  Natural Gas, LPG                                                              -                +
                                                                 hydrogen
                                             or
                                                                                    Fuel Cell
         Established tolerance levels                                  air           Stack
         Aromatics
         Organic Sulphur
                                                                                Established tolerance levels
         Inorganic Sulphur               Fuel Processor                         CO
                                                                                CO2
Decentralised production                                                        NH3
of hydrogen reformate                      Compressor                           H2S
                                                                                SO2
     !Natural gas
                                                                                etc
     !LPG
     !Gasoline
     !Diesel                                       air                        Fuel and air
     !Kerosine                                                                specification
     !Biofuels                                                                needed
              Fuel diversity and fuel cells


Natural Gas         Middle                  Liquid          Gas-to-
   LPG             Distillates             Bio-fuels        Liquids



                                                            Solar
                           Synthesis Gas                    Wind




                                                        PEMFC
                             Hydrogen
                                                        PAFC



SOFC             methane                      Biomass
MCFC
               Centralised Hydrogen production
                                                            Process steam


       Desulphurizer                                        H.T. shift

                       Reformer

                                                                 PSA purge
                                                                  gas drum
                        (Radiant
                        section)                                   PSA
       Stack                                                      System




                                                                         Hydrogen
Feed                 Heat recovery       Fuel           Heat              product
                  (Convection section)          recovery and cooling

                                                               99,999 % H2
                 Decentralised Hydrogen production


                    CPO
                    CPO
NG    Sulphur              HT            LT
       Sulphur      ATR     HT            LT      PROX
LPG   Removal        ATR   shift        shift      PROX
      Removal       SR      shift        shift
                     SR


                                                    fuel
                                                     fuel        Combined
                                                    cell
                                                     cell       Heat & Power
                                                                  (1-5 kW)


                                                   anode
                                                    anode
                                    exhaust       exhaust
                                                   exhaust
                                                 utilisation
                                                  utilisation
                   Influence of impurities

• PEMFC
• Reformer
  - Primary reformer (SR/ATR/CPO)
  - Shift (HT & LT)
  - Pref.Oxidation (Prox)
                                      Influence of CO in reformate PEMFC


                          1.0
                                                                        Conditions:
 ean cell potential [V]




                                                                        70-75 °C
                          0.8
                                                                        1 atm l=1.25/2

                          0.6

                          0.4            H2
                                         43%H2 / 41% N2 / 16%CO2
                          0.2              ,, + 10 ppm CO
M




                                           ,, + 10 ppm CO + 1.5% air
                          0.0
                                0.0        0.2           0.4           0.6               0.8
                                              Current density [A/cm²]
                          Source : ECN
                               Influence of H2S in hydrogen for
                               PEMFC
                    1


                   0.8
Cell Voltage (V)




                   0.6
                                   2 ppm H2S                        0.2 ppm H2S
                   0.4


                   0.2


                    0
                         0    50     100   150      200       250     300     350   400
                    Source : ECN                 Time (hrs)
                            Influence of CO2 in reformate PEMFC
                             Reverse watergas shift
                           CO2 + H2 ↔ COg,ads + H2O
                     800                                                         20% CO2 is
                                                       0.35 mg/cm2 Pt            equivalent to
                                                                                 10 ppm CO
j @ 0.5 V [mA/cm ]




                                                       0.35 mg/cm2 PtRu
2




                     600
                                                      - 12%
                                                                                 Reverse WGS
                     400                     - 30%                               is hindered
                                                                                 on PtRu

                     200


                       0
                            0         10         20              40
                                                                          Source : ECN
                                CO2 concentration (%)
                                Influence of NH3 concentration in
                                reformate PEMFC

                      0.66

                      0.64

                      0.62

                      0.60                                                               Reversible
   Cell voltage (V)




                      0.58                                                               degradation
                      0.56

                      0.54

                      0.52

                      0.50

                      0.48

                      0.46
                          150   250   350       450       550        650   750    850
                                            Operating time (hours)


Stationary performance of a cell fed with a mixture of 75% H2 / 25% N2           Source : ECN
and 5 ppm NH3 in the interval from 210 hours to 475 hours.
Current density is 500 mA/cm2.
                                               Influence of NH3 in cathode
Current Density @ 0.5 V [A/cm 2]
                                               air PEMFC
                                    1
                                                            10 ppm NH3
                                   0.9
                                                                                   Anode = cathode =
                                                                                   0.4 mg.cm-2 Pt
                                   0.8


                                   0.7


                                   0.6
                                         60     80      100     120    140   160
                                                        Time [hours]
                                         Source : ECN
                                               Influence of SO2 in cathode
                                               air PEMFC
Current Density @ 0.5 V [A/cm2]




                                   1


                                  0.9
                                                     0.5 ppm SO2
                                  0.8


                                  0.7


                                  0.6
                                    100        120        140        160   180
                                                      Time [hours]
                                    Source : ECN
                              Example Sulphur influence on CPO
                              reforming (typical conditions)
                        100


                        95
normailsed conversion




                                                                 Same trend is
                        90
                                                                 visible for Shift

                        85

                                  0 ppmwS
                        80
                                  10 ppmwS
                                                               Source : ECN
                                  120 ppmwS
                        75
                              0                5          10
                                              time (hr)
                 Impact on lack of fuel specifications
                 for fuel cells ; example : Sulphur

• DESIRE (WEU project).
       Initial fuel specification: NATO-F76 (0.2 wt.% S)
       R&D spent on sulphur removal: app. 200 kEuro
       By lack of succes in S removal from F-76, City diesel (10 ppm S) is now
       used.

• Celina (EU project)
        Fuel specification:3000 ppm (kerosene)
        R&D to be spent on fuel characterisation and sulphur removal: app.
        250 kEuro.
           Impact on lack of fuel specifications
           for fuel cells (2) : example : Sulphur

Optimisation of centralised production of low sulphur fuels in
refinery vs.decentralised S-removal (which needs a lot of
R&D)




                                                       Source : Fuel Cell Energy
                                    Fuels for fuel cell systems




                                    Source : TU-Delft
               Fuel specifications/conclusions


• Should not only focus on hydrogen

• Should not only focus on fuel cell, also on reformer components

• Quick decisions on future fuel specifications can save a lot of
R&D efforts and money. Especially for liquid fuels with S
presence.

• Specifications need to be a compromise between impact on cost
  for fuel cell,costs for hydrogen production and costs for
infrastructure.

• It makes no sense to have a fuel quality for the fuel cell
  which is much higher than the air quality.

				
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posted:3/31/2011
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