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.