Future directions in PEMFC and SOFC research

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1 Physics E19 Interfaces and Energy Conversion Bavarian Centre for Applied Energy Research Division 1: Technology for Energy Systems and Renewable Energies Future directions in PEMFC and SOFC research Matthias Rzepka 1 and Ulrich Stimming 1,2 1 ZAE Bayern, Abteilung 1 Walther-Meißner-Str. 6, Garching, Germany 2 Technische Universität München, Physik-Department E19 James-Franck-Str. 1, Garching, Germany

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3 2007 ~ 450 EJ = 4.5 x J Conversion factors: Exajoule (EJ) = J (Source: Heinloth, Energie Klima Umwelt, Bonn)

4 Outline Global aspects of energy resources and conversion Characteristics of fuel cells Current status Boundary conditions for future application Demands for future development Conclusions

5 Source: James Horwitz, Fuel Cell Intelligence Consulting Services; Fuel Cell Seminar 2007

6 Polymer Electrolyte Membrane Fuel Cells sealing Components of a Fuel Cell (FC) (Example low temperature FC) MEA (Membrane Electrode Assembly): Proton conducting membrane (PEM); typically Nafion ; Anode and Cathode catalyst layer. (Used catalysts are depending on the fuel Cathode catalyst layer Current connection PEM Gas Anode catalyst layer PEM diffusion layer Carbon supported catalyst

7 SOFC High temperature fuel cells: Solid oxide electrolyte with high ionic conductivity; Better kinetics at high T; Less poisoning issues; Still problems with thermal cycling. Under certain conditions internal reforming or direct oxidation of the fuel is possible.

8 PEM and SOFC: Status of development System Power density catalyst PEM Nafion C 1,5 kw/kg 0,9 W/cm 0,7 V 0.3 mg/cm 2 Pt SOFC YSZ C 2-3 kw/l < 1 kw/kg ~ 1,5 W/cm 0,75 V / 800 C

9 Source: James Horwitz, Fuel Cell Intelligence Consulting Services; Fuel Cell Seminar 2007

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11 Electricity and heat generation in a Fuel Cell Conversion of Chemical Energy in Fuel cells At high operation voltages the power output is controlled by electrocatalytic properties

12 partial load full load

13 Vaillant ONSI MTU Siemens SFC Sulzer

14 Vaillant SFC ONSI Steam 1000 MW Siemens MTU 800 W Sulzer GuD 400 MW Oil 1 MW Diesel 50 kw Gasoline 50 kw

15 Electricity and heat generation in a Fuel Cell Conversion of Chemical Energy in Fuel cells At high operation voltages the power output is controlled by electrocatalytic properties

16 Fuel storage/ transport Fuel processing Fuel Cell technology Application Natural Gas purification CHP 5 kw Coal Gas pipeline POX reforming PEM Bio Gas Compressed gas storage steam reforming CHP 1000 kw SOFC Gasoline tank CO-shift Mobile 50 kw Oil Selective oxidation

17 Single-family house PEM Fuel storage/ transport Fuel processing Fuel Cell technology Application Natural Gas purification CHP 5 kw Coal Gas pipeline POX reforming PEM Bio Gas Compressed gas storage steam reforming CHP 1000 kw SOFC Gasoline tank CO-shift Mobile 50 kw Oil Selective oxidation

18 Single-family house PEM Competitor: Gas boiler in combination with public electric grid Advantages: High total efficiency Low operating costs (partial) independency on electric grid Challenges: Costs & durability Low electrical efficiency High load change Mismatch between electric and thermal demand

19 Comparison between PEM and SOFC Systems Air natural gas desulphurization NTS 180 C HTS 450 C reformer 800 C catalytic burner 800 C exhaust Insulation selelective oxidation 150 C PEMFC C electric energy Airt Air natural gas desulphurization reformer 800 C catalytic burner 800 C exhaust Insulation SOFC 800 C electric energy Air

20 Large scale CHP-unit fed by biogas Fuel storage/ transport Fuel processing Fuel Cell technology Application Natural Gas purification CHP 5 kw Coal Gas pipeline POX reforming PEM Bio Gas Compressed gas storage steam reforming Power plant 1000 kw SOFC Gasoline tank CO-shift Mobile 50 kw Oil Selective oxidation

21 Large scale CHP-unit fed by biogas Competitor: Conventional biogas CHP-unit (internal combustion engine) Advantages: High electric efficiency Low thermal power (= losses) Challenges: Costs & durability

22 Fuel cell car Fuel storage/ transport Fuel processing Fuel Cell technology Application Natural Gas purification CHP 5 kw Coal Gas pipeline POX reforming PEM Bio Gas Compressed gas storage steam reforming CHP 1000 kw SOFC Gasoline tank CO-shift Mobile 50 kw Oil Selective oxidation

23 Fuel cell car Competitor: Conventional internal combustion engine Advantages: Challenges: Low fuel consumption electric drive train braking power recuperation low noxious emissions low noise emissions Costs & durability many system components (complexity) start-up of reformer unit

24 Regenerative energy converter application Fuel storage/ transport Fuel processing Fuel Cell technology Application Natural Gas purification CHP 5 kw Coal Gas pipeline POX reforming PEM Bio Gas Compressed gas storage steam reforming CHP 1000 kw SOFC Gasoline tank CO-shift Mobile 50 kw Oil Selective oxidation

25 Electromobility

26 E-mobility: Energy storage systems Fuel battery Super Cell Cap range 500 km 50 kwh = 3 l / 100 km equivalent gasoline consumption Storage device electric energy density mass of storage Li-ion-battery: 130 Wh / kg 400 kg Ni-MH-battery: 80 Wh / kg 600 kg Hydrogen Wh / kg + container 1100 Wh / kg + FC-efficienc. 600 Wh / kg 90 kg

27 Efficiency and losses process efficiency losses battery chargingdischarging 80 % 0,2 1 % per day Supercap chargingdischarging 95 % 10 % per day PEM Electrolysis- H 2 storage FC operation 40 % ~ 0 %

28 E-mobility: Energy storage systems

29 Renewable electricity production 16 % 20 % 19 % 2 % Renewable Nuclear Natural gas Crude oil Coal Source: DOE, 2007

30 Energy Losses in a Hydrogen Economy Energy efficiency Regeneratively produced electricity 0% % conversion to DC Gaseous hydrogen produced by electrolysis compressed for transport after transport transfer into hydrogen tanks (for internal combustion engines) transfer and conversion to electrical energy in fuel cells - in DC - in AC share of energy spent for conversion and distribution after Ulf Bossel

31 Area demand for bio ethanol production Worldwide fuel consumption for road traffic: Specific biofuel production (e.g. Brazil): ~ 2 * liter crude oil / year liter ethanol / km 2 / year -> Worldwide area demand: km 2 (10% of actual agricultural area) Brazil = 0,02 * liter ethanol / year on km 2 (= 6% of area usable for agriculture)

32 Stationary Electricity Generation

33 Direct conversion in SOFC Direct-SOFC of Franklin Fuel Cells with Cu CGO anode: Left: Ultralow-Sulphur Diesel fuel Right:Propane E. Paz, Fuel Cell Seminar 05

34 Example DCFC 34 Power plant concept of LLNL, Fuel Cell Seminar 2005, Palm Springs, CA

35 Direct Carbon Fuel Cell: Proof of Concept of ZAE Bayern / TUM E19 Fuel: carbon derived e.g. from biomass

36 Proof of Concept: Reaction with standard Components Direct Conversion of Carbon in SOFC First result for conversion of pure carbon (ECOPHIT L-Platte (SGL Carbon)) YSZ Electrolyte; Anode: NiO/GDC1 ca. 30 μm, Cathode: 8YSZ3/LSM-LSM4

37 Possible Future Scenario: Road Traffic City travel with battery operated motor bikes and small cars, possibly with small (1-5 kw) fuel cell; Long range travel with larger vehicles using mid temperature ( C) ethanol fuel cell hybridized with battery.

38 Possible Future Scenario: Stationary Electricity Production Small units (<1MW) based on SOFC with natural gas, biogas, ethanol; In niches electricity storage with electrolysis - storing hydrogen - fuel cell; Larger units (>10 MW) SOFC with natural gas, bio gas, carbon from biomass or other sources (negative CO 2 effect possible).

39 Conclusions In fuel cell development we need to match the available energy source (hopefully regenerative) with the application; Hydrogen does not seem to be an option unless we massively build up nuclear power; Direct conversion of an available fuel in a fuel cell is desirable, alcohols at all temperatures, (hydro-)carbons at high temperatures; Fuel cell research has to acknowledge the fuel problem.

40 Thank you for your attention!