Miniaturized Fuel Cell Systems: Challenges and Chances

Transcription

1 Symposium: Advances in Ceramic Science and Engineering, ETH Zurich, September 5, 2008 Miniaturized Fuel Cell Systems: Challenges and Chances Anja Bieberle-Hütter Nonmetallic Inorganic Materials, ETH Zurich, Switzerland 1

2 Outline A) Miniaturized Fuel Cell Systems in General B) Example: ONEBAT Micro-Solid Oxide Fuel Cell System 2

3 Fuel Cell Systems system size power range 1W 10 W 100 W 1kW 10 kw 100 kw 1MW 10 MW 100 MW fuel cell type Direct Methanol Fuel Cell Proton Exchange Membrane Fuel Cell Solid Oxide Fuel Cell Miniaturized Fuel Cell Systems Alkaline Fuel Cell Phosphoric Acid Fuel Cell Molten Carbonate Fuel Cell main differences of fuel cell types: - operating temperature - electrolyte material - catalyst according anja.bieberle@mat.ethz.ch, to: Nonmetallic Inorganic Materials 3

4 Price / kw [$] Fuel Cell Economics Li-ion laptop battery $10.000/kW000/kW Automobile engine $40/kW Fuel Cells > $2.000/kW engine price: $4.000 (car price: $20.000) price: $150 engine power: 100 kw average power: 15 W $4.000 / 100 kw = $40/kW $150/0.015 kw = $10.000/kW Fuel cells are much more favorable for laptops and portable electronics than for automobiles. data anja.bieberle@mat.ethz.ch, from: Kukkonen, Small Fuel Nonmetallic Cell Conference, Inorganic Atlanta Materials (2008) 4

5 Miniaturized Fuel Cell Systems 1. Reduction in overall dimensions and power range 220 kw 1kW HEXIS, CH, 2000 ETH Zurich, CH + 2. Reduction in inner dimensions (microfabrication) ~2.5 W YSZ SP 500 nm YSZ PLD ETH Zurich, CH Pt 5

6 Direct Methanol Fuel Cell (DMFC) Systems CH 3 OH + H 2 O CO 2 Sony, C H + anode electrolyte cathode O 2 H 2 O Toshiba MTI Panasonic Samsung Medis Technologies direct liquid borohydride technology 6

7 Proton Exchange Membrane (PEM) Systems C H 2 + H 2 O H + anode electrolyte cathode O 2 H 2 O Motorola / Angstrom MyFC Fraunhofer Institute for Solar Energy Systems (ISE) Jan. 2008: fuel cell powered cell phone: same size 2x talk-time refueling in minutes charger for portable electronics April 08: prototype introduced 7

8 Solid Oxide Fuel Cell (SOFC) Systems >350 C C 4 H 10 H 2 O O 2- anode electrolyte cathode Boston, USA ETH Zurich, CH Bieberle-Hütter et al., J. Pow. Sour Muecke et al., Adv.Funct. Mat in press O 2 Standford, USA, Prinz Huang et al. J. Electrochem. Soc MIT, USA, Tuller AIST, J, Suzuki Baertsch et al. Nikbin, The Fuel Cell Review J. Mat. Res Bieberle-Hütter et al. Jasinski, Microelectronics Intern. anja.bieberle@mat.ethz.ch, J. Electroceramics 2006 Nonmetallic 2008 Inorganic Materials Caltec, USA, Haile Shao et al., Nature

9 Advantages / Disadvantages of Fuel Cell Types C PEM pure hydrogen reforming required handling and storage Pt no tolerance to contaminants complex heat and water management T op μpem kind of fuel catalyst material energy density SOFC C butane, propane diverse materials feasible, exotic materials μdmfc DMFC μsofc most developed Cso far methanol (CH 3 OH) toxicity Pt methanol crossover not suited for extreme environments Manhattan Scientifics & L. Livermore National Laboratories and Sulzer Hexis, 2002 anja.bieberle@mat.ethz.ch, Rey-Mermet, Nonmetallic PhD Thesis, Inorganic 2008Materials 9

10 PEM DMFC SOFC Rey-Mermet, PhD Thesis

11 Overall Challenges for Micro-Fuel Cells main issues for the next decade: costs (fuel, system) fuel infrastructure solved issues: safety VIASPACE / DMFCC performance stability selection of best fuel cell system for specific application public awareness, acceptance US aircraft regulation 2007 system development establish new technologies battery competitors good high energy density 11

12 Chances for Micro-Fuel Cells many feasible applications long runtime geographical independence no charging time, easy charging huge and existing markets Nanomarkets Research Report: Micro Power Sources 2005 annual average growth rate for μfc ( ): 50-90% Innovative Research and Products Inc. (irap), Stamford, Conn (2006). 12

13 Summary A) Miniaturized Fuel Cell Systems in General Miniaturized fuel cells are predicted a great future DMFC most developed SOFC best potential: energy density, materials, fuel B) Example: ONEBAT Micro-Solid Oxide Fuel Cell System Beckel, Galinski, Infortuna, Muecke, Rupp, Ryll, Scherrer, Tölke, Gauckler, Rey-Mermet, Muralt,, Bieri, Hotz, Stutz, Poulikakos, Heeb, Bernard, Gmür, Hocker, Schwarzenbach NTB INTERSTAATLICHE HOCHSCHULE FÜR TECHNIK BUCHS 13

14 Aim: Development of Micro-SOFC System Thin filmsthin... film... membranes J. Rupp: Micro-Solid Oxide Fuel Cells: From Thin Films to Power Delivering Membranes am Micro-SOFC system Poster Session!! YSZ SP 500 nm YSZ PLD Pt 14

15 Micro-SOFC Membranes membrane xxxxxxxxxxxxxxxxxxxxxxxxxxx cathode electrolyte anode substrate membrane ø5 mm Si Muecke et al., Adv. Funct. Mat. (2008) in press. Bieberle-Hütter et al., J. Power Sources 177 (2008) 123. Ni supporting grid Free-standing three layer SOFC membrane: dense and crack-free total thickness < 1 μm maximum diameter up to 5 mm Rey-Mermet et al., PCT/EP2006/

16 Micro-SOFC Performance vo oltage [V] YSZ PLD/YSZ SP bi-layer electrolyte cell RT p c ( O2 ) 550 C OCV = ln nf pa ( O2 ) 500 C C powe r density [mw/cm 2 ] Pt (paste) YSZ SP YSZ PLD Pt (sputtered) 500 nm YSZ SP YSZ PLD Pt current density [ma/cm 2 ] 50_07s_z OCV = 1.06 V, P = 150 mw/cm 550 C P max = 238 mw/cm 550 C Muecke et al., anja.bieberle@mat.ethz.ch, Adv. Funct. Mat. (2008) in press. Nonmetallic Inorganic Materials mw/cm 2 / membrane at 400 C 280 mw/cm 2 / membrane at 350 C Huang et al. J. Electrochem. Soc. (2007). Shim et al. Chem. Mater. (2007). 16

17 Multi-Membrane Arrays Foturan Si 1 cm Si assume: 2.5 W system P = 350 mw/cm 2 membrane area required = 7 cm μm area tot required = 15 cm 2 active =1:1 28 cm 2 for passive = 1:3 # membranes = ø 200 μm for 36 ø 5 mm anja.bieberle@mat.ethz.ch, PhD theses Tölke Nonmetallic and Rey-Mermet Inorganic Materials 17

18 System Design gas processing unit thermal system management system integration NTB INTERSTAATLICHE HOCHSCHULE FÜR TECHNIK BUCHS 18

19 Gas Processing Unit (GPU) Can we reform butane at 550 C? How to realize this in the system design? tubular packed bed reformer: Reformer T = 550 C Rh/ceria/zirconia / i i 550 C Postcombustor T = 550 C fuel / air = 0.8 Hotz anja.bieberle@mat.ethz.ch, et al., Appl. Catalysis B: Nonmetallic Environmental Inorganic 73 (2007) Materials 336. η nc4h10,in nc4h10,out = & & n& C4H10,in 19

20 Microfabricated Si-Structures for GPU post-combustor top post-combustor bottom 1 cm 1 cm reformer bottom interconnector 1 cm NTB INTERSTAATLICHE HOCHSCHULE FÜR TECHNIK BUCHS 1 cm 20

21 Catalytic Activity of Porous Ceramic Reformer Butane conversion: C 1 μm Hotz et al., applied for patent (2008). 10 mg catalyst Rh/ceria/zirconia (2 wt% Rh, 10 nm average diameter) 30 mg SiO 2 sand (200 μm average diameter) reactor volume: 37 mm 3 exergy content of 2.2 W High catalytic activity at 550 C 21

22 Post-Combustor Flame-made Pd/Pt/alumina catalyst H Composition of 2 inlet gas 1: CO H % CO 12.1 % C 30% CH 4 H C 3 H % CH % C 4 H 10 H 2 CO C 3 H 8 C 4 H 10 CH 4 Composition of inlet gas 2: H % CO 5.1 % C 4 H % CH % Conversion: (T = 500 C) H % CO 100 % C 4 H % C 3 H % CH % H % CO 100 % C 4 H % CH % fuel exhaust gas oxidation 100% at 500 C 22

23 Component Integration into Hot Module Reformer Membranes Heat Exchanger 550 C 35 C Fuel Post-Combustor Air Exhaust planar, rectangular, multi-wafer design 23

24 Thermal System Management Main Issues: large temperature gradient of ~ 500 C uniform stack temperature of 550 C start-up of the system Experiments 3D Thermo-Fluidic FE Modeling 40 C 200 C 400 C 570 C 550 C good insulation materials exist Temperature gradient of 500 C is feasible. anja.bieberle@mat.ethz.ch, Bieberle-Hütter et al., J. Power Nonmetallic Sources Inorganic 177 (2008) Materials

25 Start-Up: Hybrid Heating RT T stop T operation ~ 300 C ~ 600 C electrical heating + heating by exothermic butane conversion (max. heat release: 7.8 W) turn-off voltage source t 1 heating by exothermic butane conversion t 1, electric t 3 min t 1, hybrid 7.8 W reduction of start-up time by 51% (max. 79%) ( reduction of exergy cost up to 86%) anja.bieberle@mat.ethz.ch, Stutz et al., J. Power Nonmetallic Sources Inorganic 182 (2008) Materials

26 System Design start up hot module Fuel Air Exhaust insulation e.g. supercap 26

27 System Design VARTA Easy Pack (Li-ion battery) ONEBAT (micro-sofc) Gas tank Gas distribution Insulation Hot module 550 C Housing El. Power 2.5 W 5 W 20 W Voltage 3.7 V 7.4 V 11.1 V 14.8 V Active surface 775cm cm 2 62 cm 2 Total Volume 65 cm cm cm 3 (system + fuel) ( ) ( ) ( ) Application mobile devices, Scanners, DSC, LP, NB, medical battery charger MDA, video phone devices, power tools 27

28 Summary A) Miniaturized Fuel Cell Systems in General Miniaturized fuel cells are predicted a great future DMFC most developed SOFC best potential: energy density, materials, fuel B) Example: ONEBAT Micro-Solid Oxide Fuel Cell System Fuel Cell P max = 238 mw/cm 2 at 550 C 5 mm free- standing membrane Gas Processing Unit at 550 C: ~80 % butane conversion % H 2 selectivity % CO selectivity Thermal System Management 550 C inside 35 C outside System Development Poster!! manufacturable system design 28

29 Outlook Gauckler`s Moore`s Law Law? Fe eature Size [μm m] Size Sy ystem E-3 1E E Year Year 29

30 Thanks to the ONEBAT consortium for the excellent work! Federal Office for Professional Education and Technology Competence Center for Energy and Mobility Swiss electricity grid companies Swiss Federal Office of Energy Mikroglas 30