Fuel Cell Activities at TU Graz

Transcription

1 Fuel Cell Activities at TU Graz Viktor Hacker Institute of Chemical Engineering and Environmental Technology Graz University of Technology IEA Workshop TU Graz September 1 st, 2010

2 Content Lifetime and degradation PEFC Neutron radiographic testing Direct ethanol fuel cell High Temperature Proton Exchange Membrane Fuel Cells PEFC operation below freezing Hydrogen production 2

3 Lifetime and degradation of PEFC H 2 + ½O 2 H 2 O Elektrolyt H 2 2 H + + 2e - 2 H + + ½O 2 + 2e - H 2 O Hydrogen Oxygen 3

4 Neutron Radiographic Testing

5 Neutron radiography Principle mode of operation: Sample fuel cell: 5

6 Neutrons Neutrons for technical applications (with high flux density) were obtained from nuclear fission: 6

7 Research reactor TRIGA MARK II Institute of Atomic and Subatomic Physics, Vienna. In service since 1962 for training, research and isotope production. Thermal power output: Neutron flux density: 250 kw cm s 1 Irradiation devices 1 neutron radiography facility: (+17 further irradiation devices) Sample size Detector diameter 9 cm thickness 5 cm exposure time: 1 up to 3 min spatial resolution: 0.1 mm 7

8 Neutron radiography / X-ray radiography Comparison of the cross section for different elements 8

9 Water is visualized Reference: Bazylak, A: Liquid water visualization in PEM fuel cells, (2009), S

10 Direct Ethanol Fuel Cell

11 Direct Ethanol Fuel Cell Project: New Materials for the Direct Ethanol Fuel Cell (Green Cell) Electrodes Membrane Cell non-pt group catalyst for anode catalyst cathode catalyst alkaline polymer anion exchange membrane stable and highly conductive construction characterisation long time stability 11

12 Non-Pt group catalyst for the EOR active as NiCoFe in organic Matrix active Fe Co Ni Cu Ru Rh Pd Ag Os Ir Pt Au platinum group 12

13 High Temperature Proton Exchange Membrane Fuel Cells

14 Hydrogen Oxygen Electrolyte Principle HTPEM fuel cells are based on the use of polybenzimidazole (PBI) membranes doped with phosphoric acid for proton conduction. operating temperature range of ºC Higher tolerance to impurities such as CO Simple system designs since the fuel cell can be air cooled Increased reaction kinetics, improving performance 14

15 Segmented CDL HT-PEM Fuel Cell Anode flow-field MEA Cathode flow-field counterpart 8 current collector rods Segmented, two-channel meander cathode flow-field (10 cm 2 active area) 15

16 Current Distribution Measurements Individual segment current output is measured via the voltage drop along the high-precision resistors of the measurement module High-precision resistors H 2 IN H 2 OUT Air OUT Air IN connectors for current collector rods current collector rods 16

17 Effects of Carbon Monoxide (CO) i-v and i-p curves; 200 C; 0-15% CO 17

18 Effects of Carbon Monoxide (CO) Graphical current distribution for increasing CO content +9% 1% CO 2.5% CO H 2 IN H 2 OUT H 2 IN H 2 OUT +6% +3% 0% Air OUT Air IN Air OUT Air IN -5% % 4% CO 4.5% CO -15% H 2 IN H 2 OUT H 2 IN H 2 OUT -20% -25% Air OUT Air IN Air OUT Air IN

19 PEFC operation below freezing

20 Cold Start Behaviour Water Management at Subfreezing Temperature Product water freezes at the catalyst layer (mainly at the cathode) covers it shuts down the reaction and leads to degradation 20

21 Cold Start Behaviour Water in the Membrane Nafion 117: about 39% of the water in the membrane freezes there is non-freezing water for the H + conduction Saito, Morihiro; Hayamizu, Kikuko; Okada, Tatsuhiro; In:J. Phys. Chem. B 109 (2005), S

22 Subzero start measurements Isothermal Coldstart at -20 c and 600mV Current Density / ma/cm² Time / s Potential / mv 22

23 Variation of the Cell Voltage 1.1kC / 7.4 C Isothermal Start, -20 C Current Density / ma/cm² kC / 6.7 C 1.4kC / 6.2 C 1.8kC / 6.2 C 200mV 400mV 600mV 800mV Time / s Lebenbauer M., Hacker V., 1th UECT, June 10th-12th,

24 Summary Material, design of cell, cell potential and initial water content of the membrane have a great influence on the subfreezing cold start performance. DOE 2010 target: FC for transportation must be able to start unassisted (passive) at -20 C and produce 90% of rated power within 30 seconds. 24

25 Hydrogen production

26 Algae-Hydrogen Research Project in co-operation with BDI- Bioenergy International AG Aim: Evaluation of the possibility and the process economics of biologically produced pure H 2 BDI: Research and Development of a photobioreactor for hydrogen production using green algaes TU Graz Preparation of flat, dense and asymmetric membranes Build-Up of a permeation test bed for single gas and mixed gas permeation Comparison of different polymers for the H 2 separation from a N 2 /H 2 /CO 2 /H 2 O-vapor mix Research and Development of a polymer membrane reactor for hydrogen separation from the product stream of the bio-reactor 26

27 Contributors Dr. Gerd Rabenstein Dr. Markus Thaler DI Astrid Stadlhofer DI Michael Lebenbauer DI Harald Moser Reinhard Strasser Daniel Plörer Thank you! 27