Fuel Cell Activities at TU Graz

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

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

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 www.keepemalive.eu 3

Neutron Radiographic Testing

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

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

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 13 2 1 10 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

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

Water is visualized Reference: Bazylak, A: Liquid water visualization in PEM fuel cells, (2009), S. 3845-3857 9

Direct Ethanol Fuel Cell

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

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

High Temperature Proton Exchange Membrane Fuel Cells

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 100-180ºC Higher tolerance to impurities such as CO Simple system designs since the fuel cell can be air cooled Increased reaction kinetics, improving performance 14

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

Current Distribution Measurements Individual segment current output is measured via the voltage drop along the high-precision resistors of the measurement module. 1 2 3 4 5 6 7 8 High-precision resistors H 2 IN H 2 OUT Air OUT Air IN connectors for current collector rods 1 2 3 4 5 6 7 8 current collector rods 16

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

Effects of Carbon Monoxide (CO) Graphical current distribution for increasing CO content +9% 1% CO 2.5% CO 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 H 2 IN H 2 OUT H 2 IN H 2 OUT +6% +3% 0% Air OUT Air IN Air OUT Air IN -5% 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8-10% 4% CO 4.5% CO -15% H 2 IN 1 2 3 4 5 6 7 8 H 2 OUT H 2 IN 1 2 3 4 5 6 7 8 H 2 OUT -20% -25% Air OUT Air IN Air OUT Air IN 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 18

PEFC operation below freezing

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

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.3112-3119 21

Subzero start measurements Isothermal Coldstart at -20 c and 600mV 0.2 900 Current Density / ma/cm² 0.15 0.1 0.05 0 800 700 600 500 400 300 200 100 0 0 20 40 60 80 100 120 140 160 180 200 Time / s Potential / mv 22

Variation of the Cell Voltage 1.1kC / 7.4 C Isothermal Start, -20 C Current Density / ma/cm² 400 350 300 250 200 150 100 50 0 1.2kC / 6.7 C 1.4kC / 6.2 C 1.8kC / 6.2 C 200mV 400mV 600mV 800mV 0 20 40 60 80 100 120 140 160 180 200 Time / s Lebenbauer M., Hacker V., 1th UECT, June 10th-12th, 2008 23

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

Hydrogen production

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

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