IFAM Fraunhofer IFAM Dresden Campus Winterbergstraße 580 employees in total (incl. students) 45 Mio. EUR annual budget

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1 Fraunhofer-Gesellschaft Joseph von Fraunhofer ( )» Scientist Inventor Entrepreneur «Hydrogen Storage and n-demand Hydrogen Generation based on Magnesium and its Alloys Lars Röntzsch1, Felix Heubner2, Marcus Tegel1, Bernd Kieback1,2 1 Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM / GERMANY 2 [Mg] Technische Universität Dresden / GERMANY [MgH2] [MgH2] [Mg(H)2] Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM Fraunhofer IFAM Dresden Campus Winterbergstraße 580 employees in total (incl. students) 45 Mio. EUR annual budget 40% contract reasearch with industry 40% joint R&D projects % public funding ne institute five locations Bremen, Dresden, ldenburg, Wolfsburg, Stade Largest organization for applied R&D in Europe 66 Fraunhofer institutes in Germany Affiliated international research centers ~ 24,000 employees Annual budget 2.2 bn. EUR 1.7 bn. EUR via contract research Hydrogen as Energy Carrier Properties Lower heating value [kwh kg-1] Self ignition temperature [ C] Hydrogen Gasoline (H2) Methane (CH4) 13.9 (-CH2-) Flame temperature [ C] Ignition limits in air [vol.%] Minimal ignition energy [mws] Flame propagation in air [m s-1] Detonation limits [vol.%] [km s-1] Detonation velocity 1.7 Explosion energy [kg-tnt m-3] Diffusion coefficient in air [cm2 s-1] LHV: 100 g-h2 = 3.3 kwhchem. = 1.6 kwhel (50%) Methods of Hydrogen Storage H 1s1 Pressure Tanks -253 C 350 bar density Metal Hydrides: Principles of Formation 90 g/m³ boiling point: -253 C Physical 700 bar -253 C Liquid H2 1 (STP): Solid-electrolyte reaction à Batteries (e.g. NiMH) Solid-gas reaction à Hydrogen storage Compression Microspheres Caverns -196 C 30 bar Liquefaction Cryo- compression Adsorption: Cryocompressed Carbons MFs Zeolites MFs, zeolites, carbons Chemical 110 Absorption: Metal hydrides Metallic Hydrides Complex Hydrides Chemical Hydrides Hydrocarbons C-H, N-H, B-H { C bar} [after L. Schlapbach, 01] 1

2 Part 1 Reversible Hydrogen Storage with Magnesium Mg + H2 heat generation MgH2 + Heat ptimal Metal Hydride (MH) à Materials Design (-76 kj/mol) heat consumption (catalysts) High hydrogen capacity (material & system level) Gravimetric à MgH2: 7.6 wt.-% Volumetric à MgH2: 110 g-h2/liter Fast reaction between hydrogen and metal alloy à fast kinetics Large surface area: Powers, Flakes, (critical dim. < 70 µm) Catalysts: Ni ; RE metals (Y, Nd, Mm, ) in sum 10 at.-% and less Fine microstructure Fast migration of hydrogen through hydride bed (diffusion, flow) Fast heat transport inside reaction bed Dimensional stability and cycle stability of storage material (> 1000) Non-flammable, non-toxic Easy and safe to produce Low price Classical Metal Hydride Materials Advanced MH Composites (amhc) GfE GfE loose powder: 70% porosity è <30 g-h2/liter ; λ < 1 W/(mK) loose powder: 70% porosity è <30 g-h2/liter ; λ < 1 W/(mK) Secondary Phases: Metal powders (Al, Cu, ) Graphite Cellular metals Materials Synthesis: Melt Spinning Stages of Hydrogenation History of Densified Hydride Beds: various patents 1980s Kim et al. IJHE 01 Sanchez et al. IJHE 03 Chaise et al. IJHE 09 Pohlmann et al. IJHE 10 amhc: % porosity è >60 g-h2/liter ; λ >> 1 W/(mK) Here: Mg-Ni alloy Chopped melt-spun flakes (thickness ~30 µm; width < 1 mm) Nanocrystalline ribbons (thickness ~30 µm) v = 40 m/s Melt spinning device at IFAM-Dresden 2

3 Hydrogenation / Dehydrogenation of Melt-Spun Mg-Ni-Y Alloys Tailoring Heat Conductivity Hydrogenated at bar H2 Mixing hydride powders or flakes with secondary phase, e.g. Cu, Al, graphite, porous metals (some vol.-%) Uniaxial compaction (> 50 MPa) Dehydrogenated at 1 2 bar H2 Example: Graphite Graphite Melt-spun flakes Composites S. Kalinichenka, L. Röntzsch et al., Intl. J. Hydrogen Energy Advanced MH Composites Advanced MH Composites Hydrogen storage material with good heat conducting material (thickness: ca. 15/ µm) Hydrogen storage material with good heat conducting material (thickness: ca. 15/ µm) Elongation of phases perpendicular to direction of compaction Elongation of phases perpendicular to direction of compaction Nearly complete ENG network Nearly complete ENG network 150 MPa 150 MPa Comparison: Thermal Conductivity Metal Hydride Storage Systems mechanical integrity à better handling to filling storage vessel! Q MH 3

4 Metal Hydride Storage Systems Metal Hydride Storage Systems mechanical integrity mechanical integrity gas permeability gas permeability 1x10-16 m² à rate-limiting thermal conductivity λ ~ 10 to W/(mK) à sufficient heat à transfer. Q H2 à FEM simulations Metal Hydride Tank Industrial Magnesium Hydride Storage Devices Sources: McPhy, CEA (France) Design as pipe bundle reactor Heat exchange via liquid or gas (HTF) à Active thermal management Modular structure à Easy dimensioning by parallel operation Source: Hydrexia (Australia) Industrial Magnesium Hydride Storage Devices Part 2 n-demand Hydrogen Generation with MgH2 H2-effervescent tablets and pastes Ultra high energy densities > 1500 Wh / kg Energy from water 4

5 Hydrolysis of Magnesium Hydride Hydrolysis of Magnesium Hydride [MgH 2 ] [Mg(H) 2 ] n Hydrolysis doubles the amount of liberated H 2 n Hydrolysis reactions take place at room temp. n PEM fuel cell without reformer + very-high energy density (ϱ el. = 2295 Wh/kg) + can be safely handled in air + can be directly reacted with liquid water + Mg is no critical element (earth crust abundance 1.9 %) + relatively inexpensive (< 1.2 / kwh) + MgH 2 and hydrolysis product Mg(H) 2 are non-toxic (brucite is a natural mineral and an approved food additive) + no requirement to recycle the reaction products But: The hydrolysis rate is limited by the formation of Mg(H) 2 But: MgH 2 is a powder à complicated dosing 3 Mg(H) 2 (s) 2 HC CH (aq) M (MgH 2) = g/mol CH H M (C 6H 8 7) = g/mol (!) Formation of a Mg(H) 2 ften proposed solution: Add an acid or a buffer (e.g. citric acid) 3 Mg 2+ (aq) 2 C 3H 4(H)(C - ) 3 (aq) 6 H 2 Storage capacity reduction = / ( * 2 / 3) = % Better solution: Mechanical activation (ball milling) n The formation of a hydroxide passivation layer remains problematic n Nano-crystalline MgH 2 is prone to ageing. Formation of a Mg(H) 2 Formation of a Mg(H) 2 Formation of a Mg(H) 2 Solution developed at Fraunhofer IFAM: n Addition of small amounts (< 3 at.%) of certain soluble metal salts Solution developed at Fraunhofer IFAM: n Addition of small amounts (< 3 at.%) of certain soluble metal salts 5

6 Normalized reaction progress (%) 100 Formation of a Mg(H) Zn(H)2 Fe(H)3 Zr(H) ph 8 no additive Zn(II)-salts Fe(III)-salts Zr(IV)-salts 6 Solution developed at Fraunhofer IFAM: 4 Addition of small amounts (< 3 at.%) of certain soluble metal salts 2 0 Normalized reaction progress (%) Hydrolysis of MgH2 Practical Issues 10 act as buffers! Hydrolysis time (min) Acid Hydrolysis of MgH2 Reactor Flow Chart MgH2 Paste Densification possible without deterioration of hydrolysis kinetics è high volumetric storage densities nly minor influence of water quality Magnesium Hydride Paste R R H2 capacity Temperature No clotting! Magnesium Hydride Paste Ultra-High Kinetics ester R MgH2 powder + metal salt + ester > 10 wt.% C 6

7 Power System with Magnesium Hydride Paste PowerPaste What we offer n Interdisciplinary expertise and all-inclusive know-how on metal hydride materials (à pre-technical studies) n Complete materials processing route (pre-industrial scale) n Master alloy generation n Milling, rapid solidification of metal or hydride powders n Mixing techniques / pelletization (compaction) n MH paste fabrication n Materials characterization (H 2 storage capacity, sorption kinetics, gas permeability, microstructure, in-situ characterization etc.) n Evaluation under realistic operation conditions (degradation, long-term and cycle stability) n End-of-life concepts n Dimensioning & design of MH storage devices (packaging, modelling, simulation) n Materials testing in prototype-like storage tank systems n Safety & reliability tests n Networking (H 2, energy, materials industry; public funding etc.) Thank You! Partly funded by Fraunhofer IFAM Winterbergstraße Dresden Germany Lars Röntzsch Phone: Lars.Roentzsch@ifam-dd.fraunhofer.de 7