Design and Operation of an Aluminium Alloy Tank Using Doped Na3AlH6 in kg Scale for Hydrogen Storage

Significance Statement

Hydrogen has been discussed as a clean energy carrier, when generated from non-carbonaceous, regenerative energy sources. Among various hydrogen technologies such as hydrogen generation (water electrolysis or hydrocarbons reforming), hydrogen processing (purification) or hydrogen conversion (electricity and heat in fuel cells), hydrogen storage makes an important contribution towards realisation of hydrogen based economy.

German researchers developed an aluminium alloy tank for the chemical storage of hydrogen using almost 2 kg of solid complex aluminium hydride Na3AlH6 doped with TiCl3 and activated carbon. The authors have stored 38 g of hydrogen in the 3 l aluminium alloy tank. Their work is now published in peer-reviewed Journal of Power Sources.

The advantages of storing hydrogen in solid state metal hydride Na3AlH6 are high volumetric storage capacity with a theoretical maximum of 253 g dm-3, which is 3.6 times the density of liquid hydrogen, lower costs for refueling of hydrogen and the possibility to thermally couple the storage tank with fuel cells.

The storage material was prepared by mechanical milling under an inert atmosphere using a planetary ball mill. The team of authors has filled this almost 2 kg of hydrogen storage material in 18 fills into the tank. After pouring of some amount of hydride the tank was placed on a densification apparatus to ensure that the material would be evenly distributed and densified. Multiple taps with the densification apparatus were recommended to provide reliable determination of tapped density of 620 g dm-3.

The hydrogen storage tank and the heat exchangers were fabricated from an aluminium-magnesium-silicon based alloy. The tank and the heat exchangers were manufactured in an extrusion moulding process, which can enable a serial production of lightweight tanks for solid state hydrogen storage. The corrugated heat exchangers are optimized for equal heat distribution.

After filling the tank, it was heated under hydrogen pressure. In hydrogenation process, when the hydrogenation pressure of 2.5 MPa was applied and a temperature of 38 °C was reached, the decomposed storage materials (sodium hydride and aluminium) started to react with hydrogen to form Na3AlH6. The absorption of hydrogen increased with rising temperature. The highest hydrogen flow reached 1022 dm3 h-1 whereas the temperature of the storage material rose to 123 °C. 45 min after the start, the flow of hydrogen began to decrease, which means that hydrogenation process came to an end.

Dehydrogenation process of Na3AlH6 was carried out when the temperature increased up to 180 °C. Hydrogen flow was kept constant at 220 dm3 h-1. After 100 min the hydrogen pressure dropped from initial value of 1.64 MPa to 0.1 MPa. In this test around 38 g of hydrogen, which corresponds to a gravimetric capacity of 2.0 mass %, was evolved. Hence the tank was subjected to 31 tests in which 16 dehydrogenation and 15 hydrogenation tests were performed without any failure.

The aim of this project was to demonstrate the operation of the lightweight aluminum alloy tank using a solid complex aluminium hydride for storing hydrogen. As a result, possible implementations of such a tank operating at lower hydrogen pressure in combination with a high-temperature fuel cell system in stationary application can be safer compared to systems working under much higher hydrogen pressure.

Aluminium Alloy Tank Using Doped Na3AlH6 in kg Scale for Hydrogen Storage
View into the empty metal hydride tank for solid state hydrogen storage fabricated from aluminium alloy with corrugated heat exchangers structures for optimized heat distribution.

About the author

Michael Felderhoff is senior scientist of the Hydrogen Storage Group at the Department of Heterogeneous Catalysis at the Max-Planck-Institut für Kohlenforschung in Mülheim an der Ruhr, Germany. He received his PhD from the University Essen, Germany in 1993. After two postdoctoral positions he started as a scientist at the Max-Planck-Institut in 1999.

His current research interests include hydrogen and heat storage materials and mechanochemical synthesis and processes.

About the author

Kateryna Peinecke works as a scientist in the Hydrogen Storage Group of the Department of Heterogeneous Catalysis at the Max-Planck-Institut für Kohlenforschung in Mülheim an der Ruhr, Germany. She studied powder metallurgy and surface coatings in Kiev Polytechnic University, Ukraine and received a diploma in chemical engineering in 1988. She also has a diploma in environmental chemistry from British Columbia Institute of Technology, Canada. She was working as a technologist in the field of PEM fuel cells at Ballard, a fuel cell company based in Vancouver, Canada.

Her current research interests include hydrogen storage of complex metal hydrides, heat storage of high temperature magnesium hydrides and ammonia fuel cell.

About the author

Mariem Meggouh received her M.Sc. in chemistry in 2008 from the Radboud University Nijmegen, The Netherlands and received her Ph.D. in solid-state hydrogen storage materials in 2013 from the University of Nottingham, United Kingdom. Continuing in the field of hydrogen storage, she started as a postdoctoral researcher at the Max-Planck-Institut für Kohlenforschung in the Hydrogen Research Group of Dr. Michael Felderhoff, which is part of the Department of Heterogeneous Catalysis of Prof. Dr. Ferdi Schüth. Currently, she is working as a scientist at Huntsman P&A Germany GmbH in Duisburg.

About the author

Stefan Peil studied chemistry at the Philipps-Universität Marburg, Germany. After his doctoral thesis in physical chemistry he worked as a post-doc at Alfred-Wegener-Institut für Polar- und Meeresforschung in Bremerhaven, Germany in the field of atmospheric chemistry (ozone hole research). Since January 2000 his research areas are energy conversion and energy storage at the Institut für Energie- und Umwelttechnik IUTA, Duisburg, Germany.

About the author

Robert Urbanczyk studied Mechanical Engineering at the University Essen in Germany with the specialization in Energy Science and graduated in February 2000. Afterwards he worked until 2007 in research and academia field and supervised projects concerned with fuel cells and synthesis gas production and utilisation for fuel cells at the same university where he also obtained his PhD in 2013.

Since April 2007 he is a member of the Institut für Energie- und Umwelttechnik e.V. (IUTA e.V.) in Duisburg Germany, where he develops hydrogen and heat storage systems based on metal hydrides.

About the author

Dieter Bathen is Full Professor of Chemical Engineering at the University of Duisburg-Essen, Germany and Scientific Director of the IUTA (Institut für Energie- und Umwelttechnik). He received a PhD from the University of Dortmund, Germany. Before his engagement in Duisburg he worked in different positions at Degussa AG (now: Evonik AG).

His personal research interest focuses on environmental technology especially adsorption and the industrial application of porous materials.

About the author

Pascal Minne, born 1984, studied Mechanical Engineering at the University of Duisburg-Essen, Germany with specialization in Energy- and Thermal Processtechnology. Since 2013 he works at the engineering department of thyssenkrupp Industrial Solutions in Dortmund, Germany (former ThyssenKrupp Uhde), dealing with process equipments for large scale fertilizer and electrolysis plants.


Urbanczyk, R.1, Peinecke, K.2, Meggouh, M.2, Minne, P.3, Peil, S.1, Bathen, D.3, Felderhoff, M.2, Design and operation of an aluminium alloy tank using doped Na3AlH6 in kg scale for hydrogen storageJournal of Power Sources, Volume 324, 2016, Pages 589–597.

Show Affiliations
  1. Institut für Energie- und Umwelttechnik e.V., Bliersheimer Str. 58-60, 47229 Duisburg, Germany.
  2. Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
  3. Universität Duisburg-Essen, Lehrstuhl für Thermische Verfahrenstechnik, Lotharstraße 1, 47057 Duisburg, Germany.


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