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Physical Storage
BMBF
Sea water electrolysis 10.4.2017

The figure shows an electrochemical cell with rotating disk electrode.
© Sören Dresp

Hydrogen from the sea

Scientists of Berlins Technische Universität Berlin and Freie Universität explore catalytic systems for hydrogen electrolysis directly from seawater. The non-precious metal catalysts should be inexpensive to produce. They make it possible to store renewable energy as hydrogen even at sites with water shortage. This option could be used for offshore wind farms or solar thermal power plants.

Project status Project completed
Type of storage Water is reversibly split into hydrogen and oxygen. The elements oxygen and hydrogen can react in the reverse reaction to water and electricity H2O -->1/2 O2 + H2
Project duration August 2013 until December 2016

Currently conventional electrolyzers for hydrogen production are installed in general, where low cost renewable electricity, often from water courses, such as in Norway or similar geographical conditions, is available. Likewise, large amounts of fresh water are there accessible. Usually this is not the case in German off-shore wind farms; nor in many seaside desert regions of the world with great potential availability of renewable electricity, but little possibility of efficient storage. The research described here, is the development of technologies that are not dependent on fresh water, but on seawater.

  • Researcher with sample after solvothermaler autoclave synthesis © Sören Dresp
  • Synchrotron radiation measuring device (BESSY) © Sören Dresp
  • Sample holder in liquid nitrogen for sample preparation for the synchrotronbeam analysis for fine structure analysis © Sören Dresp
  • Rotating disk electrode measurement to determine the activity of the material © Sören Dresp
  • The figure shows an electrochemical cell with rotating disk electrode. © Sören Dresp
  • Selectivity measurement with in-situ mass spectrometry © Sören Dresp
  • Hot press for preparing a membran electrode assembly (MEA) © Sören Dresp
  • Preparation of a membrane based electrolyzer © Sören Dresp
  • First prototyp test for membrane based electrolyzer © Sören Dresp
  • Thermogravimetry device with coupled gas chromatograph © Sören Dresp

Dieses Projekt erforscht kosteneffiziente, da edelmetallfreie, Katalysatorsysteme zur chemisch-stofflichen Speicherung von erneuerbarer Elektrizität in Form von Wasserstoff durch direkte Meerwasserelektrolyse. Solchen Elektrolyseuren wird eine große zukünftige Bedeutung bei der integrierten Erzeugung und Speicherung von Elektrizität in (Offshore-)Windparks oder solarthermischen Kraftwerken beigemessen. In Kombination mit Brennstoffzellen können solche Speichersysteme elektrische Energie und gleichzeitig Frischwasser zur Verfügung stellen, was für bestimme Regionen oder Anwendungen von großer Bedeutung sein kann.

Dicover structural properties of catalyst systems

Non-precious electrocatalysts, which split water efficiently into its components, are the prerequisite for cost-effective, scalable, membrane electrolysis technologies for future storing renewable electricity in form of hydrogen.

Within three years new suitable catalyst systems shall be identified and relevant structural properties deciphered by the working group of Prof. Dr. Strasser of the Technische Universität Berlin and in collaboration with the working group of Prof. Dr. Dau (Freie Universität Berlin). Since renewable energies are connected with strong power fluctuations, additional stability tests of heavy load changes will be conducted and will verify the catalyst stability behaviour under "real conditions". A new cost-effective technology will beable to change the future infrastructure of renewable electricity in Germany and abroad, and may become an important motor for the German export economy.

Currently conventional electrolyzers for hydrogen production are installed in general, where low cost renewable electricity, often from water courses, such as in Norway or similar geographical conditions, is available. Likewise, large amounts of fresh water are thereaccessible. Usually this is not the case in German off-shore wind farms; nor in many seasidedesert regions of the world with great potential availability of renewable electricity, but little possibility of efficient storage. The research described here, is the development of technologies that are not dependent on fresh water, but on seawater.

This project splits into four phases. The first phase deals with the preparation of novel atalytic materials for the electrochemical splitting of sea water by renewable electricity. These new materials or catalysts will be analyzed with respect to their chemical structure  and composition during the second phase. In the third phase, these materials will be tested in regards to their catalytic performance and efficiency. After about 18 months suitable catalyst systems will be selected. During the third year the remaining catalyst materials will be tested under strong load changes and the most stable systems will be identified. The selected catalysts will subsequently be implemented in a real membrane electrolysis cells and the performance of the seawater electrolyzer evaluated.

Application-oriented follow-up projects, in collaboration with industrial membrane electrode manufacturers, utilize the catalysts for marketable, flexible electrolyzers.

Sub-projects

Chemical procedures like precipitation
The sub project deals with the wet chemical preparation of new materials for the oxygen evolution reaction. These new materials will be tested for their activity and their electrochemical selectivity according to the seawater splitting. With the help of elemental analysis and x-ray diffractometrie (XRD) as well as photoelectronspectroscopie (XPS) the material structure will be correlated to the electrochemical data. These materials will be further tested for flexibility and stability via electrochemical high load changes.To conclude the material analysis the selected catalysts will be implemented and tested in a membrane based electrolyzer.

Electrochemical desposition
The sub project b (Prof. Dr. Holger Dau) deals with the preparation of new materials via electrochemical deposition methods. They will be tested for activity and furthermore for stability and self repair mechanisms. An “on line” electrochemistry/X-ray fluorescence (EC/XRF) method should enable this. Other x-ray spectroscopic methods will seek the fine structure of the materials. This technique will also enable the analysis of the degradationprocess due to monitoring the atomic structure change.

Supported by: The Federal Government on the basis of a decision by the German Bundestag

Dates

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Infobox

Research funding

The information system EnArgus provides information on research funding, including on this project (German only).