01.07.2021

New technologies for storing renewable energy

In a recently completed research project, the TU Ilmenau has succeeded to improve electrochemical energy conversion for the use of renewable energies with innovative technologies. The results of the research work at the Institute of Thermodynamics and Fluid Dynamics can be used in the future to make the generation of hydrogen more efficient and to develop better fuel cells - these are considered an energy technology of the future. This could benefit mobile electronic devices, medical applications and also the growth market of mobility: automobile traffic, local passenger traffic and air traffic. The research project within the framework of an Emmy-Noether-Nachwuchsgruppe was funded by the German Research Foundation with a total of 1.4 million euros from 2014 to 2021.

 

The world's population and consumption are growing steadily - and so is the global demand for energy. Power generation is still heavily dependent on the fossil fuels coal, oil and gas. In order to counteract climate change, which is promoted by fossil fuels, more and more electricity is to be generated from renewable energy sources. But sunlight and wind power are not continuously available. In order to ensure the stability of the energy supply, the energy generated from renewable sources must be stored using innovative technologies - hydrogen electrolysis and fuel cells are regarded as the technologies of the future. In this process, water is broken down into its components hydrogen and oxygen with the help of electric current. After the hydrogen has been stored, it is combined with oxygen again in a controlled manner in a fuel cell - the chemical reaction generates electricity.

Basic research on new storage technologies
Portraitbild Prof. Christian Cierpka, Leiter Fachgebiet Technische Thermodynamik der TU IlmenauAnLi Fotografie
Prof. Christian Cierpka, Head of the Group of Technical Thermodynamics at TU Ilmenau

At the Group of Technical Thermodynamics at TU Ilmenau, basic research is being conducted under the direction of Prof. Christian Cierpka on new storage technologies such as thermal energy storage and liquid metal batteries. However, chemical energy storage is particularly promising for the long-term storage of energy. The research objective of Prof. Cierpka's junior research group in Ilmenau was to investigate the physical processes underlying electrochemical energy conversion in order to increase the efficiency of the technology and thus the performance of future generations of fuel cells and electrolysers.

During electrochemical energy conversion, water is split into its components hydrogen and oxygen, which are formed as gas bubbles at the electrodes. The hydrogen produced in this way - or products based on it, such as methanol - can then be converted back into electricity in fuel cells in a climate-neutral manner. However, the gas bubbles adhering to the electrodes reduce the efficiency of the electrolyser. In experiments conducted jointly with scientists from TU Dresden, the Helmholtz-Zentrum Dresden-Rossendorf and the Leibniz Institute for Solid State and Materials Research IFW Dresden, the researchers from TU Ilmenau demonstrated for the first time worldwide the influence of so-called thermal marangoni currents on bubble growth. To prevent bubbles adhering to the electrodes from reducing the efficiency of water electrolysis, they also researched how these currents influence the growth of the bubbles and their detachment from the electrodes. Using external lorentz force magnetic fields, they generated additional forces to specifically detach the bubbles from the electrode surface. The effect: more hydrogen was produced in a shorter time.

Innovative fuel cells as battery replacement
Prototyp einer membranlosen mikrofluidischen Brennstoffzelle bei der elektrochemischen und strömungsmechanischen Charakterisierung auf dem MikroskopTU Ilmenau/Wiebke Rösing
Prototype of a membrane-free microfluidic fuel cell during electrochemical and fluid mechanical characterisation on the microscope

In order to measure the flow processes at the gas bubbles and in a fuel cell, the researchers led by Prof. Cierpka developed innovative measurement techniques, which were used, for example, in collaboration with scientists from the Center for Fuel Cell Technology Duisburg to improve the quick-start behaviour of direct methanol fuel cells. Such innovative fuel cells could, for example, be used in mobile devices instead of a rechargeable battery. In another sub-project, the Ilmenau scientists developed and constructed the prototype of a microfluidic fuel cell whose special geometry does not require the expensive membrane usually needed to separate fuel and oxidant. This enabled them to increase its performance and fuel yield.

The Emmy-Noether-Program is a programme of the German Research Foundation named after a german mathematician to promote outstanding young scientists. The Emmy-Noether-Nachwuchsgruppe for research into electrochemical energy conversion was funded - initially at the University of the Federal Armed Forces in Munich and from 2016 at TU Ilmenau - with a total of 1.4 million euros from 2014 to 2021. With the relocation to Ilmenau, the research work benefited from the outstanding technological capabilities of the Center for Micro- and Nanotechnologies with over 1800 square meters of laboratory space. Conversely, students at the TU Ilmenau also benefit from the research. For example, students in the mechanical engineering, mechatronics and micro-nanotechnologies courses at the TU Ilmenau are directly involved in the research work on solutions for the future of sustainable energy supply via student projects and master's theses, and an optical 3D measurement technique developed in the project is taught exclusively as part of an internship.

 

More information about the research at the Group of Technical Thermodynamics: www.tu-ilmenau.de/ttd/

 
Publications

J. Massing, N. van der Schoot, C. J. Kähler, C. Cierpka (2019) A fast start up system for microfluidic direct methanol fuel cells, International Journal of Hydrogen Energy 44, 26517-26529, DOI: 10.1016/j.ijhydene.2019.08.107

W. Rösing, T. Schildhauer, J. König, C. Cierpka (2019) Passive control of the concentration boundary layer in electrochemical microfluidic devices using Dean- ‐vortices, Microfluidics and Nanofluidics 23, 110, DOI: 10.1007/s10404-019-2274-2, open access

J. Massing, G. Mutschke, D. Baczyzmalski, X. Yang, K. Eckert, C. Cierpka (2019) Thermocapillary Marangoni convection during hydrogen evolution at microelectrodes, Electrochimica Acta 297, 929-940, DOI: 10.1016/j.electacta.2018.11.187

D. Baczyzmalski, F. Karnbach, G. Mutschke, X. Yang, K. Eckert, M. Uhlemann, C. Cierpka (2017) Growth and detachment of single hydrogen bubbles in a MHD shear flow. Physical Review Fluids 2, 093701, DOI: 10.1103/PhysRevFluids.2.093701

T. Weier, D. Baczyzmalski, J. Massing, S. Landgraf, C. Cierpka (2017) The effect of the rotating MHD flow on the detachment of gas bubbles from the electrode surface. International Journal of Hydrogen Energy 42, 20923-20933, DOI: 10.1016/j.ijhydene.2017.07.034

 

Contact

Prof. Christian Cierpka

Head of Group of Technical Thermodynamics
+49 3677 69-2445
christian.cierpka@tu-ilmenau.de