Construction and optimization of SO2 depolarized electrolyser
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Journal Title
Journal ISSN
Volume Title
Insinööritieteiden korkeakoulu |
Master's thesis
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Author
Date
2023-08-21
Department
Major/Subject
Energy Storage
Mcode
Degree programme
Master’s programme in Energy Storage
Language
en
Pages
49+2
Series
Abstract
Green hydrogen is needed as an energy carrier in the energy transition away from fossil energy sources. For this reason, large quantities of renewable energy-based hydrogen will be required in the near future. Most of this will be produced by PEM water electrolyser technology, which has the disadvantage of requiring high overvoltage to break the water molecule into hydrogen and oxygen gas products. If SO2 is added to the anode, the reaction changes, and SO2 is oxidized to sulphuric acid, but simultaneously protons are created that can transport via a proton conductive membrane to the cathode to produce hydrogen. This reaction has the advantage of significantly lower standard potential E° ~ 0.17 V compared to conventional water electrolysis. This has two implications: a larger amount of hydrogen can be produced with the same quantity of renewable energy, and as the potential of the anode is lower, the material requirements are less demanding. However, as SO2 is introduced to the system and can carry over to the cathode, it will be reduced to elemental Sulphur or H2S gas. The thesis aims at building the setup and performing preliminary experiments that would help reduce the sulphur and H2S production, thus increasing the system's reliability. The results of the thesis show that there is enormous scope for improvement in the system, and being a complex system, it consists of multiple parameters that need to be taken into account, thus opening a window of opportunities. The effect of the addition of SO2 to the anolyte, the required system improvements, and prospects have also been discussed in detail. The thesis also emphasizes the necessity for upgraded gas analysis to precisely measure gases produced in the cathode compartment, such as hydrogen, SO2, and H2S. Gas chromatography-mass spectrometry is recommended for precise detection to address the shortcomings of gas sensors. Additionally, emphasis is placed on the significance of pH assessment, leak prevention, and tank maintenance. Future studies will involve evaluating various membranes, investigating the usage of used catholyte as anolyte, implementing various flow fields, and tackling issues with the SDE system's parasitic processes and membrane properties.Description
Supervisor
Santasalo-Aarnio, AnnukkaThesis advisor
Garg, NehaKeywords
sulphur dioxide depolarized electrolyser, bibliometric analysis, hydrogen production, sulphur formation
