% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@PHDTHESIS{Rauls:1040585,
      author       = {Rauls, Edward},
      title        = {{D}ynamischer {B}etrieb von
                      {P}olymer-{E}lektrolyt-{M}embran {W}asserelektrolyseuren},
      volume       = {658},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2025-01945},
      isbn         = {978-3-95806-811-7},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {XIV, 239},
      year         = {2025},
      note         = {Dissertation, RWTH Aachen University, 2024},
      abstract     = {Dynamically operated water electrolyzers can provide
                      security of supply and power system stability in energy
                      systems with a high proportion of fluctuating renewable
                      energy sources such as wind power or photovoltaics. Polymer
                      Electrolyte Membrane (PEM) electrolyzers are particularly
                      suitable for these operating scenarios due to their ability
                      to handle highly dynamic load changes. This work addresses
                      the impact of dynamic operation of PEM electrolyzers on
                      efficiency and potential operating scenarios in future
                      energy systems. For this purpose, a dynamic simulation model
                      for PEM electrolyzers is developed, parameterized, and
                      validated on a 100 kWel electrolyzer. This model is scaled
                      up to the megawatt range and dynamic aspects are
                      investigated on different scales. The heat-up process of
                      electrolyzers has the highest average efficiency of 74.1
                      $\%LHV$ when part-load operation is directly entered at
                      moderate cell voltages around 1.80 V. Heat-up with auxiliary
                      electric heaters has a maximum efficiency of 60.0 $\%LHV$
                      and is therefore less efficient than heatup under partial
                      load but it qualifies electrolyzers as flexible power sinks.
                      Standby modes allow reduced start-up times of nominal power
                      but require electrical power to maintain operating
                      conditions. Electrolyzers of 400 kWel and larger require
                      about 2 $\%$ of their rated power in warm standby mode and
                      between 7 and 9 $\%$ of their rated power under minimum
                      load. For a 1 MWel electrolyzer, it can be energetically
                      beneficia to stay in warm standby mode for more than 24
                      hours, which shortens the return to the nominal operating
                      point from 37 minutes to a few seconds. During dynamic
                      operation, short-term fluctuations in operating temperature
                      of less than 5 K around the set point are observed,
                      affecting system efficiency by less than ± 0.5 $\%LHV.$
                      With 50 μm membranes, average cell efficiencies of more
                      than 73 $\%LHV$ and system efficiencies of more than 67
                      $\%LHV$ are possible, regardless of the nominal system
                      power. Oversizing the auxiliary heating from 2.5 to 10 $\%$
                      of the nominal electrolyzer power of a 1 MWel electrolyzer
                      does not improve the cell efficiency but worsens the average
                      system efficiency from 59.7 $\%LHV$ to 53.5 $\%LHV.$
                      Completely eliminating auxiliary electrical heating improves
                      the efficiency and part-load capability of electrolyzers.
                      For example, for a 400 kWel electrolyzer coupled to a
                      photovoltaic system, simulations demonstrated that the
                      average system efficiency over one day in increases from
                      68.7 $\%LHV$ when using auxiliary heating to 70.2 $\%LHV$ in
                      autothermal operation. The results of the present work can
                      be used for the development and optimized operation of
                      electrolysis systems. For energy system analyses, the
                      consideration of the transient operating conditions of
                      electrolyzers offers a complementary contribution towards a
                      better understanding of the effects of fluctuating energy
                      sources on grid stability provision services.},
      cin          = {IET-4},
      cid          = {I:(DE-Juel1)IET-4-20191129},
      pnm          = {1231 - Electrochemistry for Hydrogen (POF4-123)},
      pid          = {G:(DE-HGF)POF4-1231},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2504140913116.459385823088},
      doi          = {10.34734/FZJ-2025-01945},
      url          = {https://juser.fz-juelich.de/record/1040585},
}