Energetic evaluation of high pressure PEM electrolyzer systems for intermediate storage of renewable energies

Bensmann, Boris; Hanke‐Rauschenbach, Richard; Arias, Ivonne Pena; Sundmacher, Kai

doi:10.1016/j.electacta.2013.05.102

Cited by 83 publications

(55 citation statements)

References 12 publications

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“…9,12 In addition, applied pressures during water electrolysis enable efficient isothermal compression. 13 However, higher pressures increase the amount of hydrogen and oxygen diffusing through the separator, 9,10 so that porous separators that enable low gas crossover are required for efficient alkaline water electrolyzers.Composite materials of Zirconium oxide (zirconia) and polysulfone are high-performing and stable separators for alkaline water electrolysis.14,15 This type of separator combines the flexibility of the polymer with the stiffness and wettability of the ceramic zirconia. …”

mentioning

confidence: 99%

Hydrogen Diffusivity and Electrolyte Permeability of the Zirfon PERL Separator for Alkaline Water Electrolysis

Schalenbach

Lueke

Stolten

2016

J. Electrochem. Soc.

122

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The hydrogen and oxygen evolved during alkaline water electrolysis with liquid KOH electrolytes are typically separated using porous separators such as Zirfon PERL (Agfa), a commercially available composite of zirconium oxide and polysulfone. In this study, the hydrogen diffusivity (driven by concentration differences) and electrolyte permeability (driven by differential pressures) of the Zirfon PERL separator were characterized as a function of the temperature and molarity of the KOH filling. The diffusivity of hydrogen in the separator was found to be approximately 16% of that of the electrolyte filling inside its pores. With respect to water electrolysis conditions, the extent of hydrogen cross-permeation caused by the convection of the cross-permeating electrolyte was estimated and compared to that caused by diffusion. On the basis of the physically characterized mechanisms, smaller pores were predicted to reduce the differential pressure driven gas cross-permeation. In a water electrolyzer, hydrogen is evolved at the cathode (the negative pole) while oxygen is evolved at the anode (the positive pole). When both electrodes are connected by an alkaline electrolyte, hydroxide ions must permeate from the cathode to the anode in order to bring about the electrochemical reactions at the electrodes. In such alkaline water electrolyzers, typically aqueous KOH electrolytes (which provide higher conductivity than other lyes 1 ) and porous separators between both electrodes are used to provide the ionic conductivity between the electrodes and to separate the evolved gases. 2,3Alternatively, alkaline polymer electrolyte membranes can be used as the electrolyte.4-6 However, these membranes typically show low durability. 7,8 The thickness of the separator, its ionic conductivity and its gas permeability constitute a decisive property for the efficiency of water electrolysis, as these properties determine the ohmic drop and cross-permeation of the produced gases.9-11 A recent comparison of acidic and alkaline water electrolysis showed, that the lower hydrogen and oxygen diffusivities in alkaline electrolytes than in acidic electrolytes may be a decisive advantage of alkaline electrolyzers. 9Higher pressures at the gas outlets during water electrolysis means reducing the mass fraction of water in the produced gases and thus lower thermoneutral voltages. 9,12 In addition, applied pressures during water electrolysis enable efficient isothermal compression. 13 However, higher pressures increase the amount of hydrogen and oxygen diffusing through the separator, 9,10 so that porous separators that enable low gas crossover are required for efficient alkaline water electrolyzers.Composite materials of Zirconium oxide (zirconia) and polysulfone are high-performing and stable separators for alkaline water electrolysis.14,15 This type of separator combines the flexibility of the polymer with the stiffness and wettability of the ceramic zirconia. 16Agfa provides a commercially available product of this type of separator, denoted as '...

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mentioning

confidence: 99%

Hydrogen Diffusivity and Electrolyte Permeability of the Zirfon PERL Separator for Alkaline Water Electrolysis

Schalenbach

Lueke

Stolten

2016

J. Electrochem. Soc.

122

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“…1) with the carbon PTL (s. (6) in Fig. 1) on the hydrogen cathode and the titanium PTL (s. (8) in Fig. 1) on the oxygen anode side.…”

Section: Electrolyzer Cell Hardwarementioning

confidence: 99%

“…5,6 It was reported that an operating pressure of 30-45 bar could be a good compromise, 7 with differential pressure operation ( p O 2 ≈ ambient pressure) being more efficient than balanced pressure operation ( p O 2 ≈ p H 2 ). 8 However, increasing the current density and the operating pressure of an electrolyzer will increase the cell voltage, leading to a lower overall voltage efficiency and thus higher operating costs. Since the latter are, along with the capital costs, one of the main cost drivers for large-scale applications, 9 minimizing cell voltage at high current densities and pressures is essential for economic competitiveness.…”

mentioning

confidence: 99%

Influence of Ionomer Content in IrO₂/TiO₂Electrodes on PEM Water Electrolyzer Performance

Bernt

Gasteiger

2016

J. Electrochem. Soc.

280

267

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In this study, the influence of ionomer content in IrO 2 /TiO 2 anode electrodes for a proton exchange membrane (PEM) electrolyzer is investigated (Nafion 212 membrane; 2.0 mg Ir cm −2 / 0.35 mg Pt cm −2 (anode/cathode)) and the contributions of ohmic losses, kinetic losses, proton transport losses in the electrodes, and mass transport losses to the overall cell voltage are analyzed. Electrolysis tests are performed with an in-house designed high pressure electrolyzer cell at differential pressure up to 30 bar. The best performance is obtained for an ionomer content of 11.6 wt% and a cell voltage of 1.57 V at 1 A cm −2 and less than 2 V at 6 A cm −2 (ambient pressure, 80 • C). Performance losses at lower ionomer contents are the result of a higher proton conduction resistance. For higher ionomer contents, on the other hand, performance losses can be related to a filling of the electrode void volume by ionomer, leading to a higher O 2 mass transport resistance, an increased electronic contact resistance, and the electronic insulation of parts of the catalyst by ionomer. At high pressure operation, the performance corrected by the shift of the Nernst voltage increases with H 2 pressure and we propose a new explanation for this effect. In the course of the transition from fossil-based to renewable energy sources, hydrogen technology has gained considerable attention during the past decades. Proton exchange membrane (PEM) electrolyzers are well suited to be coupled with intermittent energy sources such as wind and solar and could provide electrolytic hydrogen for long-term energy storage or fuel cell mobility. At the moment, the large-scale application of PEM electrolyzers is still hindered by their high capital costs.1,2 One attempt to overcome this challenge is to increase the H 2 output by operating an electrolyzer at current densities much higher than the values typically reported in the literature (1-2 A cm −2 ). 2 Recent publications have shown that current densities of 5 A cm −2 and higher are possible. 3,4 Another factor that can be economically beneficial is the operation at high pressure because it allows direct storage of H 2 without subsequent mechanical compression. However, high-pressure operation leads to more demanding materials requirements, imposes additional safety precautions, and reduces the faradaic efficiency due to a higher gas permeation through the membrane. 5,6 It was reported that an operating pressure of 30-45 bar could be a good compromise, 7 with differential pressure operation ( p O 2 ≈ ambient pressure) being more efficient than balanced pressure operation ( p O 2 ≈ p H 2 ).8 However, increasing the current density and the operating pressure of an electrolyzer will increase the cell voltage, leading to a lower overall voltage efficiency and thus higher operating costs. Since the latter are, along with the capital costs, one of the main cost drivers for large-scale applications, 9 minimizing cell voltage at high current densities and pressures is essential for economic competitiveness...

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“…The active area of the ow plates, i.e. the area in contact with the catalyst is 12.96 cm 2 . The ow channels are 0.9 mm deep and 0.9 mm wide.…”

Section: Flow Plate Fabricationmentioning

confidence: 99%

3D printed flow plates for the electrolysis of water: an economic and adaptable approach to device manufacture

Chisholm

Kitson

Kirkaldy

et al. 2014

Energy Environ. Sci.

156

105

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The electrolysis of water is considered a promising route to the production of hydrogen from renewable energy sources. Electrolysers based on proton exchange membranes (PEMs) have a number of advantages including high current density, high product gas purity and the ability to operate at high pressure. Despite these advantages the high cost of such devices is an impediment to their widespread deployment. A principal factor in this cost are the materials and machining of flow plates for distribution of the liquid reagents and gaseous products in the electrochemical cell. We demonstrate the production and operation of a PEM electrolyser constructed from silver coated 3D printed components fabricated from polypropylene. This approach allows construction of light weight, low cost electrolysers and the rapid prototyping of flow field design. Furthermore we provide data on the operation of this electrolyser wherein we show that performance is excellent for a first generation device in terms of overall efficiency, internal resistances and current-voltage response. This development opens the door to the fabrication of light weight and cheap electrolysers as well as related electrochemical devices such as flow batteries and fuel cells. Broader contextUptake of renewable energy generation, especially wind and solar power is increasing at a dramatic rate and has the potential to contribute greatly to mankind's management of climate change due to accumulation of CO 2 . Matching supply and demand of these intermittent renewable energy sources is challenging and solutions offered oen depend on the conversion of excess electrical power to chemical or potential energy for storage until required. Hydrogen is a potential storage medium in this regard and the use of polymer electrolyte membrane (PEM) electrolysers holds great promise for the generation of hydrogen from renewable sources. Successful realisation of this goal requires product development of all parts of the PEM electrolyser from the "active" components e.g. the catalysts, to the "passive" components, namely the structural parts of the electrolyser stack. 3D printing is an emerging technology which can be used in the fabrication of many different device types. Here we present the use of 3D printing to prepare components of an electrolyser cell and demonstrate its operation. This application of 3D printing enables rapid prototyping, cost reduction and a dramatic reduction in component weight. All of which may accelerate the development of new electrolyser technologies.

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Energetic evaluation of high pressure PEM electrolyzer systems for intermediate storage of renewable energies

Cited by 83 publications

References 12 publications

Hydrogen Diffusivity and Electrolyte Permeability of the Zirfon PERL Separator for Alkaline Water Electrolysis

Hydrogen Diffusivity and Electrolyte Permeability of the Zirfon PERL Separator for Alkaline Water Electrolysis

Influence of Ionomer Content in IrO₂/TiO₂Electrodes on PEM Water Electrolyzer Performance

3D printed flow plates for the electrolysis of water: an economic and adaptable approach to device manufacture

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Energetic evaluation of high pressure PEM electrolyzer systems for intermediate storage of renewable energies

Cited by 83 publications

References 12 publications

Hydrogen Diffusivity and Electrolyte Permeability of the Zirfon PERL Separator for Alkaline Water Electrolysis

Hydrogen Diffusivity and Electrolyte Permeability of the Zirfon PERL Separator for Alkaline Water Electrolysis

Influence of Ionomer Content in IrO2/TiO2Electrodes on PEM Water Electrolyzer Performance

3D printed flow plates for the electrolysis of water: an economic and adaptable approach to device manufacture

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Product

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Influence of Ionomer Content in IrO₂/TiO₂Electrodes on PEM Water Electrolyzer Performance