High-pressure electrolysis

[[File:High-pressure PEM electrolyser stacks.jpg|thumb|ITM Power's HGas electrolyser stacks, each operating at 80bar pressure]]

[[Image:PEM electrolyzer.jpg|right|thumb|High-pressure PEM electrolyser.]] [[Image:PEM high pressure electrolyser.jpg|right|thumb]]

'''High-pressure electrolysis''' ('''HPE''') is the [[electrolysis of water]] by decomposition of water (H₂O) into oxygen (O₂) and [[hydrogen]] gas (H₂) due to the passing of an electric current through the water.<ref>{{Cite web |url=http://www.risoe.dk/Risoe_dk/Home/Research/sustainable_energy/fuel_cells/projects/SERC/Meetings/~/media/Risoe_dk/Research/SERC/Documents/280808_project1.ashx |title=High pressure electrolysis |access-date=2009-01-06 |archive-url=https://web.archive.org/web/20090502054121/http://www.risoe.dk/Risoe_dk/Home/Research/sustainable_energy/fuel_cells/projects/SERC/Meetings/~/media/Risoe_dk/Research/SERC/Documents/280808_project1.ashx |archive-date=2009-05-02 |url-status=dead }}</ref> The difference with a standard [[proton exchange membrane electrolyzer|proton exchange membrane (PEM) electrolyzer]] is the [[compressed hydrogen]] output around {{convert|120|–|200|bar|MPa|disp=flip}}<ref>[http://www.fz-juelich.de/scientific-report-2001/docs/patente/26_11600.pdf?web_session=e4af90eba1518be519b2c1b61fa42cfb 2001-High pressure electrolysis – The key technology for efficient H.2]{{dead link|date=April 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> at 70&nbsp;°C.<ref>{{Cite web |url=http://event08.ise-online.org/site/files/ise080562.pdf |title=Investigations of hydrogen compressor based on proton exchange membrane |access-date=2009-04-13 |archive-url=https://web.archive.org/web/20110725225851/http://event08.ise-online.org/site/files/ise080562.pdf |archive-date=2011-07-25 |url-status=dead }}</ref> By pressurising the hydrogen in the electrolyser the need for an external [[hydrogen compressor]] is eliminated, the average energy consumption for internal differential pressure compression is around 3%.<ref>[http://www.fz-juelich.de/ief/ief-3/datapool/page/214/solar%20energy%2075%20469-478.pdf 2003-PHOEBUS-Pag.9] {{webarchive|url=https://web.archive.org/web/20090327074743/http://www.fz-juelich.de/ief/ief-3/datapool/page/214/solar%20energy%2075%20469-478.pdf |date=2009-03-27 }}</ref>

==Approaches== As the required compression power for water is less than that for hydrogen-gas the water is pumped up to a high-pressure,<ref>[http://cat.inist.fr/?aModele=afficheN&cpsidt=15701199 Prediction of production power for high-pressure hydrogen by high-pressure water electrolysis]</ref> in the other approach [[differential pressure]] is used.<ref>[http://www.hydrogen.energy.gov/pdfs/review08/pd_10_hamden.pdf Differential pressure]</ref> There is also an '''importance''' for the electrolyser stacks to be able to accept a fluctuating electrical input, such as that found with [[renewable energy]].<ref>{{Cite web |url=http://www.itm-power.com/tech/electrolyser-stacks/ |title=Electrolyser Stacks &#124; ITM Power |access-date=2013-05-20 |archive-url=https://web.archive.org/web/20130512160613/http://www.itm-power.com/tech/electrolyser-stacks/ |archive-date=2013-05-12 |url-status=dead }}</ref> This then enables the ability to help with [[grid balancing]] and [[energy storage]].

==Ultrahigh-pressure electrolysis== Ultrahigh-pressure electrolysis is high-pressure electrolysis operating at {{convert|5000|–|10000|psi|bar|disp=flip}}.<ref name="DOE2">XI.13 High-Efficiency, Ultra-High Pressure Electrolysis with Direct Linkage to Photovoltaic Arrays (Phase II Project) ([http://www.hydrogen.energy.gov/pdfs/progress05/xi_13_jackson.pdf Available here] {{Webarchive|url=https://web.archive.org/web/20210421101128/https://www.hydrogen.energy.gov/pdfs/progress05/xi_13_jackson.pdf |date=2021-04-21 }} Accessed 2008-08-9.)</ref> At ultra-high pressures the water solubility and cross-permeation across the membrane of H₂ and O₂ is affecting [[hydrogen purity]], modified PEMs are used to reduce cross-permeation in combination with catalytic H₂/O₂ recombiners to maintain H₂ levels in O₂ and O₂ levels in H₂ at values compatible with [[hydrogen safety]] requirements.<ref>[http://vgr.ing.unipi.it/ichs/fileadmin/user_upload/CD/PAPERS/12SEPT/2.1.73.pdf Hydrogen safety aspects related to high pressure PEM water electrolysis]{{dead link|date=November 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="DOE" />

==Research== {{Update|date=January 2021}} The [[United States Department of Energy|US DOE]] believes that high-pressure electrolysis, supported by ongoing research and development, will contribute to the enabling and acceptance of technologies where hydrogen is the energy carrier between renewable energy resources and clean energy consumers.<ref name="DOE3">Alkaline, High Pressure Electrolysis ([http://www.hydrogen.energy.gov/pdfs/progress06/ii_h_5_ibrahim.pdf Available here] Accessed 2008-08-9.)</ref>

High-pressure electrolysis is being investigated by the DOE for efficient production of hydrogen from water. The target total in 2005 is $4.75 per [[Gasoline gallon equivalent|gge]] H₂ at an efficiency of 64%.<ref name="DOE">2005 DOE H2 Program Review Alkaline, High Pressure Electrolysis. ([http://www.hydrogen.energy.gov/pdfs/review05/pd26_ibrahim.pdf Available here] Accessed 2008-08-9.)</ref> The total goal for the DOE in 2010 is $2.85 per gge H₂ at an efficiency of 75%.<ref name="DOE3" /> As of 2005 the DOE provided a total of $1,563,882 worth of funding for research.<ref name="DOE" />

Mitsubishi is pursuing such technology with its [[High-pressure hydrogen energy generator]] (HHEG) project.<ref name="Mitsubishi">Mitsubishi Monitor August and September 2004 ([http://www.mitsubishi.com/mpac/e/monitor/back/0408/news.html available here] Accessed 2008-08-9.)</ref>

The Forschungszentrum Jülich, in Jülich Germany is currently researching the cost reduction of components used in high-pressure [[PEM electrolysis]] in the EKOLYSER <ref name="EKOLYSER">{{cite web|url=http://www.fz-juelich.de/iek/iek-3/EN/UeberUns/Kooperationen/EKOLYSER.html|title= Forschungszentrum Jülich EKOLYSER Project|accessdate=27 May 2013}}</ref> project. The primary goal of this research is to improve performance and gas purity, reduce cost and volume of expensive materials and reach the alternative energy targets set forth by the German government for 2050 in the Energy Concept published in 2010.<ref name="energiekonzept2010">{{cite web|url=http://www.bmu.de/fileadmin/bmu-import/files/pdfs/allgemein/application/pdf/energiekonzept_bundesregierung.pdf |title=Das Energiekonzept der Bundesregierung 2010 und die Energiewende 2011 |url-status=dead |archiveurl=https://web.archive.org/web/20130226222555/http://www.bmu.de/fileadmin/bmu-import/files/pdfs/allgemein/application/pdf/energiekonzept_bundesregierung.pdf |archivedate=2013-02-26 }}</ref><ref name="carmo2013a">{{cite journal|last=Carmo|first=M|author2=Fritz D |author3=Mergel J |author4=Stolten D |title=A comprehensive review on PEM water electrolysis|journal=Journal of Hydrogen Energy|volume=38|issue=12|pages=4901|year=2013|doi=10.1016/j.ijhydene.2013.01.151|bibcode=2013IJHE...38.4901C}}</ref>

ThalesNano Energy released a lab-scale high pressure (100 bar) hydrogen generator as a replacement for hydrogen cylinders in chemistry laboratories. <ref>{{Cite web|url=https://global.honda/innovation/FuelCell/smart-hydrogen-station-engineer-talk.html/|title=Hydrogen Generator & CO2 Cell Technology|access-date=2022-01-15|archive-date=2022-01-15|archive-url=https://web.archive.org/web/20220115142303/https://global.honda/innovation/FuelCell/smart-hydrogen-station-engineer-talk.html|url-status=dead}}</ref>

==Commercial Products== Honda installed its Smart Hydrogen Station (SHS) in Los Angeles for use by fuel cell automobiles. <ref>{{Cite web|url=https://global.honda/innovation/FuelCell/smart-hydrogen-station-engineer-talk.html|title=Smart Hydrogen Station}}</ref>

==See also== *[[Regenerative fuel cell]] *[[Electrochemical engineering]] *[[High-temperature electrolysis]]

== References == {{Reflist}}

==External links== *[http://ec.europa.eu/research/energy/pdf/efchp_hydrogen1.pdf High pressure electrolyzer] *[http://www.cder.dz/A2H2/Medias/Download/Proc%20PDF/PARALLEL%20SESSIONS/%5BS05%5D%20Production%20-%20Water%20Electrolysis/14-06-06/393.pdf EC-supported STREP program on high pressure PEM water electrolysis] {{Electrolysis}}

{{DEFAULTSORT:High Pressure Electrolysis}} [[Category:Hydrogen technologies]] [[Category:Electrolysis]] [[Category:Hydrogen production]]