- Green hydrogen requires efficient electrolyzers to handle fluctuations in power supply;<\/li>
- Current affordable alkaline electrolyzers find it difficult to handle electricity supply flexibility and use expensive materials for their electrodes;<\/li>
- TU\/e researchers have found a solution by optimizing the distance between the membrane and the cathode (“gap”).<\/li><\/ul><\/div>\n\n\n\n
The challenge: the hydrogen leak<\/h2>\n\n\n\n
So, what\u2019s the most difficult thing about these alkaline electrolyzers? To answer this, we have to go back to the basics of what happens in an electrolyzer, where a cathode and an anode are placed in a salt solution with a membrane between them. If you apply enough voltage, a current flows; hydrogen (H2) forms at the cathode and oxygen (O2) at the anode.<\/p>\n\n\n\n
The membrane is supposed to keep the hydrogen and oxygen from coming together. However, no membrane is able to keep oxygen and hydrogen perfectly apart, which can potentially create dangerous situations.<\/p>\n\n\n\n
![\"\"](\"https:\/\/archive.ioplus.nl\/wp-content\/uploads\/2023\/10\/elektrolyser.jpg\")
Illustration: Thijs de Groot<\/figcaption><\/figure>\n\n\n\n The basic principle of an electrolyzer<\/h2>
By applying a voltage to the electrodes (with the anode on the left and the cathode on the right), negative ions from the electrolyte solution move to the cathode and positive ions move to the anode. At the cathode, a chemical reaction takes place in which hydrogen is formed. At the anode, the reaction results in oxygen.\u00a0<\/p><\/div>\n\n\n\n
Explosive mixture<\/strong><\/h2>\n\n\n\n
The danger lies in the hydrogen leaking through the membrane and ending up on the oxygen side (known as hydrogen crossover). If the amount of hydrogen in the oxygen exceeds four percent, an explosive mixture is created.<\/p>\n\n\n\n
Hydrogen leakage always takes place to some extent but is especially dangerous when the electrolyzer is not running at full power. In that case, less oxygen is made, so the hydrogen leaking through the membrane is not diluted as strongly. The concentration then approaches the explosive limit more quickly.<\/p>\n\n\n\n
To mitigate this danger, the preference is now for alkaline electrolyzers to run at full power. They can be turned up or down a bit but cannot handle sudden large changes. This makes it more difficult to connect them directly to solar or wind farms. It is also tough to operate the electrolyzers with hydrogen at very high pressure because even more hydrogen will then leak through the membrane. But perhaps a change is coming.<\/p>\n\n\n\n
![\"\"](\"https:\/\/archive.ioplus.nl\/wp-content\/uploads\/2023\/10\/csm_de_Groot_Thijs_ST_AS_3529_9a8659495e.jpg\")
<\/figure>\n\n\n\nThe solution: managing the gap<\/strong><\/h2>\n\n\n\n
To enhance the flexibility of alkaline electrolyzers and ensure their safe operation when connected to variable power supply, we aim to control the hydrogen crossover. The distance between the membrane and the cathode \u2013 the gap \u2013 is very important to this.<\/p>\n\n\n\n
In the past, research has been done on these gaps at electrodes. Those studies focused mainly on the efficiency of electrolysis. And, this efficiency is greatest with a zero gap at the cathode.<\/p>\n\n\n\n
More flexibility, no explosion hazard<\/h2>\n\n\n\n
However, if there is no gap, a lot of gas will move through the membrane. This is due to a high supersaturation of hydrogen near the membrane. Supersaturation is the same phenomenon that occurs when you open a bottle of beer or a carbonated soft drink. So, this supersaturation must be brought down if you want to make your electrolyzer more flexible without the danger of an explosion.<\/p>\n\n\n\n
De Groot: \u201cFor this reason, Rodrigo Lira Garcia Barros \u2013 PhD student and first author of the article<\/a> \u2013 systematically investigated the effect of gap size during his doctoral research. This concerned, in particular, the effect on the amount of hydrogen moving through the membrane and the performance of the electrolyzer. It then turned out that with a small but measurable gap at the cathode, we can greatly reduce the leakage of hydrogen through the membrane \u2013 and with an acceptable loss in performance! In the end, you\u2019re left with a more functional and, above all, more flexible electrolyzer.\u201d<\/p>\n\n\n
<\/a><\/div><\/div>In creating future earning power, the TU\/e plays a pivotal role<\/div>Can we create new earning power in Europe by committing to investment in the knowledge and technologies essential for our major societal transitions? That\u2019s the … Continued<\/a><\/div><\/div><\/div>\n\n\nProof<\/h2>\n\n\n\n
De Groot: \u201cThat\u2019s the conclusion of our scientific analysis, so it\u2019s now time for the next step: creating a proof of concept. That\u2019s what we\u2019re going to do in our lab, through which we expect to be able to prove that a flexible electrolyzer is scalable to industry.\u201d Scalable electrolyzers can also be made in different sizes. For example, very large ones could be used for central energy storage, just as power plants now operate centrally in our grid, or smaller ones could accommodate peaks in power generation at the neighborhood or wind farm level.<\/p>\n\n\n\n
The next step: high-pressure electrolysis<\/h2>\n\n\n\n
De Groot enthusiastically goes on to talk about a new European project that is also starting at TU\/e: high-pressure electrolysis. \u201cThe hydrogen released in electrolysis is a gas. But gas can only be used, stored, and transported efficiently if it is stored at a sufficiently high pressure.\u201d<\/p>\n\n\n\n
\u201cWe currently need a compressor for that, in addition to the electrolyzer itself. Those devices are expensive, noisy, and unreliable. So, what if we could make an electrolyzer that immediately delivers the hydrogen at a high pressure? A few years back, I thought that this wouldn\u2019t be possible, just as I thought that we wouldn\u2019t be able to make a super-flexible alkaline electrolyzer. We managed to do the latter, so I\u2019m very much looking forward to again working with students on this new challenge.\u201d<\/p>\n\n\n\n
The original version of this article was published on the TU\/e website.<\/a><\/em><\/p>\n\n\n
<\/a><\/div><\/div>The Dutch are back at it: pioneering aviation a century later, now using hydrogen<\/div>The landing strip of the Rotterdam-The Hague airport is as busy as it usually is on a Thursday in October. <\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"Green hydrogen is a serious contender to become a renewable energy carrier. For example, we could use it to store solar and wind energy during peaks in order to utilize the energy when the sun is no longer shining and the wind is calm. This would require more electrolyzers that can efficiently and flexibly handle […]<\/p>\n","protected":false},"author":2589,"featured_media":523976,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"advgb_blocks_editor_width":"","advgb_blocks_columns_visual_guide":"","footnotes":""},"categories":[42],"tags":[69305,25115,2519],"location":[6763],"article_type":[36684],"serie":[],"archives":[],"internal_archives":[],"reboot-archive":[],"class_list":["post-462204","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-sustainability-nl","tag-elektrolyzer","tag-hydrogen","tag-tue-en","location-netherlands","article_type-news"],"blocksy_meta":[],"acf":{"subtitle":"An article by TU\/e researcher Thijs de Groot and his team on the usefulness of a small cathode gap in alkaline electrolyzers appeared in the International Journal of Hydrogen Energy recently.","text_display_homepage":false},"author_meta":{"display_name":"Team IO","author_link":"https:\/\/ioplus.nl\/archive\/author\/erikdevries\/"},"featured_img":"https:\/\/ioplus.nl\/archive\/wp-content\/uploads\/2021\/12\/unnamed-2.jpg","coauthors":[],"tax_additional":{"categories":{"linked":["Sustainability<\/a>"],"unlinked":["Sustainability<\/span>"]},"tags":{"linked":["elektrolyzer<\/a>","hydrogen<\/a>","TU\/e<\/a>"],"unlinked":["elektrolyzer<\/span>","hydrogen<\/span>","TU\/e<\/span>"]}},"comment_count":"0","relative_dates":{"created":"Posted 2 years ago","modified":"Updated 2 years ago"},"absolute_dates":{"created":"Posted on October 27, 2023","modified":"Updated on October 27, 2023"},"absolute_dates_time":{"created":"Posted on October 27, 2023 6:30 am","modified":"Updated on October 27, 2023 6:30 am"},"featured_img_caption":"","series_order":"","_links":{"self":[{"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/posts\/462204","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/users\/2589"}],"replies":[{"embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/comments?post=462204"}],"version-history":[{"count":0,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/posts\/462204\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/media\/523976"}],"wp:attachment":[{"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/media?parent=462204"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/categories?post=462204"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/tags?post=462204"},{"taxonomy":"location","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/location?post=462204"},{"taxonomy":"article_type","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/article_type?post=462204"},{"taxonomy":"serie","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/serie?post=462204"},{"taxonomy":"archives","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/archives?post=462204"},{"taxonomy":"internal_archives","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/internal_archives?post=462204"},{"taxonomy":"reboot-archive","embeddable":true,"href":"https:\/\/ioplus.nl\/archive\/wp-json\/wp\/v2\/reboot-archive?post=462204"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}