Automated Hydrogen Generator
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Published 2023-10-04
The theoretical voltage required to separate water by electrolysis is 1.23V, but in reality it will end up being 1.5-2.0 volts, depending on the electrolyte and electrode chemistry, as well as cell temperature. In order to maximize efficiency and minimize the occurance of heating and side reactions, the voltage on a cell should be kept as low above this threshold as possible. Most industrial devices have a cell voltage somewhere between 2.2-2.5 volts. The efficiency of electrolysis is approximately the threshold voltage divided by the cell voltage.
The calculation to approximate hydrogen production rate is:
Liters per hour = V_threshold * Current * 3600 / 287,000 * 24
The production rate of oxygen gas is half this amount.
One potential pitfall of hydrogen storage in pressure vessels or use as a working fluid in cryocoolers / heat engines is the tendency for atomic hydrogen to work its way into the crystal lattice of metals and cause it to become brittle, similar to how adding carbon to steel makes it more brittle. Supposedly this can be mitigated by ensuring the hydrogen gas is totally dry, and aluminum / copper seem to be far less affected by this issue than steel.
It's important to remember that if you're using stainless steel electrodes, over a long period of time, they can degrade and release toxic chromium salts into the electrolyte, some of which may be the hexavalent (Cr6+) form of Chromium. This electrolyte can't be dumped down the drain. To dispose of it properly, you need to evaporate the water and deliver the precipitate to a hazardous waste disposal site.
Aqueous solution conductivity chart:
pdfs.semanticscholar.org/cbc5/22cf4c5e6e690ca48984…
Music Used:
Fortaleza - Topher Mohr and Alex Elena
All Comments (21)
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A small mistake i caught. Sievert (Sv) is the unit of radiation exposure risk. What you meant would be Siemens (S) which is the unit of conductance.
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Apparently I was half-asleep when I was recording the audio for this video and mixed up Sieverts and Siemens. Also, for those wondering, Part III of the Joule-Thomson cryocooler series is in the works and should be the next video.
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This channel has the right mix of engineering, craftmanship, memes and danger. I arrived here because of the joule-thompson video, but every video I watch is a bigger surprise than the last one. Keep pumping these out, man! And be careful!
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The relationship between voltage, current, efficiency, and time in electrochemistry is insanely complicated. I took some graduate-level courses on it and would be happy to share some of that if you want to pursue it further. The relationship between current and heating is not monotonic, but depends strongly on efficiency, which you can increase with stirring or agitation to move fluid between the electrodes. Might be tricky to do this without moving gas bubbles around, but it makes a world of different. Also consider using carbon fiber weave as a high-surface area anode that doesn't put chromium into solution. And you can nickel-plate carbon fiber for a more efficient cathode.
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I used to work in an industry where we used electrolysis. We used Ruthenium-Iridium coated Titanium electrodes and potted over the electrical connections where the ring connectors were screwed to the plates. For a home-made setup, you could probably just use titanium which is less conductive, but should last longer and keep you from producing chromium salts from the stainless steel.
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I love how this is all on one plate. Engineering isn't just about what but also how.
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Have you tried sticking plastic parts together with friction welding? My favorite way to stick 3d printed parts together is to put a piece of filament in the chuck of a dremel, turn it on, and trace slowly over the seams with it. The friction gently melts the filament into the seams, forming a super strong bond. Unlike a soldering iron, the dremel actually deposits fresh plastic, rather than just melting the plastic that's already there, and it causes a lot less damage to the printed surfaces. Also, the result looks just like welded metal, which is super cool.
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I've only seen a few hydrogen generator diy builds, but this is definitely the best output to size ratio I've seen so far! Very cool
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It might work to pump the hydrogen into a gasometer in the first stage (where any stray liquid coming through should fall into the water at the bottom of the gasometer) instead of a balloon/beach ball, and then have the drying chamber between the gasometer and compressor to remove any moisture gained from the gasometer before long-term storage. Should be much easier to automate than a balloon since you can just sense the height of the gasometer.
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In the past I needed a supply of hydrogen on tap and looked towards electrolysis to provide it. For the `membrane` I used a large (10inch) ceramic (red) plant pot and the electrodes were 316 grade stainless cones, one on the inside, one on the outside. Neg electrode was on the inside, h2 came out of the plant pot hole. The plant pot being totally submerged, saturated with electrolyte, allowed transfer of ions, but disallowed migration of gases. The gas (h2) was collected in much the same way as your system, with a pump to empty the collecting jar. Doing things this way mean a lot smaller distance between electrodes, hence much lower resistance. The h2 purity was more than good enough for my purposes, (shielding gas for making vacuum tube cathodes) I hope this helps. This was the only way I found to get the resistance low enough for acceptable performance with everyday materials. Chris, UK.
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Just FYI, a flyback diode and maybe a 100n snubber cap (like a ceramic capacitor), across the pump motor might help to reduce interference/electrical noise and might also keep the MOSFET alive in the long run. Very cool project, I've been wanting to build a similar setup for RC ballooning for a while :)
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I built a 3kw hho torch a few years ago. I had a lot of trouble with the stainless steel anodes oxidizing (probably because I was using a much higher current and voltage to get a higher instantaneous production). If you are looking for a better material for the anode, I recommend nickel. It works really well in basic conditions. I replaced the stainless steel anodes in my system with nickel plated mild steel, and they work great, although figuring out nickel plating was a project by itself.
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My Dad made something similar using a 55 gallon drum and a smaller plastic drum, the outer electrode was the steel drum and the inner electrode was stainless that was inside the plastic drum. Power source was a self excited alternator on a homemade wind turbine. He had no use for the H2, but just liked tinkering around. Dude had his issues, but there are parts of him that I miss being around. Thanks for the trigger to an old memory
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I really appreciate how you explained the math out loud instead of just showing it on the screen. Really makes it a lot easier for your blind viewers. Thanks! And great project! I heard about a guy who was using solar power to split hydrogen from water, fill tanks, and then use a hydrogen powered generator to run his home off grid, or at least partially off grid. I thought that was a really clever idea, especially if there was some more convenient way to do the hydrolysis. I also like the whole weather balloon thing.
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Very nice! If you need advice or just want to talk hydrogen generators hit me up.
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I am speechless. Never have i seen such a Neat and functional H-Generator, in a DIY kind of way. It is such a Entertaining and informative video that my only real criticism are the Sievert(sv) and Simens(s) mistake. If i ever want to make an H-Generator, i will shamelessly copy your design. Have a Nice day and make great videos however long they take.
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One of my absolutely favorite channels. I tried doing the Aluminum reaction too. Never got as far as doing electrolysis. This is really amazing. Looking forward to the continuation of the Joule-Thompson cooler as well. Go get some heavy gauge wire for your current wires, and stay away from any Sieverts!
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Just the right amount of cutting-edge science and bodging! :face-blue-smiling:
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Fantastic video. Clear, concise and to the point, with a dash of humor. Can't wait for the next one!
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Your videos are, by far, the most interesting I've seen. I work at an industrial processing facility as well as run my own processes at home for fun and you've inspired me a ton to work on my projects.
