Hydrogen Generator
Posted: Wed Dec 09, 2015 2:01 am
This is related to my blimp project I've been working on. Turns out it takes $90 to fill my blimp with helium, which I'm not interested in spending. Commercial hydrogen from a gas supplier costs $20 for the fill plus tank lease, but they are paranoid about selling hydrogen and were very reluctant to sell me any. I won't get into my hydrogen phobia rant, but the final option was to make my own. I have calculated that making my own hydrogen through electrolysis will cost about $1 for the fill. So DIY hydrogen it is.
I did a bit of research on the methods being used by the guys augmenting their cars with on board hydrogen generators, but most of those are producing a mixture of both hydrogen and oxygen, not just hydrogen by itself. It is still possible to build your own separation cell that keeps both the hydrogen and oxygen separate, it is just a bit more tricky. I tried the conventional method first, which involves painstakingly cutting a bunch of rubber gaskets and silk screen membranes and then sandwiching them in a stack between two heavily bolted down plates. My initial small versions worked, but as the cell got bigger I had problems with electrolyte leaking out the gaskets and too much oxygen breeching the membranes and mixing with the hydrogen. As a last ditch effort to salvage the $240 worth of 316L stainless plates I had bought for this project, I came up with a 3D printed design which solved both the leaking AND the oxygen mixing problem. There are several other advantages as well, such as no stainless hardware required for assembly, keyed parts that prevent you from assembling one of the gaskets backwards and wrecking the whole cell and a lot less waste material. This same concept could be done on a laser cutter too, but it is about five times more expensive and you have a lot of waste leftover due to the shape of the parts. The nice thing about 3D printing is you only use the plastic you need and there is nothing going into the trash afterwards. So even if the filament costs more per pound than other forms of plastic, you still save money by using less of it.
The pictures below show a single 12v cell, which means it takes 12 volts across the terminals but only has one plate set. Typically you would put a bunch of these in parallel until you have the gas volume you need, or build a bigger one that runs on higher voltage. My next step is to build one that has 10 times the gas generating ability, which will run on 120 volts. It is going to take over 130 hours to print that bad boy though, with 60 screens being required and each screen frame requiring two pieces that take an hour each to print. So you wind up having to swap out 120 print jobs that each only take one hour to complete, then two end plates that each take 7 hours to complete. This is definitely the most elaborate thing I've attempted printing to date, but the finished unit has a market value of $2000 were you to buy an equivalent cell. This is one of those times when I REALLY wish I had a dozen M2s though!
I did a bit of research on the methods being used by the guys augmenting their cars with on board hydrogen generators, but most of those are producing a mixture of both hydrogen and oxygen, not just hydrogen by itself. It is still possible to build your own separation cell that keeps both the hydrogen and oxygen separate, it is just a bit more tricky. I tried the conventional method first, which involves painstakingly cutting a bunch of rubber gaskets and silk screen membranes and then sandwiching them in a stack between two heavily bolted down plates. My initial small versions worked, but as the cell got bigger I had problems with electrolyte leaking out the gaskets and too much oxygen breeching the membranes and mixing with the hydrogen. As a last ditch effort to salvage the $240 worth of 316L stainless plates I had bought for this project, I came up with a 3D printed design which solved both the leaking AND the oxygen mixing problem. There are several other advantages as well, such as no stainless hardware required for assembly, keyed parts that prevent you from assembling one of the gaskets backwards and wrecking the whole cell and a lot less waste material. This same concept could be done on a laser cutter too, but it is about five times more expensive and you have a lot of waste leftover due to the shape of the parts. The nice thing about 3D printing is you only use the plastic you need and there is nothing going into the trash afterwards. So even if the filament costs more per pound than other forms of plastic, you still save money by using less of it.
The pictures below show a single 12v cell, which means it takes 12 volts across the terminals but only has one plate set. Typically you would put a bunch of these in parallel until you have the gas volume you need, or build a bigger one that runs on higher voltage. My next step is to build one that has 10 times the gas generating ability, which will run on 120 volts. It is going to take over 130 hours to print that bad boy though, with 60 screens being required and each screen frame requiring two pieces that take an hour each to print. So you wind up having to swap out 120 print jobs that each only take one hour to complete, then two end plates that each take 7 hours to complete. This is definitely the most elaborate thing I've attempted printing to date, but the finished unit has a market value of $2000 were you to buy an equivalent cell. This is one of those times when I REALLY wish I had a dozen M2s though!