I’m sick of hydrocarbons. There are way better gasses out there that do the same job.
Did you know – the original engine by Rudolf Diesel was made to run on peanut oil, and the original T-model Ford was designed for ethanol fuel?
Anyway, enough of that. Before I can think about alternative automobile fuels, I need an efficient way of creating said alternative.
Hydrogen gas has already been used by a number of people and companies as an alternative to petrochemical fuels. The one commonly appearing in the media is the hydrogen fuel cell, whose appearance is similar to a battery (though the inner workings are very different) and produces electricity to power an electric motor.
This, however, requires a whole new car designed specifically for use with a fuel cell.
Unfortunately little known to the wider public, BMW actually has a fleet of cars – regular petrol cars only very slightly modified – running off hydrogen gas as a combustion fuel. They use exactly the same mechanism as if they were running off petrol, but it’s not petrol.
This got me thinking. My car runs on petrol. Perhaps I too could use hydrogen gas and have a car that produces absolutely no CO2 emissions. So this is my first step (don’t get too excited, it’s just a baby step) towards that future.
Theory
A Hoffman voltameter, or Hoffman apparatus, uses electrolysis to produce hydrogen and oxygen gasses from water.
By passing a DC electric current through the water (with an electrolyte solute to improve conductivity), energy is put into the water – enough so that the chemical bonds within H2O are broken and it splits and reforms into H2 and O. The O then finds another O that split from another molecule of water and forms O2. Hydrogen gas (H2) forms as bubbles at the negative cathode and oxygen gas (O2) at the positive anode, so if the two electrodes are kept slightly separate, the two gasses can be collected separately and used for good, or evil, depending on personal preference.
WARNING!
The following instructable contains some dangerous chemicals;
- Hydrogen gas (obviously) is a colourless, odourless, highly explosive gas. Never have a naked flame, or anything hotter than 600°, anywhere near your working area. Until you’re ready for the fun part, of course.
- Sulphuric acid is a wonderful electrolyte, but horribly dangerous if handled irresponsibly. It will burn skin and tables and faces, so always handle with the utmost care and always wear safety glasses and natural rubber (not latex) gloves.
- PVC should not be used for any purpose involving compressed gasses. It has a tendency to shatter and splinter when put under pressure. The PVC used in this instructable is simply used as feet for the apparatus and does not come into contact with any kind of pressures above atmospheric.
Did you know – the original engine by Rudolf Diesel was made to run on peanut oil, and the original T-model Ford was designed for ethanol fuel?
Anyway, enough of that. Before I can think about alternative automobile fuels, I need an efficient way of creating said alternative.
Hydrogen gas has already been used by a number of people and companies as an alternative to petrochemical fuels. The one commonly appearing in the media is the hydrogen fuel cell, whose appearance is similar to a battery (though the inner workings are very different) and produces electricity to power an electric motor.
This, however, requires a whole new car designed specifically for use with a fuel cell.
Unfortunately little known to the wider public, BMW actually has a fleet of cars – regular petrol cars only very slightly modified – running off hydrogen gas as a combustion fuel. They use exactly the same mechanism as if they were running off petrol, but it’s not petrol.
This got me thinking. My car runs on petrol. Perhaps I too could use hydrogen gas and have a car that produces absolutely no CO2 emissions. So this is my first step (don’t get too excited, it’s just a baby step) towards that future.
Theory
A Hoffman voltameter, or Hoffman apparatus, uses electrolysis to produce hydrogen and oxygen gasses from water.
By passing a DC electric current through the water (with an electrolyte solute to improve conductivity), energy is put into the water – enough so that the chemical bonds within H2O are broken and it splits and reforms into H2 and O. The O then finds another O that split from another molecule of water and forms O2. Hydrogen gas (H2) forms as bubbles at the negative cathode and oxygen gas (O2) at the positive anode, so if the two electrodes are kept slightly separate, the two gasses can be collected separately and used for good, or evil, depending on personal preference.
WARNING!
The following instructable contains some dangerous chemicals;
- Hydrogen gas (obviously) is a colourless, odourless, highly explosive gas. Never have a naked flame, or anything hotter than 600°, anywhere near your working area. Until you’re ready for the fun part, of course.
- Sulphuric acid is a wonderful electrolyte, but horribly dangerous if handled irresponsibly. It will burn skin and tables and faces, so always handle with the utmost care and always wear safety glasses and natural rubber (not latex) gloves.
- PVC should not be used for any purpose involving compressed gasses. It has a tendency to shatter and splinter when put under pressure. The PVC used in this instructable is simply used as feet for the apparatus and does not come into contact with any kind of pressures above atmospheric.
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Signing UpStep 1: Materials
All of the materials below have been chosen for their resistance to sulphuric acid. If you want to change some of the components in your own design, check the new material for its resistance to H2SO4.
5 mm thick Perspex sheet – around 500mm * 300mm of the stuff
2 high chromium stainless steel plates, 140mm*120mm, bent at 90° 20mm in from the long end. Don’t skimp on quality, you need the high chromium stuff or it will go rusty in minutes.
4 Stainless steel bolts and corresponding nuts ~30mm long and 10mm in diameter
4 Hose clamps – you know, the ones you screw with a screwdriver to tighten
8 Aluminium L bracket 100mm in length
An old bicycle tyre inner tube or other thin natural (not neoprene) rubber sheet
Scrap PVC pipe ~20mm diameter
The end of a PVC pipe threaded on the outside, and corresponding screw cap 50-80mm diameter
And 2 more threaded pipes + caps ~20mm diameter
~1m really thick wire. We’re talking 2+mm diameter of the copper, not including insulation
Two of those battery connectors that you crimp onto the wire, or alligator clamps.
A car battery or something else capable of supplying 12 volts DC an a lot of current. A computer power supply is not suitable, as the amount of current the Hoffman apparatus draws will (and did) blow up the power supply. 12 volts is an arbitrary number, but H2O requires a minimum 5 volts to split, and the higher the voltage, the faster your reaction, but the more heat will be generated. I tried a 50 volt DC converter, but the wires leading from the wall to the converter got unnervingly hot.
1 – 3 litres of sulphuric acid. This is marketed as car battery acid or electrolyte. Sometimes it is sold as industrial strength acid drain cleaner, but so is hydrochloric acid, and you MUST NOT USE HYDROCHLORIC ACID. Instead of the electrolysis producing hydrogen gas and oxygen gas, it will prefer hydrogen and chlorine. Chlorine gas was used in the First World War because it burns soft, moist flesh like lungs and eyes. It was subsequently banned from warfare and labeled inhumane. Go for battery electrolyte. If you get drain cleaner make sure you know for sure it is sulphuric acid.
I say 1-3 litres because, depending on your finances and level of clumsiness, you can choose to buy 1 litre and dilute it with 2 litres of water, or buy 3 litres. Optimum performance comes at a concentration of 31% sulphuric acid by weight. Any more or less and the electrical resistance of the system increases, though not by a huge amount. I diluted my acid to make it safer and cheaper, and ended up with about 12% acid by weight, and I produce (very) roughly 2-3 litres per minute of hydrogen gas.
Other people use safer electrolytes like salt or bicarb soda, but these have drawbacks. Using salt also produces chlorine gas, and bicarb produces carbon dioxide, nullifying the idea of green energy. The other drawback is that these electrolytes are consumed and must be topped up every so often. Sulphuric acid is not consumed in the reaction, so once you’ve bought it, it’s there forever unless you spill it. Therefore, as long as it is handled responsibly, in my opinion, sulphuric acid is the best electrolyte to use.
Sulphuric acid is a colourless liquid when you buy it, but trace amounts of rust from inferior stainless steel have discoloured my batch.
Silicone bathroom sealant (must be silicone, not polymer sealant)
Looooots of araldite (or other) 2 part epoxy glue
----- Things which I used but would suggest NOT using -----
Gas taps from a camping stove. I thought it would be good to be able to turn the gas flow on and off, but it just ended up in me forgetting they were closed, building up too much pressure and bursting a hole in the body of the apparatus. I would suggest open PVC pipes.
Jug plugs. I wanted the wires to be removable to make everything neater when not in use, but the plugs actually turned out to be the weakest link, having the highest resistance of the whole thing and heated up too much. I have since revised the design and clamped the thick wire directly to the electrode bolts. The plugs still pop up in some of the photos though.
Case clamps. I tried to have a removable lid, so I bought some case clamps and tried a number of different gaskets including silicone sealant, inner tube rubber, neoprene gasket, bits of yoga mat, camping mat + inner tube rubber, and then gave up because the clamps couldn’t provide enough force to seal properly and I couldn’t stop it leaking.
I ended up gluing the lid on. Perhaps you could try bolting the lid on evenly all around the edges.
5 mm thick Perspex sheet – around 500mm * 300mm of the stuff
2 high chromium stainless steel plates, 140mm*120mm, bent at 90° 20mm in from the long end. Don’t skimp on quality, you need the high chromium stuff or it will go rusty in minutes.
4 Stainless steel bolts and corresponding nuts ~30mm long and 10mm in diameter
4 Hose clamps – you know, the ones you screw with a screwdriver to tighten
8 Aluminium L bracket 100mm in length
An old bicycle tyre inner tube or other thin natural (not neoprene) rubber sheet
Scrap PVC pipe ~20mm diameter
The end of a PVC pipe threaded on the outside, and corresponding screw cap 50-80mm diameter
And 2 more threaded pipes + caps ~20mm diameter
~1m really thick wire. We’re talking 2+mm diameter of the copper, not including insulation
Two of those battery connectors that you crimp onto the wire, or alligator clamps.
A car battery or something else capable of supplying 12 volts DC an a lot of current. A computer power supply is not suitable, as the amount of current the Hoffman apparatus draws will (and did) blow up the power supply. 12 volts is an arbitrary number, but H2O requires a minimum 5 volts to split, and the higher the voltage, the faster your reaction, but the more heat will be generated. I tried a 50 volt DC converter, but the wires leading from the wall to the converter got unnervingly hot.
1 – 3 litres of sulphuric acid. This is marketed as car battery acid or electrolyte. Sometimes it is sold as industrial strength acid drain cleaner, but so is hydrochloric acid, and you MUST NOT USE HYDROCHLORIC ACID. Instead of the electrolysis producing hydrogen gas and oxygen gas, it will prefer hydrogen and chlorine. Chlorine gas was used in the First World War because it burns soft, moist flesh like lungs and eyes. It was subsequently banned from warfare and labeled inhumane. Go for battery electrolyte. If you get drain cleaner make sure you know for sure it is sulphuric acid.
I say 1-3 litres because, depending on your finances and level of clumsiness, you can choose to buy 1 litre and dilute it with 2 litres of water, or buy 3 litres. Optimum performance comes at a concentration of 31% sulphuric acid by weight. Any more or less and the electrical resistance of the system increases, though not by a huge amount. I diluted my acid to make it safer and cheaper, and ended up with about 12% acid by weight, and I produce (very) roughly 2-3 litres per minute of hydrogen gas.
Other people use safer electrolytes like salt or bicarb soda, but these have drawbacks. Using salt also produces chlorine gas, and bicarb produces carbon dioxide, nullifying the idea of green energy. The other drawback is that these electrolytes are consumed and must be topped up every so often. Sulphuric acid is not consumed in the reaction, so once you’ve bought it, it’s there forever unless you spill it. Therefore, as long as it is handled responsibly, in my opinion, sulphuric acid is the best electrolyte to use.
Sulphuric acid is a colourless liquid when you buy it, but trace amounts of rust from inferior stainless steel have discoloured my batch.
Silicone bathroom sealant (must be silicone, not polymer sealant)
Looooots of araldite (or other) 2 part epoxy glue
----- Things which I used but would suggest NOT using -----
Gas taps from a camping stove. I thought it would be good to be able to turn the gas flow on and off, but it just ended up in me forgetting they were closed, building up too much pressure and bursting a hole in the body of the apparatus. I would suggest open PVC pipes.
Jug plugs. I wanted the wires to be removable to make everything neater when not in use, but the plugs actually turned out to be the weakest link, having the highest resistance of the whole thing and heated up too much. I have since revised the design and clamped the thick wire directly to the electrode bolts. The plugs still pop up in some of the photos though.
Case clamps. I tried to have a removable lid, so I bought some case clamps and tried a number of different gaskets including silicone sealant, inner tube rubber, neoprene gasket, bits of yoga mat, camping mat + inner tube rubber, and then gave up because the clamps couldn’t provide enough force to seal properly and I couldn’t stop it leaking.
I ended up gluing the lid on. Perhaps you could try bolting the lid on evenly all around the edges.
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Little Willie was a chemist,
Little Willie is no more.
What he thought was H2O
was H2SO4.
And not all metals are reactive.
Assuming you had an infinite source of electrical energy available on vehicle (not produced by engine), how large would your device need to be in order to produce enough fuel to supply the needs of a vehicle at highway speeds?
Here are some assumptions to work from:
An energy consumption rate of 6MJ/min is required to maintain your vehicle's on highway speed (assumed be to 60MPH). The energy efficiency of your engine is around 15 MJ/kg for hydrogen fuel consumption (surely there's a better fuel specific unit, eh?).
1. How much gas must you produce per minute to keep your speed?
2. What size of electrode is required for this production rate?
3. What volume of water/acid is required for this production rate?
Your results will likely be on the order of, "Huge". The question then becomes, how can you reduce the size of your fuel cell while maintaining production rate, eliminating the need for storage system entirely?
Of course, there's still that "endless on vehicle electrical energy" problem, but I'm sure someone will figure that out! ;P
1. I wanted to do that course in the early 90s but I was too chicken to move to Melbourne from North Queensland lol. I'm now doing an aviation degree in Brisbane - years later!
2. I've got a couple of brief-case style solar panels that supply about 1 - 1.5 amps @ 12v - I reckon they're what I'd run this with, maybe through a regulator.
3. Now that the storage problem is being solved, I reckon hydrogen will be huge, especially as photovoltaics get cheaper. I can see a bigger version of this setup in everyone's house. Maybe outside.
4. Thanks for the instructable!
You could do something with controlling the resistance of the system, but my apparatus draws close on 10 amps, so you'd need a few panels to be able keep the volts up, I'm in the same situation so that's what I'm working on now - i'll post result when I have some.
I'm very much looking forward to hydride storage tanks, and hopefully the decriminalisation of the materials used in them. I'm can't wait until everyone is producing there own fuel at home!
Thank YOU for your support
PV power really needs 4 of 5 kilowatts to power a house with spare capacity for energy storage. I like the idea of constructing a rig like yours and slowly accruing some more PV power to make a little test system with a little hydrogen tank that can run something. 10 amps? I'm about a 3rd of the way there.
BTW I've been sketching an RC blimp recently that could use that hydrogen... I'm going to call it the Hoganburg
I think compressed nitrogen is a decent route for energy storage. Sets of tanks can power tesla turbines to generate electricity to produce H2 on demand. Storing large amounts of flammable or reactive compounds is going to elicit an implacable--and warranted--NIMBY response.
I've heard and thought about the compressed gas battery concept too. It maybe well be the case that new houses in future start with an excavation for storage tanks. have you also seen the British work on liquid air powered reciprocating engined cars? It's actually quite exciting the energy density they are getting and it's something that could also be done using household photovoltaics, wind etc.
I'm guessing they'd use MgH2 as a storage source, since it's far less pyrophoric than AlH4 or LiH. This paper seems to have some good ideas going for it--a self-sustaining reaction producing three moles of gaseous hydrogen for one mole of water once it's started. Still has the problem of having 60+ L of 300 C hydrogen gas shooting around, though.
(On a slightly discontented note; I remember how the press popularized some of these amazing things many decades ago when I was young.)
This metal hydride storage for low pressure Hydrogen gas has been announced as "just around the corner" for decades. I'm old enough to remember when this was a new idea waaaaay back when. Just where are those flying cars they also promised us?
Also, the maintenance and upkeep required to keep the hydrogen tank clean and full of liquid are just not worth the effort. There are internet sites that explain the difference between hydrogen and gasoline. Gasoline has a longer "burnability" time during the combustion explosion, ascompared with the almost instant explosion of hydrogen. Someone will eventually build a great hydrogen generator, or engine that will work with it. Hope it's you Squiggy !
I *DO* think most/all of the current attempts are less cost-effective than gasoline engine, I've never built one, but from what I THINK I know about them, you'd have to buy the sulfuric acid (which is a WHOLE lot more expensive than gas)... Does that REALLY last forever?
lets assume that lasts FOREVER, and you just have to add water.
Do you have to use distilled water, which costs about a dollar a gallon, but what is it's power output compared to gas? I've READ that it's MORE than gasoline (fumes for those who want to get technical) but my little 2.0L engine (800 RPM Idle) takes 28.25 CFM of air. at 14:1 compression, that means I need 2.02 CFM or fuel (compression is different for hydrogen than gas, so this figure will differ). or 4.54 CFM if I'm actually RUNNING the engine (1800RPM)... Can it produce this much (further reading says hydrogen needs 4 times the volume of gas, so 18.16 CFM)
If we use regular tap water, does the sulfuric acid need to be filtered every so often?
how much excess energy does the alternator create? can we run multiple Hoffman Apparatuses with that excess power without overloading the alternator?
1. Yes the acid really does last forever. It's about $7 per litre here in Australia from Autobarn. I just bought 1 litre, and it will be there or the life of the apparatus
2. I use rain water for my proof of concept, and I think it should be fine for large scale too, but if you wanted to you could use distilled water. 1L of water makes 24.5L of H2, so that works out to just over 4c per gallon.
3. If you just swapped your petrol tank for a hydrogen gas tank, you would get about 85% the power of petrol, compared to propane which puts out about 75% power.
However, if you go to the effort to install a direct injection system, power output can be increased to up to 15% more than petrol
1) good to know, but I do believe your plates are slowly 'disappearing' (for lack of the correct term.) also...
2) how FAST does it generate the H2?
Now mind you, I am *NOT* against this idea. I've always thought this sounded like a good idea, I'm just currently too lazy to build one/lack an engine to 'adapt'.. I'm just trying to point out to all the people who say 'you can't get more out than you put in' that THAT IS NOT THE CASE. you're using the energy in water, and (I'm pretty sure) your plates will degrade. It SHOULD be possible to generate MORE ELECTRICITY than you put in (again, because you're using additional fuel (I say that over and over to again, try to drive that point home to those who don't understand that MORE is coming from the other sources, not being 'magically created'))
When you stated using "high chromium stainless steel plates", what grade were/are you referring to? I'm woefully unfamiliar with steel grades and what they mean.
Also, what is your theory on using both the oxygen and the hydrogen as fuel? Both are flammable, would the resulting energy output be really any different? Obviously the result of burning both simultaneously would be water vapor, and some condensation is guaranteed, which could be problematic eventually.
What the acid actually does is increase the conductivity of the water, because pure H2O is not a conductor, it only can conduct electricity because of impurities, which is accomplished through the addition of sulfuric acid.
However, my previous statement, that the acid is not actually used up in the reaction, still stands.
That said, it would be better to use distilled water than tap water, because tap water (in the US, at least) is treated with chlorine and other nasty chemicals that you do not want to end up coming in contact with in any quantity (the little bit dissolved in water is harmless, usually).
I use rain water to avoid things like chlorine and fluorine in tap water, but if you wanted to do it absolutely you should use distilled water.
To be honest I don't know much about steel grades either as far as naming and production and things, but I do know the effects of alloying elements to steel. The chromium is what stops stainless steel from rusting. Officially "stainless" means at least 12% chromium composition, but this is the bare minimum and will still rust under extreme conditions. Medical grade stainless is up around 30% chromium. This would cost a bomb if you wanted to buy a couple of plates, but use your discretion to get something in between. The higher the chromium content, the less it wiil corrode
One of the greatest misconceptions about oxygen is that it is flammable. Oxygen is not flammable. Oxygen facilitates combustion of fuels, but if you apply heat to pure oxygen, nothing will happen. If you apply oxygen to an already burning fuel, it will increase the rate of combustion - sometimes dangerously so - but that does not mean it itself is flammable.
That aside, your question was "why don't you use both the hydrogen and oxygen together?"
You're right, I could use both, which would give me a perfect stoichiometric ratio and best efficiency. But to do that I would need to compress and carry 2 fuel tanks. twice as much fuel. The air all around us is 21% oxygen - why not use that?
And we do. That's what cars use to combust their fuel.
The main losses in energy come from the electrical resistance of the system and overvoltage required to split the water molecules. Not the fact that i'm only using half the product, so to carry oxygen really is more effort than it's worth when there's plenty of it in the atmosphere
FYI-- HEAT is the END RESULT of ANY ACTION. So, is it really any wonder the earth is heating up?
but not any old hydrogen producing machine is a Hoffman apparatus. I suggest you change the title to "hydrogen fuel cell for pure hydrogen gas"
'cause thats what this is. a fuel cell, not a advanced chemical apparatus capable of collecting accurate volumes of hydrogen.
don't understand me wrong, as a person who likes green energy sources I say this is awesome.
as a chemist I say: this is a fuel cell. ;-)