Where does our energy come from when the sun doesn't shine and the wind doesn't blow?
This is one of the most important questions regarding those new technologies and the average citizen might think of batteries. Where else would you store energy right ?
I mean .. Kind of wrong ..
And kind of right, too..
In fact, there have been impressive developments in the energy storage sector throughout the last years, making electric and hybrid cars with huge ranges possible. (While increasing lithium mining in chile and other countries, but i'm off-topic - bear with my hidden criticism- ) (Seriously though, if you mind then get informed about the consequences of mining. People often ignore what's necessary to getthat newest iFruit Phone)
However there is again a but in it.
- the process of charging is inefficient and results in a lot of 'wasted' energy
- (average) batteries aren't made to hold their charge for a very long time
- and most importantly:
- there simply is no battery with a capacity sufficient to holding enough energy to compensate for a fluctuating energy supply, while having a constant power to supply a whole country/county/city/town drawn from it
According to wikipedia there will be an estimated need for 30 terawatt-hours capacity in the year 2050 in Germany, given the fact that 80% of energy is being supplied through green energy sources. These 30 terawatt-hours are said to be necessary to compensate for seasonal and other fluctuations.
Might sound like a lot.
There are already 200 tWh storage capability available for natural gas today (in Germany).
Think about it.
Anyway what's the point of this instructable, other than stating facts ?
Step 1: Sorry, I Have Gas..
Well, you probably guessed it throughout this instructable...
The thing about the wind is:
You never really know when it's gonna blow. And while people often think of the problems this creates, they forget about the advantages.
If you check out the picture 'Daily consumption of electrical power' you can see that on average it peaks during lunchtime and early afternoon, as everybody is awake. But there is also a drop during the night - the so-called 'off-peak'. If for example the wind blows during that time, a lot of energy might go unused. You could also fire up them turbines and generate electricity. This electricity could then be used to create hydrogen gas through electrolysis.
This isn't a 100% efficient process either you say? Well, not to use this energy is 0% efficient. The wind energy would now be stored in chemical energy. The energy necessary to split up the oxygen atom and two hydrogen atoms is in theory equivalent to the energy being released when those three have a family reunion and react to water again. At todays state of technology the whole process is 30-43% efficient. Efficiency rates of up to 62% are possible when the gas is used to create a combination of electricity and heat. For comparison: Petrol Engines have up to 38% efficiency (Enough numbers already dude ! - Sorry :$ )
You might have already seen instructables on electrolysis and 'HHO gas'. The thing about HHO is, it's the perfect mixture to react back to water and therefore exactly what we don't want.
Hydrogen and HHO gas even more are not the easiest to work with. While the pure hydrogen gas is just not what all of our heating systems and engine run with and flammable in presence of oxygen(/air), this HHO stuff is plain dangerous.
Seriously! Might be fun to blow up bottles with it, but it doesn't even need presence of air, because the mixture is already perfect. Imagine a pipeline blowing up on it's whole length.
Now we don't want to switch over to hydrogen gas and pay a fortune on a new heating system.
We've gotten pretty comfortable with natural gas. Luckily, it's possible to 'methanize' hydrogen and thus synthesize natural gas.
Here's a little recipe:
You will need :
- Hydrogen gas
Say what ? CO2? That devil's stuff? Global warming and stuff ?
Well, we might argue about global warming, but yes.
In fact you wouldn't even know where to get all of that CO2 needed, because it's so expensive to filter it out of the air and natural CO2 sources are rather rare. But i guess science would figure a way out - once the money is there.
Once you've created methane you can simply feed it into your countries natural gas network.
Step 2: So How Does It Work?
For a simple electrolysis you will need:
- a power source (preferrably 'green' - I use an old car battery which I charge with solar panels in my backyard)
- some sort of container
- (cables/ croco clips; soldering iron/solder )
In our case we will need a few more components, I'll get to that in the next step. For now, I'll explain the electrolysis pretending you've never heard of it before:
Electrolysing is the process of splitting up the chemical bonding between atoms using electrical energy. In our case, an oxygen atom bonded with two hydrogen atoms. When they bonded together, a certain energy came free in form of heat and light, which you can see as a flame when you burn hydrogen. As they react they 'lose' this energy and now can not seperate from each other until it is fed back into the system. We try feeding it back by applying a voltage to the water. Now, two hydrogen atoms form molecular hydrogen gas and two oxygen atoms form molecular oxygen gas. As water consists of H2O, twice as much hydrogen is being produced more than oxygen. We will be able to prove this later on. There's only one more problem: Water doesn't really conduct electricity well. In fact it needs to dissociate into H3O+ and OH- ions to do so, which it doesn't do enough by itself. Simply spoken, those ions can be created by adding acids or bases.
Okay, hands on !
Step 3: DIY Hofmann Voltameter
What the heck is a hofmann voltameter?
Well, in order to not produce HHO gas we will need to produce the hydrogen and oxygen gas seperately from each other so they can't mix together again. This can be done expensively with a special membrane, or through the hofmann voltameter, which you can see in the picture. This constellation of the electrodes locally seperates anode and cathode so 'pure' gas is produced. Current flows through the electrolyte (in our case the 'water'), the gas rises up from the water and can be filled into a container of your choice.
Writing this instructable's next steps I will start out with the 'dirtcheap, DIY - just wanna try it out and see it bubbling version' and then give you some hints on how to make it more effective and suitable for the long run. So whicheveryou're going for - keep in mind that there are improvements yet to come.
Step 4: Get : the Simple Version
For obvious reasons you will need something to hold the water and the electrodes. As you can see in the picture a hofmann voltameter usually has three vents. Two for the gases, and one to fill in more water. We will skip the one for filling water, therefore our pipe will have a U-Shape.
The simplest way I found for building this was using Marley Pipes.
These are the PVC pipes used for indoor plumbing. They are practical for us as they already have rubber gaskets on them, which makes them air and watertight - and you can combine all different shapes and sizes to fit your needs.
For our version you will need :
- two 90° angles
- one short pipe adaptor (This one has gaskets on both sides, hence it has two 'female' ends)
- two straight female-male pieces
- two end caps
I got mine at my local hardware store for a little over 5€.
You will also need:
- rubber hoses with a small diameter
- as you can see in the picture I used the common green hose you can get in the gardening/pond section of your hardware store (I believe it was 0.5cm inner diameter)
- 2 electrodes
- hot Glue/Epoxy
The electrodes are a tricky and rather sensitive question. For the dirtcheap version you can use any kind of metal.
You want it to have an area as big as it fits in the pipe. In my case I would suggest a tight chicken wire or some other sort of metal net.
Step 5: Build : the Simple Version
1. Assemble the pipes so they form a U-shape(Picture - don't assemble the end caps yet)
2. Feed the hose through the end cap
You want this to be air- and watertight so take a drill bit the size of your hoses inner diameter or only slightly bigger and drill a hole in the center of each end cap. Feed the hose through it - take your time, even though it might be hard to get it through there. This helps getting a tight fit
3. Seal with epoxy or hot glue from the inside of the end caps
Epoxy is probably the smart mans choice, as it might get hot in there. I used hot glue, it works just as fine.
Repeat 2. and 3. for the cables. You want to have about 10cm of cable to be inside of your pipe.
4. Roll up your electrode material so it fits inside the pipe (on each side)
5. Connect with croco clips
6. Fill your pipe with water
7. Add vinegar to get your water to be conducting electricity
Alternatively you can add salt - this will make a great connection, but also it creates chlorine gas instead of oxygen. Be careful and use a well ventilated areda.
Step 6: Improvements
For a more professional electrolysis you will have to take it a step further and improve your electrode material as well as your electrolyte. In the dirtcheap version we just took metal as electrodes, but in fact this brings a bunch of disadvantages with it, which I won't explain in this instructable. You would be best off with platinum electrodes, but since you probably can not afford those, you should try graphite. When connecting the graphite, be extremely careful, as they break fairly easy (mine broke unwrapping it).
As an electrolyte try to get your hands on some sulfuric acid. You dont need a whole lot of it, just a few ml are enough.
Be careful and use your common sense when handling harmful substances.
Step 7: Try It Out!
Now you're ready!
Connect to your power source, in this case a car battery and watch how it starts bubbling. To fill a bottle with the gas fill it completely with water, then screw the lid back on.
Put the bottle into a bucket of water and when turned upside down, unscrew the lid.
Then slide in the hose. It should slowly fill the bottle.
Your cathode side will produce the hydrogen, while the anode produces oxygen in a 2:1 ratio.
If you're just going for the HHO - put both hoses into one bottle.
Have fun - and also be careful with your newest creation!