As some of you Mad Science readers will remember, we recently covered the separation of water into hydrogen and oxygen using electrolysis. Passing a current through water can rend it apart, but we can also recombine that oxygen and hydrogen to make electricity! This is the principle behind those vehicles run by hydrogen fuel cell engines.
Today, we make electric fuel. The best part is that the only exhaust is pure water!
- Jar of salt water
- Screws (2)
- Pieces of wire (2)
- 9 volt battery
Step 1 Wrap Electrodes
At the head of each screw, wrap a bit of stripped wire to make an electrical contact. You can solder these connections if you plan on long-term experiments, but wrapping is just fine for now.
Place your screws in the jar of salt water so that the wires are not submerged.
Step 2 Start Up the Cell
To get the hydrogen fuel cell going, take the ends of the screw wires and connect them to the leads on a 9 volt battery. You can use any DC power source, but 9 volts is a common source.
Image by helcohi
You will begin to see and hear bubbles forming on the screws and rising up to the surface of the water. One screw is collecting hydrogen while the other collects oxygen. Because there is twice as much hydrogen as oxygen in a water molecule, the hydrogen collecting electrode will produce much more gas.
Step 3 Harvest Energy
Here is where we turn the tables. While most of the gasses bubble up, some are trapped in the ridges of the screws. These trapped gasses can be recombined into water. While recombining, this process will generate electricity!
Remove the power supply and place the multimeter probes on the screws. You should see a small amount of voltage register. As the gas is used up, the voltage coming from the jar will decrease.
What modifications can you make to this design to crank up the usable volts? Share your insights on the forum or in the comments below. Be sure to post up pictures and videos onto the corkboard if you try this experiment yourself! If you are stuck somewhere or just have a question, ask in the comments or message me directly.