Will static electricity and your hair make energy?

Answer 1

As name imply static electricity is a static accumulation or depletion of electrons, meaning the electrons don't move, so no current is produced, only an electrostatic field. Static electricity appears when a mechanical cause changes the location of the electrons (maybe even remove them from where they are), and the condition is that these electrons cannot come back to where they were (said otherwise the material used must be an insulator). At the atomic level this cause has created ions which are atoms with more or less electrons in their cloud than the number of protons in their nucleus.

To create electrical energy from this situation we need to create a current, which is a flow of electrons. To do that we will connect together a region with depletion of electrons to a region with excess of electrons (compared to the number of protons). Doing that we'll transform potential energy into kinetic energy. The kinetic energy that will be created by this transformation is proportional to the number of electrons to move until some balance is found (electrons are balanced over all atoms, there is no difference of potential). Note that this doesn't mean the ions will disappear and the number of electrons will be the same than the number of protons. Just there will be the same excess everywhere, or the same depletion everywhere.

From the definition of the volt, we can compute the number of joules created, and this number is the energy.

We'll obtain something like a few microjoules. That's energy but that's not much! To lighten up a light of 1 watt during 1 seconde, we already need 1 joule.

A usual misunderstanding is that the difference of potential created by the static electricity can be very important. But you need to think of that like water in a dam. We indeed create energy from this water by changing its height from the dam to somewhere below in the valley. The more the height of the water, the most the energy we can produce (transform...). But what about a single drop of water at 1.000 meters above the ground? It won't produce any energy when reaching the turbine of the dam.

This is the same for electricity, the potential is the height of the water, and the number of electrons is the number of water drops in the reservoir. With static electricity we have a few drops at very high height, and in the end this doesn't produce much energy.

What about the potential (voltage) of the static electricity? This is simple to understand.

Electrons are moved by some cause so that they are not anymore well distributed in space, there is an area where they lack (positive ions), and another were they are to many (negative ions). They lay on a material not conductive of electrons (an insulator). So said otherwise: for the electrons to redistributed themselves correctly, they need to move thru the insulator or thru the air, from where they are too many to were there are too few. Why would they do that? Because of the electrostatic field created by this unbalance. If we increase the level of unbalance (by adding or removing electrons at some location), we increase the electrostatic field. At some point in time the insulator or the air won't be able to counter this force and the electrons will start to move. This move will be difficult because the insulator (the air too, it is also an insulator) offers a large resistance to electronic move (which is another name for electrical current) by definition. This will create heat in the insulator. Very large heat. This heat will in turn change the nature of the insulator by creating ions in the insulator (said otherwise by moving electrons belonging to the insulator atoms). But ions actually conduct electricity (also by definition), so this will ease the work of electrons to find their way in the insulator, which is no more an insulator in this small area where the ions have been created... More electrons will move, and this will create more heat and more ions. Etc. As soon as the phenomenon is started it will continue and the result is that a very high number of electrons will move in the insulator creating a very hot channel.

What was described above it just what we call an electric arc...! This is why you see (in the night) or hear sparks when you brush your hair. You are just creating arcs at very hot temperature locally, and the light is just a tube of atoms that have been ionized at a point that they become plasma. Plasma, the forth state of the matter like in the stars, just in your hair.

What we know by test in laboratory is that in dry air, we need a difference of potential of 4.000 V to create an arc between areas at a distance of 1 cm. So to create an arc of 1 mm we need at least 400 V. Look at the length of the arcs in your hair and calculate the difference of potential needed to create it in dry air.

Answer 2

Static electricity generated in your hair is a form of energy transfer, but it is not a useful source of energy since it is typically released as heat and light when discharged. It is not a practical way to generate or harness energy.