There are many ways to produce electricity, but not in a particular order. Friction
2. Electrochemistry
3. Magnetic Induction
4. Photoelectric effect: Light directly creates an electric potential
5. Thermoelectric effect: Heat directly creates electric potential
6. Piezoelectric effect (mechanical strain creates the electric potential).
Friction
The earliest known historical method of friction is the Van de Graaff Generator. This is how electricity got its name, Elecktros meaning amber. The Greeks discovered that amber attracts small particles if it is rubbed on fur. The same can be done by placing a balloon on your hair. Van de Graaff generators are machines that produce static electricity through friction.
A silk belt rubs up against something in the big metal ball. When the grounded metal ball touches it, it will discharge whatever charge builds up on the big metal ball. That discharge can be measured as a current, and there is a nicely defined voltage. It’s not really usable as a reliable power generator, but similar machines played a huge part in the early development of electromagnetic theory.
Electrochemistry
AKA batteries. A very simple version can be made at home. Make a copper and zinc plate, or any two other types of metals. Connect them to the ends of a low-power light bulb and then drop the plates into a cup of vinegar.
Credit: Sci-Toys – also a good reference for the layman.
To make a more powerful battery, stack multiple units of vinegar in a paper towel.
It’s an electrochemical reaction. An electron will be ripped from one metal, and then transferred to another.
A Daniell cell is a galvanic cell with electrodes of zinc and copper that are submerged in copper sulfate or zinc sulfate.
These are the half reactions to a Daniell cell:
Zinc electrode (anode): Zn(s) – Zn2+(aq) + 2 e-Copper electrode (cathode): Cu2+(aq) + 2 e- – Cu(s)
Voltaic Piles was the original name for these batteries.
Magnetic Induction
This is the largest generator of electricity.
This mechanism is basically an Motor that operates in reverse. A voltage/current applied to a wire in a magnetic field will cause a force to be exerted on it (and the magnet). With some clever design, that force can also become a torque and make things spin. You can also use the same electric motor but instead of applying voltage or current to induce a force, apply a force on the motor to induce a voltage/current.
The concept is pretty simple. And there are lots of different ways to do it. Most of the electricity in the world is produced like this, varying primarily in how the motor gets turned.
Coal power plants heat coal with steam to produce steam. The pressure of the steam drives turbines to spin the motor. Natural gas power plants burn natural gaz. Solar-thermal power generation uses sunlight to concentrate heat on a specific spot, generating steam. Wind power uses only the wind to turn the engine. Hydroelectric works by moving water through a dam to turn the motor. To generate steam, nuclear power uses heat from fission reactions.
Photoelectric effect
Photons can also knock out electrons from materials. This is most commonly used in a photovoltaic or solar panel.
The solar panels go beyond a photoelectric effect to produce electricity. It is equipped with a P-N junction semiconductor. Although the details may seem complicated, the basic principle of the device is that light hits the P-N junction and pulls an electron one way while pulling a hole the other way. This creates a voltage and current.
Credit: Images Scientific Instruments: How Photovoltaic Cells Generate Electricity
Thermoelectric effect
Because of its small effect, it is not a good generator of electricity. It can however be used to measure temperature, by producing a small voltage which can be read using a meter that is equipped for this purpose.
By putting two different metals together, if there is a temperature difference between them then it will cause some electrons to move from one to the other.
You can reverse this process, which is known as the Peltier effect. Take 2 different metals, put them together, and then apply a voltage to create a temperature difference. If done correctly, one side can be made colder than the other.
Piezoelectric effect
It is similar to the thermoelectric effect but not good for power sources. However, it can be used for sensing. Piezoelectric effect refers to the fact that certain crystals can electrically polarize when they are stressed. This creates a voltage.
It makes a good acoustic transducer, as in surface-mount microphones. It also works in reverse — apply voltage, crystal will stress. This makes it great for making very small and fine movements, and also makes it work well as a surface-mount speaker. Chances are your phone uses a piezoelectric crystal to make sound.