The basic building blocks of matter are protons, neutrons and electrons, each of which have positive, neutral and negative charge respectively. These three particles make up everything around us, and are known as elementary particles as they cannot be broken down into smaller components.
The protons and neutrons sit stationary within a structure called the nucleus (which has an overall positive charge), and the electrons rotate around this nucleus. This is important as it tells us that only electrons are free to move in space, and the position of the nucleus is fixed. The overall structure containing a nucleus and a rotating electron is called an atom.
Conductors, insulators and electricity
Electrons are not free to move all the time – in some materials the electrons are tightly bound and are fixed in position. A material where the position of electrons is fixed is called an insulator (eg. plastic) and if electrons are free to move the material is called a conductor (eg. metals).
Electricity is simply a flow of electrons from one place to another, which is caused by a difference in charge. So if a positive charge is applied to one side of a metal and a negative charge to the other side, electrons will be repelled from the negative side and attracted to the positive side, since like charges repel and opposite charges attract.
So we know we have to produce a voltage difference between two points, but how is this achieved? The answer is electromagnetic induction, discovered by Michael Faraday in 1831. By moving a conductor through a magnetic field (such as the field of a bar magnet) a voltage difference is induced between the two ends of the conductor, causing electrons to flow. This is how a bike generator works; the rear wheel of a bicycle causes a coil of copper to spin around a magnet, creating a voltage difference at either end of the coil and inducing electricity.
You may have heard of the law of the conservation of energy – one of the fundamental laws of physics. This law states that energy cannot be created or destroyed, and that there is a specific amount of energy in the universe which never changes. Energy can however be converted from one form into another. For example chemical energy contained in food is moved into muscles and then converted into kinetic (movement) energy when we move. There are a number of different types of energy: heat, light, sound, electrical, kinetic, gravitational, magnetic, chemical just to name a few! This explains how energy from your food is able, through a number of conversions, to power a light bulb!
Voltage, Current, Resistance and Power
These are all words that you might have heard in connection with electricity – and they can seem confusing! But if you remember that electricity is simply the movement of electrons from one point to another then they should make more sense.
Current is a measure of how many electrons are passing a point in a second, or the flow rate of electrons. It is measured in Amps. Current can flow in two ways: AC (alternating current) and DC (direct current). Alternating current changes direction 50 to 60 times a second (depending on the system) whereas direct current flows constantly in one direction. Mains electricity is AC, and batteries produce a DC current.
Voltage (or potential) is a measure of how different the charge is between two points – the higher the charge difference, the greater the flow of electrons between the two points. Voltage is measured in volts.
Resistance is the name for anything that impedes the flow of electrons in a circuit, converting the electrical energy into heat energy. Often this energy is lost or wasted. All components in a circuit will offer some resistance. Resistance is measured in ohms.
Power measures how much energy is being produced or used per second, and is measured in watts. The more powerful an appliance or a source, the higher the voltage and the current. More powerful appliances cost more to use as they draw more electricity.
The Basic Bicycle Generator
a. Pretty much any working bike
b. Training stand
c. Electric motor fitted with skateboard wheel
The motor with skateboard wheel fitted
Recycled 250 watt electric-scooter motors work a treat
How much power do you get from each bike?
Depends on the rider.
An average human can maintain 40 to 50 watts for an hour or more.
A professional racing cyclist could produce 400 watts for several hours, or 2000+ watts in a sprint.
So what can I do with it?
Well it’s really down to your imagination. We use a single bicycle-generator to power:
- small PA system
- LED lights
- small LED projector (for making your own pedal-powered cinema)
- low voltage light bulbs
- charging a 12v battery
- small TV… and so on.
We also use small inverters to convert the DC power created by bicycle-generators into AC. This is the same power as you have in your home allowing you to power standard household items (to the wattage limit of the inverter of course).
Generators combined: the sky’s the limit
When you combine the power of several bikes there’s really no limit to the amount of power you can generate.
As a general rule, sound and light can be had quite cheaply in energy terms.
Heat is much more expensive.
The beauty of these generators is that they scale up, ie. if you add 2 together you create twice as much power!
We’ve used this to great effect when we powered an entire family home with 80 of these, producing MASSIVE 14 KILOWATTS. If we can do it, so can you!