Fuel

Wood was the first material to be burnt for fuel by humans and is still the largest used material for this purpose. The definition of a fuel is a material than can be burnt or altered in order to obtain energy from it. Energy is released from fuel by two methods, chemically or nuclear. Obviously, it's highly important, in order for a fuel to be useful, that its energy can be stored and released when needed.

All life-forms rely on energy in order to exist, where they are animal, human or even micro-organisms. The fuels that we know of at the moment derive their energy from a range of sources. Chemical fuels generate energy by reacting with the substances that surround them, this is also referred to as oxidization. Chemical fuel was the first type of fuel known to man and it is still the most commonly used fuel in the modern age.

Biofuel can be a solid, liquid or gas and is derived from biomass. Biofuel comes from a carbon source and is able to be replenished rapidly; an example of this is seen with plants. A very early form of biofuel is wood. It was first used by humans one and a half million years ago in an area of South Africa. Wood is still very widely used in the modern day though there are now many alternatives to this.

Fossil fuels are hydrocarbons formed from dead animals and plants put under heat and pressure in the earths curst and millions of years old. Most commonly these fuels are coal and petroleum based. Fossil fuels are the fuel of choice for industry. However, this is not without its knock-on effects. The burning of fossil fuels produces is responsible for the single largest emissions of carbon dioxide. This is detrimental to the environment as carbon dioxide is a 'greenhouse gas' and as such contributes to the global warming that is destroying our planet.