What are fuels? How do you get energy from them?

Now this is where humans are different from all other life. You have learned how you can use fuels to make energy to power machines like cars, planes and computers. This way, you don’t have to work so much and you can stay warm without the fat, fur or feathers that other animals have. You get the fuel to make all this extra energy mostly by digging it out of the ground and burning it. This releases ancient energy stores - fossil fuels - made by billions of tiny plants and animals which lived millions of years ago. This stuff has been locked away underground ever since, covered up by younger rocks that got laid down on top.

I'm sure you know what these fuels are:

coal

oil

gas

These fossil fuels all come from underground; inside the Earth's crust. And that is where they should stay because burning them does a lot of damage to the air we all breathe, the oceans and living things on the land. I'll say more about that later in this guide.

You can burn any of these fuels, coal, oil or gas, to make electricity in power stations. How?

king electricity
The fuel is burned to heat water in strong tanks (boilers) to make high-pressure steam. Steam then drives big machines called turbines which, in turn, drive other machines called generators. Result? Electricity which comes to you along wires. Oh, and don't forget all that pollution which comes out of the chimneys! People do forget because most of it (carbon dioxide, CO2) is invisible. Just imagine: if carbon dioxide was a red (for danger) gas, how differently people might behave.

But electricity is only one form of energy used by people. The biggest guzzlers of energy from burning fossil fuels are

• keeping homes and offices warm in winter and cool in summer
• transport: you know... cars, buses, some trains, ships and aircraft

Fuels for heating can be any fossil fuel though people mostly use oil or gas because they're easier and less dirty.

Machines for transport almost all use the liquid fossil fuel, oil. Why?

Oil is very easy to move around and is the most convenient of all the fuels to use in engines. It's quick and easy to fill a car's gasoline tank and the fuel has a high energy density (you can drive a long way on a tankful) without being too dangerous to use (though the lighter fuels like gasoline are highly flammable

But the oil has to be refined to make gasoline

Gasoline, gas and confusion
In North America, people use the word 'gas' to mean 'gasoline' which is called 'petrol' in other countries. This is the smelly liquid people put in their cars to make them go. 'Gas' is also the stuff many people use to cook with or heat their houses. It is a real gas, like air, called methane.

, diesel

What is diesel fuel?
Diesel fuel, named after the type of engine that burns it, is a more oily sort of fuel than gasoline. Diesel engines are around 30 per cent more efficient than gasoline engines so they use much less fuel.

and kerosene

A fuel similar to diesel which gets burned in aircraft engines and in home heating furnaces. In poor countries, it is much used for cooking.

Different types of engine need different types of liquid fuel. Some engines run on gas.

Gas engines
The gas they use is liquefied petroleum gas (LPG) stored in high-pressure fuel tanks. This gas can be used in modified ordinary engines which are generally less polluting than those that use diesel or gasoline (petrol). But they're still using fossil fuel.