What different types of fossil fuels are there?
Coal, oil and gas are the main types of fossil fuels.
Why are they called fossil fuels?
These fuels are made from dead organisms (e.g. plants) that were buried millions of years ago under layers of soil and sediments. This is similar to how fossils are formed so this is why they are called fossil fuels.
The heat and pressure increases as more layers pile on top and so the organism matter starts to decompose and break down. Because the process happens in the absence of oxygen it is called anaerobic decomposition and the result is carbon-rich fuels, as organisms contain lots of carbon atoms. If oxygen was present, the carbon would react with it and form carbon dioxide as it does when we burn fossil fuels.
How do they make electricity?
The fossil fuels are burned in a power station. Burning is a chemical reaction, called combustion, where carbon atoms react with oxygen atoms in the air to form carbon dioxide and heat. During this stage we have turned chemical energy into heat energy.
This heat is used to boil water to make steam. The steam rises and turns the blades of a turbine. The heat energy has been converted to kinetic (or movement) energy. The turbine powers a generator which can then turn the kinetic energy into electrical energy.
Why are they non-renewable?
It takes millions of years for the earth to turn dead organisms into fossil fuels. However, we are using these fuels up at a very alarming rate. Think about how much your annual salary, or year’s pocket money, is. Seem like quite a lot? Now imagine spending all of that money in the first 30 seconds of the first day of the new year. You’d probably have a great 30 seconds, but what would you do for the rest of the year? This is the rate at which we are using up fossil fuels. New fossil fuel supplies will not be made quickly enough to replace the stuff we have burned so on our human time-scale the fuels will run out – they are non-renewable.
Why are they bad for the environment?
Burning these fossil fuels produces carbon dioxide which is a greenhouse gas. This is slowly warming up the earth. Oil spills from damaged oil tankers or oil-rigs can also damage the environment. Animals and birds can get covered in oil when this happens, and may stop them breathing, flying or eating. Oil can also cover plants and cover up the surface of the sea which stops light getting through to where it is needed.
Why are they still being used?
Fossil fuels have been used for hundreds of years to power factories, transport and homes and are a well-established and well-understood way of producing power. They are easy to store and use and so it is hard to stop using it.
Other problems
Many of the best places in the world to find fossil fuels have a lot of political problems, war and general unrest. This creates the problem of ‘energy security’. Because Western countries rely on this fuel, people from other countries can use it as a source of political power by holding the fuel hostage. In this way it could be an unreliable source of energy.
What about other sources of energy?
Alternatives to fossil fuels include nuclear power and other renewable energies like solar and wind. Find out more about these in our other sections.