Energy sources
Over the last 200 years an ever-increasing proportion of our energy has come from non-renewable sources such as oil and coal. While demand for energy rises these resources are running out, and scientists are exploring the potential of renewable sources of energy for the future.
Renewable and non-renewable energy resources
All life on Earth is sustained by energy from the Sun. Plants and animals can store energy and some of this energy remains with them when they die. It is the remains of these ancient animals and plants that make up fossil fuelNatural, finite fuel formed from the remains of living organisms, eg oil, coal and natural gas..
Fossil fuels are non-renewableA resource that cannot be replaced when it is used up, such as oil, natural gas or coal. because they will run out one day. Burning fossil fuels generates greenhouse gasThe gases responsible for global warming - carbon dioxide, methane, nitrous oxide and CFCs (chlorofluorocarbons). and relying on them for energy generation is unsustainableResources which cannot be used forever and cannot be replaced or recycled after they are used. The use of fossil fuels is unsustainable, for example. . Hence the need to find more renewable, sustainable ways of generating energy. Renewable or infinite energy resources are sources of power that quickly replenish themselves and can be used again and again.
Some resources can be thought of as both renewable and non-renewable, such as wood and biomassThe number of living things in a given area..
Biomass and wood
Biomass energy is generated from decaying plant or animal waste. It can also be an organic material which is burned to provide energy, eg heat, or electricity. An example of biomass energy is rapeseed (yellow flowers you see in the UK in summer), which produces oil. After treatment with chemicals it can be used as a fuel in diesel engines.
Wood is obtained from felling trees, and is burned to generate heat and light.
Advantages of biomass and wood
- A cheap and readily available source of energy.
- If replaced, they can be a long-term, sustainable energy source.
- They absorb the same amount of CO2 from the atmosphere while growing as they release when they are burned.
- There is no increase in overall CO2 levels.
Disadvantages of biomass and wood
- When burned, they give off atmospheric pollutants.
- Greenhouse gases such as water vapour, carbon dioxide, methane, and nitrous oxide are released.
- Trees absorb CO2 over many years but this can be released very quickly when burned.