Earth and beyond

Earth's energy resources

non-renewable energy sources

renewable energy sources

sources of energy in the world

unusual sources of energy

measuring work and energy

the greenhouse effect

nuclear power

trapping the Sun's energy

using solar cells

Sun and climate

Earth's energy resources

All, well almost all, the energy available to us here on Earth comes from the Sun in one way or another. The Sun's radiation provides the light and heat needed for life on Earth.

Food for thought

We get energy by eating food, for example apples. Our bodies transform chemical energy into other forms of energy, but where does the apple, or even the apple tree, get its energy from?

Image of a Sunflower in a field Plants, including grass (and apple trees) capture the Sun's energy through the process of photosynthesis. We may eat the plants (fruit, nuts and vegetables) or we may eat the animals that ate the grass and seeds, such as sheep, cattle and chickens. Whatever we eat, the energy within it originally came from the Sun.

Image of a petrol pump, cart of coal and a barrel of oil. Coal, peat, oil and gas are all major sources of energy for us...where did the energy needed to form these fuels come from? You guessed - it came from the Sun!

Fossil fuels

Fossil fuels are made from plants and animals that lived and died in swamps millions of years ago. Fortunately for us, conditions in the swamps did not allow this dead organic matter to decompose properly: mainly due to a lack of oxygen in the water. Over millions of years, the organic matter was buried by other deposits and this compacted and heated it to the point where the fossil fuels were created.

What on Earth doesn't get energy from the Sun?

In 1977 an amazing mini-volcano was discovered deep in the ocean and since then many more have been found. Officially known as hydrothermal vents, these features blast hot (around 300 °C), black water into the ocean. Because of their colour they are also known as 'black smokers'.

Image of hot vents (black smokers) left, and tube worms, right Even more surprising than the vents themselves was the fact that a whole colony of creatures was living around them. These plants and animals, like the tube worms in the picture, were thriving where no sunlight had ever reached; they must have another way of deriving energy from their surroundings.

Instead of using sunlight in the photosynthesis process, these forms of life transfer the energy they need from the chemicals in the vent water in a process known as chemosynthesis.

What is really exciting about the discovery of these forms of life is that it shows that planets with warm surfaces and thick, protective atmospheres may not always be necessary for life to evolve. That opens the possibility that life might have evolved on many other planets - planets that we had previously thought unsuitable.



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