1.4 Energy supply and demand: world and UK
The energy used by a final consumer is usually the end result of a series of energy conversions. For example, as you can see from Figure 2, energy from burning coal may be converted in a power station to electricity, which is then distributed to households and used for lighting.
The energy released when the coal is burned is called the primary energy required for that use. The amount of electricity reaching the consumer, after conversion losses in the power station and transmission losses in the electricity grid, is the delivered energy ( sometimes called final energy). After some losses in the local wires and light bulb, a quantity called the useful energy emerges as light.
Let’s now have a brief look at the world’s energy supplies.