During the 20th centaury, electricity demand in the UK increased as the population increased and so too did the number of electrical items that each household owned.
During the 21st centaury, electricity demand in the UK has decreased as devices have become more efficient (wasting less energy). For example, most individuals have energy efficient light bulbs that waste less energy because they do not get hot. Also, individuals are becoming more careful with how we use electricity in our homes (like turning devices off rather than leaving them on standby).
The UK gets the majority of its energy from fossil fuels. The fossil fuels are used to generate electricity and for transportation (petrol and diesel for cars). Fossil fuels have been used in such great quantities because they are a cost-effective way to obtain energy, reliable and quick to generate electricity (we can burn the fossil fuels and generate electricity quite quickly).
However, the burning of these fossil fuels produces large quantities of greenhouse gasses, which leads to climate change due to the enhanced greenhouse effect. The burning of fossil fuels also leads to other gases like sulfur dioxide to be produced, which causes acid rain. It is because of these negatives that the UK and other countries around the world have set themselves targets to decrease their reliance on fossil fuels and move more towards renewable energy sources. The UK government has just announced that they plan to cut emissions by 68% by 2030 based on 1990 levels. In order to achieve this goal, it will cost the UK a significant amount money because they will have to invest in new technologies. This cost will be picked up by the citizens of a country through higher taxes or higher bills as businesses pass on the increased costs to the consumer. This is why some countries are cautious about setting themselves too ambitious climate goals. There will also be questions about where to put the renewable energy sources; where we build the new wind turbines, hydroelectric power station etc. Also, most renewable energy resources are less reliable than traditional non-renewable energy resources. This means that countries will need to have a variety of different energy resources or they will have to research to increase the reliability of renewables or find ways to store the generated energy (such as batteries).
A final way that energy use has changed is by consumers making personal choices to decrease their use of non-renewable energy sources. For example, some individuals have purchased electric or hybrid (powered by petrol and electric) cars to reduce the amount of fossil fuels that they use, which reduces the quantity of carbon dioxide produced. However, these cars are quite expensive, which means that most individuals will not be able to afford to change their car to an electric or hybrid car. Also, some individuals have put solar panels on the roof of their homes to generate electricity. The cost of installing the solar panels is quite expensive, which also means that most individuals will not be able to afford to/ want to do it.