UNIT 5 – EARTH AND SPACE


Sources of energy The sources of energy used to produce electricity are either non-renewable or renewable.


Non-renewable energy sources Coal, oil and natural gas are non-renewable energy sources, meaning they will eventually run out.


: Fig. 39.5 Fossil fuels


These sources of electricity are called fossil fuels because they form from the decayed remains of animals and plants over millions of years. When fossil fuels are burned, the heat released is used to generate electricity.


The majority of the power plants that generate our electrical energy continue to rely on coal and natural gas. This is a big issue facing society, as it is predicted that all fossil fuels will be used up in the next 50 to 150 years, based on current use.


Another major disadvantage of fossil fuels is that they release carbon dioxide (CO2


) into the atmosphere when they are burned, which contributes to global warming.


: Fig. 39.6 Moneypoint Power Station in Co. Clare burns coal


Renewable energy sources These sources of energy are called renewable because they can keep being produced and will not run out in our lifetime. The advantages and disadvantages of renewable sources are outlined in the following tables:


Solar energy Description


• Photovoltaic solar panels generate electricity when sunlight strikes them.


• Thermal solar energy uses sunlight to heat water, which can heat a building or make steam in a turbine generator.


Advantages


• Produces energy every day • Emits no CO2


Disadvantages • High installation costs


• Efficiency depends on the amount of sunshine


) Fig. 39.7 Solar panels on a house


380 Elements of Science


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