1. Not renewable energy
Fossil fuels comprise of crude oil, coal and natural gas. It is not renewable and cannot be replaced. Plants and animals that existed millions of years ago became buried underneath the Earth’s surface. This formed as the fossil fuels. Since fossil fuels has limited supply, it can’t fulfil the world’s energy demand. Therefore, alternative energy source is needed to replace the fossil fuels.
2. Emission of carbon dioxide
Combustion of fossil fuels produce carbon dioxide which is the major contributor to global warming. Carbon dioxide is one of the greenhouse gases. According to the analysis, there will be a rise of 1 degree Fahrenheit (1°F) in the global average temperature on the 20th century.