Compare and contrast fossil fuels and the Sun as direct sources of energy.

(N/A) Fossil fuels are energy sources,such as coal and petroleum,obtained from underneath the Earth's crust. They are directly available to human beings for use. Hence,fossil fuels are a direct source of energy. These are limited in amount.
These are non-renewable sources of energy because they cannot be replenished in nature. Fossil fuels take millions of years for their formation. If the present fossil fuel reserves of the Earth get exhausted,their formation will take millions of years.
Fossil fuels are also very costly.
On the other hand,solar energy is a renewable and direct source of energy. The Sun has been shining for several billion years and will continue to do so for the next $5$ billion years.
Solar energy is available free of cost to all in unlimited amounts. It is continuously replenished by the nuclear fusion reactions occurring within the Sun itself.