What are the disadvantges of fossil fuels?

Answer 1

Fossil fuels depend upon the material laid down millions of years ago, and really represent 'stored sunlight'. But they will run out! They cannot last forever. And they produce CO2 as a by-product that will harm the atmosphere of the Earth.

In the long run we will have to rely on renewable fuels, and on nuclear power plants. But even these nuclear plants will eventually run out of fuel.