Question

what will we use as fuel if petroleum is no more ?

Answer 1

Look up, there's the sun. You can do a load of things with solar, wind and hydroelectric power my friend!

Answer 2

If we run out of petroleum, we will have to go for other alnernative like solar energy, tidal, electricity, nuclear, or geothermal power. These are very hard to own because the whole world has practised the use of petroleum. So, it would be better if we start using petroleum only when needed and not waste it. Hope this helps... :) ;)