Which energy source is made from plants that have decomposed and been compressed?

Fossil fuel is an energy source formed by natural processes from plants which undergo an anaerobic partial decomposition, which contains energy originating in photosynthesis. Another theory came up that has a clearer explanation of this is that fossil fuel was created from the fossilized remains of the dead plants by exposure to heat and pressure in the earth’s crust millions of years. Furthermore, fossil fuel is compressed to become natural gas, petroleum, kerosene, propane and coal.

Coal A fossil fuel that is made up of fossilized plants, which are formed when plant material is buried in oxygen-poor conditions and subjected to high heat and pressure over a long period of time

-indirect form of solar power: formed from photosynthesis which uses energy from the sun