Understanding Fossil Fuels

Fossil fuels are non-renewable energy sources that formed over millions of years from the remains of ancient plants and animals. These organic materials were buried under layers of sediment and rock, subjected to intense heat and pressure, which transformed them into energy-rich substances like coal, petroleum, and natural gas.

Let's look at the given options to determine which one is NOT a fossil fuel:

• Natural Gas: This is primarily composed of methane and is formed through the same geological processes that create coal and petroleum. It is extracted from underground deposits and is widely used as fuel. Natural gas is considered a fossil fuel.
• Petroleum: Also known as crude oil, petroleum is a liquid mixture of hydrocarbons that formed from the remains of marine organisms over millions of years. It is refined to produce various fuels like gasoline, diesel, and kerosene. Petroleum is a classic example of a fossil fuel.
• Coal: This solid fossil fuel is formed from the remains of ancient trees and vegetation that were buried and compressed over geological time. Coal is a major source of energy for electricity generation. Coal is definitely a fossil fuel.
• Wood: Wood is biomass, which is organic material derived from living or recently living plants or animals. While wood can be burned to produce energy, it is a renewable resource (as trees can be replanted) and is formed relatively quickly through biological processes, not over millions of years through the geological transformation of ancient organic matter. Wood is not considered a fossil fuel.

Based on the definition and formation process of fossil fuels, wood is distinctly different from natural gas, petroleum, and coal. Therefore, wood is the substance among the options that is NOT a fossil fuel.