Ever Wonder Where Fossil Fuels Come From?

By Howard J. Bennett

Many people are concerned about climate change and how and why the Earth seems to be getting warmer. Steps to prevent this trend from continuing include recycling, reducing your “carbon footprint” and finding new ways to produce energy that doesn’t pollute and is renewable. That means it can created again and again.

Reducing your carbon footprint means releasing less carbon dioxide into the environment. Most scientists believe that carbon dioxide is one of the gases that contributes to the “greenhouse effect.” If have ever been inside a greenhouse, you know that it traps heat inside its glass walls, making the building very warm. Scientists believe that trapped carbon dioxide in the Earth’s atmosphere may be doing the same to warm up the planet. By current estimates, we are producing twice as much carbon dioxide that can be absorbed by plants and other natural sources. What’s left over is what may be causing the warming.

What are fossil fuels?

Part of the discussion about limiting climate change involves reducing our use of “fossil fuels.” Although adults use this term all the time, kids may not know what it means. Fossil fuels include the following:

• coal

• petroleum (which gets turned into gas for cars among other uses)

• natural gas

It takes tens of millions of years for fossil fuels to be created. Because we are using them faster than they can be made, fossil fuels are referred to as a “non-renewable” source of energy.

How are fossil fuels created?

After an animal or plant dies, bacteria and fungi break it down in a process called decay. However, many dead organisms become trapped in sediment in such a way that they do not decay. We call these ancient organisms fossils. An example would be an animal that died and was buried in sand.

Over millions of years, the Earth’s crust changes due to volcanoes, earthquakes and other natural forces. As this happens, fossils become trapped under more and more layers of rock. The heat and pressure that build up over time act like a gigantic press that converts fossils into basic chemicals, including carbon.

A good way to understand the pressure that comes from descending into the Earth is to consider what happens in a swimming pool. If you dunk your head into a few inches of water, you won’t feel any pressure. However, if you jump to the bottom of the deep end, there is a lot more water “on top of you.” You feel this weight as pressure in your ears and sinuses. The pressures that create fossil fuels are thousands of times stronger than that.

The type of fossil fuel that develops depends on its surroundings. Coal is made up of almost pure carbon. Natural gas and petroleum-based products (gasoline, oil) contain carbon and hydrogen. That is whey they are referred to as hydrocarbons.

Fossil fuels can be burned to release energy. Because fossil fuels are carbon-based, burning them releases heat and carbon (in the form of carbon dioxide) into the environment. The heat is what we use. The carbon dioxide is the unwanted side effect.

(First published in the Washington Post 1/22/12.)

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