Generating Electricity: Fossil Fuels

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Learn how energy from fossil fuels can be used to generate electricity.

Fossil Fuels in Canada

Fossil fuels are a common source of energy for electricity generation in Canada. In 2016, Canada got about 9.3% of its electricity from coal, 9.6% from natural gas and 0.5% from oil and diesel. Most of the electricity in Alberta, Saskatchewan, Nova Scotia, and Nunavut comes from fossil fuels. Other provinces also use fossil fuels to generate some electricity. Over 60% of the world uses coal, oil and natural gas for electricity production. 



Graph - Text Version

Pie chart illustrates Canada’s electricity generation by fuel type in 2016. Hydro accounted for 58.8% of electricity generation, followed by 14.6% nuclear, 9.3% coal, 9.6% natural gas, 4.7% wind, 2% biomass, 0.5% oil and diesel, and 0.5% solar.

Did you know?

In 2003, 25% of electricity in Ontario came from burning coal. The last coal-fired power plant in Ontario closed in 2014.

What are fossil fuels?

Fossil fuels are the remains of dead plants and animals. Over millions of years, heat and pressure changes these things into oil, natural gas, and coal. There is a limited amount of fossil fuel on our planet. This makes it a non-renewable resource. If we continue to use large amounts of fossil fuels, it will run out.

How do we use fossil fuels to generate electricity?

We burn, or combust, fossil fuels to generate electricity. The term for burning matter to generate electrical energy is thermal generation. Electricity isn’t produced from the combustion itself. The burning of coal or oil heats giant boilers filled with water. This transforms liquid water into steam. The steam creates a lot of pressure in the boiler. The pressure rotates a steam turbine. This drives a generator to produce electricity. 

Workings of a coal-fired power plant
Process of electricity generation at a coal-fired electricity generation plant (Let’s Talk Science using a public domain image by the Tennessee Valley Authority via Wikimedia Commons).


The process is a bit different in natural gas plants. Natural gas plants use gas turbines instead of steam turbines. In a gas turbine, natural gas combusts in the presence of air. The heated air expands and causes the turbine to spin.

The rotation of the turbine drives a generator. It is the generator that produces electricity. Other moving things such as wind and water can also rotate turbines.

Generators are devices that convert mechanical energy into electrical energy. First, pressure from heated air makes a rotor turn. A rotor is a shaft found in the centre of the generator. The rotor connects to a coil of wire. The wire spins inside a fixed magnet around it called the stator. The magnetic field pushes electrons along the wire. This forms an electric current. This name for this process is electromagnetic induction.

Parts of a generator
Parts of a generator (Let’s Talk Science using an image by Graphic_BKK1979 via iStockphoto)

How much power can fossil fuels generate?

People use fossil fuels because they are more energy dense than other sources. For example, 1 kilogram of natural gas contains 53.1 megajoules of energy. 1 kilogram of wood contains only 19.8 megajoules. This means that 1 kg of natural gas can generate a lot more electricity than an equal amount of wood. 

Did you know?

The Joule is a unit people use to measure energy. It is named after James Prescott Joule. He studied the relationship between heat, electricity, and mechanical work.

Energy values for various fuel sources
Energy contents for a variety of energy sources (©2020 Let’s Talk Science. Data source: The Brookings Institute). 
Image - Text version

The energy content of natural gas is 53.1 Megajoules per kilogram, the energy content of gasoline and diesel fuel is 45.8 Megajoules per kilogram, the energy content of charcoal is 34.7 Megajoules per kilogram, the energy content of coal is 30.2 Megajoules per kilogram, the energy content of wood is 19.8 Megajoules per kilogram and the energy content of a lithium-ion battery is 0.5 Megajoules per kilogram.


325 kilograms of coal are needed to power one 100-watt incandescent light bulb for 24 hours a day for a year. A standard 500 megawatt coal power plant produces about 3.5 billion kilowatt-hours each year. This is enough energy to power 4 million light bulbs for 24 hours a day for one year.

Advantages of Fossil Fuels for Electricity Generation

Using fossil fuels is an inexpensive method of generating electricity. This is because taking coal, natural gas, and oil out of the ground is straightforward. Fossil fuels are easy to store and transport because of their high energy density. The things needed extract, transport, and use fossil fuels already exist. This makes them even cheaper to use. Fossil fuels also do not rely on things like weather. These factors mean make fossil fuels a reliable source of energy.

Coal mine in Alberta
Coal mine in Alberta (Source: bgsmith via iStockphoto).


Disadvantages of Fossil Fuels for Electricity Generation

Being easy to use and cheap makes fossil fuels seem like a good source of electricity. Yet, the cost to society of fossil fuels is much higher than their current price tag. Burning fossil fuels contributes to climate change. This is because it releases carbon dioxide and other greenhouse gases into the air. Electricity generation is one of the main sources of greenhouse gases. It accounts for about 25% of global emissions. Burning coal for electricity releases large amounts of greenhouse gases. In 2016, 67.8% of Canada’s electricity generation greenhouse gas emissions came from coal. But only 9.3% of Canada’s electricity came from coal. 



Graph - Text Version

Pie chart illustrating greenhouse gas emissions by fuel type in 2016. Coal produced 67.8% of Canada’s emissions from electricity generation, followed by 28.9% from natural gas 3.2% from oil and diesel.


Generating electricity with fossil fuels produces other pollutants as well. For example, burning coal and oil releases nitrogen oxides and sulfur dioxide gas. These pollutants can lead to acid rain, which harms soils, forests, lakes, and rivers. Burning fossil fuels, particularly coal, also releases particulate matter into the air. Particulate matter can lead to heart attacks, strokes, lung cancer, and other diseases. 

There are many issues with burning fossil fuels. But burning fossil fuels has led to a lot of progress we have made as a species. For many decades, electricity was only possible because of fossil fuels. Fossil fuels powered the Industrial Revolution. And it improved the quality of life around the world. Many developing countries rely on fossil fuels. For them, fossil fuels may play a role in increased energy production that reduces poverty.


Learn More

The Story of Fossil Fuels

Learn more about the history of fossil fuels in this four part series of articles from NASA’s Climate Kids. 

Generating Electricity

Learn more about how we use fossil fuels to generate electricity from this BBC article. 

What is Fracking? (2018)

Learn more about how we extract natural gas from rocks in this article from Let’s Talk Science. 


Afework, B et al. (2020, April 28) Power Plant. Energy Education, University of Calgary

Gross, S. (2020, June). Why are fossil fuels so hard to quit? Brookings Institution 

kraftwerkforschung. (n.d.). The difference between steam and gas turbines.

Morse, E. (2013, February 21). Non-renewable energy. National Geographic.

Natural Resources Canada. (n.d.). Electricity Facts.

Natural Resources Canada. (n.d.) About Electricity.

Tennessee Valley Authority. (n.d.). How a coal plant works.