What is energy? When we talk about energy, we might talk about how we could eat a meal of chicken and pasta a couple of hours before playing an important game to keep our energy up. We might say that the two-year-old running around the mall has a lot of energy. At other times, we might turn out the lights when we leave a room so we do not waste electrical energy. When we think about it, every aspect of our lives involves energy!

In science, energy is often defined as the ability to do work or the ability to cause change or make things move. In the examples above, the chicken and pasta we eat give our body energy to be active and to work (or play!). The running child is demonstrating energy by moving around. Light bulbs in a room convert electrical energy into light energy.

 

Energy can take many forms, some of which you may already be familiar with, but you may learn of some new ones as well. These forms include: heat (thermal), mechanical (kinetic), electrical, light, sound, and chemical. You will learn more about these different types of energy in the next activity.

People use energy for everything from making a jump shot in basketball to sending astronauts into space. There are two types of energy: stored (potential) energy and working (kinetic) energy. Potential energy is energy that is stored and is waiting to be used later. Kinetic energy is the energy of motion.

  

 

For example, the food a person eats contains chemical energy and a person's body stores this energy until he or she uses it as kinetic energy during work or play.

Energy sources can also be categorized as renewable or nonrenewable. When people use electricity in their homes, the electrical power was probably generated by burning coal, by a nuclear reaction, or by a hydroelectric plant on a river, to name just a few sources. Therefore, coal, nuclear, and hydro are called energy sources. When people fill up a gas tank, the source might be petroleum refined from crude oil or ethanol made by growing and processing corn. Therefore, energy sources are divided into two groups:

renewable (an energy source that can be easily replenished)

nonrenewable (an energy source that cannot be easily replenished)

Renewable and nonrenewable energy sources can be used as primary energy sources to produce useful energy such as heat or used to produce secondary energy sources such as electricity.

The chart below shows the energy consumption in Canada in 2014 for the different areas. As you can see, the highest energy consumption types in Canada are in the areas of oil, natural gas, and renewable energy sources.