Energy Basics

Energy might seem like an abstract term, but it is all around us: everything that moves carries a certain energy, even the light of the sun. A lot of things contain a form of energy, be it thermal, chemical or mechanical energy.

In our societies, we need energy to power our homes, and to move around.

Here are the different forms of energy:

The different forms of energy can be transformed from one form into the other. Basically, everything that happens in the universe can be described as a transformation from one form of energy into another:

• A plant grows by transforming radiant energy from the sun into wood (chemical energy).
• When we later burn this wood, we transform this chemical energy into heat (thermal energy).
• When the sun warms the earth, it creates wind (mechanical energy).
• Wind turbines can transform this movement of the air into electrical energy.

All these transformations follow two laws of nature, and this is where it gets interesting. Read on further down!

Its full name is the First Law of Thermodynamics. It states that:

Energy cannot be created or destroyed, only converted from one form to another.

What this means is simple but important: You can't get out more energy than what you put into a process. Energy cannot be magically created.

The Second Law of Thermodynamics is more difficult to grasp. It states that:

When energy changes form, a part of it transformed into waste heat.

The more energy efficient a process is, the less waste heat will be produced by it. Some energy transformations are naturally more efficient, like in electric motors, and some aren't, like in combustion engines. But whichever way you turn it, your efficiency can never reach 100 %, there is always a loss.

Energy can be measured in units:

• Joule (J); Kilojoule 1 kJ = 1000 J; Megajoule (1 MJ = 1000 kJ) : Used in science and often for thermal energy
• Watt-hours (1 Wh = 3600 J); Kilowatt-hours (1 kWh = 1000 Wh) : Widely used for electrical energy

/*To get an idea, what common amounts of energy are see this page!*/