1. What is Energie?

Energy is an omnipresent but nonetheless hard to grasp physical property as it appears in many different forms. Even though a very simple statement can be made: Everything is energy. Even you, me and all the things around us. This was first shown by Albert Einstein with the 20th century’s probably most famous formula:

E = mc²

E stands for energy, m for mass and c for the speed of light. The latter’s order of magnitude of 300’000’000 m per second implies that mass is in fact nothing else than an extremely concentrated form of energy. It is also the reason why we do not notice the relationship between mass and energy in everyday life: If we charge a battery, its mass only grows by an unnoticeable small amount.

Another very important aspect is that energy can neither be created nor destroyed:

In a closed system, i.e., a system that is isolated from its surroundings, the total energy of the system is conserved.

Hence, we are not only surrounded by energy and are made up from energy ourselves but also the total amount of energy in the universe is a fixed quantity. But why then is it so hard to  satisfy our lust for energy? The answer lies in studying for what we actually need the energy. We want to provide so-called “energy services” to ourselves. These comprise for example the three services shown below. I will provide more details about energy services in a later post.

  • space heating
  • lighting
  • cooking

To perform these energy services, we need energy in an accurate form defined by the energy service itself. For example we need heat (or thermal energy) at exactly specified temperatures for space heating and cooking and radiative energy for lighting. The energy problem is thus not concerned with the creation of energy that is not possible anyway but with energy conversion from one form to another.

Before we dive deeper into this topic in the next posts, I list the most common types of energy below. I will then introduce them briefly in the next post.

  • potential energy
  • kinetic energy
  • chemical energy
  • radiative energy
  • magnetic energy
  • nuclear energy
  • electrical energy
  • thermal energy