Electrical energy

Electrical energy surrounds us wherever we walk and stand – at work, at home and, thanks to modern technologies, on the move. The following article explains what electrical energy actually is, presents the formula for calculating electrical energy and shows why electrical energy is so important.

Electrical energy definition

What is electrical energy simply explained? Electrical energy is one of many forms of energy that is on the same level as mechanical, chemical, magnetic, thermal and nuclear energy. 1 Electrical energy is transmitted using electricity, but it can also be stored in special electric fields. Basically, electrical energy is therefore a capability of electric current. It makes mechanical work, the generation of heat or the emission of light possible. 1

Electrical energy can be stored in electric and magnetic fields and can be converted into other forms of energy. This fact is used, for example, in fuel cell technology. The formula symbol E and the unit watt-second (Ws) are used for electrical energy. One watt corresponds to one joule (Js).3

Discovery of electrical energy

Who discovered the electric energy? As early as ancient times, people discovered the existence of charged particles, or rather the phenomena that cause them. Thales of Miletus, who was born around 624 BC, noticed that amber (Greek ""electron"") attracts small particles when there is friction. Small charged particles collect on the surface of the amber, which then in turn attract other particles.

After that, it took quite a long time to learn how to use these particles technically and generate a continuous flow of electrons. Alessandro Volta invented the first functioning battery around 1775. Similar to today’s hydrogen fuel cell and direct methanol fuel cell, this first battery generated electricity through chemical reactions. Because of his invention, Volta became the namesake of the unit of electrical voltage, the volt.

The precondition for the construction of generators was created by André Marie Ampère. He discovered the connection between current and magnetism – and was the first to describe current and voltage with mathematical equations. He thus laid the foundation for the operation of generators in electric power plants. These were developed by Werner Siemens around 1866. The so-called dynamo machine was able to convert kinetic energy into electrical energy. Regardless of whether they are coal, wind, water or nuclear power plants, generators are still used today to produce electricity. 4

Generation of electrical energy

Only by using other energy sources do we get electrical energy, or electrical current. It is therefore not generated from nothing, but is created by converting one form of energy into another. Thus, power plants are named after the form of energy with which a generator is set in motion and with whose help electric current is generated. For this reason, a distinction is made between hydroelectric and wind power plants, solar power plants, biomass power plants, coal or gas turbine power plants, nuclear power plants and several other types.

Larger quantities of electricity or electrical energy are therefore generated in power plants. But a small dynamo, for example on a bicycle, can also produce electrical energy in a similar way. When the bicycle moves, a permanent magnet in an induction coil rotates. This creates a current flow that causes the lamp to light up.

The exact process required to generate electricity differs depending on the energy producer. If, for example, water is used as an energy generator, there is no need for combustion processes at all. In this case, the turbines are driven by the pure kinetic energy of a flowing body of water. This energy also drives the generator, whereupon it is converted into electricity. 5

Electrical energy function

Although electricity is invisible to humans, simply everything around us is made up of small particles called atoms. Atoms have an atomic nucleus surrounded by small electrons. These particles are the basis for electric current and are very, very small. They are positively or negatively charged and generate electric fields through their charge. If the particles move in one direction, flowing current is generated. 6

Electrical energy examples

How and where is the electric energy used? Thanks to electrical energy, we have light in our homes, but it also gives rise to the lightning during a thunderstorm. The electricity generated in power plants is then fed into the power line system. If you then connect a device to the power grid and switch it on, the circuit is closed and the current flows. In addition to flowing electricity, there is electrical energy that is stored in batteries. These provide power not only for watches, flashlights or electronic toys, but even for cars.

Whether it’s charging a smartphone or surfing the Internet, electrical energy is enormously important and an integral part of our daily lives. Electricity keeps vital appliances such as the refrigerator and stove running and supplies our entertainment systems such as televisions and computers with electrical energy. It even makes trains and subways run. If there were no electricity, we would not be able to manufacture many industrial products or treat many patients. Research and electronic capabilities in the medical field would be very limited without electricity. 4

Electrical energy also determines our flow of information. Digital devices such as smartphones, tablets and laptops are powered by electrical energy. If this were to disappear, we would no longer be able to obtain information from all over the world as easily. 5

Electrical energy calculation

How is electrical energy calculated? The electrical energy unit is joule. To calculate electrical energy, you need three values to multiply. The current strength indicates how much electrical charge flows through a conductor, for example a cable, per second. It has the unit ampere (A) and the formula symbol I. Also important is the electric voltage, which indicates how large the drive of the electric current is. The unit for the electric voltage is Volt (V), the formula sign for the calculation is U. Last but not least one needs the value of the time. Decisive here is the period for which one wants to calculate the electrical energy. This value is given in seconds and has the designation t in the calculation.

The electrical energy formula, to which these three values are combined, then looks as follows:

E = U ⋅ I ⋅ t

For the correct calculation of the electrical energy, the condition that both the electrical voltage and the charge must be constant applies.

Logically, this means that the greater the electrical voltage and the electrical current, the greater the electrical energy converted in a circuit. And: The electrical energy increases the longer the current runs. 2

The electrical energy output can also be measured or calculated. It indicates the energy consumption, i.e. how much electrical energy is consumed in a certain time. In principle, electrical power (P) can be calculated by multiplying voltage (U) and current (I): 7

P = U · I

What else should you know about electrical energy?

Experts agree that the increase in climate-damaging emissions and the accompanying climate change are due to human activities. Saving energy accordingly serves to avert climate change and helps to reduce emissions that are harmful to the climate.

Through the consumption of heat and electricity, the use of mobility services, etc., every German generates eleven tons of CO2 per year. However, this figure should not exceed two tons if global warming is to be halted at 2 degrees Celsius. In addition to politicians and industry, every individual is therefore called upon to reduce greenhouse gases and thus their own energy consumption.

Whether it’s heating, mobility or electricity, one of the most effective ways to protect the climate is to save energy. After all, if you consume less electricity, you need fewer power plants, transmission lines and storage capacities. In addition, an all-round supply from renewable energies can be achieved more easily if overall consumption is lower. 8


Electrical energy surrounds us in all our lives. It is not simply created out of thin air, but is converted from other forms of energy. The process of producing electricity differs depending on the energy producer. Because electrical energy and its generation process in power plants still have a negative impact on the climate, consumers should adopt a conscious approach to electricity and take conservation measures.