AtlasGrid and Networks Timon Droll, Charis Gersl, and Flavio Thommen

They are over, under, between and next to us. They surround us. They connect us. They make our cities function and the life that we know possible. The grids of communication are omnipresent in our lives, but physically hidden at the same time.

AC high voltage lines (alternating current) do not transport electricity from producer to consumer over very long distances, because of the energy loss. However, there are plans for a super grid with DC high voltage transmission lines (direct current) to connect alternative energy sources from north to south.With such a grid, the local potential of renewable energy could be fully utilised and transported to regions where the energy is needed.

The total length of all power lines in Germany (high voltage, medium voltage, low voltage) is 1,921,000 kilometres. This equals to 48 times the circumference of the earth. Only 35,000 kilometre are the high voltage lines (1,8 %), which are constructed over ground. Low-voltage lines make up the largest part with 1,260,000 kilometres (66 %). They lie underground and are therefore invisible for our yes.

In the first quarter of the 2022, Germany supplied large amounts of electricity to foreign countries, compared to the amount of imported electricity. A major reason for the large export volumes was the growing amount of wind and solar power in the country. Most of the electricity, produced in Germany, flowed to Austria and Switzerland, while small volumes of imports came from Denmark and Sweden, as well as from Norway. In the entire quarter, there were only seven days on which Germany purchased more electricity from abroad than it exported. However, these short-term imports did not mean that all domestic capacity was exhausted. Cross-border electricity deliveries follow primarily market laws rather than technical necessities. In cross-border trade, electricity always flows from the cheaper to the more expensive country.

For decades, Russian coal, oil and gas have contributed significantly to Germany’s energy mix. With the proclamation of the Energiewende and in the face of the 2022 energy crisis due to the Russian-Ukrainian war, the state has advanced the expansion of renewable energies.

Today, around half of the power produced in Germany comes from renewable sources like sun or wind. At the same time, the demand and importance of coal-fired power grew, due to the stop of gas delivery from Russia. Therefore, coal still marks the main energy source today with around a third of the total amount of electricity. In contrast, alternative sources like biomass, nuclear or hydropower contribute little to the energy mix.

What kind of energy source feeds electricity to the grid is highly dependent on the weather, among other things: sun and wind do not always generate the energy when it is needed. This can mean that not enough electricity is produced when it is dark or there is no wind. In such cases, the missing amount of electricity must be compensated with other energy sources.

The electricity pricing is based on a uniform principle throughout Europe. The power plants that can offer the best price are always the first to be selected. Wind and solar are among the cheapest electricity suppliers. The uniform regulation states that the most expensive power plant determines the price of electricity. In the case of Germany, gas determines the price. This means that all other less expensive suppliers sell the energy at the same price like gas. While the gas plant operator covers only the production costs, the other suppliers make profit.

Although electricity is not visible, it is constantly present and the foundation of modern life. Without electricity, no trains run, refrigerators do not work, and cashless bank transactions can not be completed.

In order to bring electricity from the renewable energy sources to the consumer quickly and with little losses, a well-developed electricity grid is important. Today, electricity is usually not used where it is generated. In order for the electrical energy to reach the consumers, a multi-level electricity grid with seven different levels is needed. Between the four networks of extra-high, high, medium and low voltage there are three transformer levels, where the extra-high voltage is gradually converted into low voltage.

The electricity grid consists of a transmission grid and a distribution grid. On the way from the power plant to the household the voltage is gradually reduced to 230 volt. At the beginning is the power source. From the power sources the electricity is fed into the extra-high voltage grid (380 kV). In this way, large amounts of electricity can be transmitted over long distances. They bring the electricity to the region of the consumers where it is reduced to a lower voltage. From the transmission grid the electricity is transferred to the high-voltage grid (36-150 kV). Here, it is taken over by industrial plants and local energy suppliers. For regional use the voltage is reduced a second time and fed into the medium-voltage (1-36 kV)grid. From this grid the electricity is distributed to city districts, villages and small and medium-sized industrial plants. Finally, the voltage is transformed to low voltage (>1 kV). The electricity then reaches the socket via the local power grid.

Some people consider electricity infrastructures as ugly or dangerous for the human health. Even though there are no studies proofing that these concerns are justified, surveys from the Bundesamt für Strahlenschutz (BfS) in Germany show, that many people are afraid of being too close to the infrastructures of the electrical grid.

Today, earth cables are becoming more common, because they are not as visible as overhead lines. They are often used near or in cities where there is not a lot of space or where it is more likely that people could reject the construction of new visible power lines. In addition, they have less outages and no noise emissions because they are protected in the ground. But if there is an outage it takes more time and money to repair it. That is s why overhead lines are used more often in the countryside because they are cheaper, can be repaired faster and have a longer life expectancy. Also, their energy transmission loss is smaller because they do not get as warm as the cables in the ground.