31.01.2018 | How Axpo’s power reaches the electrical outlet

Electricity's journey

Electricity is generated from water, wind, sun or nuclear power. It is transported through grids and converted. When it arrives the electrical outlet it makes radios, TV's, washing machines or stoves work. That is electricity's journey simply explained.

They populate the landscape. The structures are green or grey and stand on springs, cross through forests, or stand at an angle at the top of a mountain face. These are the power masts. Common to everyone, most of see through them, over them, or try to ignore them all together. Nevertheless they represent progress – or better said, civilisation. They are indicators: People live here and have light and hot water. In short: There is electricity available here.

We use this power every day around the clock to charge our mobile phones, cook dinner, or turn up the heat in the winter, to say nothing of the energy required for industrial production or the Internet and computer-dependent office work. Electricity is simply indispensable for modern society.

Accordingly power is constantly transported from one place to another. This takes place in a grid system - similar to a regional network of roads - so that power is always available from the electrical outlet when it is needed.

From generation to distribution

Power is often generated in power plants. Take for example a hydropower plant, the most important energy source in Switzerland: The energy of flowing water is used to put turbines into motion, and by means of torque they convert the energy into electricity. Once generated and fed into the grid, electricity's journey to the electrical outlet begins.

From generation to distribution to consumption. At various levels, the electricity finds access to the grid.

Graphic as PDF document

On its journey, electricity passes through various transmission and distribution grids. These grids have various levels that are defined by different voltages or transport capacities. The grid lines are above (overhead) or under ground (cable networks). The Swiss power grid covers a total distance of over 250,000 kilometres. The lower the voltage, the more underground cable networks there are. With increasing voltage the complexity of grid construction and operation increasing dramatically.

To come back to the frequently used analogy of the road network: Similar to driving where the front door of one's house is not directly connected to the motorway, households are not directly connected to the extra-high voltage grid. Exits and intersections are needed. In power lingo these are substations and transformers.

The different grid levels

The Swiss power grid has seven grid levels. There are three transformer levels (levels 2, 4 and 6) between the extra-high, high, medium and low voltage grids. The voltage levels are connected to each other at substations, also known as switching stations. The transformer that converts extra-high voltage to high voltage is located at the substation.

A comparison of the four voltage levels:

  • Extra-high voltage / Transmission grid (level 1)
    This grid level brings electricity from large-scale power plants as well as imports from abroad closer to consumers. This grid is designed to transport over long distances and has a high voltage, in Switzerland from 380 kV or 220 kV. These are the transmission grid "motorways".
  • High voltage / Supra-regional distribution grid (level 3)
    Power is distributed at a high voltage ranging from > 36 kV - 150 kV. To ensure national energy supply, this level serves the cantonal, regional, municipal distribution grid operators and large industrial plants. Here the electricity travels on federal and cantonal roads.
  • Medium voltage / Regional distribution grid (level 5)
    Districts, towns, as well as small and medium-sized industrial operations are supplied via the medium voltage grid with 1 kV - 36 kV. The electricity travels on the roads between the municipalities or the main streets in cities.
  • Low voltage / Local distribution grid (level 7)
    Ultimately, the electricity arrives at households as well as agricultural and commercial enterprises with a low voltage of < 1 kV. For the most part, this grid is invisible in Switzerland because it is underground. Once the power has reached its destination - the consumer can use it directly from the electrical outlet. Here the electricity travels on a neighbourhood street to reach the household.
Axpo maintains its own grid infrastructure in Switzerland. The Axpo distribution grids connect the transmission grid of the national grid company, Swissgrid, to customer distribution grids.
Balance is crucial for Axpo

Axpo controls the operation of its grid and power plants from the Network Control Center in Baden – around the clock, 365 days a year. The complex grid structure requires a great deal of know-how in order to ensure stability and reliability. In addition, it must constantly adapt to new requirements. When it comes to electricity, it's not quite as simple as driving a car to get from A to B.

This is because the electricity is not only fed in on the first level, but finds its way into the grid from other levels as well. Predominately renewable energy sources (wind power, hydropower, biomass, etc.) play an increasingly important role here. In Switzerland some 60 per cent of power production comes from hydropower. Production from abroad and pan-European energy trading also create challenges. The idea is not to produce as much electricity as possible to feed into the grids, but instead to find a balance between production and consumption. 

Axpo's supply region includes all of Northeastern Switzerland, the Principality of Liechtenstein, as well as parts of the cantons of Schwyz, Zug, Grisons and Valais - an area with three million residents. Axpo's grid infrastructure primarily covers high voltage with its supra-regional distribution grids. As a result, the connections to the transmission grid of the national grid company Swissgrid take place via Axpo's own distribution grids, and at the other end via the customers' distribution grids, for example cantonal and regional electricity utilities.

So the next time you have a view of a natural landscape, you might be able to see masts with a new perspective and appreciate their important role in everyday life. They deserve it.

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