Excitement on the Enns

Hydropower: a technology that needs explaining

There are already several run-of-river power plants on the Mur - for example the one in Rabenstein near Frohnleiten.

(Bild: Verbund)

New power plant plans regularly meet with resistance from the population. This was also the case recently on the River Enns. However, many people do not know how hydropower plants work. How is one constructed? And why is it a sensitive intervention in nature?

Hydropower plants come in different forms. They are available as storage or pumped-storage power plants with a lake - but they are also available as wave, tidal or run-of-river power plants. The latter variant has recently hit the headlines again: Up to 18 power plants are to be built on the previously unspoiled Styrian Enns.

"On the one hand, of course, we need green energy, but on the other hand, we in the Enns Valley live from our unique natural environment," Mathias Schattleitner, Managing Director of the Schladming-Dachstein Tourism Association, said recently. It is clear that hydropower cannot be viewed in a one-sided way. It is a controversial technology with good arguments on both sides.

At the moment, the Styrian Enns is still completely undeveloped.

(Bild: Alexander Maringer)

However, a common knowledge base is needed for an in-depth discussion among the population. So how exactly does a run-of-river power plant work? Run-of-river power plants use the flow of rivers to generate energy - because we have plenty of them in Austria, it is the most common way of utilizing hydropower.

From kinetic to electrical energy
A high and constant flow rate of the water is important, but this can be regulated by a dam directly upstream of the power plant. A floating debris rake in front of the inlet channels protects the plant from washed-up wood. The water finally reaches the turbine through a pipeline, where the power of the water takes effect. The blades of the turbine and the associated generator convert kinetic energy into a mechanical rotary motion and then into electrical energy. So-called Kaplan turbines are usually used, which are designed for low gradients but large volumes of water.

How a run-of-river power plant works.

(Bild: stock.adobe.com, Krone KREATIV)

Finally, a transformer converts it into the right voltage for the power grid. Run-of-river power plants usually cover the base load in electricity demand - they supply a steady and relatively constant amount of electricity. The area upstream of the power plant is called upstream, the area downstream is called downstream.

And the disadvantage of green technology? It is a huge intrusion into nature. Run-of-river power plants can serve as flood protection or even as a lock for ships. But they often have negative consequences for the animals that live there. Fish ladders do not always function reliably and there is a risk that they will die in the turbines. Flotsam also provides a habitat for animals and plants, which disappears as a result of hydropower plants.