Lilla Edet

History and technology

The choice of Lilla Edet as the site of a hydro power plant both had advantages and disadvantages. One of the advantages was that the Göta Älv river has the most water of any of Sweden’s rivers, with an average flow rate of 550 m3 per second. The main disadvantage at that time was the low head of only about four metres. However, when a floodgate was built to the municipality of Trollhättan, a dam was also built in 1916, which increased Lilla Edet's head to 6.5 metres.

Lilla Edet was the first power plant to use Kaplan turbines and, on completion, the Kaplan turbine built as unit 1 was the largest in the world. Since, at that time, the Kaplan turbine had not yet been properly tested, Lawaczeck turbines were chosen for the other two units. However, one of these was later replaced with a propeller turbine. In 1982, a fourth unit with a 13 MW bulb-type turbine was added. This makes Lilla Edet power plant unique, because it combines four different types of turbine in a single power plant.

Lilla Edet's machine room was designed by the architect Erik Hahr. He broke away from the monumental architectural style which characterised Vattenfall's older power plants in Trollhättan, Porjus and Älvkarleby. Lilla Edet was also built from different materials: during the 1920s, granite was replaced by concrete. The new turbines required higher ceilings than had been needed previously, so the machine room looked a bit like a church.

In 2021, Vattenfall started an extensive dam project in Lilla Edet to secure the production of renewable hydro power for at least another 100 years. The current dam will be replaced with a new one. Work on the new dam is expected to be completed in 2024 at a cost of approximately SEK 370 million.

Fishway

At one time, the Göta Älv river was one of the best rivers in Sweden for salmon fishing. To improve conditions for the salmon population and to help the salmon swim upstream, a fish ladder was built at Lilla Edet power plant. The fish ladder was later replaced by a new fishway on the eastern side of the river. The fishway has been fitted with a counter, which counts the salmon that migrate upstream. Every year, Vattenfall releases 35,000 smolt downstream of Trollhättan and Lilla Edet t to compensate for the natural spawning grounds which disappeared when the river was expanded.

About the Göta Älv river

The Göta Älv river, on which Lilla Edet is situated, has its source in Lake Vänern, Sweden’s largest lake. Flowing from Lake Vänern to the Port of Gothenburg and out into the Kattegatt, the Göta Älv river transports more water than any other river in Sweden. The 44-metre drop is mainly concentrated in the upper reaches of the river at Vargön, Trollhättan and Lilla Edet. The Göta Älv river has been a major transport route for centuries, particularly following the construction of the Göta Canal.  Vattenfall owns and operates the four hydro power plants on the Göta Älv river: Vargön, Hojum, Olidan and Lilla Edet. The newest of these is Hojum, which was completed in 1941, and the oldest is Olidan, which was completed in 1910.