Ljósafoss Power Station

Ljósafoss Power Station was commissioned in 1937 with two turbine units and an installed capacity of 8.8 MW. A third turbine was added in 1944, increasing the station’s capacity to 15 MW. Today, the station has an annual generation capacity of 105 GWh.

The commissioning of Ljósafoss Power Station quadrupled the electricity supply to the capital area and marked a major step in the electrification of Icelandic homes. Electricity production increased severalfold, making it possible for households to use electric cookers instead of coal-fired stoves. To encourage the transition, electric cookers manufactured by the Icelandic company Rafha were offered through electricity subscription schemes.

As its name suggests, Ljósafoss Power Station is located beside Ljósafoss waterfall on the Sog River. Water is conveyed from the river through penstocks to the powerhouse before returning downstream of the waterfall.

Construction of Ljósafoss Power Station began in 1935 and was completed in 1937. At the time, it was one of the largest construction projects ever undertaken in Iceland. A temporary village housing around 250 workers was built beside the Sog River, and King Christian X of Denmark laid the cornerstone of the powerhouse.

The commissioning of Ljósafoss Power Station marked a major milestone in the development of Iceland’s electricity system. It significantly increased electricity supply to the capital area and made it possible to use electrically powered industrial machinery on a much larger scale, helping to accelerate industrial development in Iceland.

Ljósafoss Power Station during construction.

The Sog is Iceland’s largest spring-fed river. It flows from Lake Þingvallavatn through Lakes Úlfljótsvatn and Álftavatn before joining the Hvítá River to form the Ölfusá River. Most of its water originates from springs on the floor of Lake Þingvallavatn, giving the river an unusually stable and consistent flow.

From Lake Þingvallavatn to the Hvítá River, the Sog flows for only about 20 kilometres. Along this short stretch, a considerable head is available for hydropower generation, first between Lakes Þingvallavatn and Úlfljótsvatn and then at the waterfalls Ljósifoss, Írafoss and Kistufoss.

These natural conditions made the Sog one of Iceland’s most favourable locations for early hydropower development. The first plans to harness the river were prepared in the 1920s, and electricity generation began in 1937 with the commissioning of Ljósafoss Power Station.

Over the following decades, three power stations were built on the river: Ljósafoss Power Station, Írafoss Power Station and Steingríms Power Station. Together, they played a key role in the electrification of Iceland and supplied a large share of the country’s electricity during the formative years of its power system.