Hydro and geothermal energy

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Hydro a geothe energy 1

Renewable energy in Iceland Icelanders generate 99% of their electricity using renewable resources. Landsvirkjun generates two-thirds of that energy, mostly by means of hydropower, but also by geothermal power.

Our role is to maximise the returns from the energy sources entrusted to us, through sustainable use, value creation and efficiency.

Landsvirkjun’s aim is to be a leader in the sustainable harnessing of renewable energy sources in Iceland.

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The highest concrete-faced rockfill dam in Europe forms Hálslón Reservoir, the main reservoir for the Fljótsdalur Power Station.

Water from the reservoir runs through a tunnel where it falls vertically more than 400 metres to the station’s turbines.

Landsvirkjun energy sources 1. Geothermal 4% 2. Hydropower 96%

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Landsvirkjun operates a total of 13 hydropower stations and two geothermal stations. The annual energy production is approximately 12.000 GWh, and the company is the eighth largest in the field of renewable energy in Europe.

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12

Power stations

Capacity MW

On-line

Hydropower

4

11

10

9 1 5

1 Fljótsdalur Station

690

2007

2 Búrfell Station

270

1969

3 Hrauneyjafoss Station

210

1981

4 Blanda Station

150

1991

5 Sigalda Station

150

1977

6 Sultartangi Station

120

1999

7 Vatnsfell Station

90

2001

8 Írafoss Station

48

1953

9 Steingrímsstöd Station

26

1959

10 Ljósafoss Station

15

1937

11 Laxá III Station

14

1973

12 Laxá II Station

9

1953

13 Laxá I Station

5

1939

Hydropower

1,797

Geothermal Power 8

14 Krafla Station 15 Bjarnarflag Station Geothermal Power Total

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60

1977

3

1969

63 1,860

7

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Harnessing geothermal energy Energy from the Earth’s core

Electricity generated from geothermal energy  1. Steam is led from boreholes to turbines in the powerhouse.

2. The pressure and heat difference in the steam drives the turbines.

3. The turbine drives the magnetised rotor inside the generator.

Surrounding the rotor are copper coils and when the magnet is in motion, electrical current starts to run through the coils.

Geologically, Iceland is relatively young.

The country is a volcanic island, located on a hotspot on the Mid-Atlantic Ocean Ridge, where the North American and Eurasian plates meet. Geothermal heat is considerable in most parts of the country, and in many places hot water from just below the surface is used to heat homes and for energy production.

4. Electricity is carried along high-voltage transmission lines to the electricity grid.

2 Turbine

3

Generator

Steam is led from boreholes to turbines inside the powerhouses of geothermal plants, transforming thermal energy into electricity.

The total installed capacity of geothermal energy in Iceland is 575 MW. Landsvirkjun operates two geothermal plants with an installed capacity of 63 MW.

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1 Borehole

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When precipitation runs through the hot bedrock, the water heats up, resulting in hot springs on the surface and steam chambers underground. In low-temperature areas, hot water is primarily used to heat homes,

while high temperature areas produce hot steam under pressure.

Reinjection

High temperature Low temperature The high temperature areas are located near the tectonic plate boundaries, while the lowtemperature areas are further away.

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Krafla Power Station At Krafla Power Station, high- and lowpressure steam from 18 boreholes drives two 30 MW turbines.

Built by the Icelandic government, Krafla came under the ownership of Landsvirkjun in 1985. Construction began with trial boreholes in 1974, the first turbine unit started up in August 1977, and regular operations began in February 1978. Krafla’s development was a pioneering endeavour, hampered by political feuds for years, as well as volcanic activity and technical complications.

The installation of the station’s second turbine unit began in 1996. New boreholes were drilled and older ones were repaired. Steam extraction has been successful with improved technology, among those being directional drilling. Since additional drilling and renovations were completed in 1997, Krafla has been operated at its full 60 MW capacity.

Bjarnarflag Power Station The Bjarnarflag Geothermal Station in the Lake Mývatn area is the smallest geothermal station owned by Landsvirkjun and the first of its kind in Iceland. The station generates 3 MW, using the steam from the geothermal area near Námafjall Mountain.

In addition to generating 18 GWh of electricity annually, Bjarnarflag provides steam for the local district heating system and industrial use, as well as geothermal water for the nature baths at Lake Mývatn.

Krafla Power Station

Bjarnarflag Power Station 1969

A year after construction work began at Krafla, the ground opened in a volcanic eruption only three kilometres away from the station.

The eruption sent corrosive magma vapours into the geothermal system that destroyed the borehole linings. A series of nine volcanic eruptions began on 20 December 1975 and lasted until September 1984.

The seismic and volcanic impact was reduced once the eruptions ceased. In 1996, Landsvirkjun decided to install the second turbine unit and prospect for more steam. Work began immediately with improved technology. Methods used included directional drilling, a process that has proved quite successful. New holes were drilled and older ones repaired. The results were good and sufficient steam to drive the station’s second turbine was obtained.

Installed capacity

60 MW

2 steam turbines

2x30 MW

Generation capacity

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1977/1997

500 GWh p.a.

Installed capacity

3 MW

1 steam power unit

3 MW

Generation capacity

18 GWh p.a.

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Harnessing waterways River power

Electricity generated from hydropower 1. The reservoir behind the dam maintains the water level and creates pressure.

2. The water flows down the penstock pipes and drives the turbine wheel.

3. A turbine drives the magnetised rotor inside the generator. Copper coils surround the rotor, and as the magnets turn, an electrical current begins to flow through the coils.

4. The generator now produces electricity that is then carried along high-voltage lines to the electricity grid.

Water that collects at an altitude of up to 800 metres above sea level, releases an enormous amount of energy as it travels down from the highlands. Landsvirkjun operates 13 hydropower stations of varying sizes and types that harness this energy.

5. Finally, the water flows from the powerhouse.

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Roughly 80% of the energy generated goes to energy-intensive industries, and the rest is distributed to households and smaller businesses. The total installed capacity of Landsvirkjun’s hydropower stations is approximately 1800 MW.

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Generator

1

3

Reservoir 2

2 Pe nstoc kp

Turbine

5 Outflow

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Landsvirkjun’s Hydropower Stations

ipe 1.

2.

3.

4.

5.

Ljósafoss, Írafoss and Steingrímsstöd Blanda Laxá I–III Fljótsdalur Búrfell, Sultartangi, Hrauneyjafoss, Sigalda and Vatnsfell

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5

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Ljósafoss and Írafoss Power Stations The oldest power station in the River Sog is located near Ljósafoss by Lake Úlfljótsvatn’s outflow. The station is located on the river bank east of the waterfall, and the water runs through pipes to the station’s turbines and from there into the river below the waterfall.

Operation of the Ljósafoss station began in 1937, when two turbine units were installed with a combined capacity of 8.8 MW. The third turbine was installed in 1944 with 6.5 MW.

The Írafoss Station harnesses two of the waterfalls, Írafoss and Kistufoss, in the lower part of the River Sog. A dam has been built across the River Sog above Írafoss at virtually the same altitude as the Ljósafoss Station outflow.

The station went on-line in 1953 using two 15.5 MW generating units and was expanded with the addition of a 16.7 MW turbine in 1963.

Steingrímsstöd Power Station The Steingrímsstöd Station is the third station built in the River Sog area. The station harnesses the head where the Upper Sog drains from Lake Thingvallavatn into Lake Úlfljótsvatn. A dam was built at the outflow of Lake Thingvallavatn, with the headrace tunnel running through Dráttarhlíd, which separates Lake Thingvallavatn and Lake Úlfljótsvatn, and into an open-air surge

Steingrímsstöd Station

pond above the powerhouse. The outflow from Lake Thingvallavatn is on average approximately 100 m3/s.

The station came on-line in 1959, and the installed capacity is 27 MW.

Ljósafoss Station

The start-up of Ljósafoss Station in 1937 quadrupled the supply of electricity in the Reykjavík city area. The electricity produced from the river Ellidaá in the days before Ljósafoss was primarily used for lighting. The addition of Ljósafoss opened up the possibility of using electric stoves instead of coal stoves in Icelandic homes. To create a market for the electricity from the station, households were given the option of obtaining a Rafha electric stove with their electricity subscriptions.

Írafoss Station

1953 / 1963

16 MW

Installed capacity

48 MW

Installed capacity

27 MW

3 Francis turbines 2x4.4 MW and 6.5 MW

3 Francis turbines

3x16 MW

2 Kaplan turbines

2x13.5 MW

Installed capacity

Generation capacity Head Maximum flow

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Steingrímsstöd Station

1937 / 1944

Ljósafoss Station

105 GWh p.a.

17 m 104 m3/s

Generation capacity Head Maximum flow

236 GWh p.a.

38 m 150 m3/s

Generation capacity Head Maximum flow

1959

Írafoss Station

122 GWh p.a.

20.5 m 150 m3/s

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Blanda Power Station The Blanda Station came on-line in 1991.

It is located on the northern edge of the high-lands near the end of the Kjalvegur Mountain Road. To the north is a view over the Blöndu-dalur Valley where the River Blanda flows out to the sea near the town of Blönduós. The Blanda Station is an underground plant, located approximately 230 metres below the surface.

The river flows through grassy fields in the lowlands, but its source is in a region that only a few decades ago was a desert. After the creation of a 56 km2 storage reservoir, extensive revegetation efforts were initiated.

Since 1981, Landsvirkjun has cultivated over 5000 hectares at an altitude of 400–600 m by fertiliser treatment and sowing. This is one of the most extensive reclamation projects ever undertaken in Iceland’s highlands.

Ideas for harnessing the River Blanda were originally proposed around 1950. The Blanda Hydro Station is the first large-scale power station that is entirely of Icelandic design. The first turbine units were brought on-line in the autumn of 1991, and the station had reached full operational capacity by March 1992.

From the intake reservoir, water runs through a 1300 m long canal to the station’s intake, where it is diverted to the turbines in the powerhouse. The drop to the turbines from the harnessed head is 287 m. From the turbines, the water is lead through a 1700 m tailrace tunnel back into the river course.

1991

Installed capacity

150 MW

3 Francis turbines

3x 50 MW

Live storage

910 GWh p.a.

Blanda dam

287 m

Dam height

44 m

Dam height

25 m

60 m3/s

Dam length

800 m

Dam length

1300 m

Generation capacity Total head

Blanda Station

Gilsárlón Reservoir

Blanda Reservoir

Blanda Station

Maximum flow

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A dam was built in the River Blanda near the Reftjarnarbunga Hill, an ideal area for a reservoir. A dam was also built near the source of the River Kolkukvísl which flowed into River Vatnsdalsá. These dams formed the Blanda Reservoir, which has a live storage capacity of 412 Gl and is the third-largest lake in Iceland.

From the Kolka Dam, the water is diverted through diversion canals and lakes on a 25 km long route to the station’s intake reservoir, Gilsárlón. The reservoir has an area of 5 km2 and has a live storage capacity of 20 Gl.

Blanda Reservoir Maximum area

Gilsárlón Reservoir 56 km2 412 Gl

Area

5 km2

Live storage

20 Gl

Kolka dam

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Fljótsdalur Station’s Catchment Area

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Fljótsdalur Station

Tailrace tunnel

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Headrace tunnel

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The water from all the reservoirs comes together in the headrace tunnel, which runs almost level at 100-200 metres depth under the Fljótsdalsheidi Moor. The headrace tunnel ends in two pressure shafts, where the water falls 400 metres vertically into the Fljótsdalur Station’s Powerhouse, about 1 km inside the mountain.

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Two smaller saddle dams were built at Kárahnjúkar, Desjará Dam to the east and

Most years, Hálslón fills up in late summer.

When this happens, the spillover is diverted through a chute down to the canyon edge, where it becomes the waterfall Hverfandi (Vanisher). Almost 100 metres high, Hverfandi can, at times, become more powerful than Dettifoss, its neighbour to the north and one of Europe’s most powerful waterfalls.

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Kárahnjúkar Dam is the tallest concrete-faced rockfill dam in Europe and among the largest of its kind in the world. The River Jökulsá á Dal is dammed at Fremri Kárahnjúkar with the largest of the Kárahnjúkar dams. Most of the rockfill was quarried just upstream of the dam within the reservoir area and placed in compacted layers. During construction, the river was diverted through two diversion tunnels under the dam on the western bank.

Saudárdalur Dam to the west. Together, the three dams form the Hálslón Reservoir which covers an area of 57 km2, and reaches all the way to the Brúarjökull Glacier.

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Fljótsdalur Station came on-line in 2007.

The Station’s catchment area covers over 2200 km2 and the station’s reservoirs are formed by five dikes that are over five kilometres in length. The water is diverted to the Fljótsdalur Station’s turbines from the reservoirs in the highlands north of the Vatnajökull Glacier, through a tunnel system that is approximately 72 km long.

Hálslón Reservoir

Ufsarlón Reservoir Grjótárlón Reservoir Hálslón Area of full reservoir Live storage

Desjará Dam 57 km2 2100 Gl

Kárahnjúkar Dam

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Maximum dam height Dam length

Ufsarlón Reservoir 70 m 1100 m

Saudárdalur Dam

Maximum dam height

198 m

Maximum dam height

Dam length

700 m

Dam length

Maximum area Live storage

1 km2 3 Gl

Kelduárlón Reservoir Lake Saudárvatn

Kelduárlón Reservoir 29 m 1100 m

Maximum area Live storage

7.5 km2 60 G

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Fljótsdalur Power Station Four years passed from the beginning of construction work at Kárahnjúkar in 2003 until the Fljótsdalur Power Station reached full operational capacity in 2007. Concurrent with the construction work at Kárahnjúkar, an aluminium plant was built in Reydarfjördur. Most of the energy generated is sold to the Reydarfjördur plant.

On its long journey from the reservoirs in the highlands to the station’s intake, the water drops approximately 200 m. Two-thirds of the total head runs through an approximately 400 m high vertical pressure tunnel near the Fljótsdalur Station.

Fljótsdalur Station Installed capacity

690 MW

6 Francis turbines

6x115 MW

Generation capacity Total head Maximum flow

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2007

4800 GWh p.a.

599 m 144 m3/sec

The water’s total drop therefore, is more than 600 m. The water drives six powerful turbines in the powerhouse and then flows through a tailrace tunnel and canal into the river Jökulsá in Fljótsdalur, east of Valthjófsstadur Mountain, at an altitude of 26 metres. The underground powerhouse is located inside Valthjófsstadur Mountain and is accessed through an 800 m tunnel.

Electricity is transmitted from the station through a separate cable tunnel to the switchgear house and from there through high-voltage lines to Alcoa’s aluminium plant in Reydarfjördur.

Tunnels Total

72 km

Headrace tunnel from Hálslón Reservoir (diameter 7.2–7.6 m)

39.7 km

Headrace tunnel from Ufsarlón Reservoir (diameter 7.2 m)

13.3 km

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Thjórsá and Tungnaá Catchment Area There are five hydropower stations in the catchment area of Rivers Thjórsá and Tungnaá: Búrfell, Sultartangi, Hrauneyjafoss, Vatnsfell and Sigalda, with combined energy of 850 MW. The sixth, Búðarháls Station, is under construction to be brought on-line in 2013. Water for all the power stations is provided by three main reservoirs, Thórisvatn, Hágöngulón and Kvíslarveita, along with smaller reservoirs connected with each station.

Lake Thórisvatn, Iceland’s largest lake, is the largest reservoir and an important part of Landsvirkjun’s utility system. All water accumulated in Kvíslarveita and Hágöngulón reservoirs runs through Lake Thórisvatn.

Lake Thórisvatn became a reservoir with the harnessing of River Thjórsá at Búrfell Mountain in 1970-1972. River Kaldakvísl was diverted into the lake at the northern edge of the lake and a controlled outflow constructed at the southern edge.

A canal was dug from the lake and a concrete gate structure built in the canal to manage the flow rate. The canal is named the Vatnsfell Canal, and carries water from Lake Thórisvatn through the Vatnsfell Station into the Krókslón Reservoir above the Sigalda Station, and from there to other stations further down in the catchment area.

Hágöngulón Reservoir

Kvíslaveita Reservoir

ÞJjó

Work on the Kvíslaveita Reservoir began in 1980 and was completed in 1997. Kvíslaveita is the collective name for the dams, canals, bottom outlets and gate structures that manage the flow rate from the River Thjórsá and its tributaries into Lake Thórisvatn.

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The Háganga Reservoir was constructed in 1997–1999 and covers an area of 27 km2. Its purpose is to increase the efficiency of the catchment area of River Kaldakvísl. During the summer months, water accumulates in the Hágöngulón Reservoir, with very little water flowing down the Kaldakvísl riverbed.

Th

Sultartangalón Reservoir

Sultartangi Station

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R sá

Búðarháls Station

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Kvíslaveita

Area (fully utilised)

83 km2

Maximum area

Live storage

1400 Gl

Live storage

Catchment Area

2783 km2

Maximum depth

109 m

Area of Thjórsárlón Thjórsá/Thórisvatn dam

1980-1997

Hágöngumidlun area

24 km2

Hágöngulón Reservoir

400 Gl 3.5 km2

Area Live storage

1997-1999

Búrfell Station

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Riv

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Lake Thórisvatn

Hrauneyjafosslón Reservoir

Hrauneyjafoss Station Sigalda Station

Lake Thórisvatn

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Vatnsfellslón Reservoir Vatnsfell Station Krókslón Reservoir

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gn

R aá

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Bjarnarlón Reservoir

37 km2 320 G

53 km

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Búrfell Power Station When Landsvirkjun was established in 1965, it embarked on the construction of the Búrfell Hydropower Station, which came on-line in 1972. It took almost ten years to complete the construction and it was the largest power station in the country until the inauguration of Kárahnjúkar Hydropower Station in 2007.

The River Thjórsá is harnessed at Búrfell with a tailrace tunnel from the Bjarnarlón Reservoir to the powerhouse located in the Thjórsárdalur Valley. The River Thjórsá, which previously flowed south of Mountain Búrfell, is diverted above the mountain into Bjarnarlón Reservoir, and from there through a tunnel passing through the basalt strata of Sámstadamúli into the Thjórsdárdalur valley.

The diversion system in the riverbed of Thjórsá is equipped with a special ice-

Búrfell Station

The front wall of the Búrfell powerhouse is decorated with a mural by artist Sigurjón Ólafsson, who also made the sculpture “The Noise Troll” (Hávadatröllid) standing in front of it. Visitors are invited to view a multimedia exhibition on renewable energy sources in the powerhouse’s visitors’ room.

Installed capacity

270 MW

6 Francis turbines

6x45 MW

Generation capacity Total head Maximum flow

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1972 / 1998

2,300 GWh p.a.

115 m 300 m /sec 3

barrier structure. In earlier years, the role of the ice barrier structure was to rinse aside ice and slush to prevent it from reaching the Bjarnarlón Reservoir. Today, the flow rate of the river can be better managed and with the construction of a canal between the Sultartangi and Búrfell stations the amount of ice and slush has been reduced.

The need for the structure has therefore been greatly diminished.

From the powerhouse turbines, the water exits via draft tubes into a short canal before entering the River Fossá, which joins the River Thjórsá 2 km downstream.

The station’s equipment was partially renewed in 1997-1999. This increased the station’s installed capacity to 270 MW, from 210 MW.

Bjarnarlón Reservoir Maximum area Live storage

1 km2 5 Gl

Diversion system in River Thjórsá Length of installation

370 m

Four spillway gates and two ice gates

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Sultartangi Power Station The Sultartangi Station, located 15 km northeast of the Búrfell Station, was built at the end of the last century and came on-line in 1999. The Station utilises water from the River Tungnaá which has already driven the turbines of the Hrauneyjafoss and Sigalda stations on its way down from the highlands.

It also utilises the River Thjórsá’s flow rate, as the two rivers are joined in the Sultartangalón Reservoir above the station. As a result, it is not as sensitive to fluctuations in water supply as many other stations are. In this regard it resembles the Búrfell Station.

construction of the power station, the dam crest was raised by 1 metre, increasing the reservoir’s surface area from 18 to 20 km2.

A headrace tunnel (3.4 km) moves water from the reservoir through Sandafell Mountain to a surge basin on its southwestern side. At the end of the surge basin is the station intake, where two penstocks lead to the powerhouse.

A tailrace canal, just over 7 km long, lies from the powerhouse at the foot of Sandafell Mountain and follows Thjórsá River almost all the way to the Búrfell Station Reservoir dam where it enters the Thjórsá riverbed.

The Sultartangi Dam is the longest in Iceland, 6.1 km in length. In conjunction with the

Sultartangi Station Installed capacity

120 MW

2 Francis turbines

2x60 MW

Generation capacity Total head Maximum flow

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1999

1020 GWh p.a.

Sultartangalón Reservoir Maximum area Live storage

20 km2 109 Gl

Dam

44.6 m

Dam height

23 m

320 m3/s

Dam length

6100 m

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Hrauneyjafoss Power Station The Hrauneyjafoss Station is Iceland’s third largest power plant, producing 210 MW. It is located near the Sprengisandur Route on the edge of the highlands; southwest of the Sigalda Station, and utilises the same water as Sigalda Station. Hrauneyjafoss Station came on-line in 1981.

The Tungnaá River is dammed on rather flat land approximately 1.5 km above the Hrauneyjafoss Waterfall and 7 km below the Sigalda Station. The difference in altitude is approximately 15 m. Hrauneyjalón, an 8.8 km² reservoir, was formed by the dam. A low

Hrauneyjafoss Station Installed capacity

210 MW

3 Francis turbines

3x70 MW

Generation capacity Total head Maximum flow

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1981

1300 GWh p.a.

soil wall dam stretches along the lava flatlands on the south bank of the river. A headrace channel runs 1 km northwards from the reservoir through a dip in the Fossalda Hill to an intake point at its northern edge. Three steel penstocks (4.8 m in diameter) run 272 m down the hill to the powerhouse. The tailrace canal, just over one kilometre in length, enters the Spordöldukvísl waterway, which runs into the Tungnaá River.

Hrauneyjalón Reservoir Maximum area Live storage

8.8 km2 33 Gl

Hrauneyjafoss dam

88 m

Dam height

15 m

270 m3/s

Dam length

3000 m

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Sigalda Power Station The Sigalda Station is located just above the Hrauneyjafoss Station, south of Lake Thórisvatn. The station came on-line in early 1978.

A short tailrace canal links Sigalda Station with Hrauneyjafoss Station.

There have been plans for power development in River Thjórsá for a long time. Einar Benediktsson, an Icelandic poet and entrepreneur, was probably the first person to seriously consider harnessing the river with his company Títan in the early 20th century. Around 1960, Thjórsá development was given serious consideration, but national use of electricity was too limited to fully utilise the energy that could be harnessed. As a result, ideas were put forward to use the development for heavy industry to ensure its economic viability.

Sigalda Station was built following the development at Búrfell. Its construction was a race against time as there was great demand for more hydropower stations to satisfy energy requirements in Iceland following the powerintensive industrial growth in Straumsvík and Hvalfjördur.

The Sigalda Dam dams the Tungnaá River at the top of the canyon above Sigalda Hill, where it forms Krókslón, a 14 km2 reservoir. The rock-fill dam is 925 m long, clad with asphalt, and 40 m tall at its highest point. The water is carried 1 km through an intake canal from Krókslón Reservoir to the western edge of Sigalda Hill. Three pressure shafts, 216 m long and 4.3 m in diameter, run to the powerhouse north of the old riverbed, in part buried inside the Sigalda hillside. The harnessed head is 74 m. A 550 m tailrace canal leads from the powerhouse into the Hrauneyjafoss Reservoir.

Sigalda Station

1978

Krókslón Reservoir

Installed capacity

150 MW

3 Francis turbines

3x 50 MW

Generation capacity Total head Maximum flow

28

920 GWh p.a.

Area

14 km2

Live storage

140 Gl

Dam

74 m

Dam height

42 m

260 m3/s

Dam length

925 m

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Vatnsfell Power Station The Vatnsfell Station began operations in 2001, with construction work beginning in 1999. The station’s capacity is 90 MW, and it is the northernmost power station in the Thjórsá and Tungnaá River area.

Vatnsfell Station utilises the head in the diversion canal between the Thórislón Reservoir and Sigalda Station’s reservoir Krókslón. Unlike the other stations, it only produces electricity during winter.

Harnessed head and power stations in the rivers Thjórsá and Tungnaá m.a.s.l.

Hágöngumidlun Reservoir

800 700

Power Stations

Kaldakvísl River Kvíslaveita

1. Vatnsfell 90 MW

Thórisvatnsmidlun reservoirs

600

Tungnaá River

1

500

2

Thjórsá River

400

2. Sigalda 150 MW 3. Hrauneyjafoss 210 MW 4. Sultartangi 120 MW 5. Búrfell 270 MW

3

300

Reservoir Dam Canal /pipe Power Station

4 5

200 100 0 180

160

Vatnsfell Station

120

100

80

2001

Installed capacity

90 MW

2 Francis turbines

2x45 MW

Generation capacity Total head Maximum flow

30

140

490 GWh p.a.

60

40

20

0 km

Vatnsfellslón Reservoir Maximum area Live storage

0.6 km2 3 Gl

Dam

65 m

Dam height

30 m

160 m3/s

Dam length

750 m

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Laxá Power Stations I, II, and III The three Laxá Stations harness a 70 m head on an 1800 m strecth of River Laxá to produce a total of 27.5 MW of electricity. The inflow to Lake Mývatn is mostly underground, through layers of lava, largely immune from seasonal fluctuations and ideal for harnessing hydropower.

leading to the power station. The station operates two turbine units, coming on-line in 1939 and 1944. For the Laxá II Station, the river is dammed 300 metres below Laxá I, diverting the water 380 metres to the power station via a penstock and a surge tank.

Laxá I and II are low head hydro stations that harness the natural flow of River Laxá. Station III, the latest addition, utilizes the same head as Laxá I but runs its water through a tunnel to the power station, 60 metres inside the rock.

The Laxá III Station is the most recent power station in the river Laxá. The underground vault housing the station’s turbine unit was initially designed for two 25 MW turbines.

The plans called for the construction of a 56 m high dam in the upper part of the canyon, making the total head 83 m. The local population of Þingeyjar strongly protested the plan. The Laxá III Hydropower Station was inaugurated in 1973 with one turbine instead of two, and further plans for the region were shelved.

The town of Akureyri and the Icelandic Government built the Laxá Stations which joined Landsvirkjun in 1983.

Laxá Stations I and II The Laxá I Station is the oldest power plant in the river Laxá. From the dam at the top of the canyon, the water is first diverted through an underground tunnel and then through a channel approximately 670 m in length,

Laxá III Station

Laxá II Station

Laxá I

1939

Laxá II

1953

Laxá III

Installed capacity

5 MW

Installed capacity

9 MW

Installed capacity

13.5 MW

2 Francis turbines

2x 2.5 MW

1 Francis turbine

9 MW

1 Francis turbine

13.5 MW

Generation capacity Total head

32

3 GWh p.a.

39 m

Generation capacity Total head

78 GWh p.a.

29 m

Generation capacity Total head

1973 Laxá Stations I and III

92 GWh p.a.

39 m

33

Units of measurement MW = megawatt

1 MW = 1,000 kW = 1,000,000 W

kW = kilowatt

Power is measured in watts and describes the ability to perform work.

W = watt

Power describes the capacities of the turbines in a power station.

TWh = terawatt hours

1 TWh = 1,000 GWh = 1,000,000 MWh = 1,000,000,000 kW

GWh = gigawatt hours MWh = megawatt hours

The amount of electricity produced or consumed is measured in watt hours.

kWh = kilowatt hours kV = kilovolt

1 kV = 1,000 V

V = volt

Current is measured in volts. The current in the country’s most powerful

high-voltage lines is 220 kV.

Gl = gigalitre

1 Gl = 1,000,000,000 l = 1,000,000 m3

l = litre

Capacity in reservoirs are measured in gigalitres.

m3 = cubic metre

E

The Francis turbine Most of Landsvirkjun’s stations use

CO

141

Francis turbines. In such turbines, the

LABELLIN G

858

Printing company

water is diverted through a penstock

Magnetic poles

pipe to the turbine wheel which is driven

a draft tube that further increases the

Electrical current

pressure on the wheel.

Stator Shaft

The turbine wheel connects to a shaft that drives a magnetic rotor surrounded

Water flow

by copper coils. The rotation causes an

Turbine wheel

electrical current to pass through the coils, transforming kinetic energy to electricity, which is distributed to the transmission system.

34

Draft tube

The printing of this brochure has Nordic Swan Ecolabel accreditation.

The paper used for the brochure has Nordic Swan

Copper coils

Ecolabel accreditation and carries the FSC label.

Francis turbine

Penstock pipe

turbine wheel, the water is lead through

Generator

under considerable pressure. From the

Paper:

Munken Polar, 170 gr.

Design: Jónsson & Le’macks Printing: Prentmet January 2012

and rmal Landsvirkjun HĂĄaleitisbraut 68 103 ReykjavĂ­k Iceland Tel: +354 515 9000 landsvirkjun.com landsvirkjun@lv.is 36

Hydro a geothe energy