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General Information


Some pictures from Iceland

 

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The 1973 eruption on the island of Heimaey a must see.

Basic Facts

Capital: Reykjavik
Population 2001: 283.000
President (since 1996): Mr. Ólafur Ragnar GRÍMSSON
Prime Minister (since 2004): Mr. Halldór Ásgrímsson
Currency: Icelandic kronurs (1US$ = 84,89 ISK as per 1. Aug 2002)
Total area: 39,756 square miles, slightly smaller than the State of Virginia.
Location: Island nation in North Atlantic, 5½ hrs. flight from New York City.
Form of Government: Republic since June 17 1944. Independent since December 1 1918.

Brief History of Iceland 

Irish monksThe first people known to have inhabited Iceland were Irish monks who settled there in the eight century, but left with the arrival of the pagan Norsemen, who systematically settled Iceland in the period 870-930 AD. Iceland was thus the last European country to be settled.

The main source of information about the settlement period in Iceland is the Landnamabok (Book of Settlements), written in the 12th century, which gives a detailed account of the first settlers. According to this book Ingolfur Arnarson was the first settler. He was a chieftain from Norway, arriving in Iceland with his family and dependents in 874. He built his farm in Reykjavik, the site of the present capital. During the next 60 years or so Viking settlers from Scandinavia, bringing some Celtic people with them, spread their homesteads over the habitable areas.

In the year 930, at the end of the Settlement period, a constitutional law code was accepted and the Althingi established. The judicial power of the Althingi was distributed between 4 local courts and a Supreme Court of sorts was conducted annually at the national assembly at Thingvellir. 

In the year 1000 Christianity was peacefully adopted by the Icelanders at the Althingi, which met for two weeks every summer, attracting a large proportion of the population. The first bishopric was established at Skalholt in South Iceland in 1056, and a second at Holar in the north in 1106. Both became the country's main centers of learning. 

In the late tenth century Greenland was discovered and colonized by the Icelanders under the leadership of Erik the Red, and around the year 1000 the Icelanders were the first Europeans to set foot on the American continent, 500 years before Columbus, although their attempts to settle in the New World failed. 

In 1262-1264 internal feuds, amounting to a civil war, led to submission to the king of Norway and a new monarchical code in 1271. When Norway and Denmark formed the Kalmar Union in 1397, Iceland fell under the sovereignty of the King of Denmark. 

After the "Golden Age" of independent Iceland ended, things went from bad to worse. The Danish kings brought about the Reformation of the Church in 1551, which resulted in Danish control over the Church, and confiscation of its great wealth. They replaced the Hansa and English trade with an oppressive Danish trade monopoly, and established absolute monarchy in 1662, thus transferring all governing power to Copenhagen. While this arrangement was very profitable for the Danish Crown, these changes were disastrous for the Icelandic economy. Further problems arose in the food supply due to cooling of the climate during the 16th and 17th centuries. 

The eighteenth century marked the most tragic age in Iceland's history. In 1703, when the first complete census was taken, the population was approximately 50,000, of whom about 20% were beggars and dependents. From 1707 to 1709 the population sank to about 35,000 because of a devastating smallpox epidemic. Twice again the population declined below 40,000, both during the years 1752-57 and 1783-85, owing to a series of famines and natural disasters. 

At the end of the 18th century the Althingi had dissolved and the old diocese replaced by one bishop residing in Reykjavik. As a consequence of the plight of the populace the trade monopoly was modified in 1783 and all subjects of the Danish king were given the right to trade in Iceland. In 1843 the Althingi was reestablished as a consultative assembly. In 1854 foreign trade was given entirely free. In 1874, when Iceland celebrated the millennium of the first settlement, it received a constitution from the Danish king and control of its own finances. 

In 1904 Iceland got home rule and finally in 1918 independence. Finally, on June 17 1944, the Republic of Iceland was formally proclaimed at Thingvellir. 

Calendar of Historical Events

874-930: Iceland is settled, mainly from Norway but also from the Viking areas of the British Isles.

930: The Althingi is established - now the world's oldest existing national assembly - at Thingvellir. Iceland's republican system of government was unique in its day.

930-1030: "Saga Age".

982: Erik ("the Red") Thorvaldsson discovers Greenland.

1000: Christianity is adopted peacefully by a decision of the Althingi at Thingvellir. The Icelander Leif ("the Lucky") Eriksson becomes the first European to set foot in America.

1003: Birth of Snorri Thorfinnsson on the East coast of North-America, the first European-American. He was the son of the Icelandic immigrants Thorfinnur Karlsefni Thordarson (Leif Eriksson’s brother-in law) and his wife Gudridur Thorbjornsdottir.

1030-1120: "Age of Peace".

1120-1230: "Age of Writing".

1230-1264: "Sturlung Age".

1241: Snorri Sturluson is killed.

13th Century: "Golden Age" when the Icelandic Sagas are written. The Sagas include some of the classics of world medieval literature and are written in the ancient Viking language which is still spoken in Iceland today.

1262: Iceland becomes part of the Norwegian crown.

1380: Iceland, with Norway, becomes part of the Danish crown.

1402-1404: Black Death plague.

1537: Norway is dissolved as a state (until 1814) and becomes part of Denmark. Iceland comes directly under the King of Denmark.

1540-1550: The Reformation.

1602: Royal trade monopoly.

1783-1785: The disastrous Lakagigar eruption.

1787: Trade monopoly is extended to all Danish subjects.

1800: The Althingi is dissolved.

1818: The National Library is founded.

1843: The Althingi is re-established as a consultative body.

1854: Monopoly on foreign trade is entirely removed.

1863: The National Museum is founded.

1874: Millennium of the settlement of Iceland is celebrated at Thingvellir. A Constitution is granted by the King of Denmark.

1879: Jon Sigurdsson, the leader of the independence movement, dies.

1904: Home rule. Appointment of the first Icelandic government minister, Hannes Hafstein.

1911: The University of Iceland is founded.

1918: Act of Crown Union with Denmark, Iceland becomes an independent, sovereign state, with the Danish King as head of state.

1920: The Supreme Court is founded.

1930: Millennium of the establishment of the Althingi Parliament is celebrated at Thingvellir.

1940: Iceland is occupied by British forces.

1941: US forces take over the defense of Iceland. Iceland becomes the first foreign country where US troops are deployed before Pearl Harbor during the Second World War.

1944: June 17. The Republic of Iceland is established at Thingvellir, following a referendum in which 97% of the population voted in favor of cutting ties with the Danish Crown.

1945: The first international flight by an Icelandic aircraft.

1946: Iceland joins the United Nations.

1947: Iceland becomes a founding member of the OEEC (forerunner of OECD).

1949: Iceland joins NATO.

1950: Iceland joins the Council of Europe. National Theater and Symphony Orchestra founded.

1951: A defense agreement is concluded between Iceland and the US.

1952: Iceland joins the Nordic Council. Fishery limits are extended to 4 miles.

1958: Fishery limits are extended to 12 miles.

1970: Iceland joins EFTA.

1971: Arrival of the first Icelandic manuscripts from Copenhagen.

1972: Fishery limits are extended to 50 miles.

1973: A volcanic eruption in Heimaey, the only inhabited island in the Westmann Islands.

1974: 1100th anniversary of the settlement of Iceland is celebrated at Thingvellir.

1975: Fishery limits are extended to 200 miles.

1986: Reykjavik celebrates its bicentenary. Reagan-Gorbachev Summit held in Reykjavik.

1994: 50th anniversary of the modern Icelandic Republic. The agreement on a European Economic Area (EEA) takes effect, giving Iceland full access to the internal market of the European Union (EU). Government


Government

Iceland has a written constitution and a parliamentary form of government. A president is elected by direct popular vote for a term of four years, with no term limit. Most executive power however rests with the Government, which is elected separately from the presidential elections every four years.

The Althingi is a legislative body of 63 members elected for a term of four years by a popular vote. Anyone who is eligible to vote can run for a Parliamentary seat, with the exception of the President and the judges of the Supreme Court. After every election, the President gives one of the parliamentary leaders of the political parties the authority to form a cabinet, usually of the largest party first. If he is not successful, the President will ask another political party leader to form a Government.

A cabinet of ministers stay in power until the next general election or a new government is formed. The ministers sit in the Althingi, but if they have not been elected, they do not have the right to vote in parliament.

Population

Iceland was settled by Norsemen from Scandinavia and Celts from the British Isles. Both the language and culture of Iceland were purely Scandinavian from the outset, but there are traces of Celtic influence in some of the Eddaic poems, in personal and place names and in the appearance of present-day Icelanders who have a higher percentage of the dark and red hair than the other Nordic nations.

The early blending of Nordic and Celtic blood may partly account for the fact that the Icelanders, alone of all the Nordic people, produced great literature in the Middle Ages. Immigration has been minimal since the first settlement, and there are no Inuit (Eskimos) in Iceland.

Iceland is the most sparsely populated country in Europe with an average of about seven inhabitants per square mile. Almost four-fifths of the country is uninhabited, the population being limited to a narrow coastal belt, valleys and the lowland plains in the south and southwest.

Around the year 1100 the population, then entirely rural, is estimated to have been about 70 - 80,000. Three times in the eighteenth century it sank below 40,000, as stated earlier, but by the year 1900 it had reached 78,000. In 1925 it had passed the 100,000 mark, in 1967 it reached 200,000 and is now over 280,000. The average life expectancy for men is 74 years and for women 80 years - one of the world's highest averages.

In 1880 there were only three towns in Iceland, where 5% of the population lived. By 1920 about 43% of the population lived in towns and villages with more than 200 inhabitants. By 1984 there were 23 towns and 42 villages where 89.2% of the population lived, while only 10,8% lived in rural districts.

Language

Icelandic is the national language and it has changed very little from the original tongue spoken by the Norse settlers. English and Danish are widely spoken and understood. Icelandic has two letters of its own, Þ/þ and Ð/ð, which were used in old English. "Þ" is pronounced "th" as in "thing" and "Ð" is pronounced "th" as in "them".

By law, Icelanders must follow the ancient tradition of deriving their last name from the first name of their father (patronymic system). For example, if a man named Erik names his son Leif, his last name will be Eriksson (the son of Erik). His daughter Thordis would be named Thordis Eriksdaughter (actually Eiríksdóttir, the daughter of Erik). She would keep her own name even if she marries. For this reason, Icelanders always have to be referred to by their first names. Last names are never used alone. Icelanders say, for example, "the President of Iceland, Ólafur Ragnar Grímsson," or even "President Ólafur," but never "President Grímsson". There is a limited number of Icelanders who do have family names.

Religion

The established church in Iceland is the Evangelical Lutheran Church. There are many Lutheran churches in Iceland. There is also a Catholic church in Reykjavik, and a number of churches for other groups. The breakdown is as follows - Church of Iceland: 92,2%; Other Lutherans: 3,1%; Roman Catholics: 0,9%; Others: 3,8%.

Education

Literacy has been universal in Iceland since the end of the eighteenth century. In 1907 school attendance was made obligatory for all children aged 10-14. Before the age of ten they were generally taught at home. In 1946 compulsory school attendance was extended, and at present it covers the ages between seven and 16. Those who wish to continue their education either go to various specialized schools or to secondary schools.

Academic education in the full sense did not begin in Iceland until 1847 with the formation of a Theological Seminary. It was followed in 1876 by a Medical School and in 1908 by a School of Law. These three institutions were merged into one in 1911 when the University of Iceland was established. Later, a fourth Faculty of Philosophy was added, primarily dealing with Icelandic philology, history and literature. The university’s main building was opened in 1940.

Social Affairs

Since World War II Iceland has enjoyed a high standard of living, comparable to that of the other Nordic countries. From 1901 to 1960 real national income rose ten-fold with an annual average rate of growth just over 4 percent. During this period the national economy underwent dramatic changes, transforming from a subsistence economy into an exchange economy through rapid urbanization and other features of industrialization. Today, the living standard is among the best in the world and per capita income is comparable to that of the United States.

The quality of housing in Iceland is very high, while the road system in the countryside is comparatively poorer than in neighboring countries. This is mainly due to the large size of the country and the small population.

Fisheries

Fish and fish products constitute more than 70% of Iceland’s exports in goods and it is the most important industry. The continental shelf around Iceland, where the warm Gulf Stream and the cold currents from the Arctic meet, offers very favorable conditions for various kinds of marine life, and are extremely rich fishing grounds. The fishing grounds, which are Iceland’s main natural resource, require strict conservation, and fish catches are tightly controlled. The main species of fish are cod, haddock, saithe, redfish, herring and capelin.

Agriculture

Agricultural land in Iceland is mostly used for growing grass for the making of hay and silage as fodder for livestock. Sheep and dairy cattle make up the main livestock in Icelandic farming.

Industries

It is estimated that the potential total exploitable hydro-electric power in Iceland amounts to 64,000 Gwh p.a., of which 45,000 Gwh p.a. are considered to be economical. However, only 4200 Gwh p.a. were being utilized in 1990.

No one knows exactly how much geothermal power is available in Iceland but it is without much doubt tremendous. In 1990 the exploited capacity had reached about 5000 Gwh p.a., bringing 81% of the population geothermal heating for their houses. Power is therefore among the most important resources in Iceland. Presently aluminum accounts for about 11% of the country’s exports, while other manufacturing products account for about 12%, including ferro-silicon.

Weather

Sayings like, "There is no weather in Iceland, only samples" or "If you don’t like the weather, just wait five minutes," indicate the variability of the Icelandic climate. It is cool, temperate and oceanic, influenced by the country’s location where the polar front separates air currents of polar and tropical origin. The weather is affected also by the confluence of two different ocean currents, the Gulf Stream flowing clockwise around the south and west coasts, and the East Greenland polar current curving southeastwards round the north and east coasts, which meet off the southeast coast. A third element affecting the climate is the Arctic drift ice brought by the polar current, which occasionally blocks the north and east coasts in late winter and early spring. The advance of drift ice causes a considerable fall in the temperature and usually some decrease in precipitation. Fluctuations in average annual temperature are more pronounced in Iceland than most other places. In Britain, for instance, the deviation is only one-third of that in Iceland.

For two to three months in summer there is continuous daylight in Iceland, and early spring and late autumn enjoy long twilights. The really dark period (three to four hours daylight) lasts from about mid-November until the end of January.

The Icelandic Coat of Arms

The Icelandic Coat of Arms (as seen on page 1) is a silvery cross in a sky-blue field with a fiery red cross in the silvery one. The shield-bearers are the four guardian spirits of the land: A bull to the right of the shield, a giant to the left, a vulture to the right above the bull, and a dragon to the left above the giant. The shield rests on a slab of basalt.

The Icelandic National Flag

The Icelandic National Flag is sky-blue (Color: SCOTDIC No. 693009) with a snow-white (Color: SCOTDIC No. 95) cross and fiery red (Color: SCOTDIC Iceland Flag Red) cross in the white cross. The arms of the crosses extend entirely to the edges of the flag, and their width is 2/9th, but the red cross is 1/9th of the width of the flag. The blue field is thus divided into rectangular squares: Those nearest to the flag-pole are equilateral and the outer squares are equally wide, but twice as long. The proportional figures for the width and length of the flag are 18:25.

Geothermal Heat

Iceland is richer in hot springs and high-temperature activity than any other country in the world. High-temperature activity is limited to certain fields. They are characterized by steam vents, mud pools, and precipitation of sulfur.

The main high-temperature areas are Torfa glacier east of Hekla and Grims lakes in the Vatna glacier. Next in order of size are Hengill near Reykjavik, which is now being exploited to provide hot water for space heating in the capital, Kerlingar mountains, Náma mountain, Kverk mountains and Krisu bay. The total power output of the Torfa glacier area, which is the largest, is estimated to be equivalent to 1,500 megawatts. Some of the high-temperature areas have workable sulfur deposits.

Hot springs are found all over Iceland, but they are rare in the eastern basalt area. There are about 250 low-temperature geothermal areas with a total of about 800 hot springs. The average temperature of their water is 75° Celsius (167° F). The biggest hot spring in Iceland, Deildartunguhver, has a flow of 150 liters (40 gallons) of boiling water per second. Some of the hot springs are spouting springs or geysers, the most famous being Geysir in Haukadalur in south Iceland, from which the international word geyser is derived. It ejects a water column to a height of about 180 feet, but has had limited activity in recent years. Another renowned geyser in the same field as Geysir is Strokkur, which spouts every few minutes. Springs charged with carbon dioxide are to be found in some districts, mainly in Snaefellsnes, but have not yet been utilized. Since the last Hekla eruption, springs rising from under the new lava have also been found to be charged with carbon dioxide.

Glaciers

Among the most distinctive features of Iceland are its glaciers, which cover over 4,500 square miles (11,800 km²) or 11.5% of the total area of the country. During the past few decades, however, they have markedly thinned and retreated owing to a milder climate, and some of the smaller ones have all but vanished.

By far the largest of the glacier caps is Vatna glacier in southeast Iceland with an area of 3,240 square miles (8,400 km²), equal in size to all the glaciers on the European mainland put together. It reaches a thickness of 3,000 feet (1 km). One of its southern outlets, Breidamerkur glacier, descends to sea level.

Avalanches are common in the northwest, north and east, where the steep mountain slopes, covered with deep snow, threaten the inhabited areas. In many of those areas farms have been destroyed and people killed by avalanches. A disaster of this kind occurred in the town of Neskaupsstadur on the East coast in December 1974, when an avalanche destroyed a large fish-processing plant and some houses, killing thirteen people. On January 17, 1995 an avalanche killed 14 people in the small town of Sudavik on the West coast.

 

History of the utilization of geothermal sources of energy in Iceland 

 When Ingolfur Arnarson sighted land on the voyage which would make him the first settler in Iceland, he threw the pillars of his high seat overboard and relied on the gods to direct him to where he should settle. His slaves found them washed ashore in a bay where "smoke" rose out of the ground. Therefore they called it Reykjavik -"Smoky Bay". But the smoke after which Iceland's capital is named was not the result of a fire, but was rather steam rising from hot springs.
Ancient records only mention the use of geothermal springs for washing and bathing. The best known examples are the Thvottalaugar (Washing pools) in what is now Laugardalur in Reykjavik, and the hot pool where saga writer Snorri Sturluson bathed at his farm in Reykholt in western Iceland.
The first trial wells for hot water were sunk by two pioneers of the natural sciences in Iceland, Eggert Olafsson and Bjarni Palsson, at Thvottalaugar in Reykjavik and in Krisuvik on the southwest peninsula, in 1755-1756. Further wells were sunk by Thvottalaugar in 1928 through 1930 in search of hot water for space heating. They yielded 14 hires per second at a temperature of 87°C, which in November 1930 was piped three kilometers to Austurbacjarskoli, a school in Reykjavik which was the first building to be heated by geothermal water. Soon thereafter more public buildings in that area of the city as well as about 60 private houses were connected to the geothermal pipeline from Thvottalaugar.
The results of this district heating project were so encouraging that other geothermal fields began to be explored in the vicinity of Reykjavik. Wells were sunk at Reykir and Reykjahbd in Mosfellssveit, by Laugavegur (a main street in Reykjavik) and by Ellidaar, the salmon river flowing at that time outside the city but now well within its eastern limits. Results of this exploration were good. A total of 52 wells in these areas are now producing 2,400 liters per second of water at a temperature of 62-132°C.
Hitaveita Reykjavikur (Reykjavik District Heating) supplies Reykjavik and several neighboring communities with geothermal water. There are about 150.000 inhabitants in that area, living in about 35.000 houses. This is way over half the population of Iceland. Total harnessed power of the utility's geothermal fields, including the Nesjavellir plant, amounts to 660 MWt, and its distribution system carries an annual flow of 55 million cubic meters of water.

How the plant works

A mixture of steam and geothermal brine is transported from the wells to a central separation station. After being separated from the brine, the steam is piped through moisture separators to steam heat exchangers inside the plant building. The steam can be piped to steam turbines for co-generation of electricity. Unutilized steam is released through a steam exhaust.
In the steam heat exchangers, the steam is cooled under pressure into condensate whose heat is then transferred to cold fresh water in condensate heat exchangers. The condensate cools down in the process to 20°C. Separated geothermal brine has its heat transferred to cold fresh water by geothermal brine heat exchangers. Since the mineral-rich geothermal brine causes scaling that coats the heat exchanger pipes, steel particles are allowed to circulate in the stream, impacting against the pipes to remove any scaling as it occurs. Cold water is pumped from wells at Grumelur, near the shore of Lake Thingvallavatn, to a storage tank by the power house. From there, it is pumped to the heat exchangers where its temperature is raised to 85-90°C.
Since the fresh water is saturated with dissolved oxygen that would cause corrosion after being heated, it is passed through deaerators where it is boiled at low vacuum pressure to remove the dissolved oxygen and other gases, cooling it to 82-85°C.

The heating process

Heat exchangers

Hitaveita Reykjavikur operated a pilot heating plant at Nesjavellir during 1974 - 1990. Various types of heat exchangers have been tested. Conventional plate heat exchangers are used for the condensation of steam from the separators and to cool the condensate. They are equipped with EPDM-gaskets and made of titanium plates to avoid stress corrosion, as it is not possible to guarantee problem free operation if stainless steel plates are used.
Conventional heat exchangers cannot be used for the separated water due to the high content of dissolved solids (TDS 1200 PPM) which would cause severe scaling of silica. A new type of heat exchanger, in the geothermal context, has been tested successfully in the pilot plant. These are the so-called "fluidized bed heat exchangers", or FBHX made by Eskla Heat exchangers BV in the Netherlands. They are shell and tube heat exchangers operating in a vertical position . Stainless steel balls, 1.5 mm in diameter, circulate in the flowstream of the separated water. They impact continuously against the pipe surfaces and remove any scaling that may form. A mechanical device is fitted to the inlet and outlet of the heat exchangers to keep the steel balls evenly distributed in the flow stream. The FBHX heat exchangers make possible the direct utilization of the heat in the water from the separators and contribute to the overall economy of the heating process.

Deaeration

The cold ground water is saturated with dissolved oxygen and becomes very corrosive when heated. A conventional thermal deaeration method is used where the ground water is boiled under vacuum after heating to remove the oxygen. The cold ground water has a pH-value of 7.5-8.5. It is partially degassed through boiling after heating. This raises the pH-value to 9.0-9.5 and the oxygen content is reduced down to about 50 ppb. The remaining dissolved oxygen is removed through injection of small amounts of geothermal steam that contains acid gases (H2S and CO2). Hydrogen sulfide gas reacts rapidly with the dissolved oxygen. The final water product then has a pH-value of 8.5-9.0. It is free of dissolved oxygen, and contains 0.5-2.0 PPM of H2S. The remaining H2S gas reacts against any oxygen absorption in accumulators and ensures that the "pleasant smell", which the users of geothermal water in Iceland have become accustomed to, is retained.
Amorphous Mg-Si scaling was formed in the distribution system in Reykjavik during the first months of operation of the plant, due to the high pH-value of the mixture of the geothermal water from the low-temperature fields and the heated ground water from Nesjavellir. Different ratios of these two water types control the pH-value. Scaling can only be avoided by reducing the amount of geothermal water in the mixture below 10-15%. Therefore the original plan of mixing these two water types in the distribution network has been abandoned. They will be used separately.

The waste geothermal water

Geothermal heating plants in high-temperature fields only utilize the thermal energy of the geothermal fluid, which, after use in heat exchangers. must be disposed of with minimum risk to the environment. This disposal can be performed in two different ways, i.e. at surface or into subsurface aquifers. Surface disposal can be carried out in a similar way to the natural disposal of flow from the hot springs, i.e. into the brook in the Nesjavellir valley, which disappears into a lava field before reaching Lake Thingvallavatn. Subsurface disposal requires that the waste water is pumped back into the geothermal reservoir. This latter method is obviously more friendly to the environment but more expensive. It can also be more difficult to operate due to scaling in the reinfection wells and their aquifers.
There are two important features of the waste water from high-temperature fields that may have a negative effect on the environment. These are the raised temperature of surface waters and ground water aquifers and the presence of hazardous chemicals in the waste water, i.e. arsenic, mercury, boron, etc. Extensive research has been carried out at Nesjavellir with respect to disposal of the waste water. Chemical and biological measurements have been carried out at Lake Thingvallavatn since 1979 to define the pre-exploitation value for future reference. All the wells at Nesjavellir were flow tested in 1984-1987 as a part of the exploration program. Large amounts of geothermal water were disposed of at the surface during these tests without any apparent effects on water chemistry at the shoreline of the lake. This is in agreement with the prediction of a ground water model that simulates fluid flow and distribution of chemicals in the ground water system at Nesjavellir.
Chemical analysis of the geothermal fluid show that dangerous chemicals, which may be expected from the condensate of the steam phase, are almost absent.
All arguments seem to indicate that surface disposal of the waste water can be used for the geothermal power plant at Nesjavellir.

THE GEOTHERMAL POWER PLANT

General outline


Due to scaling, the geothermal fluid from the Nesjavellir field cannot be used directly in the space heating distribution network. The power plant therefore uses the geothermal energy to heat cold ground water indirectly in heat exchangers. The heated water is treated so that it can be used directly in the network.
The geothermal power plant at Nesjavellir consists of the following five sub-systems all of which have separate functions:

  • Cold water supply
  • Geothermal fluid supply
  • Heating and treatment of cold ground water
  • Transmission pipeline to Reykjavik
  • Electricity co-generation
These five sub-systems of the power plant are described below along with their main functions.
The planned capacity of the co-generation power plant is 400 MA for district heating and over 80 MWe when fully developed. The design is for two power stations of similar size which will be developed in steps as follows:
Power station I:
Phase 1: 100 MWt
Phase 2: 100 MWt + 8 MWe
Phase 3: 30-37 MWe

Power station II:
Phase 4: 100 MW, + 23 MWe
Phase 5: 100 MWt + 23 MWe

The first phase of power station I became operational in September 1990 but the second phase is being built in two steps in 1991 (already in operation) and 1993.

 

The cold water supply

Cold ground water (4°C) is pumped from 30 m deep wells, at Gramelur, 6.2. km north of the power house, in a lava field at the shore of Lake Thingvallavatn. The nominal capacity of each pump is 278 kg/s, but larger pumps can be installed. Four wells have been drilled so far with only 5 m spacing.
Pumping tests of up to 600 kg/s have confirmed a very high permeability of the lava formation. The pumping station is designed so that it can be enlarged for future developments and house additional wells.
The cold water is piped 6.2 km through a DN 900Æ mm pipe from Gramelur to the power house. The pipe is made of ductile iron and has the same capacity as the transmission pipeline to Reykjavik, i.e. about 1900 kg/s. The water is piped to an 1000 m3 storage tank by the power house, before entering the heat exchangers and deaerators.

The geothermal fluid supply

The geothermal fluid supply system gathers the fluid from the production wells, separates water and steam and then pipes them individually to the power house.
Figure 15 shows a schematic flow diagram of the system. It includes two phase pipes from the production wells, separators, pressure control valves and the mist eliminators by the power house.
The wells discharge a mixture of water and steam, which is transported along the two-phase pipes to a central separator station close to the power house instead of a number of separators nearer to the wells. The two-phase pipes are therefore relatively long, which is made possible by the high enthalpy of the well fluid and favorable topography.
The dissolved solids are largely confined to the separated water phase, as steam and water are almost completely (over 99.9%) separated in the separators. The separator station is situated 400 m away from the power house. The separated steam pipeline is constructed so that some condensation occurs in the pipe. The condensate washes out remaining dissolved solids in the steam. It is drained through control valves on the pipe and the remaining droplets are removed in the mist eliminators.
Three wells (no. NJ-11, 13 and 16) are connected to the separator station for the first phase, with well NG-6 as a reserve. These wells have a very high steam fraction (enthalpy 2000 kJ/kg). It was therefore decided to operate the steam separators at 15 bara, which is an unusually high pressure for a geothermal power plant. The advantages are smaller pipes and more efficient electricity generation. Power station II will utilize wells with lower fluid enthalpy and a lower separator pressure will be more practical, probably 8 bara.
Vertical separators have hitherto been chosen for steam separation in geothermal power plants. Nesjavellir is the first one to operate conventional horizontal separators with Chevron-filters, their main advantages being less height, hence lower cost for separator building and much easier water level control. The capacity of each separator equals 35 kg/s or about 50 MWt (at 15 bara).
The mist eliminators are in principle of the same size and type (horizontal) as the main separators but are fitted with "wire-mesh" filters.
No steam turbine is installed in the first phase of the power plant. The steam pressure must therefore be lowered in control valves from 15 to 2 bara before entering the heat exchangers. This causes superheating of the steam and very high noise level due to sonic flow. The control valves are therefore placed in a separate building. Here, condensate is injected into the superheated steam to cool it to saturation conditions to protect the gaskets in the plate heat exchangers.
Electricity generation is planned in phases 2 and 3. The high pressure steam will then expand in back pressure turbines, down to 2 bara, relieving the control valves of the high flow load. The exhaust steam from the turbine will be piped directly to the heat exchangers.

The heat exchangers

The indirect heating of the cold ground water takes place in the heat exchangers. About 82% of the heat is transferred in the steam heat exchangers. The condensate heat exchangers cool the condensate from the steam heat exchangers down to 20°C and add about 14% to the heating process, whereas the heat exchanger for the separated geothermal water finally contributes only 4% to the heating in the first phase of the power plant.
Steam heat exchangers. Three out of four of the installed steam heat exchangers have titanium plates, but one of the heat exchangers has plates of ANSI 316 stainless steel for testing the long-term corrosive resistance of this material. The steam temperature is kept below 120°C (2 bara), the maximum temperature that the EPDM material in the gaskets can withstand for a longer period. They are manufactured by REHEAT in Sweden. Each titanium heat exchanger is composed of 329 plates with a total heat exchange surface area of 280 m2, whereas the stainless steel heat exchanger has 367 plates and heating surface of 312 m2. The heat transfer coefficient is stated to be 4300 W/(m2K) for clean plates.
Condensate heat exchangers. The condensate heat exchangers are of the conventional plate type. They extract the heat of the condensate from the steam heat exchangers through cooling from about 90 to 20°C. Two heat exchangers connected in parallel were installed in the first phase of the power plant, one acts as a reserve. They are manufactured by REHEAT of Sweden. The plates are made of the ANSI 316 stainless steel and have a heat exchange surface area of 190 m2
Heat exchangers for the separated water. There are two fluidized bed heat exchangers (FBHX) connected in series, which transfer heat from the separated water to the cold ground water. Each FBHX is equipped with 19 steel pipes (ID 50 mm, length 9 m). These heat exchangers contribute only 4% to the heating process of the first phase, as stated earlier. They are therefore installed mainly to obtain operational experience, as they will play an important role in power station II when the low enthalpy wells will be connected. The separated water is cooled down to 20-35°C before entering the waste water system.

Deaeration of the heated water

The main role of the two deaerators installed in the plant is to remove oxygen from the heated fresh water. It enters the vessel at the temperature of 85-88°C and is deaerated through boiling by vacuum pressure down to 83°C. The main flow enters the central part of the deaerators. The water boils vigorously as it sprays over the filling material. Steam and gas rise to the top. There the steam is condensed through injection of cold water before the gas is ejected. At the bottom of the vessel a small amount of geothermal steam is injected into the deaerated water to dissolve hydrogen sulfide. This lowers the pH, rids the water of any remaining oxygen and acts against oxygen absorption.
The deaerators are made of stainless steel. They are 2.5 m in diameter and 11 m high. The nominal capacity of each is 278 kg/s of heated water or 50% of the first phase.

The control system

The computerized control system for the geothermal power plant at Nesjavellir is identical to the one that is used to supervise and control the pumping stations for the low-temperature fields and the distribution network in Reykjavik. This control system was tailor-made for Hitaveita Reykjavikur [Magnusson and Gunnarsson, 1989]. The advantage of using the same type of control system is to reduce the investment, training and maintenance costs.
The data processors. The control system is built around process computers of the Texas Instruments 565 PC type. They take care of sequence and closed loop controls. They are situated in the cold water pumping station, in the transformer station and in the power house. Two process computers are connected together in the power house in a hot back-up configuration, as they control the most critical part of the heating process.
The SCADA System. The process computers are connected to a SCADA system (Supervision Control and Data Acquisition). The SCADA system is based on a PDP 11/83 computer in the control building at Nesjavellir . Peripherals such as color screens and printers are located in the control rooms at Nesjavellir and in Reykjavik . The power plant is operated round the clock from Reykjavik as the control room at Nesjavellir is usually unmanned. The peripherals in Reykjavik are connected to the PDP 11/83 computer through a 64 kbit/s data multiplex and a fiber-optical data link.
The color VDU display system used is of the ABB Tesselator type. One of the advantages of this system is that it can be connected to the SCADA computer by modem. The Tesselator system can therefore easily be moved around, which facilitates all process tests and remote monitoring.
Should the SCADA system fail, the power plant can be controlled from switch boards that are connected directly to the PC's processors.
The operation of the power plant is fully automated. It can run all day without any manual intervention, except during breakdowns. A closed loop control is used at all stages and reserve pumps take over automatically in case of pump failure. Restarting of the plant after shut-down is at present done manually but automation will be gradually increased as experience is gained in the operation.
The process simulator. A computer model has been developed for the dynamic behavior of the plant. It runs on a PC computer and the whole process is incorporated into the model. A lot of effort was made to make the program code as effective as possible for real time simulation.
The simulator consists of a PC computer that simulates the process, a process computer with the same software as is used for the control system of the plant and a SCADA system similar to the one used in the power plant. The process computer program had to be modified to communicate with the PC computer instead of the sensors and control system of the power plant.
The main advantages of the simulator are expected to be:
· The designers and operators can optimize regulation and control strategies in a simple way. Tests that are either too risky or time consuming can be simulated.
· Training of personnel can be carried out without disturbing the operation of the plant. Both normal operation and various types of breakdowns can be simulated.
· Development of an expert system for operation and maintenance of various parts of the system.

Ventilation of buildings

The atmosphere at Nesjavellir is contaminated with H2S gas from the geothermal field. Its concentration varies depending on weather conditions, but is estimated to be around 100 ppb on average. H2S is especially corrosive for copper and silver, materials that are common in electrical and electronic equipment. Instruments are therefore largely situated in air-tight buildings . These buildings are fitted with airlocks and an independent ventilation system where the hydrogen sulfide gas is absorbed in active carbon filters. The requirements for the indoor conditions are that the H2S content is below 3 ppb and relative humidity around 40%.
This is expected to be achieved with the ventilation system by pressurizing the building up to 100 kPa, recirculating about 85% of the air inside the building and placing the fresh air intake about 6 m above the roof of the power house (20 m above ground level).
The power plant buildings have two additional ventilation systems installed. One is for the visitors' reception hall and the other for the process halls. Both of these are conventional systems without gas purification but they use the same fresh air intake.

Output & Distribution of heat and electrtricity

Hitaveita Reykjavikur (the Reykjavik Municipal District Heating Service) supplies geothermal water to the greater Reykjavik area (except Seltjarnarnes), where over 53% of the population of Iceland lives.
Today the Hitaveita utilizes three low-temperature geothermal fields. The present maximum capacity of the low-temperature fields is about 460 MEW. Hitaveita Reykjavikur needs a further 140 MWt in order to meet peak power demands. It is not possible to increase production from these geothermal fields. They are fully exploited and their production capacity has declined by about 4% annually over the past few years due to extensive pressure drop in the reservoirs. Temperature decrease and scaling due to changes in fluid chemistry have been observed in a few production wells so their utilization was stopped.
Hitaveita Reykjavikur has carried out detailed geothermal exploration in the vicinity of Reykjavik in search of new exploitable low-temperature reservoirs. No usable reservoirs have been discovered so far. Exploration was also carried out at Nesjavellir and Kolvidarholl, which belong to the Hengill high-temperature area situated some 20-30 km east of Reykjavik. Nesjavellir has been found to be the most economical alternative to increase the geothermal production capacity of Hitaveita Reykjavikur.
New connections to the distribution system increase by 3-4% a year on average. During the past few years this has been met by increasing storage capacity from 18,000 m3 to 72,000 m3 and by the installation of additional oil-fired boilers.
The City Council of Reykjavik decided on 20 November 1986 to begin construction of a geothermal power plant at Nesjavellir. The first stage in this development is a thermal power plant with a capacity of 100 MWt. The plant went into operation in September 1990.


Well Capacity at Nesjavellir

Since 1972, all exploratory wells have been designed so as to function as production wells later. Results have been good. On average, each well has a thermal power of 60 MWt, which would yield a net output of 30 MWt from a thermal power plant. This would be sufficient to supply space heating for a community with 7,500 inhabitants.
Of 18 wells drilled so far at Nesjavellir, 13 are production wells.
Five of them have so far been activated to allow the Nesjavellir plant to produce a total thermal power of 150 MWt. The plant is designed for a maximum capacity of 400 MWt.
A numerical simulation model of the geothermal reservoir indicates that it can support an operation of the power plant over 30 years.
Since energy demand can be expected to grow beyond the productivity of the present area, Hitaveita Reykjavikur is already securing land with geothermal sources for future development in the vicinity of Nesjavellir and the Hengill fissure system. There is intense geothermal activity in a wide area around the Hengill volcanic system, both adjacent to Nesjavellir and as far west as Kolvidarholl. Studies of their potential for development are already under way.
Alongside thermal production for space heating, the Nesjavellir plant offers the possibility of economical co-generation of electricity, using steam turbines. Some of the wells produce virtually pure steam. The maximum electrical generation capacity is 80 MWe, comprising 40 MWe from a back-pressure turbine and 40 MWe from a condensing steam turbine. The plant's own energy requirement for driving the wells at a production capacity of 400 MWt is 14 MWe.

Transmission Pipe To Reykjavik

The Nesjavellir power station is situated at an elevation of 177 meters above sea level. The water is pumped through a main pipeline of 90 cm in diameter to a storage tank in the Hengill area at an elevation of 406 meters.
From there the water flows by gravity , through a pipeline which is 90 cm. In diameter, to storage tanks on Reynisvatnsheidi and Grafarholt on the eastern outskirts of Reykjavik. Those tanks are at an elevation of 140 meters above sea level, and have control valves to regulate the flow of water through the pipeline and maintain a constant water level in the tank in the Hengill area.
From the storage tank, near Reykjavik, the water is fed through pipelines to the communities which are served by Hitaveita Reykjavikur.
From Nesjavellir to Grafarholt, the transmission pipe measures about 27 kilometers in length. It is designed to carry water at up to 96 °C, with a transmission rate of 1870 liters/s.
During phase I of the project, its flow rate was around 560 liters per second, whereby the water took 7 hours to run the length of the pipe and cooled by 2 C on the way. Good insulation and a high volume of water are the most crucial factors contributing to this low heat loss. At later construction stages at Nesjavellir, the flow rate will be tripled, reducing the heat loss to less than 1 C.
The steel pipe is insulated with rockwool and covered with aluminum sheets where it lies above the ground, and insulated with polyethylene and covered with PEH plastic where it lies underground. Its high insulative properties are shown by the fact that snow does not melt on the part that lies above the surface. For environmental and traffic reasons, a 5 km section of the pipe is underground. The surface section also runs under automobile crossings at several points which have been well marked.

Eldfell, Heimaey, Iceland

Location: 63.4N, 20.3W
Elevation: 915 feet (279 m)

Last Updated: 10 April 2001
 

The 1973 eruption on the island of Heimaey is a classic example of the struggle between man and volcanoes. With a heroic effort the people of Iceland saved the town of Vestmannaeyjar and the country's most important fishing port.

Except where noted, all photographs are by the late Svienn Eirikksen, fire marshal of the town of Vestmannaeyjar. Photographs courtesy of the U.S. Geological Survey.

The island of Heimaey with the growth of the island in 1973, the location of the eruptive fissure, and the location of Eldfell, the 1973 cone. Modified from Williams and Moore, 1983.

View of Heimaey before the eruption. The town of Vestmannaeyjar and the harbor are in the foreground. Helgafell, a prehistoric cone, is in the background on the right. From Williams and Moore, 1983.

Eldfell ("fire mountain" in Icelandic) is a volcano on the island of Heimaey in the Vestmannaeyjar archipelago 15 miles (25 km) south of Iceland. In January of 1973, an eruption began along a 1.5 mile (2 km) long fissure not far from the center of the town of Vestmannaeyjar. The fissure extended across the entire island, producing a spectacular curtain of fire. Nearly all of the island's 5,300 residents were evacuated to the mainland.

Within two days, activity became localized to a central vent and fire fountains constructed a cinder and spatter cone 350 feet (100 m) above sea level.

Strong winds blew tephra from the eruption and buried homes in the town Vestmannaeyjar.

Massive block lava flows threatened the town and the fishing port.

A submarine eruption cut the cable that supplied power from the mainland. The initial eruption rate was close to 130 cubic yards (100 cubic meters) per second. By the middle of April, the eruption rate had dropped to 7 cubic yards (5 cubic meters) per second. The eruption stopped in early July.

About 70 homes and farms were buried under tephra and 300 buildings were burned by fires or buried under lava flows.

This eruption is famous because the Icelanders sprayed sea water on the lava to slow and stop its movement. It was the largest effort ever exerted to control volcanic activity. More than 19 miles (30 km) of pipe and 43 pumps were used to deliver sea water at rate up to 1.3 cubic yards (1 cubic meters) per second. By the end of the eruption 8 million cubic yards (6 million cubic meters) of water had been pumped onto the flows.

View in July 1974 of the same scene as above after removal of the lava. The building were restored. From Williams and Moore, 1983.

The town of Vestmannaeyjar and the harbor after the eruption. Eldfell and the 1973 lava flows are just beyond the town. Photograph by Robin Holcomb, U.S. Geological Survey.

Not only did the tremendous efforts save the port they actually improved it. The residents returned to rebuild their town and even used the heat from the cooling lava to construct a district heating system. This vertical aerial photograph of the island shows the improved harbor, Helgafell and Eldfell cones, and the new land added to the island. Photograph by Iceland Geodetic Survey, September, 8, 1973. From Williams and Moore, 1983.


Sources of Information:
Einarsson, T., 1974, The Heimaey eruption in words and pictures: Heimskringla, Reykjavik, 56 p.

Grove, N., 1973, Volcano overwhelms an Icelandic village: National Geographic Magazine, v. 144, no. 1, p. 40-67.

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.

Thorarinsson, S., Steinthorsson, S., Einarsson, T., Kristmannsdottir, H., and Oskarsson, N., 1973, The eruption on Heimaey, Iceland: Nature, v. 241, no. 5389, p. 372-375.

Williams, R.S., and Moore, J.G., 1983, Man against volcano: The eruption on Heimaey, Vestmannaeyjar, Iceland: U.S. Geological Survey General Interest Publication, 27 p.



 

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