Thorgils Jonasson and Sveinn Thordarson: Geothermal district heating in Iceland: Its development and benefits

Transcription

1 Thorgils Jonasson and Sveinn Thordarson: Geothermal district heating in Iceland: Its development and benefits A paper presented at the 26th Nordic History Congress 8-12 August 2007

2 Introduction... 2 Laugaveitan... 6 Hitaveita Reykjavikur (Reykjavik District Heating)... 9 Artesian-flow deep well pumps Nesjavellir District heating systems Orkuveita Reykjavikur (Reykjavik Energy) Benefits of the geothermal energy source References

3 Introduction The main purpose of this paper is to give a glimpse into the history of why and how Iceland became self-sufficient with energy for space heating. We shall also recount the history and the development of the oldest district heating system, Reykjavik District Heating, and lastly, remark on the benefits. 1 Volcanic activity and earthquakes in Iceland are due to its location on the Mid-Atlantic Ridge. These natural phenomena have for centuries wrought havoc on the people with disastrous consequences. At the same time they provide geothermal energy, which is a valuable asset, and are now as a whole considered to be a renewable energy source. In the volcanic rift zone, bisecting the country from southwest to northeast, there are hightemperature areas that are usually linked to the active volcanic systems. The low-temperature areas, however, about 250 in all, are distributed nearly all over the country. They are most scarce in the East. The most powerful ones are found on the flanks of the high-temperature areas in the volcanic zones, the largest ones in Borgarfjardarsysla in the West and Arnessysla in the South (Fig. 1). A common distinction between the types of geothermal system is that a lowtemperature system is where the temperature is less than 150 C at a depth of a 1,000 metres, but a hightemperature system where the temperature exceeds 200 C at the same depth. The geothermal areas in Reykjavik and Mosfellssveit (now Fig. 1. Volcanic zones and geothermal areas in Iceland. Mosfellsbær) are lowtemperature areas. The inhabitants of Reykjavik have for ages used the hot water in the Thvottalaugar in Laugarnes close to Reykjavik for washing clothes and for bating and the same was practised elsewhere in the country where hot springs or geothermal wells were found. The most renowned high-temperature areas are Reykjanes, Svartsengi, Nesjavellir, Hellisheidi, Namafjall and Krafla 1 We would like to extend our thanks to Reykjavik Energy and Samorka (a federation of district heatings, electric utilities, and waterworks in Iceland) for their support. 2

4 where geothermal power plants are located. Utilization of steam for generating electricity started in Namafjall in For centuries the people of Iceland slept under blankets in unheated turfhouses and had to make do with the body heat of each other. By moving out of a house made of turf and into a house of wood or concrete at the end of the nineteenth and the beginning of the twentieth century the need for space heating of some sort was necessary. At first it was fulfilled by burning coal or peat in stoves or ovens. In many houses central heating with coal furnaces was installed. It is estimated that in 1928 one out of every four inhabitants in Reykjavik enjoyed the benefits of central heating. Such heating systems facilitated connecting the houses to a district heating system when the time came. For many the cost of heating was sometimes more than they could afford. Until the middle of the last century the fuel was mostly coal, but at that time oil burners were introduced. All fuel, however, was imported. Fuel prices depended on world affairs on which Iceland had little influence. During World War I coal prices soared to their highest level (Fig. 2). The same happened during World War II and in the seventies oil crisis hit the world. Soon after the introduction of coal furnaces the idea of utilizing geothermal heat for space heating popped up. Experiments proved that it was technologically possible and could be advantageous. A farmer at Sudurreykir in Mosfellssveit piped water from a geothermal well to his house in 1908 and in 1911 a farmer at Sturlureykir in Borgarfjordur harnessed steam from a hot spring for Fig. 2. The chart depicts the coal prices during World War I up till 1930 and by comparison a worker s basic salary. space heating. There was also a mention of how much the net savings for the population of Reykjavik would be if all houses were heated with geothermal heat. Such heating would also be healthier than the burning of coal. 3

5 For the first three decades of the twentieth century the harnessing of geothermal heat and utilizing it for that purpose and for generating electricity as well was widely discussed. In 1930 the so called Laugaveita began operation. Out of it grew Hitaveita Reykjavikur (Reykjavik District Heating), now part of Orkuveita Reykjavikur (Reykjavik Energy), but its adolescence years were not without setbacks. For a number of years there was a shortage of water which meant that not all the town's inhabitants could enjoy the benefits of district heating. Consequently, its network did not develop as it should have and what made things worse was the steady stream of newcomers. The population of Reykjavik more than doubled in the forties. Technological difficulties added to other problems. In 1960 a decision was made to provide all dwellings in Reykjavik with geothermal space heating. A decade later, the goal was to supply all houses in the vicinity with hot water and harness geothermal heat elsewhere in the country for the same purpose as well. At that time district heating had been introduced in many of the low-temperature areas where hot water was present near the earth's surface but their history, their victories and setbacks are in many respects similar to that of the history of Reykjavik District Heating. Laugaveitan and Reykjavik District Heating were pioneering projects and in many ways a prototype for district heating systems that were established in a number of communities in the North and the South where there were a geothermal fields nearby. The largest ones were the district heating in Olafsfjordur (1944), Hveragerdi (1947), Selfoss (1948) and Saudarkrokur (1953). Community schools were built in "hot areas", i.e. in places where hot springs were a short distance away. No one expected that geothermal heat could be found in "cold areas". But they have been proven to be wrong. There and elsewhere new technology in drilling has made all the difference, for example in the East (Fig. 3). In the Northwest, Skagafjardarveitur is the most successful of all other district heating systems but the oldest one is Olafsfjor- Fig. 3. 4

6 dur District Heating. In the Northeast, Nordurorka (Akureyri Municipal and Power Company) is the largest but in the East Hitaveita Egilsstada serves the greatest number of people in that area. In the South Selfossveitur is the largest system but Hitaveita Hveragerdis, which is now one of Reykjavik Energy's daughter companies, has the longest history. For decades hot water came solely from boreholes in the low-temperature areas but since 1976 Hitaveita Sudurnesja in Svartsengi has utilized geothermal steam and saline brine to heat cold ground water up to 80 C for space heating. In 1990 Hitaveita Reykjavikur harnessed geothermal steam in Nesjavellir, about 28 kilometres east of Reykjavik, for the same purpose. 5

7 Laugaveitan In the beginning of the twentieth century Reykjavik underwent metamorphosis; it changed from a town to a city. The first major projects were the laying of a water pipeline from the Gvendarbrunnar to Reykjavik in 1909 and the construction of quays and piers in Reykjavik harbour, finished in The water system was of course of great importance for those who lived in Reykjavik, but only a few could foresee hot water being piped through pipes all over town in the same way as the cold water. Reykjavik's council decided in 1907 to build gas works for lights and cooking according to a model from abroad although a number of people, both laymen and experts alike, had for years drawn attention to the Ellidaar River where it was feasible to build a hydroelectric power plant. The Ellidaar River runs to the sea from Ellidavatn Lake which belongs to a farm with the same name. The power plant was built in 1921 and was inaugurated in June Its first phase had a capacity of one MW. Fully constructed its capacity was three times greater Rafmagnsveita Reykjavikur (Reykjavik Electricity) was established that same year. The electricity from the Ellidaar River was only intended for lights and cooking but neither for space heating nor industry. Demand was immediately greater than the Fig. 4. Drilling in the Thvottalaugar. power station could supply and since harnessing geothermal steam in Larderello in Italy for the production of electricity was known to some it was decided to try drilling for steam in the Thvottalaugar area in order to generate electricity. It just so happened that a drill rig was available in Reykjavik (Fig. 4). A gold-mining company in Reykjavik had bought it from Germany a few years earlier. Only two boreholes had been drilled in the Vatnsmyri, where Reykjavik Airport is now, when the company went bankrupt. Consequently, the drill rig had not been used for a number of years. The con- 6

8 sensus was that its capacity (hoisting capacity, weight of pipes and pump pressure) would be sufficient to drill boreholes to a depth of 200 metres. Reykjavik Electricity bought the drill rig and had it transported to Thvottalaugar in the spring of Drilling commenced on June 28 and ended early in All in all, 14 boreholes were drilled. The deepest one was metres. It became clear that by drilling it was possible to obtain more water than the geothermal area had yielded before. At first, inaccuracy in the measuring of the flow indicated that it was 22 l/s. More accurate measurements indicated that the artesian-flow was at least 15 l/s of hot water with a temperature of 91 C which was well suited for space heating in Reykjavik. But the steam traction was insufficient for traditional turbines for generating electricity. At that time a housing project was underway in Skolavorduholt which then was the easternmost part of Reykjavik. Among the houses were official buildings like the Landspitali (the National Hospital), Austurbæjarskolinn (an elementary school) and the Sundholl (an indoor swimming pool). Reykjavik Electricity made space heating of the new houses in Skolavorduholt with geothermal water a reality by building a pumping station in Thvottalaugar and laying insulated and welded steel-pipes from there to Skolavorduholt. The length of the pipeline was 2,450 metres and the pipe's diameter 175 mm. On November hot water from Thvottalaugar flowed to the first building, the Austurbæjarskoli school. Temperature drop on the way there was only 3 C. A swimming pool, that was built in Laugarnes in 1908, also got water from the pipeline and the Laugarnesskolinn elementary school when it came into use in This district heating system is usually called Laugaveitan. The pumping station in Thvottalaugar still exists with all its equipment. All in all, the water was sufficient for space heating of about 70 houses, 50 of which were dwellings where 2 3% of the city's population lived. The main problem the Laugaveitan faced was that it had only the abovementioned 15 l/s to sell. Endeavours were made to use all backflow where possible. The capacity of the Laugaveitan was only 3.4 MW when all available water was utilized down to 35 C. Its water supply could therefore not possibly fulfil the wishes of the residents in other districts in Reykjavik to be connected to the pipeline. 7

9 But they were quick to grasp that it was to their advantage to live in the district heating area in the Skolavorduholt and not having to burn coal or even peat in furnaces as was sometimes done when times were harsh. In the meantime, or until a district heating network had reached every house in Reykjavik, oil burners replaced the coal furnaces and many a house proprietor had to use them for decades. But the district heating system in Reykjavik was an issue in the council elections for a number of years and the wishes of the people for equal quality in space heating were finally fulfilled (Fig. 5). Fig. 5. District heating was one of the main issues in the council elections in Reykjavik in Here there are two opposites depicted, on the one hand black coal smoke looming over the city so that the sun is blackened, and on the other clean air when a district heating system has been introduced and the population can see the sun. 8

10 Hitaveita Reykjavikur (Reykjavik District Heating) Hitaveita Reykjavikur (Reykjavik District Heating) took over Laugaveitan by providing hot water from Sudurreykir in Mosfellssveit in the autumn of 1943 (Fig. 6). On November 30 that year, Hnitbjorg in Skolavorduholt (the art museum of Einar Jonsson) was the first house connected. Construction work was finished a year later but at the end of ,850 houses hat been connected to the system with 3,375 central heating systems (Fig. 7). The houses that Laugaveitan provided with hot water are not included. The amount of water from Sudurreykir was 210 l/s, but by pumping air down the boreholes it was increased to 287 l/s. The water temperature at the pumping station was 85 C. Six years later 3,357 houses were supplied with water from the system. Nine out of ten of these were dwellings but this was little more than half of all dwellings in the city. In the autumn ,275 or a little over half of the city's population occupied these houses. Reykjavik District Heating was operated until 1999 when it was merged with Reykjavik Electricity and Reykjavik Waterworks into a new company, Orkuveita Reykjavikur (Reykjavik Energy). Fig. 6. A borehole at Sudurreykir. The houses in the background are the ones first heated with geothermal water in Iceland in Fig. 7. There is a clear change in the share of energy sources in 1943 when Reykjavik District Heating began operation. From the beginning, the procurement of hot water has mostly been based on boreholes in Reykjavik, then in Mosfellssveit and finally in Nesjavellir. For a long time it also de- 9

11 pended upon artesian-flow of the hot water to the earth's surface first in Thvottalaugar and then in Mosfellssveit. The municipality of Reykjavik and the national government established the company Gufuborun rikisins og Reykjavikurborgar (The State and Reykjavik Steam Drilling Company). The purpose was to buy a big earth drill rig of the best kind and have it replace the drill rigs that Reykjavik District Heating had been operating that were small, old and out of date as well. The new drill rig, the Steam-drill, was first used in the spring of 1958 and was operated until It could easily drill down to a depth of more than two thousand metres but the deepest hole it drilled in Reykjavik was 2,312 metres deep. The drilling speed and the new rig s capability to drill wide boreholes made the cementing of the casing to great depths much easier than before, thus facilitating the instalment of pumps in the wells. 10

12 Artesian-flow deep well pumps Artesian-flow is caused by a difference in pressure. Hot water in the geothermal areas rises but cold water dissipates into the ground on its outskirts. It was obvious that by lowering the level of the hot water more water could be retrieved. The best method was to use well pumps, usually called deep well pumps. It was, however, not self-evident that deep well pumps, that were useful in pumping cold water, would do the same for hot water. In the years from 1942 through 1965, a number of boreholes were added in various places in Reykjavik, all characterized by the letter H. All in all, these and the boreholes in Thvottalaugar were 42. It was impossible to install deep well pumps in but a few of them. Reykjavik District Heating purchased the first deep well pump of the type Craelius from Sweden in the autumn of It was installed in borehole H-16 which is located where the farmhouse of the ancient farm Raudara once stood, not far from Laugarnes. The pump was first tested on March Problems immediately arose bearing tolerances and seals changed at the high temperature because of thermal expansion and eventually the rotation of the lineshaft stopped. The only solution at that time was to allow for more clearance of all the parts in a lathe. Nevertheless, 4 l/s of 91 C hot water was pumped till 1967 from borehole H-16. However, it was possible to install larger pumps in boreholes drilled with the Steam-drill. In 1958 a deep well pump from Craelius was installed in one of them, located where there is now a parking area on the north side of The Kjarvalsstadir Gallery (Fig. 8). It is called R-2 but all boreholes in Reykjavik that are wider, deeper and with a more rigid casing than the H- boreholes, are characterized with the letter R, the deepest one more than three kilometres deep. Before long, deep well pumps were submersed in R-5 and R-7. By the summer of 1963 Craelius deep well pumps had been installed in a number of R-boreholes. In the spring of 1963 Reykjavik District Heating published a tender notice for deep well pumps. Bids came from producers of pumps in Europe and the United States. First, pumps of the type Floway from Goulds Pumps International in New York were bought. The first Floway-pump was installed in R-21 in September 1963 and the next two, in R-11 and R-15, in December that same year. These pumps could easily be submersed to a depth of 60 metres. 11

13 Th. Jonasson In the summer of 1964 the first pump from Fairbanks Morse was bought from the company's factory in Pomona in California. Again in 1965, several pumps were added, from Fairbanks Morse and Gould Pumps. There was some difference in the technical arrangement of the bearings in these Fig. 8. The borehole R-2 at Kjarvalsstadir in Reykjavik. pumps. But the result was the same as before; deep well pumps were expensive. Nevertheless, they often failed, especially during the coldest periods of winter when they were most needed. As it turned out, bearings made of a white metal alloy lasted the longest. Finally, a solution to the bearing problem was found when Johannes Zoëga, the director of the Reykjavik District Heating, came up with the idea of having bearings made of Teflon which is an especially heatresistant material as is well known and was discovered by DuPont in the United States in At Sudurreykir in Mosfellssveit the Steam-drill was first used in the winter of Ten years later, both there and in Th. Jonasson The first deep well pump with Teflon-bearings was bought from Fairbanks Morse in It was put to a test in Laugarnes in the spring of 1967 and the result was not a disappointment. To make a long story short, similar pumps had been installed in all the best wells when a new year arrived. The bearing problem was history. It has become clear that deep well pumps of that type can run for years. Water production has been constant and reliable ever since. Fig. 9. The Steam-drill drilling in Mosfellssveit. 12

14 Mosfellsdalur, the boreholes yielded abundant water (Fig. 9). Deep well pumps could easily be installed in them to increase the water production. At around this time 98% of the population in Reykjavik were connected to Reykjavik District Heating. The deep well pumps ensured that hot water was available for steam heating in the neighbouring towns of Kopavogur, Gardabær, Hafnarfjordur, Alftanes and Kjalarnes when the market called for it. Oil prices soared on the world markets in the autumn of After that the government emphasized the use of indigenous energy for space heating instead of imported oil. 13

15 Nesjavellir Reykjavik District Heating bought Nesjavellir in Grafningur in the summer of It is a large farm 27 square kilometres in size. To the north of Nesjavellir is Thingvallavatn, but the mountain Hengill to the south. The value of Nesjavellir lies in the geothermal heat. Nesjavellir is north of the high-temperature area of the Hengill and all over the earth s surface there are geothermal manifestations. In the summer of 1965 the first three boreholes were drilled in search of steam. Drilling was continued in 1967, 1970 and Then there was an intermission until 1982 but from 1984 to 1987 drilling was completed and steam ensured for the first phase of a power station (cf. fig. 10). The highest temperature in a borehole in Iceland was measured in a borehole in Nesjavellir in the summer of The borehole is 2,265 metres deep. Close to the bottom there is an over-pressured vein in the rock stratum where a thermometer showed a temperature in excess of 380 C. From the beginning it has been known that because of the high-temperature the hot steam would have to be used for heating cold water to a suitable temperature for space heating like in Svartsengi as mentioned above. Consequently, in the years of 1975 to 1982 drilling for cold water continued, first Fig. 10. A borehole at Nesjavellir. in Nesjahraun but then in Gramelur on the banks of Thingvallavatn. The boreholes in Gramelur were only 31 metres deep but yielded abundant cold water. Gramelur is six kilometres away from the power station that was built in Sig. Hardarson 14

16 District heating systems At the end of the year 2006 there were 22 district heating systems with a confirmed directive and a franchise for the distribution and selling of hot water within its network. The Ministry of Industry and Commerce confirms the directive and the franchise. The networks are 61 when all are counted. However, district heating systems without a directive, small and very small, are nearly two hundred. They are sometimes referred to as B- networks to distinguish them from the networks with a directive. They are most numerous in Arnessysla and Borgarfjardarsysla. Information about their operation is limited but most of them utilize boreholes a few use hot springs or geothermal wells. Of those small systems, that sell water from its own boreholes and serve a population of a hundred or more, the largest ones are Hitaveita Reykdæla at Laugar in Reykjadalur in the North, Hitaveitufelag Gnupverja in the South and Hitaveitufelag Hvalfjardar in the West. District heating systems with a directive use 185 boreholes, 18 of which are reserve holes, and eleven hot springs and geothermal wells. Of those Deildartunguhver in Reykholtsdalur in Borgarfjordur yields the most abundant water. It is estimated that the artesian-flow is 180 l/s. Table 1. The general rule is to utilize hot water down to 35 C. Supply of water from the above-mentioned boreholes, hot springs and geothermal wells is close to 7,100 l/s and the capacity 1,700 MW. Rafmagnsveitur rikisins (State Electricity), Orkubu Vestfjarda and Hitaveita Sudurnesja also use electric and oil boilers to heat cold water up to 80 C (R/O-systems). Such boilers are also present in Vestmannaeyjar in the South, in Patreksfjordur, Flateyri, Bolungarvik, Isafjordur in the Vestfirdir Peninsula (Westfjords) and in Seydisfjordur and Hofn in Hornafjordur in the East. In Sudureyri in the Vestfirdir Peninsula, however, 15

17 geothermal water, nearly 60 C hot, is heated up to 70 C. The electric boilers capacity is 50 MW, the oil boilers are 54.6 MW. On 1 December 2006 about nine out of ten of the total population of Iceland had district heating, 86.7% of those or 269,562 were connected to a district heating system utilizing geothermal water (Table 1). Electricity for heating for the 9.5% of the population with electrical heating is subsidized by the state and energy companies to ensure that everyone has access to space heating at a reasonable prize. The share of geothermal space heating may exceed 90% in the future for two reasons, i.e. movement of the population and the incessant exploration for geothermal energy in the so-called cold areas. Collection pipes from the geothermal areas were at the end of the year 2005 nearly 750 km long and would reach more than half the way around Iceland if they were laid along the Ringroad. But Table 2. the distribution network is much longer, more than five times that distance or in all 3,804 kilometres (Table 2). There is a double distribution network in the systems that use electric or oil boilers. A number of systems have a single network but 25 35% a double network. Measured or estimated hot water consumption in 2005 was more than 118 million cubic metres (23,462 TJ). Most of it is for space heating, swimming pools come second. At the end of the year 2006 swimming pools were close to 170. Other usage is snowmelting, greenhouse growing, fish farming and industry but the drying of fish with hot water is a grow- Fig

18 ing industry. One fifth of the total geothermal usage is for generating electricity (Fig. 11). Most district heating systems sell the water through a volume meter. At the end of 2005 the meters numbered all in all 66,522. Skagafjardarveitur, Hitaveita Olafsfjardar and Hitaveita Sudurnesja sell almost solely through previously adjusted limiters. Orkuveita Reykjavikur sells only through limiters to summer houses. Limiters were 8,743 at the end of The State Electricity sells hot water through energy meters in Seydisfjordur and Hofn in Hornarfjordur and also Orkubu Vestfjarda in the Vestfirdir Peninsula where there are oil and electric boilers. The turnover of district heating systems with a directive (from sales of water and renting of meters) amounted to 8.6 billion kr. in

19 Orkuveita Reykjavikur (Reykjavik Energy) As already mentioned Reykjavik District Heating, Reykjavik Waterworks and Reykjavik Electricity were merged into Reykjavik Energy. Reykjavik Energy sells hot water in Reykjavik, Kopavogur, Hafnarfjordur, Gardabær og Alftanes but has been expanding elsewhere, in the West and South. The distribution system of Reykjavik Energy reaches from Grundarhverfi in Table 3. Kjalarnes to Vallarhverfi east of Hvaleyrarholt in Hafnarfjordur. Part of it is double and thus it is possible to utilize the backflow for mixing. Sales in 2005 were 60 million cubic metres. Maximum load that same year was 14,400 cubic metres per hour. That equals 3,811 l/s or 825 MW. Reykjavik Energy is as a whole ten times the size of the one next in line, Hitaveita Sudurnesja (Table 3). 18 Sig. Hardarson The average water temperature in Laugarnes in 2005 was C. R-11 yields the hottest water, C. The average production was 160 l/s, highest in 1983, Fig. 12. The reservoir tanks in Oskjuhlid in Reykjavik and the old pipe220 l/s. The average line from Mosfellssveit. A steel tank, that was later added, is in the foreproduction from 1963 ground. to 2005 was 163 l/s. The capacity in Laugarnes in 2005 based on water-production, temperature and utilization down to 35 C is 60.2 MW.

20 Sig. Hardarson As previously mentioned, hot water from Mosfellssveit has been used in Reykjavik since 1943 but that year the laying of the first pipeline from Mosfellssveit to the two Fig. 13. A new pipeline laid from Mosfellssveit reservoir tanks in Oskjuhlid in Reykjavik for regulating water was completed. The first pipeline was of steel, 350 mm in diameter, in a concrete culvert and double in order to ensure that there would not be a shortage of water in Reykjavik if one of the two failed. The main insulation material was dried turf mats. A new pipeline was laid to Reykjavik from 1972 to It is 700 mm in diameter (Fig. 12). The reservoir tanks in Reykjavik were eight originally, built in the years (cf. fig. 12). Three were of concrete but the others of steel. The capacity of each steel tank was 1,000 cubic metres but of each of the concrete tanks 1,118 cubic metres. S. Thordarson Shortly after 1960 two steel tanks with a capacity of 9,000 cubic metres each were temporarily added. They were located north of the old ones and used for some years. They were dismantled in 1985 and assembled again to serve the main line from Nesjavellir as did a third steel tank that was added in Its capacity is 11,000 cubic metres. In Grafarholt, a Fig. 14. A deep well pump, one of many in Reykjavik. In the background is Hotel Nordica. In front of the hotel there is another deep well pump. 19

21 new housing area in the east of Reykjavik, there are also six 8,000 cubic metre steel tanks to serve the line. The old tanks in Oskjuhlid had served their time when they were taken down in The new tanks in Oskjuhlid are six, all of steel and have the same capacity, 4,000 cubic metres each. Of course they serve the same purpose as before, to collect water and regulate it under a varying load. On top of the tanks is the Pearl, a panorama view deck and a restaurant of steel and glass. The rotating floor is electrically driven and completes a full rotation in two hours. The diameter of the glass dome is 40 metres. Apart from the reservoir tanks in Oskjuhlid there are not many signs of structures belonging to Reykjavik District Heating. The earth s strata serve as a huge reservoir tank and collection pipes and the distribution networks are for the most part underground. S. Thordarson S. Thordarson The manmade structures are inconspicuous small buildings here and there in Reykjavik that house Fig. 15. A pumping station in Reykjavik, Bolholtsstod. the motor for a deep well pump and pumping stations for the distribution system, 21 on in all (Fig. 14 and 15).. 20

22 Benefits of the geothermal energy source There is no doubt that the geothermal energy is Iceland's most valuable energy source. Energy use per capita in Iceland is among the greatest in the world but the proportion of renewable energy is nowhere as high. Geothermal energy was a little over 50% of all primary energy available in Iceland in 2004 (Fig. 16). For the most part, it was used for space heating or 75%. But that is only half the story. It has been estimated that only about 1% Fig. 16. of sustainable geothermal energy in Iceland has been used so far. The financial benefits of utilizing the geothermal energy source are immense and it follows that less pollution of the environment is also a benefit as was foreseen in the beginning. It has been estimated that from 1991 to 1995 the sum on the heating bill for Iceland would on average have amounted to nearly 13 billion kr. per year if all houses had been heated with oil burners. In the same period, hot water was sold for 5,5 billion kr. The difference, about 7,5 billion kr., was the sum saved every year these five years or 30 thousand kr. per capita. That sum equalled for example the total value of export earnings for deep sea fishing in In Reykjavik savings each year are obviously higher than elsewhere or on average the same amount as the sales of hot water. The difference is net savings (cf. fig. 17). If oil had been used for space heating in Reykjavik, emission of carbon dioxide would have been equal to the emission from three aluminiumplants of the size of the plant in Straumsvik, south of Reykjavik. By harnessing geothermal heat for space heating, the air is cleaner, healthier, as predicted in the beginning. This seemed evident from the start. For ex- 21

23 ample, in the fifties and the sixties, doctors in Reykjavik saw a marked reduction in cases of common cold caused by smoke from coal furnaces in comparison to cases elsewhere. Most important of course is the fact that the standard of living seemed and is higher than it would otherwise have been. And last but not least, it is obvious that Iceland is now close to being fully selfsufficient with energy for space heating. Fig. 17. The effects of the oil crisis, especially in 1983, are evident in the graph. 22

24 References Jonasson, Thorgils. Jardboranir a Islandi. BA-thesis. Iceland University Gull og vatn i Reykjavik. Reykjavik og vatnsöflunarvandinn. Natturufrædingurinn 74 (3 4) Pp , Orkumal Palmason, Gudmundur: Jardhitabok. Edli og nyting jardhita. Hid islenska bokmenntafelag. Reykjavik Steingrimsson, Benedikt: Evidence of a supercritical fluid at depth in the Nesjavellir field. Pp Proceedings Fifteenth Workshop Geothermal Reservoir Engineering. January 23 25, Stanford University, Stanford, California. Thordarson, Sveinn: Audur ur iðdrum jarðar. Saga hitaveitna og jardhitanytingar a Islandi. Hid islenska bokmenntafelag. Reykjavik Zoëga, Johannes. Æviminningar. Heimur. Reykjavík Borholudælur Hitaveitu Reykjavikur. A presentation Jardhitafelagid 15. April