Geothermal Energy. Þórir M. Wardum VIA University Horsens Dissertation 7. Semester

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1 Geothermal Energy Þórir M. Wardum VIA University Horsens 2010 Dissertation 7. Semester

2 Preface This dissertation is a part of my curriculum for the 7 th semester B.sc in Architecture Technology and construction management. To make this report I have read many articles and books on this subject and I also visited a real geothermal energy power plant and got a private tour in it. The reason for my choosing this subject was that I am from Iceland and it has always been around me, but I have never really put much thought in it until I moved to Denmark. That s when I really realised how lucky we are to have so much access to geothermal energy. It s cost also intrigued me when I got my electricity and heat bill when I was living in Denmark. This dissertation is built up into 9 chapters to make it easier to read. I built up my report basically from what areas you can find it and all the way to technical data about harnessing it. In the conclusion I will clarify all my research questions which I asked myself in the problem statement. Abstract My research focus in this report is geothermal energy, which such questions as What is geothermal energy and where does it come from. I have used various research methods, such as books, articles and study guides, to find the information I needed to answer these questions, as well as the others I have asked myself in the problem statement. My findings have shown that it comes from deep in the earth, and in specific areas around the globe, where the conditions are right. In my conclusion I state that geothermal energy is a very good contender for replacing coal and oil power plants, but in order for this, it is necessary to reform the way governments handle energy supplies by taxation and other methods. 2

3 Table of Contents Preface... 2 Abstract... 2 Table of Figures... 5 Introduction Problem Formulation what is it, and where does it come from? Where do you find geothermal energy Tectonic plates Divergent boundaries Convergent boundaries Oceanic Continental Convergence Oceanic-Oceanic Convergence Continental-Continental Convergence Transform Fault Boundaries Countries using geothermal energy to produce electricity The depth of geothermal energy The temperature of geothermal energy Low heat zones High heat zones Harnessing geothermal energy Dry Steam Flash steam Binary steam Research and exploration methods Schlumberger method

4 3.2 TEM method MT-measurement Ground vibration measurements A reflectivity measurement Wave breaking measurements Drilling for geothermal energy Geothermal powerplants Reykjanesvirkjun Svartsengi Power plant Power plant Power Plant Power plant Power plant Power plant The Geysers Advantages and disadvantages of geothermal energy The advantages The disadvantages Future of geothermal energy Conclusion Literature list

5 Table of Figures Figure 1: The earth layers... 7 Figure 2. The plate boundaries in the world... 8 Figure 3. Mid Atlantic ridge divergent... 8 Figure 4. Temperatures at depth of 6 km in the USA Figure 5. Heat zones in Iceland Figure 6: Dry Steam plant Figure 7: Flash steam plant Figure 8: Binary cycle plant Figure 9: Schlumberger method Figure 10: A 2D data received from Schlumberger measuring Figure 11: TEM Method Figure 12: A 3D data received from TEM measuring Figure 13: The most common drill head Introduction In this report I wanted to investigate what geothermal energy is, and where it comes from. The report is divided up into eight separate chapters, excluding the literature list, which enables me to start from the basics of what geothermal energy is, to where you can find it, and at what depth. The following chapters after that are about the more technical aspects of geothermal energy, followed by information about some of the largest geothermal power plants in Iceland. What I hope to achieve in writing a report about this subject, is a broader knowledge in this field, which I possibly could use after I am finished with the 7 th semester. I have developed a strong interest into the techniques and developments of this field, and am avidly following the progress of the local power stations. At the moment in Iceland, these geothermal power plants are under a lot of media coverage because the government in power have halted much of the progress going on, by the wishes of the 5

6 environmental party. This is something a significant amount of the population is displeased with, as their ground for doing so doesn t hold much ground. This is one of my main reasons for writing this report, as I will fully understand the important information about geothermal energy, and be able to make up my own mind whether or not I believe their claims about it being destructive to the surrounding environment to be true. 1. Problem Formulation What is geothermal energy? Research questions: 1. Where do you find geothermal energy? 2. How deep do you need to drill for it? 3. How hot is the water or the steam? 4. How do you harness it? 5. Can you use it to make electricity? 6. What are the advantages and disadvantages of geothermal energy? 7. What is the future of geothermal energy? 6

7 2. what is it, and where does it come from? Geothermal means earth heat. The geothermal energy comes from under the ground and has its source all the way from the earth s core, as you go deeper into the earth s ground the hotter it is 1. The earth has 5 layers, inner core, outer core, mantle, upper mantle and the crust 2. The earth s core is about 6000 Celsius, and if you start from the earth s surface and go down, the temperature rises about 17 to 30 Celsius per every kilometre 3. Geothermal energy comes from two things, Figure 1: The earth layers primordial and radioactive decay. Primordial heat comes from when the earth was formed 4.5 billion years ago, from the energy created when masses from colliding cosmic matter happened. Radioactive decay is from materials that were radioactive when the earth was formed and it still today produces heat underground additionally with the earth s core. When the earth s atmosphere cooled down and also cooled the ground it works as an insulator for the massive heat in the ground Where do you find geothermal energy The geothermal energy escapes to the surface through cracks in the earth s layers. The cracks are where the tectonic plates meet; it s also often called the ring of fire. Tectonic plates are floating on top of one of the earth s layers called the mantle. The earth has many tectonic plates around the world. And where the plates meet there can be volcanoes and earthquakes also is geothermal/ is geothermal/ 5 of fire volcanoes/ Figure 1: 7

8 2.2 Tectonic plates There are many tectonic plates and they are always moving and they are all connected in a chain, no plate moves without affecting another plate. And that s what creates the geothermal areas as well as earthquakes and volcanoes on the boundaries of these plates 6. There are 3 main types of plate boundaries 7 : Figure 2: The plate boundaries in the world 2.3 Divergent boundaries Divergent boundaries exist when two plates are pulling away from each other. When that happens under the sea it just creates more ocean but when it happens on land which is actually happening in my homeland it will make a rift or a small canyon (but very slowly) until it will eventually tear Iceland apart as you can see in this picture I took at Reykjanesskagi in Iceland. Figure 3: Mid Atlantic ridge divergent 2.4 Convergent boundaries A convergent boundary exists when two plates collide with one another and one of them gives in and slides under the other plate. You will find mountains and volcano areas where the plates converge Figure 2: Figure 3: Personal photo 8

9 There are three kinds of convergence boundaries 9 : Oceanic Continental Convergence Oceanic continental convergence is when an oceanic plate meets a continental plate and pushes under. The continental plate pushes up and creates mountains. But as the oceanic plates get pushed down it breaks into small pieces and creates earthquakes and volcanoes Oceanic-Oceanic Convergence Oceanic-oceanic convergence is when two oceanic plates meet under the sea and one of them pushes under it, creating a crack. Often they create volcanoes and islands like in Vestmannaeyjar, the volcano in Iceland. It created an island called Surtsey today Continental-Continental Convergence Continental-continental convergence is when two plates hit each other head on but don t really push one of them down but breaks them up and pushes them up and sideways, creating mountains. For example; the Himalayas were formed that way millions of years ago. 2.5 Transform Fault Boundaries Transform fault boundaries 11 are boundaries were two plates are running and hitting each other horizontally with one another and it can create large earthquakes. Almost all of the fault boundaries are down in the ocean floor. There are very few places on the planet where this happens on land, but one of the few places it occurs is California in USA

10 You can also find geothermal areas in rifts on the plates and the most famous one is the Rio Grande rift that made the national Yellowstone park in Colorado. It goes all the way from Colorado (USA) down to Mexico Countries using geothermal energy to produce electricity From a report from the International Geothermal Association done in 2007 it says that 24 countries are using geothermal energy for direct electricity production but 72 countries use it for both district heating and electricity 13. List of top 10 countries that use geothermal energy for producing electricity 14 : 1. USA MW 2. Philippines 1909 MW 3. Mexico 953 MW 4. Italy 791 MW 5. Indonesia MW 6. Iceland MW Japan MW 8. New Zealand 437 MW 9. El Salvador 161 MW 10. Costa Rica MW energy.org/currentuse.aspx Report GeoThermal Energy Indonesia.html

11 2.7 The depth of geothermal energy The depth is different from where you are in the world and the heat zones are characterized into two, high and low heat zones. Most holes in Iceland are from 50m up to 4000m, all depends if you are drilling for low heat or high heat 16. But Iceland is a special case when it comes to this. Most holes are Figure 4: Temperatures at depth of 6 km in the USA from 1000m to 4000m for example the largest geothermal plant in the world, The Geysers in San Francisco California there the holes are up 3000m The temperature of geothermal energy The temperature is different from where you are in the world and the heat zones are characterized into two, high and low heat zones. The high heat zones are measured as over 200 in above 1000m depth and low heat areas are measured as lower than 150 in 1000m depth 18. Anything lower than 180 is not usable for making electricity that s why it is characterized into two, low and high zones Low heat zones Low heat zones is when the heat is lower than 150 in 1000m depth but it can be found just 50m to 200m down in Iceland. 87% of all homes in Iceland are heated directly from Figure 4: geothermal be a major part of our energy plan

12 the hot water and also the tap water is fresh hot water. According to studies there are about 250 low heat areas in Iceland High heat zones High heat zones is when the heat is higher than 200 in 1000m depth and they are not as common as the low heat areas as you can see in the picture about the heat zones in Iceland 21. Figure 5: Heat zones in Iceland 2.9 Harnessing geothermal energy Today there are 3 types of geothermal power plants 22 : Dry Steam Dry steam power plant is where you use direct steam from the ground and it generates the turbines or the generators just with the steam itself. The steam temperature is usually above 235. This is the oldest method of using geothermal energy and the cheapest way also. Figure 6: Dry Steam plant 20 a islandi/laghitasvaedi/ 21 Figure 5: a islandi/hahitasvaedi/ 22 Figure 6: Figure 7: Figure 8: 12

13 2.9.2 Flash steam Flash steam power plants tap into holes where there is water around 180 C and up, they pump it up and the water pressure decreases and the water condemns into steam and powers the turbines. The water that doesn t turn into steam is pumped back down to the well for reuse. This is the most common way of power plants to do it. Figure 7: Flash steam plant Binary steam Binary cycle is a method when the water is not hot as the other methods. So they use the hot water to heat up liquids that have a lower boiling point. These liquids are heated up by the hot water and the liquids turn into steam and power the generators or the turbines and make electricity. Then the hot water is pumped back down to be heated up again for reuse. This method of using geothermal energy is going to be the most common way in the future because you don t need as hot water to power the generators. Figure 8: Binary cycle plant 13

14 3. Research and exploration methods Almost every one of geothermal areas that are being used today are close to hot springs and steam coming up through the earth s surface. After they have found areas like that they take samples and temperature writings and research the data. If the areas have high enough temperatures research it further and are even used for harnessing geothermal energy. But there are geothermal areas that have been harnessed and used even if there were no signs of hot springs or steam 23. When the research starts in the area for geothermal energy the first thing you need to do is conduct a very detailed land and geologically land survey. The main focus is on cracks and ground materials that indicate a water vein and if it looks good you start measuring it. Even though a lot of information can be made by measuring and taking ground samples you cannot be sure until you make shallow drilling holes for research. 24 Measurements and research methods 25 : 3.1 Schlumberger method Schlumberger method uses two transmitter electrodes (A and B) that you stick into the ground up to 2-4 Km and then two receiver electrodes (M and N) and connected between them is an electric transmitter. They are all set up in a direct line and in the middle there is an electric or a voltage meter that receives the Figure 9: Schlumberger method data that bounces back after you have shot electricity into the ground and thereby mapping the ground layers beneath you. 23 Systems, Ernst Huenges, page Jarðhitabók, Guðmundur Pálsson, page Jarðhitabók, Guðmundur Pálsson, page Figure 9: geophysics.com/methods_resistivity_1d.html 14

15 The longer the distance the deeper the measurements are. For example when the distance between A and B is about 2km, you can measure down to m down. These measurement expeditions are usually made by a group of 4 people and are often hard because of tough terrain and remote areas, also so they can maybe just take one or two measurements a day. This measurement method cannot be made in snow or on frozen ground. 3.2 TEM method TEM method gives similar readings as the Schlumberger method. The main difference is that it gives you a 3D reading. It is way simpler and it costs a lot less then the Schlumberger method. It uses the laws of electromagnetism about the connection between electricity and magnetic field. You start with laying an electric cable in a loop covering about 300m in diameter, which then you shoot electricity into, then you switch off the electricity that s going through the loop. After it is switched off electricity suddenly shoots up from the ground and a measurement device which is Figure 10: A 2D data received from Schlumberger measuring Figure 11: TEM Method placed in the middle reads and measures the electricity coming up and changes it into data Jarðhitabók, Guðmundur Pálsson, page Figure 10: html Figure 11: Figure 12: isgs/monthly repts/apr2009/actsall.shtml 15

16 The TEM method started to be used in the 1980s and is in many ways much better then Schlumberger method. You don t have to stick electrodes into the ground and thereby allowing you to take measurements on remote places, and also on frozen ground too. It can also be made by only two men instead of 4, like with the Schlumberger way, and the cost is much lower also. But there are some disadvantages with it; it is very sensitive for outer interruption like electric lines for example close to cities or towns were electric line goes Figure 12: A 3D data received from TEM measuring into. But the advantages are more than the disadvantages and it has almost replaced the Schlumberger method completely. 3.3 MT-measurement MT-measurement (Magnetotellurics) is a technique based on using natural fluctuations in the earth s magnetic field. By measuring these magnetic fluctuations you can make pretty thorough readings of the layout of the underground layers, up to even 30km down. It has mainly been used to measure the earth s crust or to survey a very large area. 3.4 Ground vibration measurements Ground vibration measurements are a combination of two ways of measuring ground vibration. The vibrations are measured on a seismograph on different location from the spot you are measuring. Tough s two types are called reflection measurements and refraction measurements. 16

17 3.5 A reflectivity measurement A Reflectivity measurement is a measurement tool which receives data from waves which bounce back from earths layers and records them. The way they use this method is they lay down a cable, often over 2400m with wave sensors about 25m apart from one another. The first readings from the hit are useless but with extensive work and time consuming computer work you will get very accurate readings of the ground layers. This measurement method is very effective in areas where the ground layers are in sediment and that s why this is the most common way to look for oil. This method is very expensive and oil is worth more than geothermal, that s the reason why this is not a common way of measuring for geothermal. Geothermal energy is usually found in crystalline bedrock. 3.6 Wave breaking measurements Wave breaking measurements works by comparing the travelling time between when you shoot the wave down until it bounces back from the ground to the receiver. The distance between where you shoot down the wave and the receiver is much more than a reflectivity measuring for example. To measure depths down to 5km you need the distance to be 10-15km between the start of the wave and the receiver. 17

18 4. Drilling for geothermal energy When all necessary measurements and research have been done and all official approval has been given you can start drilling. But there are many factors to think about also. You need roads and facilities in the area to do this and most important thing is that you need access to water to cool the drill down. So there are many things to consider before you ever start drilling the hole. Even though geothermal energy has been used for centuries in bathhouses and to launder clothes it wasn t really used until they started drilling holes in geothermal areas in modern times. By drilling down for it you could multiply the running water and harness a lot hot water then it was in pools and geysers on the surface. The first drills were hand powered or powered by farm animals, and there are tales of these kinds of drills all the back to the year 1200 in China. In the beginning of the 19 century in Toscana Italy they started to drill (hand powered) down for the purpose of using it to make electricity 27. The drill is drilled circularly into the ground and if it drills down on water vain in the earth s crust, and if there is enough pressure or water in the hole the drilling is stopped and considered a successful hole. If the hole is to be used permanently you will have to make very good finishing work on the hole like sealing the walls in the hole to prevent rocks falling down or even collapsing especially in high heat zones. To seal and secure the hole, a steel pipe is hammered down the hole to protect it from collapsing, or letting other exterior things getting into the hole like cold water from the bedrock or the crust. All geothermal drilling technology basically came from oil drilling but there has been a lot of advances in drilling technology in the past decades. The most common way of drilling uses the same method as an oil drill. You screw the drill head on the first steel bar which are about 10m long, and then you mount the drill motor on the bar and start drilling down. Figure 13: The most common drill head 27 Jarðhitabók, Guðmundur Pálsson, page 122 Figure 13: 18

19 When the 10m bar has been drilled down you detach the drill motor and screw a new 10m steel bar on it and drill it down again. You repeat this process and you put on as many steel bars as you need to reach down to the depth you need. The drill head has three drill heads on it, and it turns as soon as the steel bars start turning, turning around times a minute, which breaks and crushes the earth s rock into as fine sand as found on a beach. But how many times you must replace the drill head depends on how hard the ground layers are, and that takes a long time depending on how deep you are down. You need to unscrew all steel bars off until you reach the drill head and then redo everything again until you reach the bottom of the hole and continue drilling 28. The deepest drill hole in the world is in Kola, Russia. It started in 1970 and it was being drilled on an off till it stopped in It was part of a program to drill many holes reaching 10-15km depth during the time of the Soviet Union to research the earth s crust, pressure and research the techniques and technology for deep drilling for oil and gas at the depth of up to 15km. 29 They reached a temperature of 180 C in the bottom of the hole and this was not a geothermal area so the possibilities are every were if there is a will to reach heat from the ground. 28 Jarðhitabók, Guðmundur Pálsson, page pdf 19

20 5. Geothermal power plants In this chapter I investigated and researched three power plants and I visited one of them to get a better understanding of the variety of power plants. Each of them has their own qualities and environment to produce electricity and hot domestic water. 5.1 Reykjanesvirkjun Reykjanesvirkjun is a geothermal power plant in Iceland and is owned by HS Orka hf. And the plant is located in an area called Reykjanes in Iceland. They also have other geothermal power plants in another area called Svartsengi. I visited and got a private tour around the power plant. Reykjanesvirkjun produces 100 MW of electricity (only electricity) and it s a very unique geothermal power plant and actually only one of its kinds in the world. This is due to the hot water it uses is almost pure sea water. It also uses sea water to cool down the steam and water after it has gone through the generators. It is located on the coast so it has easy access to cold sea water, which is one of the main problems with establishing a geothermal power plant around the world, as not all cities are located in coastal areas. It gets water and steam from 16 drill holes reaching depths of 2-3 km deep, and in the total of 35km deep. Most the holes reach heat from C but there is one that reaches 316 C. The pressures in the holes are from bars. The water goes from the holes to a separation station through pipelines and there it is separated and changed into steam. Each separation tank can take water from 6 holes and after that process the pressure goes down to 18 bars. Then it goes through 1220m of pipelines to a moisture separation tank. There always slips some water through the separation station and in such long pipe lines, moisture is just unavoidable. That s why it goes into a moisture separation tank and there all moisture is filtered out and the steam is dried. It is very important to dry the steam before it goes into the turbine generators. From the moisture tanks it goes into the generators (turbines) and it is let into the generator on each side to balance the steam or energy coming in. The turbine is the 20

21 machine that generates electricity, the steam comes into the generators and goes through the turbines making them turn as the steam goes through them and that generates electricity, and in Reykjanesvirkjun there are two generators. The turbine rotates 3000 rpm as the steam goes through them so you can see why it is important to dry the steam so the moisture or water doesn t go through. But there is always some moisture and that s why Reykjanesvirkjun has double flow generators to minimize erosion and damage. The wind flow in the generators is 1000 kph so you can imagine the stress and pressure the generators are put through, and there is about 17% of moisture in the steam when it enters the generators. That means there is about 14kg per sec. In 1000 keep going through the generators and that s why they use double flow generators to ease the immense pressure on the generators. There are two generators in Reykjanesvirkjun and each produces 50 MW, a total of 100 MW, which goes to a high voltage station next to the plant, and then to its destination. After the steam has produced electricity in the generators it goes into a condenser to cool it down. From there the steam is cooled down into water inside a big tank. It works like a double radiator that runs together side by side until it cools down from the cold sea water, not unlike a closed radiator system in a house where you heat up the hot water again in a circular closed heating system. The seawater is pumped up from twelve 60m deep drill holes 200m at a rate of 4000 l per sec. from the coastline, to avoid getting sea life and seaweed into the condenser. The earth layer is so open under all that area and the seawater just runs through the ground. So after the steam has been cooled down it is 45 C and it is pumped back into the ocean. It has to be cooled down to 45 C to not affect the sea life in the area. That s what makes Reykjanesvirkjun so unique compared to others, because it s the only one in the world that uses seawater to cool down the steam. But the sad part about the steam that comes out of the generators is that it is still usable and would produce 50MW extra, but the tour guide from HS Orka told me that they are not allowed to use it 21

22 because of some rules and legislation around the geothermal energy and they even have the third generator just lying on the floor unused Svartsengi Svartsengi is HS Orkass second area of geothermal power plants and also where they started out producing electricity and also hot and cold water for homes and business in the area. The first hole to be drilled in the area by HS Orka was in 1971 and it was 262m deep but it turned out to be useless. The second one was drilled the year after and it was 239m deep but it turned out to be useless too. But later that year they drilled the third one and which was 402m deep and it was a success, and they used it until There have been drilled 22 holes total in the area. This power plant very unique also, mainly because it delivers preheated cold water to the hot water supply to homes and it was one of the first ones in the world to pump the water back down into the ground, and actually 60% of the water that is pumped up is pumped back down. The landscape is also very open with centuries of old hardened lava rocks and that lets the rain water easily pass down to the ground layers. So while it rains and they pump the water back down, there is an endless supply of geothermal energy. In Svartsengi there are 6 power plants all in all: Power plant 1 Power plant 1 was the first of its kind in the world. It was the first to produce both electricity and hot water for domestic use. In it was for heat exchange channels which produced 50 MW of thermal power capacity (domestic hot water) and two generators which made 2 MW of electricity. This power plant was designed and engineered entirely by Icelanders. 30 Brochure from HS Orka hf. 22

23 5.2.2 Power plant 2 Power plant 2 produced only hot water for domestic use in three heat exchange channels which produced 75 MW of thermal input. The engineers came up with two things to make it different than in its predecessor. They used plate heat exchangers and three air vent columns to make it more efficient and this was another thing they developed after a lot of research and work Power Plant 3 Power plant 3 is entirely electricity plant and it produces 6 MW of electricity. The generator is made by Fuji Electric. Fuji came in after a poor performance of the generator in power plant 1, since it was never produced specially for the harsh steam and heat from the ground. After the first power plant it was clear that it had to be made especially for this use and special demands were made of materials to be used inside of the generators. It was a complete success both for HS Orku and Fuji Electric and they are still working together today, and the generator has been in use ever since Power plant 4 Power plant 4 was done in collaboration with Ormat in Israel and it s for generating electricity. In 1987 it started with three turbines but in 1991 four more turbines were added totaling in on seven, and they produce 8.4 MW. Plant no. 4 was also the first of its kind in the world because it uses the processed steam from plant no 3. This is the binary method; the binary cycle is a method when the water or steam is not as hot as the other methods. So they use the less hot water or steam to heat up liquids that have a lower boiling point. These liquids are heated up by the hot water or steam and the liquids turn into steam and power the turbines Power plant 5 Power plant 5 produces both electricity and domestic heat water. It generates 30 MW of electricity and 75 MW of thermal input or hot water and it was started up in It is a combined technology from the other power plants but of course up to date with the technology of the generators at that time

24 5.2.6 Power plant 6 Power plant 6 is also the first of its kind. It generates 30 MW of electricity in a single generator with three steam intakes and each has a different pressure intake, that s what makes it so unique. HS Orka wanted to come up with a way to use steam direct from under the ground, steam from the other power plants and also hot water. That created a lot of problems because the steam had a pressure of about 20 bars and it needed to be lowered down to 5.5 bars, and the older plants were just throwing out steam to get it down to 5.5 bars. So they developed a top pressure valve to lower the pressure without wasting any energy but still reuse the steam from the other plants, and also hot water. And it also updated the older ones with this technology. Power plant 6 is the ultimate power plant in reusable energy and new. At first Fuji did not like this idea at all and thought it was impossible to make these kinds of generators, but after a year of discussions and work they turned and changed their minds, and actually saw that a multi pressure generator is often a very useful solution in other countries where the heat is not as high. Together HS Orka and Fuji Electric developed and designed the generator for the plant and it was a complete success The Geysers Geysers geothermal power plant is in California just outside San Francisco and it is the largest geothermal power plant in the world producing 2043 MW from 23 sites. In 1921 the first geothermal power plant was put in use powering only 250 kilowatt. It only powered a resort that was there and some street lights but it could not compete with other power resources at that time and was soon shut down. In 1950 experiments and research began on the area for a potential power plant. And in 1955 they successfully drilled a well that was used to produce electricity and 5 years later they built the first geothermal power plant for commercial use; it produced 11 MW of electricity. In 1967 an oil company came into the project bringing in valuable technology and financial capability to research the area better and to drill for more wells 33. The

25 power plant has only grown since, and it is the world s biggest geothermal power plant. It supplies the state of California with 25% of all renewable energy and it produces 40% of all electricity made with geothermal energy in the US. The Geysers power plant consists of 23 power plants, 350 steam wells and 58 injection wells producing over 2000 MW of electricity. It s a dry steam power plant and it pumps down water through the injection wells to produce steam to power the turbines to make electricity. They get their water from recycled wastewater from the state of California through some of the 80 miles of pipelines going in and out of the power plant

26 6. Advantages and disadvantages of geothermal energy 6.1 The advantages The advantages of a geothermal energy are many but the biggest ones are, you do not need a big space for the power plant compared to others like oil, nuclear, gas or coal power plants. So the cost of buying land for building a power plant is reduced right there. It powers itself completely from its own electricity production which is completely free. The resource is completely free; it s just using the steam or the hot water from underground, it does not need coal or gas from another place to run its generators. And most importantly it does not pollute at all, there is no pollution from geothermal energy power plants. It does not release any greenhouse gases either. And in some countries you will get tax discounts because of your plant is not releasing any pollution into the air The disadvantages The disadvantages of a geothermal energy are not that many but there is one that is big. First it takes often many years of surveying and researching the area and then starts the drilling process which can also take some time and there is no guarantee that you will find big enough well to process steam, but that is becoming less of a problem due to today s technology in ground surveying, but it can take even up to 10 years from surveying to actually producing electricity in a power plant. The wells can also dry out for even 10 years and the ground is a factor too, the bedrock can be so hard that it is almost impossible to drill down or too expensive. But the main disadvantages are its location, these places where there is geothermal energy is often in remote places and miles from any civilization or any structure at all. And many geothermal power plants also need cold water to cool down the steam before pumping it back down energy ideas.com/articles/advantages_of_geothermal_energy.html 36 energy ideas.com/articles/disadvantages_of_geothermal_energy.html 26

27 7. Future of geothermal energy Now at the turn of the century the Earth's population is about six billion. Of which two billion do not have access to energy sources other than firewood or similar heating and living. It is important to give the poorest nations the opportunity to increase prosperity by taking the machines and technology in their service. It is expected that mankind will double in numbers in the 21 century, and the energy consumption is also expected to double in the 21 century. It is a huge task to provide 12 billion people enough energy and even more to provide them with clean energy. It is hoped that energy consumption will improve in this century like in the last years there has been made drastic changes for the good in air pollution from some energy resources like coal or oil. But it is still clear that it will be hard to reduce the pollution or even reducing that kind of energy production. Greenhouse gases and air pollution is substantially less with using renewable energy resources than using oil or gas. That s why it is becoming the main focus in most countries around the world today to use renewable energy. It is still going at turtle pace, and it will probably continue to do so in the next two decades or so. The renewable energy resources are much bigger than even today s energy consumption is in the world, but it is met with a lot of resentment from today s leading energy companies, mainly because of financial factors. They don t really want to stop selling oil and gas, there is just too much at stake for them and that is the main reason. They control the energy market. But to increase interest in renewable energy there has to be some technological advancement in renewable energy production and mainly in cost. Or put more taxes on fossil fuels to make renewable energy a better investment. Water power and geothermal energy are competitive with fossil fuel regarding to cost, biomass and wind power are not that far from it neither, but solar power has a long way to go. International energy predictions assume that renewable energy will be 20-50% of all energy consumption in the world in the latter part of the decade. And it is predicted that sun power will be the far biggest renewable energy source and then biomass. 27

28 It is clear that not any other energy resource will replace fossil fuel as the world biggest energy provider unless there are some changes made in the governing of energy in the world. In the end you will need to use that energy resource that pollutes the least which is available in your area or country

29 8. Conclusion In this report I asked myself various question and the first of them was, what is geothermal energy? Geo means earth and thermal means heat so that s were the word geothermal comes from and geothermal energy comes from under the ground. It can be in different depths depending on where you are in the world, or geothermal areas and its energy or source goes as deep as the earth s core which is 6000 Celsius. The locations of most geothermal areas are where the Tectonic plates meet, that s also were a lot volcanoes and earthquakes occur. The Tectonic plates are floating on one of the earth s layers called the mantle and they are constantly moving and are all in a chain of action. No plate moves without another moving but when they collide there is a massive release of energy like volcanoes and earthquakes. Tough s places are the most common area where geothermal energy is. The depth of geothermal energy various from where you are in the world for example in Iceland it s from 50m to 4000m but in Geyser California most of the holes are around 3000m. It can go as far as m but you really just need to reach steam to produce electricity. But before you can drill anything there is a long time that goes into research and ground measuring before you start drilling and there a many ways of measuring it, but the most common one is the Schlumberger method, but with today s technological advantages it s only going to get better. The heat of the steam can go as low as 150 or even less, to over 300 and is some cases you need to cool down the steam before letting it go through the generators. To harness this energy and produce electricity there are mostly three kinds of power plants in the world. The first one is a dry steam power plant and that one uses the steam directly from under the ground with a temperature around 235. The second one is called flash steam power plant and it pump s up water around 180 and when the water condenses it uses the steam to power its generators. The water that is still left is then pumped back down into the same well and is reused and this is the most common geothermal power plant. The third one is called binary steam plant and it pumps up hot water that is still not hot enough to condemns, but it is used to heat up other liquids materials that have a much lower boiling point than ever water and when that liquid has condemns it uses that steam to power the generators. The hot water is then pumped back down like the flash one. This method is most likely to be the most common one 29

30 because it does not need as hot water to power the turbines. I also asked myself what are the advantages and disadvantages of geothermal energy? The advantages are far better than the disadvantages, mainly because it does not pollute the air at all or release any greenhouse gases either. The space it needs is also significantly less than other power plants, like oil or coal and it as also renewable energy unlike fossil fuel. The disadvantages are not many but mostly it is location. It can be hard to build power plants where these geothermal areas are, and to cool them down. Many geothermal power plants need cold water to cool down the steam and that can be difficult to provide because many geothermal areas are in remote places. It s other disadvantages is that it can take a long time before ever drilling down, due to research work and it can take up to 10 years from researching the area to producing electricity in a power plant. In the end I asked myself what is the future of geothermal energy? It is clear that geothermal energy will never be the only energy provider in the future but it will play a big role in it. Fossil fuel will always be used until it is cheaper to use other energy resources like geothermal energy. There are many things that need to changes in the world s governing like taxing fossil fuel to force cleaner and renewable energy resources. It is predicted that geothermal energy will be around 3-4 th biggest energy provider after solar biomass and wind. 30

31 9. Literature list Books: Systems, Ernst Huenges, 2010 Jarðhitabók. Eðli og nýnig jarðhita, Guðmundur Pálsson, 2005 Articles and Reports: The ring of fire: the use of geothermal energy in Indonesia Kola super deep drilling project Brochure from HS Orka hf about Reykjanesvirkjun. Brochure from HS Orka hf about Svartsengi power plant Article about Geysers power plant Report about the future of geothermal energy Web Pages: Canadian Association Info about climate change and geothermal energy 31

32 Articles and info about the ring of fire and volcanoes Plate Tectonic. A web book about the tectonic plates The Environmental Institution in Iceland Cooperative Institute for Research in Environmental Science Association The Energy Institution in Iceland Jarðboranir is a ground drilling company in Iceland Geysers is a power plant in California A high school project from Fjölbrautarskóla Suðurlands in Iceland The Energy Institution in Iceland The Energy Institution in Iceland 32

33 The Science web in Iceland Info about geothermal energy Geysers is a power plant in California Clean Energy Ideas: web page with info and articles about renewable energy Clean Energy Ideas: web page with info and articles about renewable energy 33