Name: Mohammed Fayez abd elaty abd elhameed Code: 20120581 Report in: geothermal power plant Presented to : Dr / nesreen mohammed Geothermal Energy Abstract: Geothermal name origins from the Greek roots geo meaning earth, and thermos meaning heat . Geothermal energy is the earth’s natural heat available inside the earth. This thermal energy contained in the rock and fluid that filled up fractures and pores in the earth’s crust can profitably be used for various purposes. It is believed that ultimate source of geothermal energy derived from the earth due to radioactive decay occurring within the earth at deep crustal depths. 0.1% of the energy stored in Earth’s crust could satisfy the world energy consumption for 10,000 years. At all locations, the heat reaches the surface of the earth in a defusing manner. The earth’s heat increases with depth at a rate of 30 o C per km and this way the centre of the earth is estimated to have about 5000 o C . However, due to geological processes and tectonic disturbances, heat sources become relatively shallow at certain locations. Greater the temperature higher will be its utility. For example, the heat source of high temperature is generally used for electric power generation. As on today, geothermal electric power generation in US is approximately above 2200 MW. This is equivalent to 4 large nuclear power plants. The low and moderate temperature resource can be used for direct applications and also using ground source heat pumps. Application of direct use involves heating of the buildings, industrial processes, greenhouses, aquaculture and in holiday resorts Introduction : Ground heat source uses the groundwater as a medium of transport that can be used to transfer the heat from the soil down below to the surface. As on today, the current world production of geothermal energy for both direct and indirect uses has occupied a third place among the various renewable energy sources such as hydroelectricity, biomass, solar power and wind power. Although its potential is impressive from various users in different countries, its utility in India is near zero. The success of geothermal use depends on the technical information about the various geothermal provinces. Schematic diagrame Geothermal resource: In this section we know about Below Earth's crust, there is a layer of hot and molten rock, called magma. Heat is continually produced in this layer, mostly from the decay of naturally radioactive materials such as uranium and potassium. The amount of heat within 10,000 meters (about 33,000 feet) of Earth's surface contains 50,000 times more energy than all the oil and natural gas resources in the world. The areas with the highest underground temperatures are in regions with active or geologically young volcanoes. These "hot spots" occur at tectonic plate boundaries or at places where the crust is thin enough to let the heat through. The Pacific Rim, often called the Ring of Fire for its many volcanoes, has many hot spots, including some in Alaska, California, and Oregon. Nevada has hundreds of hot spots, covering much of the northern part of the state. These regions are also seismically active. Earthquakes and magma movement break up the rock covering, allowing water to circulate. As the water rises to the surface, natural hot springs and geysers occur, such as Old Faithful at Yellowstone National Park. The water in these systems can be more than 200°C (430°F). Seismically active hotspots are not the only places where geothermal energy can be found. There is a steady supply of milder heat—useful for direct heating purposes—at depths of anywhere from 10 to a few hundred feet below the surface virtually in any location on Earth. Even the ground below your own backyard or local school has enough heat to control the climate in your home or other buildings in the community. In addition, there is a vast amount of heat energy available from dry rock formations very deep below the surface (4–10 km). Using the emerging technology known as Enhanced Geothermal Systems (EGS), we may be able to capture this heat for electricity production on a much larger scale than conventional technologies currently allow. While still primarily in the development phase, the first demonstration EGS projects provided electricity to grids in the United States and Australia in 2013. If the full economic potential of geothermal resources can be realized, they would represent an enormous source of electricity production capacity. In 2012, the U.S. National Renewable Energy Laboratory (NREL) found that conventional geothermal sources (hydrothermal) in 13 states have a potential capacity of 38,000 MW, which could produce 308 million MWh of electricity annually [4]. State and federal policies are likely to spur developers to tap some of this potential in the next few years. The Geothermal Energy Association estimates that 125 projects now under development around the country could provide up to 2,500 megawatts of new capacity [3]. As EGS technologies improve and become competitive, even more of the largely untapped geothermal resource could be developed. The NREL study found that hot dry rock resources could provide another 4 million MW of capacity, which is equivalent to more than all of today’s U.S. electricity needs [4]. Not only do geothermal resources in the United States offer great potential, they can also provide continuous baseload electricity. According to NREL, the capacity factors of geothermal plants—a measure of the ratio of the actual electricity generated over time compared to what would be produced if the plant was running nonstop for that period—are comparable with those of coal and nuclear power [5]. With the combination of both the size of the resource base and its consistency, geothermal can play an indispensable role in a cleaner, more sustainable power system. Equipment & operation:  Currently, the most common way of capturing the energy from geothermal sources is to tap into naturally occurring "hydrothermal convection" systems, where cooler water seeps into Earth's crust, is heated up, and then rises to the surface. Once this heated water is forced to the surface, it is a relatively simple matter to capture that steam and use it to drive electric generators. Geothermal power plants drill their own holes into the rock to more effectively capture the steam. There are three basic designs for geothermal power plants, all of which pull hot water and steam from the ground, use it, and then return it as warm water to prolong the life of the heat source. In the simplest design, known as dry steam, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water. In a second approach, very hot water is depressurized or "flashed" into steam which can then be used to drive the turbine. In the third approach, called a binary cycle system, the hot water is passed through a heat exchanger, where it heats a second liquid—such as isobutane—in a closed loop. Isobutane boils at a lower temperature than water, so it is more easily converted into steam to run the turbine. These three systems are shown in the diagrams below. The three basic designs for geothermal power plants: dry steam, flash steam, and binary cycle. Image: U.S. Department of Energy The choice of which design to use is determined by the resource. If the water comes out of the well as steam, it can be used directly, as in the first design. If it is hot water of a high enough temperature, a flash system can be used; otherwise it must go through a heat exchanger. Since there are more hot water resources than pure steam or high-temperature water sources, there is more growth potential in the binary cycle, heat exchanger design. The largest geothermal system now in operation is a steam-driven plant in an area called the Geysers, north of San Francisco, California. Despite the name, there are actually no geysers there, and the heat that is used for energy is all steam, not hot water. Although the area was known for its hot springs as far back as the mid-1800s, the first well for power production was not drilled until 1924. Deeper wells were drilled in the 1950s, but real development didn't occur until the 1970s and 1980s. By 1990, 26 power plants had been built, for a capacity of more than 2,000 MW. Because of the rapid development of the area in the 1980s, and the technology used, the steam resource has been declining since 1988. Today, owned primarily by the California utility Calpine and with a net operating capacity of 725 MW, the Geysers facilities still meets nearly 60 percent of the average electrical demand for California's North Coast region (from the Golden Gate Bridge north to the Oregon border) [6]. The plants at the Geysers use an evaporative water-cooling process to create a vacuum that pulls the steam through the turbine, producing power more efficiently. But this process loses 60 to 80 percent of the steam to the air, without re-injecting it underground. While the steam pressure may be declining, the rocks underground are still hot. To remedy the situation, various stakeholders partnered to create the Santa Rosa Geysers Recharge Project, which involves transporting 11 million gallons per day of treated wastewater from neighboring communities through a 40-mile pipeline and injecting it into the ground to provide more steam. The project came online in 2003, and in 2008 provided enough additional electricity for approximately 100,000 homes [7].    One concern with open systems like the Geysers is that they emit some air pollutants. Hydrogen sulfide—a toxic gas with a highly recognizable "rotten egg" odor—along with trace amounts of arsenic and minerals, is released in the steam. Salt can also pose an environmental problem. At a power plant located at the Salton Sea reservoir in Southern California, a significant amount of salt builds up in the pipes and must be removed. While the plant initially put the salts into a landfill, they now re-inject the salt back into a different well. With closed-loop systems, such as the binary cycle system, there are no emissions and everything brought to the surface is returned underground. Advantages &disadvantages: Geothermal Heat Pumps: - produces 4 times the energy that they consume. -initially costs more to install, but its maintenance cost is 1/3 of the cost for a typical conventional heating system and it decreases electric bill. This means that geothermal space heating will save the consumer money. -can be installed with the help of special programs that offer low interest rate loans. Geothermal plants do not require a lot of land, 400m2 can produce a gigawatt of energy over 30 years. Binary and Hot Dry Rock plants have no gaseous emission at all. Geothermal electric plants production in 13.380 g of Carbon dioxide per kWh, whereas the CO2 emissions are 453 g/kWh for natural gas, 906g g/kWh for oil and 1042 g/kWh for coal. Flash and Dry Steam Power Plants emit 1000x to 2000x less carbon dioxide than fossil fuel plants, no nitrogen oxides and little SO2. Geothermal plants can be online 100%-90% of the time. Coal plants can only be online 75% of the time and nuclear plants can only be online 65% of the time. In large plants the cost is 4-8 cents per kilowatt hour. This cost is almost competitive with conventional energy sources. US geothermal companies have signed $6 billion worth of contracts to build plants in foreign countries in the past couple of years. Geothermal energy is “homegrown.” This will create jobs, a better global trading position and less reliance on oil producing countries. Useful minerals, such as zinc and silica, can be extracted from underground water. Advantages of Geothermal Energy When a power station harnesses geothermal power in the correct manner, there are no by products, which are harmful to the environment. Environmentalists should be happy about that! There is also no consumption of any type of fossil fuels. In addition, geothermal energy does not output any type of greenhouse effect. After the construction of a geothermal power plant, there is little maintenance to contend with. In terms of energy consumption, a geothermal power plant is self-sufficient. Another advantage to geothermal energy is that the power plants do not have to be huge which is great for protecting the natural environment. . Disadvantages of Geothermal Energy There are several disadvantages to geothermal energy. First, you cannot just build a geothermal power plant in some vacant land plot somewhere. The area where a geothermal energy power plant would be built should consist of those suitable hot rocks at just the right depth for drilling. In addition, the type of rock must be easy to drill into. It is important to take care of a geothermal site because if the holes were drilled improperly, then potentially harmful minerals and gas could escape from under ground. These hazardous materials are nearly impossible to get rid of properly. Pollution may occur due to improper drilling at geothermal stations. Unbelievably, it is also possible for a specific geothermal area to run dry or lose steam. Brine can salinate soil if the water is not injected back into the reserve after the heat is extracted. Extracting large amounts of water can cause land subsidence, and this can lead to an increase in seismic activity. To prevented this the cooled water must be injected back into the reserve in order to keep the water pressure constant underground. Power plants that do not inject the cooled water back into the ground can release H2S, the “rotten eggs” gas. This gas can cause problems if large quantities escape because inhaling too much is fatal. One well “blew its top” 10 years after it was built, and this threw hundreds of tons of rock, mud and steam into the atmosphere. There is the fear of noise pollution during the drilling of wells. . CONCLUSION: We shallTo make sure we have plenty of energy in the future, it's up to all of us to use energy wisely. Imagination is more We must all conserve energy and use it efficiently. It's also up to those who will create the new energy technologies of the future. knowledge, for knowledge important than is limited, whereas imagination embraces the All energy sources have an impact on the entire world - stimulating environment. Concerns about the greenhouse progress, giving birth to effect and global warming, air pollution, and energy security have led to increasing interest evolution. and more development in renewable energy sources such as solar, wind, geothermal, wave - Albert Einstein power and hydrogen. But we'll need to continue to use fossil fuels and nuclear energy until new, cleaner technologies can replace them. One of you who is reading this might be another Albert Einstein or Marie Curie and find a new source of energy. Until then, it's up to all of us. The future is ours, but we need energy to get there. Reference : http://www.slideshare.net/bhaumikamber/final-geothermal-pbl-report?next_slideshow=5 http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-geothermal-energy-works.html http://www.eia.gov/kids/ http://www.tvakids.com/electricity/geothermal2.htm http://www.alliantenergykids.com/EnergyandTheEnvironment/RenewableEnergy/022401 http://www.kids.esdb.bg/geothermal.html