Geothermal Energy

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Matt Arnold

9/17/96

Physics 009

Professor Arns

GEOTHERMAL ENERGY

The human population is currently using up its fossil fuel supplies at staggering rates. Before long we will be forced to turn somewhere else for energy. There are many possibilities such as hydroelectric energy, nuclear energy, wind energy, solar energy and geothermal energy to name a few. Each one of these choices has its pros and cons. Hydroelectric power tends to upset the ecosystems in rivers and lakes. It affects the fish and wild life population. Nuclear energy is a very controversial subject. Although it produces high quantities of power with relative efficiency, it is very hard to dispose of the waste. While wind and solar power have no waste products, they require enormous amounts of land to produce any large amounts of energy. I believe that geothermal energy may be an alternative source of energy in the future. There are many things that we must take into consideration before geothermal energy can be a possibility for a human resource. I will be discussing some of these issues, questions, and problems.

In the beginning when the solar system was young, the earth was still forming, things were very different. A great mass of elements swirled around a dense core in the middle. As time went on the accumulation elements with similar physical properties into hot bodies caused a slow formation of a crystalline barrier around the denser core. Hot bodies consisting of iron were attracted to the core with greater force because they were more dense. These hot bodies sunk into and became part of the constantly growing core. Less dense elements were pushed towards the surface and began to form the crust. The early crust or crystalline barrier consisted of ultra basic, basic, calc-alkaline, and granite. The early crust was very thin because the core was extremely hot. It is estimated that the mantel e

200 to 300 degrees Celsius warmer than it is today. As the core cooled through volcanism the crust became thicker and cooler.

The earth is made up of four basic layers, the inner solid core, the outer liquid core, the mantel and the lithosphere and crust. The density of the layers gets greater the closer to the center of the earth that one gets. The inner core is approximately 16% of the planet's volume. It is made up of iron and nickel compounds. Nobody knows for sure but the outer core is thought to consist of sulfur, iron, phosphorus, carbon and nitrogen, and silicon. The mantel is said to be made of metasilicate and perovskite. The continental crust consists of igneous and sedimentary rocks. The oceanic crust consists of the same with a substantial layer of sediments above the rock.

The crust covers the outer ridged layer of the earth called the lithosphere. The lithosphere is divided into seven main continental plates. These continental plates are constantly moving on a viscous base. The viscosity of this base is a function of the temperature. The study of shifting continental plates is called Plate Tectonics. Plate Tectonics allows scientists to locate regions of geothermal heat emission. Shifting continental plates cause weak spots or gaps between plates where geothermal heat is more likely to seep through the crust. These gaps are called Subduction Zones. Heat emission from subduction zones can take many forms, such as volcanoes, geysers and hot springs. When lateral plate movement induced gaps occur between plates, collisions occur between other plates. This results in partial plate destruction. This causes mass amounts of heat to be produced due to frictional forces and the rise of magma from the mantle through propagating lithosphere fractures and thermal plumes sometimes resulting in volcanism. During plate movement, continental plates are constantly being consumed and produced changing plate boundaries. When collisions between plates occur, the crust is pushed up sometimes forming ranges of mountains. This is the way that...
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