Geothermal energy pdf free download

The reason is the electronic devices divert your attention and also cause strains while reading eBooks. The most common examples include wind, solar, geothermal, biomass, and hydropower. This is in contrast to non-renewable sources such as fossil fuels. Most renewable energy is derived directly or indirectly from the sun. Sunlight can be captured directly using solar technologies. Plants also rely on the sun to grow and their stored energy can be utilized for bioenergy. Not all renewable energy sources rely on the sun.

Herewith we listed mostly used Renewable Energy Books by the students and professors of top Universities, Institutions and Colleges. LearnEngineering team try to Helping the students and others who cannot afford buying books is our aim. For any quarries, Disclaimer are requested to kindly contact us , We assured you we will do our best. Thank you. Please Note : This list is not the final book list. In some cases, the heated water or steam produced get to the surface of the Earth as hot water bodies, mostly through fractures.

In instances where the water remains trapped beneath the Earth, wells are dug and the heated underground water is pumped to the surface. Geothermal energy, the energy produced from this heated water is a clean, sustainable energy. Geothermal systems are currently exploited in a number of geological environments where the temperatures and depths vary accordingly.

Energy produced from them can be used in a range of applications; from electric power generation to commercial, industrial and residential direct heating purposes, and for efficient home heating and cooling through geothermal heat pumps GHPs.

This rate of increase in temperature with respect to increase in depth is termed the Geothermal Gradient of the Earth. Away from tectonic plate boundaries and regions with thermal anomalies, it is about 25oC per km depth 1oF per 70 feet depth in most parts of the world.

The geothermal gradient is a very important factor in the search for geothermal resources. Resources are usually explored for in areas with unusually higher geothermal gradients such as regions around plate boundaries or with active volcanoes as they have potentials of producing high-temperature resources. The major heat- producing isotopes in the Earth are Potassium, Uranium, Uranium, and Thorium- It is widely agreed that much of the heat produced in the Earth is provided by radioactive decay.

Generally, geothermal heating is caused by this continuous decaying of radioactive particles, and the convection and conduction of heat from the very hot inner core and mantle. In fact, geothermal energy has been in use at least since the Paleolithic times. Recent technologies only expanded the range of use of geothermal energy in applications such as electric power generation, space heating, cooling and heating through heat pumps etc. The earliest industrial exploitation began in with the use of geyser steam to extract boric acid from volcanic mud in Lardello, Italy.

In the 20th century, the demand for electricity led to the consideration of geothermal power as an electric generating source. Further researches in the subject led to the development of new technologies in the use of this resource. The most recent is the production of electricity from a record low fluid temperature of 57oC oF. A continuous research on this field as well as development of new technologies, can further expand the range of applications than what we have today, and reduce the harmful effects of utilizing this energy resource.

However, most geothermal energy resources cannot be seen as they are deep underground. The surface manifestation of a geothermal resource existing underground gives the geologists clues when searching for the resources. When there are no clues above ground that a geothermal resource is present below, wells are drilled and their temperatures tested to be sure there is a reservoir.

The most active resources are found along major plate boundaries where Earthquakes and volcanoes are concentrated. This is practically true, as it is observed that most geothermal activities in the world occur in a region that borders the Pacific Ocean, known as the Ring of Fire. Classifying energy resources is then important to be able to use and understand consistent terminologies in addressing geothermal issues such as location, quality and feasibility of development and potential impacts.

For this terminology to be accepted, it must encompass both the fundamental geological nature of geothermal resources and the practical technological and economic aspects of resource exploitation, while remaining understandable to the broad community of non-specialists Colin et al, Geothermal energy resources have been characterized thus, by geologic settings, intrinsic properties, and viability for commercial utilization.

The diversity of both the nature and exploitation of geothermal resources pose a great challenge in the context of resource classification.

Classification of this resource has been the feature of many investigations, and until now, no one approach for classification has been accepted as a basic framework for classification. However, with technical changes, a recent classification based on more detailed understanding of geologic and tectonic processes and the potential development of new types of resources have been adopted by major geothermal industries. This classification is the basic framework for characterization developed by Muffler and Cataldi in It is foundational to resource assessments.

The subdivisions are easily illustrated through a modified McKelvey diagram Fig 2. The criteria are also used by geologists or geothermal industries that consider both identified and unidentified resources. The geothermal resource base is all of the thermal energy existing beneath the ground in a specific area, measured from the local mean annual temperature. The geothermal resource is that fraction of the geothermal resource base at depths shallow enough to be tapped by drilling, that can be recovered as useful heat economically and legally at some reasonable future time.

The geothermal reserve is the identified portion of the resource that can be recovered economically and legally at the present time using existing technology. The three bases for classification are discussed below. Geothermal energy has a lot to do with temperature. The exploration, identification and utilization of geothermal energy all depends on the temperature of the resources. It is the fundamental measure of the quality of the resources, and therefore the primary element of most classification systems.

Different temperature classes exist; some dividing resources into two high and low , and others into three high, low and intermediate classes. In each case, the temperature boundaries are set at temperatures significant in either a thermodynamic or an economic utilization context.

The temperature classes are then observed to define a progression of resources from low to high temperature or enthalpy geothermal resources. The classification approach proposed by Sanyal , which focuses on thermal boundaries of significance to the geothermal developer, is given below. Table 2.

Geologic Setting A geothermal system requires basically; water geothermal fluids , a permeable host rock, and a heat source. Geologic controls on geothermal resources are therefore considered when classifying the resources, as most or all the features of a geothermal system are controlled by geologic processes.

The geologic setting of a geothermal system has a fundamental influence on the potential temperature, fluid composition and reservoir characteristics.

Resources have been classified into two in this context. They are the Amagmatic and Magmatic geothermal resources. Amagmatic Geothermal Resources: This refers to resources obtained from environments that are not associated with magmatic activities or processes. Heat is derived from amagmatic systems solely by deep circulation. Temperatures of resources obtained from these systems range from oC to oC. Fig 2. Magmatic Geothermal Resources Magmatic geothermal resources are those related to or associated with magmatic activities.

These systems are observed in volcanic environments associated with recent magmatism. This is illustrated in the diagram below, showing geothermal manifestations within an island- arc volcano. Given the high temperature involved in such settings, it is expected to find heat sources at much shallow depth in magmatic systems, compared to amagmatic systems. Generally, resources obtained from magmatic geothermal systems are higher in temperature and larger in volume than the deep circulation amagmatic systems.

Conductive Geothermal Resources and Enhanced Geothermal Systems This classification is based on the characteristics of the reservoir, and the technology utilized in exploiting the resources. Resource classifications for sedimentary geothermal resources have been focused on the methods of exploitation. Though there are diverse utilization scenarios for the resources, there is consistency in the geologic and thermal environment as the resources are associated with the predominantly conductive settings of sedimentary basins.

Most processes, features and production in such reservoirs are naturally-occurring. By contrast, Enhanced Geothermal Systems cover essentially the entire range of geothermal environments from reservoir creation in low permeability and porosity crystalline rocks at depth, through high porosity-low permeability sedimentary rocks to augmented production in a producing convective geothermal reservoir.

Enhanced Geothermal Systems would produce geothermal fluids of higher temperatures at shallow depths when compared to Conductive Geothermal Resources. Since geothermal resources occur underground, exploration methods include a wide range of disciplines including Geology, Geophysics, Geochemistry and Engineering.

The objectives of geothermal explorations are to identify and rank prospective geothermal reservoirs prior to drilling, and to provide methods of characterizing reservoirs that enable the estimates of geothermal reservoir performance and lifetime. Exploration of prospective geothermal reservoirs involves estimation of its location, lateral extent and depth with geophysical methods and then drilling exploration wells to test properties.

Geothermal wells are drilled over a range of depths down to 5km using methods similar to those used for oil and gas. Advances in drilling technology have enabled high-temperature operation and provide directional drilling capability.

Wells are drilled from the same pad, heading in different directions to access larger resource volumes, targeting permeable structures and minimizing the surface impacts.

For other geothermal applications such as Geothermal Heat Pumps and direct use applications, smaller and more flexible rigs have been developed to overcome accessibility limitations. When water is heated by the heat of the Earth, hot water or steam can be trapped in permeable and porous rocks over a layer of impermeable rock and a geothermal reservoir can form.

A geothermal reservoir is a collection of heated water or steam trapped in permeable and porous rocks including fractured crystalline rocks underlain by impermeable rock layers. The reservoir system may be formed entirely by natural geologic processes or may be adjusted artificially to meet this definition.

They are the conventional and unconventional geothermal reservoirs. Conventional Geothermal Reservoirs: They are hot, wet, porous, permeable and often fractured.

They are exploited by producing hot water or steam from the reservoir and disposing off the depleted steam to the atmosphere or condensing and injecting it back to the reservoir. Typical oilfield practices such as hydraulic fracturing are used to enhance production, provided the temperature does not exceed the limits of available technology.

Fig 3. Unconventional Geothermal Reservoirs: they are hot, dry, no porosity or permeability, and no fractures. They require hydraulic fracturing and horizontal wells to obtain a flow path through which water can be circulated in a closed loop. To determine the volume of geothermal resources and the optimal plant size. To ensure safe and efficient operation during the lifetime of the project. First a conceptual model using available data is built, and is then translated into a numerical representation, and calibrated to the unexploited, initial thermodynamic state of the reservoir.

Future behavior can be forecast under selected load conditions using a heat and mass transfer algorithm, and the optimum plant size is selected. Injection management is an important aspect of geothermal development, where the use of isotropic and chemical tracers is common. Depletion of production zones by injected water that has had insufficient contact with hot reservoir rock can result in production declines. Given sufficient and accurate calibration with field data, geothermal reservoir evolution can be adequately modeled and proactively managed.

Field operators monitor thermodynamic and chemical properties of geothermal fluids, and map their flow and movement in the reservoir. This information, combined with other geophysical data is fed back to recalibrate models for better predictions of future production.

Steam condensing turbines utilizing flash systems, flash or separate fluids in a series of vessels at successively lower pressures, to maximize the extraction of energy from the geothermal fluids. The only difference between a flash plant and a dry-steam plant is that dry-steam plants do not require brine separation, resulting in a simpler and cheaper design. Binary plants are more complex than condensing units since the geothermal fluids pass through a heat exchanger heating another working fluid.

There are also combined or hybrid power plants, which comprises two or more of the basic types, to improve efficiency and cover a wide resource temperature range. The power plants in the binary and condensed unit-types are described below. Flash Power Plant: Geothermally heated water under pressure is flashed or separated in a surface vessel called a separator, into steam and hot water.

The steam is delivered to the turbines, which in turn powers a generator. The liquid is injected back into the reservoir. An example is the Dixie Valley flash power plant in Nevada. Dry Steam Power Plant: This plant is installed in areas where steam can be produced directly from the geothermal reservoir. No separation is needed in this system. Steam from geothermal reservoirs is delivered directly to run turbines that power the generator.

The used steam is condensed and injected back into the reservoir as water. Used up steam is given off into the atmosphere in some steam power plants, while they are reused in other to maximize the benefits of the resources. Steam power plants are usually installed around surface manifestations of underground geothermal activities, such as geysers without affecting them.

In this plant type, organic fluids such as Isobutane work together with the geothermal fluid, but as a secondary fluid. The organic fluid the secondary should boil at a lower temperature than the heated water the geothermal fluid. Geothermal water produced from the reservoir transfers its heat energy to the organic fluid, while kept completely separate from it through the use of a heat exchanger, expanding the organic fluid into gaseous vapour.

It is the force of this expanding vapour, like steam, that drives the turbines which power the generators. All of the produced geothermal fluid is injected back into the reservoir.