Geothermal Energy – Geophysics Geophysics is a field of science that deals with the properties of the earth and its environments. It is the study of magnetic and gravitational fields, internal properties of the earth, water cycles, mineral deposit formation, and the solar terrestrial relations. Geophysics specializes in finding resources under the earth’s crust and determining the potential threats such as earthquakes. It also entails qualitative analysis to identify the best sites for mining, oil drilling and geothermal deposits. Branches of Geophysics Various branches of Geophysics are − Study of solid earth − Solid earth properties range from tectonic study to seismic analysis for earthquakes. This branch studies the oil and mineral deposits. The soils samples are analyzed for any unusual deposits or textures. Study of water − This is the study of fresh water as well as water under the earth surface. Study of water is done by hydrologists who analyze water cycles and water tables. Oceanography, the study of the oceans and the ground beneath, also falls under this category. Study of air − Air is a major component of the earth. The study of air helps in predicting weather conditions and guard against extreme conditions such as hurricanes. Life and geophysics − The interaction of organisms and the earth is an important factor. It is important to note that oil deposits mainly result from decaying matter. Conditions below the ground are studied to assess their effect on the existence of organisms. Aquifers Some rocks, called aquifers, provide a good environment for water to flow through naturally. These rocks are porous and filter water running through. Aquifers are best sites where wells are drilled to provide constant water flow. Rocks that make good aquifers are sand, granite, conglomerate, sandstone, and fractured lime. Aquifers lie underneath the water table such that precipitation immediately replenishes water pumped from wells. Aquifers are very important in sustaining the earth’s water cycle. Wells are drilled into aquifers surrounded by non-porous rock. These rocks generate pressure that helps in pumping the water. These kinds of wells are known as artesian wells. Hydrogeology Tests Hydrogeology utilizes several tests in aquifers to capture their characteristics. These tests are conducted in controlled environments called control wells. The three major tests are − Pumping test − Water is extracted and pumped back into the well at constant intervals. Behavior of neighboring wells is recorded as a result of the changes. This test helps in determining the permeability of the aquifers surrounding the well. Slug test − Slug means a swift change in water level. In this test, the effect on the neighboring wells and the duration it takes to recover its original level is measured. This could be achieved by drawing from the lake or water could be pumped into the well to drastically change the level. Constant-head test − This is done using an experimental well called a control well. In a control well the thermal drawdown can be maintained at a level. The effect is recorded for the neighboring wells. Drawing from the well regularly may dent the water table. This may cause depression and cause abnormal flow. Learning working make money
Category: renewable Energy
Geothermal Energy – Introduction Geothermal energy refers to heat energy stored under the ground for millions of years through the earth formation. It utilizes a rich storage of unutilized thermal energy that exists under the earth’s crust. Geothermal energy is site specific but can be very cheap especially when used for direct heating. It is a challenge to estimate power from this source since it occurs underground at extremely high temperatures. The earth’s crust has immense heat (thermal) energy stored over millions of years. There exists a huge temperature difference between the earth’s crust and the surface. The temperature difference is known as geothermal gradient. This energy is sufficient to melt rock. The molten rock, called magma, at times erupts through cracks on earth surface as volcanoes. Geothermal energy is converted to produce to electricity. The presence of geothermal deposits in form of hot geothermal fluid is a sign of a good site. The site should have a shallow aquifer to allow injection of water. The inherent geothermal product should be about 300o F. Advantages of Geothermal Energy The major advantages include − No fuel is burnt since heat is derived from an abundant underground reservoir. The renewable energy source could solve the risk of running out of fossil fuels. It has no emissions and produces 10% carbon dioxide, which is very little compared to the amount consumed by plants. Unlike other sources of renewable energy (solar, wind and water), it is not affected by whether and will always be available throughout the year. Geothermal energy is relatively less expensive especially when directly used, for example, as source of heat in greenhouses. The only disadvantage of geothermal energy is the release of hydrogen sulfide identified by the signature rotten egg smell. Enhanced Geothermal Sources (EGS) In some geothermal sources, water is injected into the wells containing geothermal deposits. Inside these deposits, water gets superheated and hence changes into steam. Water is pumped down under very high pressure to expend rock fissures. Some lower temperature geothermal energy is utilized directly as heat. Green houses may be supplied with this energy as temperature regulator. This technique is also used in fisheries and mineral recovery. Learning working make money
Solar Energy – Cell Efficiency Efficiency refers to the ratio of power input to power output. In the case of a photovoltaic, efficiency is the ratio of power output in terms of electricity to the solar energy incident on the cell. Now, Output power, pm = Voltage (v) * current (I) in the circuit (max value). And, Input power Pi = Incident energy G (Wm-2) * Surface area of cell, A (m2). Thus, Efficiency is calculated as − $$eta:=:frac{P_{m}}{G: times:A_{c}}$$ Where, Pm must be the maximum power of the circuit. It is obtained by using the voltage across open circuit (Voc) and current across the short circuit (Isc) and the fill factor (FF). $$P_{max}:=:V_{OC}I_{SC}FF$$ These measurements must be measured under standard conditions i.e. 25°C, Air mass of 1.5gm-3, and incident energy, G of 1000Wm-2. The factors that affect output of a photovoltaic cell include − The wavelength of the incident light Recombination of electrons and holes Electrical resistance Temperature Fill factor Reflection factor of the material Therefore, to maximize power, the cell should be constructed to have a greater fill i.e. surface area utilized. Positioning of a solar cell also determines its output for two reasons. First, the angle determines the level of reflection on the cell, and secondly the positioning determines the amount of sunshine captured from 9 am to 3 pm. For maximum efficiency, it is important to avoid any shadowing on cells. Learning working make money
Solar Energy – Types of Photovoltaics The Photovoltaic technology utilizes two technologies; crystalline form and the amorphous silicon. The amorphous is still a new exploration and may take longer to achieve optimal performance. Crystalline cells The crystalline silicon technology gives two types of photovoltaic cells − Mono-crystalline cells − Mono-crystalline solar cell is constructed from a single crystal cylinder sliced off to produce all the wafers in the array. The wafers are circular in shape, though at times they may be cut into other shape variations for crystal utility purposes. It is characterized by a uniform blue color. Other features include − Relatively high efficiency, among all PV technologies, available today. Most expensive cells because it is developed from purely same crystal. The cells are rigid and have to be well positioned and mounted on a rigid backing. Poly-crystalline cells − These are also known as malty-crystalline cells and are made by casting the silicon into a square mould. The resulting cast is then cut into a number of square wafers. The square block is made up of several crystals composed of arrays of blue variations. This is the technology behind the glittery, gemstone-like surface of some solar panels in the market today. Poly-crystalline cells have distinct features including − Slightly less efficient compared to mono-crystalline cells. Cheaper than mono-crystalline. Less waste of material (purified silicon). Given solar panels of same specification, the poly-crystalline panel is slightly wider than the mono-crystalline counterpart. Amorphous Cells Thin-Film PVs − The use of amorphous form of silicon to make photovoltaic cells is a new technique that the experts are still researching to curb the challenges of the crystalline forms. The characteristics of this technology include − They are much cheaper than both the crystalline forms. They are flexible. Thus, they should have a movable mounting to best utilize this feature. However, the shape of the surface should accommodate the panel for safety purposes. Less susceptible to power loss due to shedding of cells. In addition, they are more powerful at a dimly lit environment. Less durable. They gradually degenerate in terms of power production especially for the first month before gaining stability. Least efficient in power production and therefore covers larger space The new technology makes it possible for the panel to be mounted on windowpanes and curved surfaces. Photovoltaic Circuit Properties An equivalent circuit of a photovoltaic cell is given below − Current obtained, Iph = Area of cell * Intensity of light, H * response factor, ξ. Given, Loss due to resistance by conductor = Rp Loss due to non-ideal conductors = Rs If the cell produces current I at a voltage V, then, The relationship between I and U of a single cell is expressed as − Current, $I:=:I_{ph}-I_{o}[explgroupfrac{lgroup U_{cell}+I_{cell}R_{s}rgroup}{U_{t}}-1rgroup]-frac{lgroup U_{cell}+I_{cell}R_{s} rgroup}{R_{p}}$ Where thermal voltage is given by $U_{t}:=:frac{qkT}{e}$ Temperature is in Kelvin and K = 1.38-23(Bowman’s const), e = 1.602e-19. Getting maximum I and U, we can obtain maximum power. Imax is obtained when V = 0 i.e. short circuit while Vmax is obtained when I = 0 i.e. open circuit. Note − Cells in parallel add current while cells in series add up voltage. Learning working make money
Solar Energy – Developing a Solar Panel To construct a solar panel, one requires several solar cells made of doped silicon as has been discussed before. These cells are connected in series to add up the resultant current. This gives strips of clustered cells called a module. A single module could be constructed into a solar panel or combined with others in cases where a large panel is required. A solar panel consists of several layers that sandwich the photovoltaic cells. These layers are used to protect the fragile cells. An illustration of the layers is given below − The layers consist of the following parts − Cover Glass − This is the top cover and is transparent to allows light to enter. It prevents the cells from mechanical damage. It is made of hard glass to prevent against scratch. Non-reflective layer − Silicon can reflect most of the sunlight. Therefore, this layer is used to counter this and ensure maximum absorption of photons. In other words, it helps to maximize absorption. Contact grid − At this layer, all the contacts joining top to bottom of cells are connected together. The contact extends to the external parts of the panel like charge controller, combiner box and battery storage or grid system. P and N Silicon plates − This layer is actually a combination of two layers − the Ndoped silicon layer and P-doped silicon layer. This layer gives the solar panel its color. Back plate − This is a hard layer for supporting the crystalline photovoltaic panels. At times, flexible synthetic fibers may be used for thin-film type panels. Aluminum frame is used to frame the panel and to make it weatherproof. The benefits are − The frame provides a means of mounting the panel on surfaces such as rooftops. The frame is tight enough to protect the panel against extreme weather conditions such as storms. The solar panel should also be under constant care to prevent dust particles from resting on it. During the installation process, the panels should be fixed at an angle to receive maximum light. A proportional battery should be set in place in cases of no direct usage, to avoid waste. Learning working make money
Renewable Energy – Introduction Renewable energy is a term used to refer to forms of energy that are naturally obtained from the environment and from sources that can be replenished naturally. These include solar energy, wind energy, geothermal energy, hydropower, and biomass. The term renewable energy should not be confused with alternative energy, which describes sources of energy outside the regular forms like gasoline that are considered more environment-friendly or less harmful. Advantages of Renewable Energy Advantages of using renewable sources of energy are − Less maintenance cost as most sources entail few or no moving parts, hence, less mechanical damages. They are economical and can cut costs spent on fossil fuel. They emit little or no waste in the environment. Renewable energy sources do not deplete. Therefore, these have a better prospect for the future. Sources of Solar Energy This tutorial explains five major sources of renewable energy. Each source will be reviewed briefly, although detailed discussion will be provided in the subsequent chapters. Solar energy − Energy from the Sun is referred to as solar energy. Solar energy could be used as either active solar or passive solar. Active solar is directly consumed in activities such as drying clothes and warming of air. Technology has provided a number of ways to utilize this abundant resource. Geothermal energy − This refers to heat energy stored under the ground for millions of years through the earth formation. It utilizes a rich storage of unutilized thermal energy that exists under the earth’s crust. Hydro-power − This is a major renewable energy source used all over the world today to produce electricity. Wind energy − In ancient times, wind energy was used to move ships by impacting on the sails. Biomass energy − In energy generation, it refers to waste plants that are utilized to generate energy by combustion. Learning working make money
Renewable Energy Tutorial Job Search Renewable energy is a term used to refer to forms of energy that are naturally obtained from the environment and from sources that can be replenished naturally. These include solar energy, wind energy, geothermal energy, hydropower, and biomass. This tutorial explains the basic concepts of each form of renewable energy and the efficiency of each form. Audience This tutorial is meant for all those readers who want to learn the basic concepts of renewable energy, its sources, production, and utilization. Prerequisites It is a very basic introductory tutorial. Any student who wants to gather knowledge on Renewable Energy and its sources can go through the tutorial. Learning working make money
Solar Energy – Introduction Solar energy is the energy obtained by capturing heat and light from the Sun. Energy from the Sun is referred to as solar energy. Technology has provided a number of ways to utilize this abundant resource. It is considered a green technology because it does not emit greenhouse gases. Solar energy is abundantly available and has been utilized since long both as electricity and as a source of heat. Solar technology can be broadly classified as − Active Solar − Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Active solar is directly consumed in activities such as drying clothes and warming of air. Passive Solar − Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air. Conversion of Solar Energy The solar energy is the energy obtained by capturing heat and light from the Sun. The method of obtaining electricity from sunlight is referred to as the Photovoltaic method. This is achieved using a semiconductor material. The other form of obtaining solar energy is through thermal technologies, which give two forms of energy tapping methods. The first is solar concentration, which focuses solar energy to drive thermal turbines. The second method is heating and cooling systems used in solar water heating and air conditioning respectively. The process of converting solar energy into electricity so as to utilize its energy in day-to-day activities is given below − Absorption of energy carrying particles in Sun’s rays called photons. Photovoltaic conversion, inside the solar cells. Combination of current from several cells. This step is necessary since a single cell has a voltage of less than 0.5 V. Conversion of the resultant DC to AC. In the next chapter, we will learn the Photovoltaic method of converting solar energy into electricity. Learning working make money
Discuss Renewable Energy Renewable energy is a term used to refer to forms of energy that are naturally obtained from the environment and from sources that can be replenished naturally. These include solar energy, wind energy, geothermal energy, hydropower, and biomass. This tutorial explains the basic concepts of each form of renewable energy and the efficiency of each form. Learning working make money
Renewable Energy – Useful Resources The following resources contain additional information on Renewable Energy. Please use them to get more in-depth knowledge on this. Useful Video Courses 19 Lectures 3 hours 25 Lectures 3 hours 7 Lectures 2 hours 11 Lectures 2.5 hours 7 Lectures 1 hours 4 Lectures 1 hours Learning working make money