DESIGN OF AN EARTH BATTERY SYSTEM
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DESIGN OF AN EARTH BATTERY SYSTEM
https://www.researchgate.net/publication/349214200_DESIGN_OF_AN_EARTH_BATTERY_SYSTEM
DESIGN OF AN EARTH BATTERY SYSTEM
BY
OGBONNA VICTOR CHIMAROKE 20141925043
A PROJECT SUBMITTED TO THE
DEPARTMENT OF MECHANICAL ENGINEERING,
SCHOOL OF ENGINEERING AND ENGINEERING TECHNOLOGY,
FEDERAL UNIVERSITY OF TECHNOLOGY, OWERRI
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF BACHELOR OF ENGINEERING (B.ENG) DEGREE IN
MECHANICAL ENGINEERING
NOVEMBER, 2019
CERTIFICATION
This is to certify that this work, “DESIGN OF AN EARTH BATTERY SYSTEM” was carried out by Ogbonna Victor Chimaroke (20141925043) at the department of Mechanical Engineering, Federal University of Technology, Owerri.
Approved by:
………………………………….…. ….………………………………
DR. A.C. OKORONKWO DATE
(PROJECT SUPERVISOR)
…………………………………….. ………………………………….
ENGR. DR. G. O. OSUEKE DATE
(HEAD OF DEPARTMENT)
..…………………………………… …………………………………
ENGR. PROF. J. C. EZEH DATE
(DEAN OF S.E.E.T.)
…………………………………… …………………………………
EXTERNAL EXAMINER DATE
DEDICATION
To God Almighty for the grace, strength and wisdom He showered on us throughout the period of this project.
ACKNOWLEDGEMENT
I am most grateful to God almighty for the inspiration, knowledge and wisdom to write this project. I would like to appreciate my supervisor, Dr. A.C. Okoronkwo for his positive contributions towards the success of this work.
My appreciation goes to my Head of Department, Engr. Prof. G.O. Osueke, my class adviser, Engr. C. Onwuachu and the entire staff of Mechanical Engineering for their advice, support and contribution throughout my years in school.
I am grateful to my parents, siblings, friends and well wishers for their support and encouragement. I am forever indebted to them. God bless you all.
ABSTRACT
Earth battery involves the use of soil as the medium for generating electrical energy. Soil naturally contains energy in the form of telluric current that is capable of generating a DC supply electricity. Different types of soil contain different electrical resistivity and conductivity values. The selection of the clay soil is due to its low resistivity and high moisture content. Electrodes made of two dissimilar metals, copper and zinc, were used to conduct electricity. The consideration of the arrangement of the cells, the pH value of clay soil, and the conductivity of the electrodes were taken in order to achieve the optimum value of output voltage. Thirty (30) earth battery cells were arranged in series and each cell was isolated in a plastic container to maximize a DC output voltage of about 19v. This output voltage charges a battery of 12v through a charge controller incorporated in an inverter which powers the inverter and consequently produces an AC output of 850VA. This study on earth batteries using copper and zinc electrodes is very encouraging and portrays the viability of the earth battery as an alternative source of electricity in an environment where the supply of electricity is deficient.
TABLE OF CONTENTS
TITLE PAGE……………………………………………………………………..…i
CERTIFICATION………………………………………………………………….ii
DEDICATION……………………………………………………………………..iii
ACKNOWLEDGEMENT…………………………………………………………iv
ABSTRACT………………………………………………………………………..v
TABLE OF CONTENTS………………………………………………………….vi
LIST OF FIGURES………………………………………………………………..ix
LIST OF TABLES………………………………………………………………….x
1.4. SIGNIFICANCE OF STUDY.. 4
2.1 THEORETICAL FRAMEWORK OF THE STUDY.. 6
2.2 BACKGROUND INFORMATION ON EXISTING SYSTEMS. 7
2.3 EMPIRICAL REVIEW OF RELEVANT LITERATURE. 11
2.4 SUMMARY OF LITERATURE REVIEW… 12
3.1.1 Tools and equipment for construction. 13
3.1.2 Instrument for Data Collection. 14
3.1.9 Material of the electrode. 18
3.2.2 Arrangement of DC Supply of earth battery. 20
3.2.3 Procedures to assemble an earth battery system.. 24
4.1 PRESENTATION OF RESULTS. 30
CONCLUSIONS AND RECOMMENDATIONS. 40
5.2 CONTRIBUTIONS TO KNOWLEDGE. 40
LIST OF FIGURES
Figure 2.1: Earth battery cells connected in series………………………………………… 8
Figure 3.1: Soil horizons………………………………………………………………………. 14
Figure 3.2: Serial connection of batteries………………………………………………….. 22
Figure 3.3: Parallel connection of batteries……………………………………………….. 23
Figure 3.4: Cascade (series-parallel) connection of batteries…………………………. 24
Figure 3.5: Serial connection of 15 earth battery cells on bare earth……………….. 25
Figure 3.6: Serial connection of 15 earth battery cells in isolated plastic buckets. 26
Figure 3.7: Serial connection of 30 earth battery cells in isolated plastic buckets. 28
Figure 3.8: A schematic representation of an earth battery, inverter and battery connection………………………………………………………………………………………………………… 29
LIST OF TABLES
Table 3.1: Bill of materials for the design of earth battery………………………..13
Table 3.2: Soil groups……………………………………………………………..15
Table 3.3: Type of soil with average resistivity and typical resistivity value…….18
Table 3.4: Comparison among series, parallel and cascade connections…………….24
Table 4.1: Voltages of individual cells……………………………………………30
Table 4.2: Voltages of individual cells after 1 hour………………………………31
Table 4.3: Voltages of individual cells after 2 hours……………………….…….32
Table 4.4: Voltages of individual cells after introducing plastic containers………33
Table 4.5: Voltages of individual cells 1 hour after introducing plastic
containers………………………………………………………………34
Table 4.6: Voltages of individual cells 2 hours after introducing plastic
containers………………………………………………………………..35
Table 4.7: Voltages of individual cells with electrode length of 0.5m…………….36
Table 4.8: Voltages of individual cells with electrode length of 0.5m after
1 hour……………………………………………………………………37
Table 4.9: Voltages of individual cells with electrode length of 0.5m after
2 hours……………………………………………………………..….38
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CHAPTER ONE
Energy plays a very important role in the socio-economic and technological development of every nation. The electricity demand in Nigeria far outstrips the supply which is epileptic in nature. The country is faced with acute electricity problems which are hindering its development notwithstanding the availability of vast natural resources in the country. It is widely accepted that there is a strong correlation between socio-economic development and the availability of electricity.
Access to modern energy services is an enormous challenge facing the African continent because the energy is fundamental for socio-economic development and poverty eradication. Today, 60% to 70% of the Nigerian population does not have access to electricity (Hopkins, 1902). There is no doubt that the present power crisis afflicting Nigeria will persist unless the government diversifies the energy sources in domestic, commercial and industrial sectors and adopts new available technologies to reduce energy wastages and to save cost.
Power demand has increased with population growth, industrialization and civilization. Most householders are barely conscious of the conservative measures for the available limited supply, while the environmental impact has rarely been taken into cognizance by consumers.
Adequate power supply is an unavoidable prerequisite to any nation’s development, and electricity generation, transmission and distribution are capital-intensive activities requiring huge resources of both funds and capacity. In prevailing circumstances where funds availability is progressively dwindling, creative and innovative solutions are necessary to address the power supply problem.
An Earth battery consists of a pair of electrodes made of two dissimilar metals, such as iron and copper, which are buried in the soil. Earth batteries act as water activated batteries and if the plates are sufficiently far apart, they can tap telluric currents. Telluric current is an electric current which moves underground or through the sea. Telluric currents result from both natural causes and human activity, and the discrete currents interact in a complex pattern. The currents are extremely low frequency and travel over large areas at or near the surface of the earth. Earth batteries are sometimes referred to as telluric power sources and telluric generators. Common metals used as electrodes are copper and iron or zinc.
Earth battery was constructed by a Scottish inventor Alexander Bain in 1841. This invention was first used to power his electric clock. The combination the plates that he used is zinc and copper. An earth battery is the simple homemade cell. Almost any liquid or moist object that has enough ions to be electrically conductive can serve as the electrolyte can serve as the electrolyte for a cell (Cooper, 1995). Production of small amount of electricity can be demonstrated by insert two electrodes into a lemon, potato and glass of soft drink. These homemade cells are of no real practical use because it just can produce small current and cost far more per unit energy generated than commercial cells. Earth batteries were used around the end of the 19<sup>th</sup> and beginning of the 20th century to power telegraph lines. They were buried in convenient locations along the power lines and supplied free for that infrastructure. The technology was discarded and replaced with hydroelectric because hydro was a measurable, finite source that industry could use to make money.
The earth battery bears resemblance to the common chemical or acid battery. Basically, the battery consist of two metal sheets or rods; one copper or carbon and the other zinc or aluminium. These metals are present as positive and negative terminal of the battery. An earth battery acts as the electrolyte system in voltaic cell because the conductive plates from different location are buried in the ground. This cell operating just like operating devices, these devices were not continuously reliable owing to drought condition. To obtain natural electricity, experiment would thrust two metal plates into the ground at a certain distance from each other in the direction of a magnetic meridian or astronomical meridian (Kelvin, 1800).
Power is essential to everyone for their daily activities. We need power for almost everything. Some of these sources of power pose a threat to the environment and to human health (through the emission of carbon dioxide, carbon monoxide and other exhaust gases which will result to global warming) while some are intermittent.
The use of the normal battery or dry cell leads to the greenhouse effect. The environment will be contaminated because of the mercury, silver, lithium, cadmium, lead and acid in dry cell or normal battery. If these batteries are burned or land filled, the heavy metals in prototype can affect the environment and the effect faced in the long term is harmful.
There is an alternative way to reduce the cost and generate electricity through the soil. It is very easy to construct and also devoid of pollution. Other than that, relationship between combinations of material utilized as a part of the setup and the measure of voltage produce need to be considered wisely. Besides that, it is important to know the relationship between the types of connection to generate lots of energy.
Therefore, by using earth battery we will be reducing the greenhouse effect and give benefit to the green technology. However, earth battery produce low voltage compared to the dry cell battery.
Earth battery only requires constant enrichment of the soil/electrolyte. The plates, one copper and another iron or zinc, are connected above ground by means of a wire with as little resistance as possible. In such an arrangement, the electrodes are not appreciably chemically corroded, even when they are in earth saturated with water, and are connected together by a wire for a long time.
The main objective of this study includes;
· To generate power that is environmental friendly,
· With a cost-efficient energy source
· Provide a DC voltage of 19V from the earth battery
· To power some appliances with the power generated from the earth battery
This particular work will elaborately highlight the advantages of using earth soil chemical reactions and electron affinity based earth batteries to generate power that is environmental friendly, less expensive and provides a DC of 19V.
The major benefit or impact of this project work is that it will show the importance or relevance of untapped energy present in the earth crust in the form of telluric current. It also cuts across other fields of study such as Electrical Engineering and Soil Science Technology. It also shows the ever expanding correlation between these field of study.
This project work will focus on the design of the Earth battery . It will also emphasize on it’s working principles which includes the composition of the soil as an electrolyte and how it aids power generation.
The work will involve some principles of electrical engineering, chemistry and soil science technology featuring energy and power generation.etc.
It will be a pilot experiment that will be set up at the automobile workshop of Federal University of Technology, Owerri to generate a DC of about 19 volts from the soil (an earth battery) which will be converted to an AC of about 850VA using an inverter. This will power some selected appliances in a room.
This chapter will present the past articles that are related to this project. This case study review about the type of soil used for earth battery, potential difference or voltage output of two metal electrodes that have been chosen, the depth of the electrode in soil and the distance between two electrode. Basically literature review will expose the previous work to understand this project. Literature review also helps to find overall information about earth battery to make sure the objective of this project is fulfilled.
Basically the operation of the earth battery is the production of electrical energy from chemical reaction between two type of material of the electrode and the organic soil as the electrolyte medium. The effect of this reaction will convert the chemical reaction to electrical energy.
2.1 THEORETICAL FRAMEWORK OF THE STUDY
Earth battery is one of the alternative energy that can be used to produce electricity. It is the combination of clay soil and electrodes such as Copper electrode (Cu) with Zinc electrode (Zn) or other metals that can produce potential difference (V) and current (A).
It consists of conductive plates from different locations in the electro potential series, buried in the ground so that the soil acts as the electrolyte in a voltaic cell. As such, the device acts as a rechargeable battery.
When the electrodes are connected with the appropriate soil condition, the electrochemical reaction occur to ensue production of zinc ions from the zinc metal which travel through the ground toward the copper terminal. The chemical reaction of zinc will affect the plant and topsoil but it also affect groundwater, so it is important to limit the amount of zinc.
The soil is an unutilized chamber of natural energy. The chemical reaction in the soil produce independent ions which are left unresolved. The soil take actions as an electrolyte with two dissimilar electrodes buried in the soil and thus produce a potential difference. This process is called an ‘earth cell’. To increase the voltage, connection in series is needed whereas to increase the current, connection in parallel should be done. Earth battery consists of electrodes buried in the earth, as therefore constructed, have not been capable of giving an electromotive force greater than that obtainable from a single couple.
2.2 BACKGROUND INFORMATION ON EXISTING SYSTEMS
One of the earliest examples of an earth battery was built by Scottish inventor Alexander Bain in 1841. In addition to his battery experiment, he invented and patented the electric clock. One of the projected uses of his earth battery was to power his electric clock whose resulting voltage of Bain’s earth battery was about one volt. The Earth battery, in general, generated power for early telegraph transmissions and formed part of a tuned circuit that amplified signaling voltage over long distances.
The simplest earth batteries consist of conductive plates from different metals of the electro potential series, buried in the ground so that the soil acts as the electrolyte in a voltaic cell. As such, the device acts as a primary cell (device acts as a non-rechargeable battery).
Figure 2.1: Earth battery cells connected in series
The formal name of these current is “telluric currents. Because of the incorporation of these currents in the success of this type of battery, earth batteries are sometimes referred to as telluric power sources and telluric generators.
As was cited earlier, these batteries differ little from traditional batteries. They include conductive plates and include an electrolyte. The simplest earth batteries consist of conductive plates buried in different locations. The choices of these plates as is found in the accompanying table aids in the voltages created. When buried in the ground, the moist earth acts as the electrolyte found in a traditional voltaic cell. This form of cell, however, device acts as a non-rechargeable battery.
Due to the continuous variation of the moisture content in the earth’s soil, an earth battery is not continuously reliable. It should be noted these devices were used by early experimenters as energy sources for telegraphy. This helped explain the theory of telluric current. The long distances between telegraph offices aided engineers in their discovery there were electrical potential differences between most pairs of telegraph stations. This was cited as the result from natural electrical currents flowing through the ground. They were named telluric currents.
Some early experimenters did recognize that these currents were, in fact, partly responsible for extending the earth batteries’ high outputs and long lifetimes. Later, experimenters would utilize these currents alone and, in these systems, the plates became polarized.
Lord Kelvin adds to the study of the earth’s current. He cited that continuous electric currents flowed through the solid and liquid portions of the earth, and the collection of current from an electrically conductive medium in the absence of electrochemical changes (and in the absence of a thermoelectric junction. It should be noted that Lord Kelvin’s “sea battery” was not a chemical battery. Lord Kelvin observations there were variables, such as the placement of the electrodes in the magnetic field and the direction of the medium’s flow affected the current output of his device. Variables of this nature do not affect traditional battery operation.
To obtain this natural electricity, experimenters would thrust two metal plates into the ground at a certain distance from each other in the direction of a magnetic meridian or astronomical meridian. It was learned the stronger currents flow from south to north.
This phenomenon possesses a considerable uniformity of current strength and voltage. As the Earth currents flow from south to north, electrodes are positioned, beginning in the south and ending in the north, to increase the voltage at as large a distance as possible.
The current produced is highest when two events occur:
· when the two metals are most widely separated from each other in the electro potential series,
· when the material nearer the positive end is to the north and the negative end is towards the south. The plates, one copper and another iron or zinc, are connected above ground by means of a wire with as little resistance as possible. In such an arrangement, the electrodes are not appreciably chemically corroded, even when they are in earth saturated with water, and are connected together by a wire for a long time.
Also it was discovered in early experiments that the current would be strong when the northerly electropositive electrode is driven deeper into the medium than the southerly electrode.
In other experiments, a pair of plates with differing electrical properties and with suitable protective coatings was buried below the ground. A protective or other coating covered each entire plate. A copper plate could be coated with powdered coke. A layer of felt would be applied to a zinc plate. This type of enhanced aid to better use this natural electricity, were used fed electromagnets, a load, that were part of a motor mechanism.
Organic wastes as additives are used in the soil of ground-based earth batteries to improve its performance. Three types of organic wastes were studied; Palm Oil Mill Effluent (POME), pineapple waste and lemon waste. Each organic waste is added into separate damped clay soil containers with a ratio of 20:80.
2.3 EMPIRICAL REVIEW OF RELEVANT LITERATURE
In a related study carried out by: Khan, Saleem and Abas in Lahore (Pakistan), “Experimental Study of Earth Batteries”, Different combinations of metallic and non-metallic solid electrodes were investigated for maximum potential difference (Ryeczek, 1984). In view of robust and cost effective use of this natural power technology by unskilled village consumers. Most suitable combinations of the commonly available metals were selected for further detailed characteristic studies. Combinations of Magnesium anode and Coke cathode; Zinc anode and Graphite cathode; Aluminum anode and Carbon cathode; Zinc anode and Copper cathodes gave 2.05, 1.40, 1.10 and 0.9 volts per cell. Typical rated power of a single Zn-Cu cell was measured to be few tens of microamperes. Small power electronic devices such as calculators, electronic watches, baby toys and cell phones and white light LEDs were operated on site. The voltage level was found to increase linearly by connecting multiple earth battery cells in series like commercial lead acid battery. The load current was found to increase by connecting earth cells in parallel. The source current capacities were also found to increase by increasing surface areas of the electrodes. However, single cell voltage was found to remain constant irrespective of the electrode sizes. This paper reports detailed characteristic study of the most cost effective and accessible metal electrodes earth batteries. Operation of earth battery as a free electricity source was demonstrated successfully
2.4 SUMMARY OF LITERATURE REVIEW
In this chapter, literary works done by other researchers were reviewed or discussed. It began with conceptual framework of concepts such as; chemistry, energy and finally, earth battery.
Empirical framework of this study reviewed the works done by the past and recent researchers in related fields. A study carried out by Khan et al operated on earth battery as a free electricity renewable source of energy using different combinations of metallic solid, liquid and gas electrodes (Emme, 1900).
This project aims to efficiently harness the power generated from the earth that will not only be used to power an electric clock or used as an energy source in telegraphy but will be able to power some appliances in a room. The earth battery will produce a DC output voltage of 19V that will charge a battery which consequently powers an inverter to generate an AC of 850VA. This output power will be able to power some appliances in the home.
The materials used for this research work include soil(loam), electrodes (copper and zinc pipes), copper wire, aluminium wire, masking tape, iron saw blade, plastic container, screwdriver, inverter, multimeter, Charge controller, 12V Battery.
Table 3.1 Bill of materials for the earth battery
3.1.1 Tools and equipment for construction
1. Iron saw blade
2. Masking tape
3. Screwdriver
4. Pliers
5. Measuring tape
3.1.2 Instrument for Data Collection
A DT-830D digital multimeter was used basically for data collection and results were obtained from the experiment that was carried out.
The soil consists of one or more distinct layers called horizons. These layers are alluded to as O, A, E, B, C and R depending on their position and nature (Cooper, 1995).
· O: Layers overwhelmed by natural material. Generally not introduced under warm dry conditions.
· A: The mineral soil horizon that is as a rule at the surface or beneath an O horizon. It more often than not has more natural carbon than hidden layers. In some cases this layer is missing or truncated because of disintegration or evacuation. Likewise, all surfaces coming about because of furrowing, feeding, or comparable aggravations are alluded to as A horizon.
· E: Horizon characterized by eluviations (removal of materials such as silicate clay, iron, aluminum, or organic matter), if distinct from the A horizon. It is frequently not present and usually more pale-coloured than the A horizon.
· B: A skyline, framed underneath An, E, or O skyline, which is ruled by demolition of all or quite a bit of the first shake structure and which shows proof of soil development, for example, alluvial (moved down from an above skyline) amassing of silicate dirt, iron, aluminum, humus, carbonates, gypsum, or silica; improvement of soil shading or structure; or weakness, and so on.
· C: Horizons or layers, barring hard bedrock, that are minimal influenced by pedogenic (soil framing) procedures what’s more, that need properties of O, A, E or B skylines.
· R: Hard bedrock
Table 3.2 Soil groups
The soil groups are coarse soil, fine soil and other soils. In the coarse soils, it consists of gravel and sand while the fine soils consist of silt and clay whereas the other soil is organic soil (Daniel, 1800).
Gravel and sand contain of rock fragment of different sizes and shape that can be either rock fragment or single mineral. The term uniform was describe as the narrow range of particle sizes present while the broad range of particle sizes is describe as well graded (Dieckmann & George, 1885).
Silt is the intermediate among fined sand and clay. Silt is less plastic and more permeable than clay. Quick behaviour in silt is the impulse of silt to liquefy when shaken or vibrated. Dilatancy refers to the tendency to sustain volume increase when deformed (Deffeyes, 2002).
Clay consists of particles with a grain size of less than 4 micrometre and present in properties of cohesion and plasticity. Those properties are not present in gravel or sand. Cohesion is the fact that material will stick together whereas plasticity is the property that grant substance to be deformed without volume change or rebound and without cracking or crumbling (Deffeyes, 2002).
Organic soil is different category from coarse or fine soils and it does not behave like silt or clay if the organic content is high. When the content of the organic is small to moderate, it still contains the properties of silt or clays (Goodstein, 2005). Organic matter comprises of dead plant parts and creature and microbial waste items in different phases of disintegration. In the long run, these things separate into humus, which is generally steady in the dirt.
Soil conductivity is a measure of the amount of salt in the soil. Soil conductivity is an important material in an earth battery. Soil conductivity determines the output power of the cell. The conduction in dirt occur through the moisture-filled pores that happen between individual soil particles. Naturally excess salt in soils containing in arid and semi-arid climates. Salts level in the soil can increase as a result of cropping, irrigation and land management (Rogner, 1997). Although soil conductivity does not give a direct measurement of specific ions or salt compounds, it has been correlated to the concentrations of nitrates, potassium, sodium chloride, sulphate and ammonia. Therefore, the electrical conductivity of soil is determined by the following soil properties (Ruppert, 2005).
a. Porosity: The higher soil porosity, the more efficiently electricity is conducted. Soil with lot clay content has bigger porosity than sandier soil.
b. Water content: Dry soil is much lessened in conductivity than moist soil.
c. Salinity level: Increasing absorption of electrolytes (salts) in soil water will dramatically increase soil electrical conductivity. The salinity level in most soils is very low.
d. Cation exchange capacity (CEC): Mineral soil containing high levels of organic matter (humus) and/or 2:1 clay minerals such as Montmorillonite, illite , or vermiculite have a much higher ability to retain positively charged ions (such as Ca, Mg, K, Na, NH4, or H) than soil lacking these constituents. The presence of these ions in the moisture-filled soil pores will enhance soil electrical conductivity in the same way that salinity does.
e. Temperature: As temperature decreases toward the freezing point of water, soil electrical conductivity decreases slightly. Below freezing, soil pores become increasingly insulated from each other and overall soil EC declines rapidly.
Table 3.3: Types of soil with average resistivity and typical resistivity value [9]
3.1.9 Material of the electrode
The next parameter to be considered is the type of electrode. Generally, materials have characteristics behaviour of resisting the flow of electrical charge. Metal is used because of its high conductivity and electrical value. Different types of electrode gives different values of potential difference. Electrode selection is based on the conductivity value of a material. In this part, to increase the voltage, the electrode used must have features such as low resistivity/high conductivity, high melting point and durable.
Based on the requirements for electrodes, the following materials are the most suitable for the design of earth battery:
Copper has the highest conductivity of any non-precious metal and one that is 65% higher than aluminium. This, combined with its high ductility, medium strength, good resistance to corrosion etc makes copper the first choice as a conductor for electrical applications. Copper is low in the reactivity series (which means that it does not corrode easily). The standard electrode potential of a copper electrode is +0.337V
Zinc is a moderately good conductor of electricity. It is relatively resistant to corrosion in air or water, and therefore is used as a protective layer on iron products to protect them from rusting. The standard electrode potential of a zinc electrode is -0.7628V
Aluminum is soft, durable, lightweight, ductile and malleable metal with appearance ranging from silvery to dull grey, depending on the surface roughness. It is nonmagnetic and does not easily ignite (Kleveman, 2004) aluminum has about one-third the density and stiffness of steel. It is easily machined, cast, drawn and extruded. Aluminum is a good thermal and electrical conductor, having 59% the conductivity of copper, both thermal and electrical conductivity, while having only 30% of copper’s density. Corrosion resistance can be excellent due to a thin surface layer of aluminum oxide that forms when the metal is exposed to air, effectively preventing further oxidation. The strongest aluminum alloys are less corrosion resistant due to galvanic reactions with alloyed copper (Fesquet, 1878).
Brass is alloy of combination between copper and zinc. The physical properties of brass are malleable and ductile, with alloys that contain less than 35% zinc able to be cold- rolled. The conductivity of brass is only between 23 and 44% of the conductivity of copper, which is still fairly high. The uses of brass vary depending on the percentages of zinc and copper, and which other metals have been added to alloy to bring out specific properties (Katz, 2007). It conducts heat very well. Brass material with more zinc is stronger and harder. The color of brass is light yellow color close to that of gold. Brasses with less zinc are more of a red brown color.
After considering some factors such as cost, electrical conductivity/resistivity, durability of material, pollution and availability of materials, copper and zinc emerged as the most suitable electrodes for the earth battery design in order to achieve optimal performance.
The materials were carefully selected after some tests for best performance. The copper electrode was tested with a bar magnet to ensure that the best copper pipes were used.
The following procedure describes how to design DC supply of earth battery. The constant variables are the soil and metal electrode. The metal electrode made from copper and zinc has high value of conductivity is chosen. The combination of the soil and these electrodes with series-parallel arrangement may have a high output voltage and suitable with a small load such as 3V LED lamp. As the distance between the electrode and the interface between the two soils increases, the apparent resistivity decreases.
3.2.2 Arrangement of DC Supply of earth battery
The next parameter involved is the arrangement of the earth battery. The arrangement means how the cells can be connected. The arrangement that will be reviewed in this project is series, parallel and cascade (series and parallel). Method of arrangement of position or type of connection that will be done applies in order to optimize the output voltage from the DC supply of clay soil battery.
3.2.2.1 Series Connection
A series circuit is a circuit composed entirely of components connected in series. In a series circuit, the current flowing through each of the components is the same, and the voltage across the circuit is the sum of the voltages across each component. To increase the output voltage in a circuit, series connection will be used.
However, disadvantage of this circuit is that if one of the components of the series circuit is faulty such as overloaded or short circuit, the whole circuit will then be damaged.
For series connection:
Current
I<sub>t </sub>= I<sub>1</sub> = I<sub>2</sub> = I<sub>3 </sub>= I<sub>n</sub> (3.1)
Voltage
V<sub>t</sub> = V<sub>l</sub> + V<sub>2</sub> + V<sub>3 </sub>+……+ V<sub>n</sub> (3.2)
Resistance
R<sub>t</sub> = R<sub>l</sub> + R<sub>2</sub> + R<sub>3</sub> +……+ R<sub>n</sub> (3.3)
Figure 3.2: Serial connection of batteries
3.2.2.2. Parallel Connection
The second method is parallel connection. In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component as stated in Kirchhoff’s current law [24]. If two or more components are connected in parallel, they have the same voltage across their ends. The same voltage means the average of the output voltage of the connection. The advantage of parallel connection is that it increases the current at constant voltage at the supply end, and if there is a short circuit or overload, only the overloaded or short-circuited device will be damaged. This makes it easier to isolate faults and perform repairing to the faulty branches. In other words, if one branch fails, the other branches can still keep on working. However, the disadvantage is the output voltage is less than the output voltage of series battery connection.
For parallel connection:
V<sub>t</sub> = V<sub>1</sub> = V<sub>2</sub> = V<sub>3 </sub>= V<sub>n </sub>(3.3)
Current
I<sub>t </sub>= V<sub>t </sub>(1/R<sub>t</sub>) (3.4)
Resistance
1/R<sub>t</sub> = 1/R<sub>1</sub> + 1/R<sub>2</sub> + 1/R<sub>3</sub> +……+ 1/R<sub>n </sub> (3.5)<sub></sub>
Figure 3.3: Parallel connection of batteries
3.2.2.3. Cascade Connection
This method is the combination of series-parallel connection in one circuit. To calculate the output of the voltage and current of this circuit, the theory of series and parallel is applied. The series-parallel combination has same advantage as series and parallel, but this type of connection needs more battery to increase the voltage.
Figure 3.4: Cascade (series-parallel) connection of batteries
Table 3.4: Comparison among series, parallel and cascade connections
3.2.3 Procedures to assemble an earth battery system
1. The Iron saw was used to cut the copper pipes and Zinc pipes to a length of 1m.
2. A masking tape was used to hold the two dissimilar metals (copper and zinc) which are separated by an insulator to prevent lagging.
3. A pair of electrodes was inserted into the soil to form a cell.
4. Repeat the procedures above to produce 14 other cells.
5. The soil was moistened with about 5litres of water per cell.
6. The voltage of each cell was measured independently with the multimeter and the readings were recorded. Readings were also taken at intervals of 1hour.
7. The set-up was then connected in series with aluminium wire.
8. The voltage of the serial cell combination was measured using a multimeter.
Figure 3.5: Serial connection of 15 earth battery cells on bare earth
Due to the short circuiting of electrodes, the voltage cannot increase on bare earth surface. We need to isolate individual cells to add up the voltage. To demonstrate serial addition of voltages, 15 DC earth battery cells were prepared in separate plastic buckets and moistened with about 10litres of water each. The isolated earth battery cells were connected in series to increase the voltage as shown in Fig.3.5
Figure 3.6: Serial connection of 15 earth battery cells in isolated plastic buckets
After the individual cells were isolated from each other and the ground. The voltages of individual cells were measured and recorded. The overall serial voltage of the cells was also measured and recorded. The voltage increased drastically due to the isolation of the cells from each other and the ground. The overall voltage in serial connection was approximately the sum of the individual cell voltages.
The electrodes were cut to a length of 0.5m and the voltages of individual cells were measured and recorded. The overall serial voltage of cells was also measured and recorded.
15 more plastic buckets were introduced and 15 other pairs of electrodes were inserted into the buckets to give a total of 30 cells as shown in fig.3.6. The voltages of the new individual cells were measured and recorded. The overall serial voltage of the 15 new cells was also measured and recorded. The overall serial voltage of the whole 30 cells were measured and recorded at intervals of 1 hour.
Figure 3.7: Serial connection of 30 earth battery cells in isolated plastic buckets
The output of the DC earth battery is connected to a charge controller which regulates the amount of charge entering the battery. The charge controller consists of a diode that prevents charge reversal. The earth battery charges the 12V battery through the charge controller and the battery is connected to the inverter. The inverter has an in-built step-up transformer that boosts the input of the battery to an output of 850VA
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Figure 3.8: A schematic representation of an earth battery, inverter and battery connection
4.1 PRESENTATION OF RESULTS
The various experimental procedures carried out have been described in the previous chapter. There were about 9 different tests undertaken to determine the voltage of individual cells and the overall serial voltage.
Table 4.1: Voltages of individual cells
Table 4.2: Voltages of individual cells after 1 hour
Table 4.3: Voltages of individual cells after 2 hours
Table 4.4: Voltages of individual cells after introducing plastic containers
Table 4.5: Voltages of individual cells 1hour after introducing plastic containers
Table 4.6: Voltages of individual cells 2hours after introducing plastic containers
Table 4.7 Voltages of individual cells with electrode length of 0.5m
Overall series connection for 30 cells = 19.18V
Table 4.8 Voltages of individual cells with electrode length of 0.5m after 1 hour
Overall series connection for 30 cells = 19.20V
Table 4.9 Voltages of individual cells with electrode length of 0.5m after 2 hours
Overall series connection for 30 cells = 18.75V
Inserting the electrodes directly into the earth decreases the overall output voltage when connected in series. This is because the arrangement is short-circuited when the electrodes are connected directly into the earth. Charges are also lost into the earth when these electrodes are inserted directly into the soil. This reduces the potential difference of the cells due to loss of charges.
When the plastic containers were introduced, the charges became isolated from the ground. The plastic containers served as insulators to prevent the diffusion of charges into the ground as the charges were now confined.
The overall serial voltage increased drastically from 2.5V to 9.87V. This result is approximately equal to the overall ideal serial voltage which is obtained by the summation of the individual cell voltages.
That is:
From equation (3.4)
V<sub>T</sub> = V<sub>1</sub> + V<sub>2</sub> + V<sub>3</sub> +………..+ V<sub>n</sub>
The earth battery was proven from the result to work best when damped. The salinity level of the soil drastically improves the conductivity of the soil, hence, making the earth battery more efficient.
CONCLUSIONS AND RECOMMENDATIONS
Results of experimental study on earth batteries using copper and zinc electrodes are very encouraging and portrays the viability of the earth battery as an alternative source of electricity. The initial results for week operation of earth batteries has shown reasonable potential for use in remote locations for signaling as well as charging cell phone and white light illumination applications. This interesting study has enlightened us on one of the sources of energy around us that is readily availability but has not been properly investigated.
5.2 CONTRIBUTIONS TO KNOWLEDGE
1. This study will serve as a guide for further studies in this area.
2. This study will help us understand the relationship between electricity and the earth.
3. This study will also provide the good knowledge base that will be useful in harnessing energy from the earth.
1. Further research work should be considered on other types of soils such as clay soil.
2. Further work should be done on how to embark on a larger scale production to harness energy from the earth which will yield larger amount of power for commercial and industrial purposes.
3. Further research work should consider replicating the methodology of this research and also adding sewage water on the earth batteries to increase its efficiency
4. Further research work should consider replicating the methodology of this research on other electrode material types such as silver, aluminium, brass etc
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