Renewable Energy Soures(Solar, Wind)

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Thermal and Electrical Power Generation 
Renewable Energy Sources (Solar- Wind)
By: Yarin Cristy Mendes Monteiro
email: yarinflor2@gmail.com/yarinflor@hotmail.com
Teacher: Eng. Pavel Atanasoae 
Erasmus 2017/2018 
Indication
	Introduction	3	Solar Energy	4
	How to turn Solar energy into electrical energy	5
	Types of Solar Power	6
	Advantages and Disadvantages of Solar Energy	6
	Advantages:	6
	Disadvantages:	7
	Generation capacity of Solar Energy	7
	Thermal energy	8
	How do the plants work?	9
	Photovoltaic energy	9
	Advantages and Disadvantages of a photovoltaic panel	11
Advantages:	11
.Disadvantages:	11
	History of Wind energy and its purpose	12
	The development of wind turbines of large organizations	13
	The wind resource	14
	Factors that influence the speed of winds	15
	Types OF TURBINES FOR ELECTRIC POWER GENERATION	16
 Spinners of Vertical Axis………………………………………………………….16
Spinners of Shaft Horizontal……………………………………………………….17
	Components of a wind turbine horizontal axis	19
	Applications OF WIND POWER SYSTEMS	20
Isolated Systems…………………………………………………………………...20
 Hybrid Systems…………………………………………………………………….21
 Interconnected systems to the network………………………………………….22
Off-shore systems………………………………………………………………….22
	The main advantages and main disadvantages of wind energy	22
 Benefits for society in general……………………………………………………23
 Main disadvantages of wind energy…………………………………….............24
Conclusion……………………………………………………………………………………..25
Webgraphy……………………………………………………………………………26
Introduction
At the beginning of the 20th century the production of electrical energy was responsible for about a little more than two-thirds of total carbon dioxide emissions to the atmosphere, with a tendency to increase. With alerts for climate change and its arising consequences, it was necessary clean feasible alternatives to decrease this number. In this way solar energy gained greater prominence, although it had already reached a peak of popularity in the 1970s, due to a crisis in the oil industry.
To make solar energy even more advantageous and competitive compared to other power options, it is necessary to have much investment in this area, since only a small percentage of energy coming from the sun can be harnessed and transformed into energy, due to the poor performance of these panels, however there was already a notable development both globally and nationally.
Solar Energy
The production of electricity with solar energy is possible through photovoltaic cells or by heating a fluid. In the first option, the cells are made of silica, phosphorus and boron which, when they receive the sun's rays, result in the production of electricity, which can be stored in a battery or injected directly into the electrical grid through an inverter. 
In the second option, mirrors are used to gather sunlight to heat a fluid, generating steam that turns the blades of a steam turbine to produce electricity. 
The Sun can also be used to heat water or buildings. This type of use can replace traditional means of heating, avoiding the use of electricity or gas. The solar potential is lower in winter than in summer; however, it is the other way around in the case of hydro or wind. The wind resource, on average, is a little more intense during the night than during the day; Solar resource exists only during the day. We have a solar resource which is roughly twice that of the Germany. The use of the sun to generate electricity is complementary to other sources and is, in fact, abundant in Portugal.
How to turn Solar energy into electrical energy
 Nowadays, human being uses electrical power from solar energy, in practically everything. Some examples of how we use the electricity are: to light the house, to watch TV, to satisfy our basic needs such as hygiene and nutrition, to access the internet, load the phone, among many things. We need the power in large part of day-to-day activities. 
After a great evolution in the means of transforming solar energy into electrical energy (because initially there was no use of the solar energy in order to produce electricity, which sometimes caused environment pollution,) finally came the two forms more reassuring to our environment of how to produce electric energy, which arose from the use of renewable energies: photovoltaics and thermal. In summary, the photovoltaic energy is produced by photovoltaic cells, which are normally for silicon. 
These cells are meant for gathering photons (present in solar radiation) to proceed to the formation of electrons, causing the photoelectric effect, discovered by the scientist Albert Einstein. On the other hand, the thermal energy is produced from heat generated by the sun, that is, the heat is transformed into electricity through the production of steam, which is responsible for turning turbines connected to generators of energy. The countries that most generate energy from solar power and residential cards are, respectively, Germany, China, France, United States and Japan.
Types of Solar Power 
The methods of capture of solar energy can be divided into direct and indirect and active and passive: 
 Direct - means that there is only one possible transformation to make solar energy a form of energy used by man. 
 Indirect - means that it is necessary to have more than single transformation in order to conceive useful energy.
  Passive - are generally direct, although they involve (sometimes) flows in convection, which is technically a conversion of heat into mechanical energy. 
 Active - are generally indirect and are considered systems that call for the aid of electrical devices, mechanical or chemical means to increase the capacity of energy production.
Advantages and Disadvantages of Solar Energy 
As all resources used by the human being, the solar energy also has advantages and disadvantages:
 Advantages:
It is renewable;
It is abundant;
Doesn't pollute the environment (does not emit greenhouse gases into the atmosphere); minimal maintenance; 
Helpful in places with difficult access. 
Disadvantages: 
It is costly; 
It dependents on atmospheric conditions;
It is of low yield level; 
Storage inefficient compared to fossil fuels, etc.
Generation capacity of Solar Energy
The ability to generate this energy and the costs of investments in the same has been behaving in a reverse order, due to lower prices of equipment, the resulting investments are proportionately lower, which does not invalidate the rise in quantity of photovoltaic energy generated recently reaching more than 102 GW, saving 53 million tons of CO2. However, within this development of energy generation capacity, there are some countries representing more than half of the monopoly of the industry, these countries have driven the development of clean energy the most. Germany, which according to the EPIA (European Photovoltaic Industry Association) has grown exponentially over a decade, and even the most developed country in the industry at global level, with the ability to generate 32.411 GW. 
Also in Europe Italy stands out with a generation capacity of 16.3 GW, however, despite the numbers, the EPIA affirms the existence of a significant drop of recent production. Although in Asia, China was the country that invested the most in renewable energy, according to UNEP (United Nations Environment Program), having the capacity to generate about 8, 3GW. In Asian continent, Japan asserts itself with a capacity of 6,9GW such number being driven by demand by encouraging the use of clean energies. Finally, in America, the US has the ability to generate 7.7 GW of energy with a view to growth of 4GW in a short space of time, due to the use of new solar parks and small installations.
Thermal energy 
Another method to capture the sun's rays and consequent use of it for energy production are the solar thermal central. These use the heat of the sun, in this case, as all other power stations,however it is not necessary to burn fossil fuels for energy production. 
Although it has all the benefits of being a clean energy, its flaw is the fact that it is not only dependent on weather conditions as well as it has high costs and need large investments.
 Even in the face of these counterparts, it has been dominating a small part of the industry as it continues to be developed by the countries that dominate the monopoly of the industry, such as Spain and the United States, thus possible improvements in areas such as the cost of maintenance and also the cost of components that make up the panels.
How do the plants work?
 Unlike the photovoltaic installations that convert photons from sunlight directly into electrical energy, this type of solar rays are reflected by mirrors, which vary in shape depending on the method of capture, being in turn directed to the collector, directing the rays to warm a fluid, more recently liquid sodium due to its high capacity of heating allowing retain heat for several days, increasing the profitability, in turn this fluid will rotate a turbine, due to its steam or the mechanical force exerted by the same, and produce electricity.
Figure 1 Solar plant of high temperature
Photovoltaic energy 
Over the past few years, at the end of the 20th century and early 20th century, the human being has come to be touched and alerted to the danger and damage to nature that has been happening on the part of man due to the increased use and reliance on non-renewable energy sources. It became essential to find alternative systems of energy that glimpsed a balanced world, without damage to the nature, being environmentally friendly. Solar energy is one such alternative sources that can be used as a solution, though, still today is not a definitive solution to the problem. From renewable energies available on the planet, the sun is without doubt the most abundant. In fact, the solar energy that Earth receives from the Sun in a minute is sufficient to cover the energy needs of the world's population during one year. However, the world uses only a small portion of solar energy at our disposal, in part because the relationship between the cost and the efficiency of energy technologies including solar still is not ideal for the majority of the population. Solar energy is a safe, clean, renewable and independent. It is safe because it does not use means that endanger the life, clear because it does not generate waste at its process, renewable because its source of raw material is the sun and independent (it can be used individually or in community). The conversion of solar energy into electrical energy is done through the photovoltaic effect discovered by French physicist Alexander E. Becquerel in 1839. The conversion is achieved through a photochemical reaction that occurs inside the solar photovoltaic panels, where they are installed. To understand how they work the photovoltaic cells is crucial to know that light is composed of small particles called photons. Photovoltaic cells are mostly composed of a positive and negative layers, consisting of semiconductor materials, for example the silicon, crystalline characteristics. It should be noted that these cells do not allow the storage of energy. The energy absorption of photons by the cell allows the release of electrons that move to the bottom of the cell and thus create a stream of electrons, or electricity. These cells are grouped together to form the panels or photovoltaic modules.
Advantages and Disadvantages of a photovoltaic panel 
This type of energy, although it does not require any type of maintenance, and is a clean energy, non-polluting, has advantages and disadvantages in their use.
 Advantages: 
High reliability, has no moving parts, which is very useful in applications in isolated places; 
Easy handling of modules enables simple mounting and adaptable; 
Cost of operation is reduced, it does not require maintenance, fuel or transport; the photovoltaic technology presents environmental qualities because the final product is non-polluting, silent and does not disrupt the environment. 
 Disadvantages: 
The cost of the manufacture of photovoltaic modules is quite high, although it has been becoming cheap over the years;
 The actual yield of conversion of a module is small compared to the cost of investment; 
The photovoltaic generators are rarely competitive from an economic point of view, compared to other types of generators (example of the generators to diesel).
Wind Energy
History of Wind energy and its purpose
Wind energy has been used since ancient times to move the boats powered by sails or to operate Mills’ gear grinder. In wind mills, wind power was transformed into mechanical energy, used in the grinding of grain or pumping water. The mills were used for the production of flour and channel drainage, particularly in the Netherlands. Over thousands of years, the strength of the wind has been used in many forms, from the impetus of sailboats and sailing boats, to the natural ventilation of buildings. The use of wind to produce mechanical energy appeared relatively late in antiquity. The wind wheel of the Greek engineer Herao de Alexandria, conceived during the 1st century AD, is the oldest tool known designed to capture the wind strength to power a machine.
At least since the ninth century, probably since the late VII, the first windmills appeared in Persia. The use of windmills became common in the Middle East and Central Asia, coming later to China and India. Around the year 1000, the windmills were used to pump water from the sea to the salt marshes in China and in Sicily, and from the eleventh century are already used intensively in western Europe in the milling of flour, and drainage of wetlands for cultivation or construction. The technology from the Old Continent was taken to America by the first Europeans. In 1881, William Thomson proposed the use of wind energy in the absence of coal.
In July of 1887, James Blyth, an engineer from Scotland, had built a turbine with clothed blade in the garden and used the electricity produced to charge accumulators which used to light up his house. His experiment would origin in 1891 to a patent. In the winter of 1888, American inventor Charles Francis Brush produced electricity using a generator powered by wind energy, which supplied electricity to his residence and laboratory. In the late 1890s, the Danish inventor Poul la Cour constructed wind turbines to produce electricity, which used to produce hydrogen and oxygen through electrolysis, thus saving up a mixture of the two gases to use as fuel. La Cour was the first to discover that the turbines spinning at a higher speed and with fewer blades were more efficient to produce electricity. In 1904 he founded the Society of the Electricians Wind.
In the mid-1920s, some companies began to manufacture wind turbines for electricity of 1-3 kilowatts,] which had a wide acceptance in the rural regions of North America. However, the installation of electrical networks during the 1940s and the need for more energy has made these small generators obsolete. 
The development of wind turbines of large organizations
The trade of wind turbines in the world has developed rapidly in technology and sizes over the last 15 years. Figure 1 shows the impressive development of the size and power of wind turbines since 1985. A wide variety of types and models available on the market have yet not stopped growing. With the demand for new projects off-sho.
Figure 2 A variation of the dimensions of wind turbines throughout the ages
The wind resource
	
Wind energy comes from solar radiation since the winds are generated by non-uniform heating of the earth's surface. An estimate of the total energy available from the winds around the planet can be made from the hypothesis that approximately 2% of solar energy absorbed by the earth is converted into kinetic energy of the wind. 
Although this percentagemay seem small, it represents 100 times the power annually installed in power stations in the world. The winds that blow on a global scale and those that manifest in small scale are influenced by different aspects among which stand out the height, the roughness, the obstacles and relief. The following will describe the mechanisms of generation of the winds and the key factors of influence on the system of winds of a region.
Factors that influence the speed of winds
 The statistical behaviour of wind throughout the day is a factor which is influenced by the variation of wind speed over time. The topographical features of a region also influence the behaviour of the winds because in a single area there may be differences in speed causing the reduction or acceleration in the wind speed. In addition to the topographic variations and roughness of the soil, the speed also varies its behaviour with the height. Considering that the wind speed can vary significantly over short distances (a few hundred meters), the procedures for assessing the location in which you want to install wind turbines must take into account all the regional parameters that influence on wind conditions. Among the main factors of influence in the scheme of the winds are:
 The variation of speed with the height; 
The roughness of the terrain, which is characterized by vegetation, use of land and buildings; 
 Presence of obstacles in the vicinity;
Relief that may cause effect of acceleration or deceleration in the flow of air;
The information necessary for the survey of regional conditions can be obtained from topographic maps and a visit to the site of interest to evaluate and model the roughness and obstacles. The use of aerial images and satellite data also contribute to a more accurate analysis. Figure 6 shows a generic form, as the winds behave when they are under the influence of the characteristics of the soil surface.
Types OF TURBINES FOR ELECTRIC POWER GENERATION
Spinners of Vertical Axis
 In general, the rotors to vertical axis has the advantage of not requiring follow-up mechanisms for changes in wind direction, which reduces the complexity of the project and the efforts arising from the forces of Coriolis Effect. The rotors of vertical axis can also be moved by forces of support (lift) and by forces of drag (drag). The main types of rotors of vertical axis Darrieus are, Savonius and turbines with tower of vortices. The rotors of the type Darrieus are moved by forces of support and are of curved blades (two or three) of aerodynamic profile, lashed by the two ends of the vertical axis.
Figure 3 Experimental turbine vertical axis
Spinners of Shaft Horizontal
 The rotors of horizontal axis are most common and most of the world experience is geared for their use. It is moved by aerodynamic forces called forces of support (lift) and the forces of drag (drag). A body that obstructs the movement of the wind undergoes the action of forces that act perpendicular to the disposal (forces of support) and forces that act in the direction of runoff (forces). Both are proportional to the square of the relative speed of the wind. Additionally, the forces of support depend on the geometry of the body and the angle of attack (formed between the relative speed of the wind and the axis of the body). 
The rotors that spin predominantly under the influence of forces of support allow you to release much more power than those that spin under the influence of forces of drag, for a same speed of wind. The rotors of horizontal axis along the wind (wind turbines) are predominantly moved by forces of support and must have mechanisms to allow the disc swept by the wind blades is always perpendicular to the wind. These rotors can be constituted of a wind blade and counterweight, two wind blades, three wind blades or multiple blades (multivane fans). Constructively, the wind blades may have the most varied forms and employ the most varied materials. In general, we use wind blades of rigid wood, aluminium or fibre glass reinforced. 
Figure 4 -Turbine of horizontal axis
As to the position of the rotor in relation to the tower, the disc swept by the wind blades may be downstream of the wind (downwind) or the amount of wind (up wind). In the first case, the "shadow" of the tower causes vibrations on the wind blades. In the second case, the "shadow" of the blades causes vibratory efforts in tower. 
The amount of wind Systems need mechanisms of orientation of the rotor with the flow of wind, while in the systems downstream of the wind, the orientation is accomplished automatically. The rotors more used for electricity generation are the horizontal axis of the type propeller, usually composed of 3 wind blades or in some cases (average speeds too high and possibility of generating greater acoustic noise) 1 or 2 wind blades.
Components of a wind turbine horizontal axis
 The main settings of a wind turbine horizontal axis can be seen in Figure 5. These turbines are differentiated by the size and shape of the nacelle, the presence or absence of a multiplier box and the type of generator used (conventional or multipoles). The following are the main components of the turbine that, in a general way can be presented as the tower, nacelle and rotor.
Figure 5 A view of the inside of the nacelle of a wind turbine
Applications OF WIND POWER SYSTEMS
A wind system can be used in three different applications: isolated systems, hybrid systems and network interconnected systems. The systems must follow a basic configuration, it requires a power control unit and, in certain cases, a storage unit.
Isolated Systems
Isolated Systems generally, uses some form of energy storage. This storage can be done via batteries, with the aim of using electrical appliances or in the form of gravitational energy with the purpose of storing the pumped water in reservoirs for later use. Some isolated systems do not need storage, as in the case of systems for irrigation where all water pumped is directly consumed.
Figure 6- Configuration of an isolated wind system
The systems that store energy in batteries require a device to control the loading and discharging of the battery. The charge controller’s main objective is not to allow any damage to the battery from overcharging or deep discharge. The charge controller is used in systems of small businesses in which the apparatus used are low voltage and direct current (DC). An inverter is necessary for feeding equipment that operates with alternating current (AC). This device usually incorporates a follower of the point of maximum power required for the optimization of the produced power. This system is used when you want more comfort with the use of conventional appliances.
Hybrid Systems 
The hybrid systems are those that, have multiple sources of energy generation disconnected from the conventional network, for example, wind turbines, diesel generation, photovoltaic modules, among others. The use of various forms of electric power generation increases the complexity of the system and requires the optimization of the use of each of the sources. In these cases, it is necessary to perform a control of all sources for maximum efficiency in the delivery of energy to the user. 
In general, hybrid systems are employed on systems of medium to large size intended to serve a larger number of users. By working with loads in alternating current, the hybrid system also requires an inverter. Due to the great complexity of arrangements and multiplicity of options, the form of system optimization becomes a particular study each case.
Figure 7 Configuration of a hybrid solar wind diesel system
Interconnected systems to the network
The systems connected to the network use a large number of wind turbines and do not require energy storage systems because the whole generation is delivered directly from the mains. The total installed power in the world of wind systems connected to the network addabout 60 GW (WWEA,2006) of which 75% are installed in Europe. 
Off-shore systems
 The off-shore installations represent the new frontier in the use of wind energy. Although they represent larger installations cost of transportation, installation and maintenance, the off-shore installations have grown each year mainly with the depletion of areas of high wind energy potential on earth. 
This depletion is presented primarily by the large concentration of wind farms in these areas and the restrictions environmental standards on the use of the ground. The wind industry has invested in technological development of the adaptation of wind turbines for use at sea. In addition to technological development, the projects off-shore installations require special strategies regarding the type of carriage of machinery, its installation and operation. The entire project should be coordinated in order to use the periods where the water conditions provide an offset and an installation with security. 
Figure 8 Off-shore systems
The main advantages and main disadvantages of wind energy
 
Benefits for society in general
Is inexhaustible;
It does not emit gaseous pollutants nor generates waste;
Reduces the emission of greenhouse gases (GHG).
 The main disadvantages of wind energy
The flashing, i.e., wind is not always blowing when electricity is needed; therefore, making it difficult the integration of its production in the program of exploitation;
Can be overcome with fuel cells (H2) or with the technique of hydro pumping.
Causes considerable visual impact, mainly for the nearby residents, the installation of wind farms generates a large modification of the landscape;
Impact on the birds of location: mainly by wind blades hitting birds, unknown effects on the modification of their migration behaviour;
Noise Impact: the sound of the wind hits the blades producing a constant noise (43dB(A)). The dwellings closer should be at least 200 meters away.
Conclusion
	It is clear that consumption and demand for energy is increasing in the world, and the search for new ways to generate clean and renewable energy is itemized every day.
And in relation to the topic addressed in this work that in the case is solar energy, it is concluded that the solar energy system is an investment with short-term return, an advantageous alternative to isolated locations such as regions where the power transmission network by hydroelectric It does not reach. And the most important of this type of energy is contributing to the development of a sustainable planet.
	It seems that in the future the solution to the problem of energy will have to pass not only by the exploration of a perfect method but also by the search for a balance between the different methods applied to different realities.
More important than looking for new ways to get energy, to seize it or to store it, is undoubtedly to reduce your expenses.
	Thus, it is unquestionable that renewable energies will contribute to a better future. Because the minutes of today build those of tomorrow.
Webgraphy
http://pt.wikipedia.org/wiki/Painel_solar.
http://www.solarenergy.com.br/.
http://www.sunlab.net.br/Energia_solar_Sunlab.htm
http://painelsolares.com/
http://energiasrenovaveisa1.blogspot.pt/2008/05/energia-elica.html
https://pt.wikipedia.org/wiki/Energia_renov%C3%A1vel
http://www.portal-energia.com/vantagens-desvantagens-da-energia-eolica/
Figure 1 Solar plant of high temperature
Figure 2 A variation of the dimensions of wind turbines throughout the ages
Figure 3 Experimental turbine vertical axis
Figure 4 Turbine of horizontal axis
Figure 5 A view of the inside of the nacelle of a wind turbine
Figure 6 Configuration of an isolated wind system
Figure 7 Configuration of a hybrid solar wind diesel system
Figure 8 Off-shore systems