Renewable Energy Resources Explained

Renewable energy Renewable resources : A resources than can be used repeatedly and does not run out because it is naturally replaced such as solar , wind , hydro geothermal and biomass energy 1- Solar cells: They are consists of semiconductors that convert solar energy directly into electrical energ...

Renewable energy Renewable resources : A resources than can be used repeatedly and does not run out because it is naturally replaced such as solar , wind , hydro geothermal and biomass energy 1- Solar cells: They are consists of semiconductors that convert solar energy directly into electrical energy. It is considered one of the modern methods that preserve the environment and minimize pollution resulting from the use of fossil fuels to obtain electrical energy. BENBAN STATION in Aswan considered the capital of solar energy and it is a group of solar stations contain 32 stations its capacity reaches 1465 megawatt How a photocell works: When light falls on the surface of a semiconductor material such as silicon, photons of light displace electrons to one of its two surfaces, a potential difference arises between the two surfaces that can create an electric current if connected to an external circuit.  To determine the efficiency of a solar cell, we compare the electrical energy produced by the cell to the light energy provided by the sun on its surface. If the cell is able to convert all the light energy that falls on it into electrical energy, then the efficiency of the cell is 100%. In practical applications, no solar cell is perfect. The ability of the solar cell to generate electricity from time to time during the day depending on the angle of inclination of the sun's rays, the presence or absence of clouds, and environmental factors such as wind, dust, and humidity. Recently, scientists have developed techniques to improve the efficiency of solar cells, where nanotechnology has been used in which materials are characterized by new properties on the solar cell that are characterized by a high ability to absorb sunlight to increase its efficiency.  The electrical energy (E) is calculated in joules from the relation : E = VIt Where I is the current in amperes (A), V is the voltage in volts (V), and t is the time of passing current in seconds (s). In practical applications, we prefer to deal with power (P) and its unit of measurement is the (Watt) Watt represents the energy produced or consumed per second, and is calculated from the relationship: P = VI Efficiency of solar cell = (electrical power produced / optical power falling on the cell ) x 100 - there are many devices that can work with solar energy and used in daily life such as: 1- Solar heaters : Solar water heaters are used to heat water at home and use it for multiple purposes, thus reducing the use of electricity significantly, and this type of heater is characterized by high efficiency. 2- Air conditioners Residents of hot countries need air conditioners and cooling systems a lot, and solar-powered air conditioners are very convenient for residents, as their use reduces electricity consumption by a large percentage. 3- Solar lamps To the list of solar-powered devices for the home, we add solar lamps. Solar lamps can be relied upon to illuminate and decorate gardens alike, and are used when there is a power outage, as they are considered a main alternative to lighting and consume less electricity. Solar lamps work by placing them under the sun's rays, and have an automatic operation feature, in addition to being environmentally friendly and not producing any exhausts. 2- Wind energy: is one of the most important sources of environmentally friendly alternative energy that depends on converting wind energy into clean electrical energy. - It relies on the operation of wind turbines by the movement of air. It consists of streamlined and curved blades or fans, turbines, and generators. When the air current passes over the two sides of the blade, two zones of different atmospheric pressure are formed due to the different speed of air movement on both sides of the blade, which causes it to move. The turbine blades are connected by a transmission shaft to a generator to convert the kinetic energy into electrical energy - The efficiency of wind turbines depends on the speed of wind movement in the area, so it is preferable to build them in open areas such as deserts and high altitude areas. 3- Hydroelectric power: Dams are used to store water in a reservoir. Thus, the water gains potential energy due to its position. The dam contains gates to control the movement of water. When the gates are opened, water flows from upstream to downstream in front of the dam to fall on turbines that rotate due to the falling water, and then this movement is transmitted to electrical generators that convert the energy into electrical energy.