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Solar Energy

Currently, renewable energy is being used to combat the negative effects of climate change by replacing fossil fuels. Instead of obtaining energy by burning coal and petroleum, renewable energy sources acquire energy from natural sources that are constantly replenished such as sunlight and wind power. There are many types of renewable energy sources such as solar energy, wind energy, hydroelectric power, and biomass energy, but the most commonly used sources are solar and wind power. Solar energy is the most abundant energy resource on Earth and its energy can be captured and used in many different ways.

Since the sun is a massive star, there are multiple nuclear fusions taking place deep in its core. These fusions produce tremendous amounts of energy that radiate past the surface of the Sun and into space in the form of light or heat. This energy can then be converted into usable energy in two different ways. The first method that can be used to capture energy from the sun are photovoltaics. Photovoltaics (PV) solar systems are most commonly used for smaller uses of energy such as residential solar panel installations. In a solar PV system, solar panels are used to create electricity from the sun that can be used promptly or stored in a battery. The way solar panels capture energy is through a process known as the photovoltaic effect. Most solar panels are composed of silicon. There are two layers of silicon sandwiched between two conductive layers. Each silicon atom is connected to each other by four strong bonds. This keeps the atoms in place so no current can flow. The first layer of silicon molecules are called the N type silicon and have extra electrons and the silicon in the second layer are called P-type silicon have extra spaces for electrons called holes. The two layers meet at the p/n junction, leaving one side positively charged and one side negatively charged. When sunlight, also known as photons, hits the solar cell with enough energy, it can cause a silicon atom to lose an electron, creating one loose electron and one hole. The electron molecule and the hole are free to move around but because of the electrical field at the p/n junction, they can only move in one direction, with the electron traveling in the N side and the hole traveling in the P side. The loose electrons are then captured by thin metal strips called fingers at the top of the solar cell and create electricity by flowing through an external circuit. This creates a direct current, or DC, which only allows electricity to flow in one direction. These direct currents are then converted into alternating currents, or AC, through a solar inverter. This is a necessary step because a majority of household appliances utilize AC electricity.

The second way to capture solar energy is through the use of solar thermal energy. This involves capturing heat directly from solar radiation and then using that heat for a variety of uses. Solar thermal energy is ideal for a larger range of uses and falls into three different categories. The first is low temperature solar thermal energy systems, and is primarily used for heating and cooling. The second is called mid temperature, and is used for heating water and the third is high temperature solar thermal energy and is used for electrical power generation. In addition to solar power, wind power is also used as an alternative to fossil fuels. Wind power involves the usage of wind turbines in order to convert wind energy into electricity. Wind turbines usually have three propellers called rotors that rotate when the wind blows. The movement of the blades drives a generator that creates energy by converting the kinetic energy of the rotors into electricity.

The main issue with using renewable energy is that the sun is not constantly shining light, and the wind is not consistently blowing, causing renewable energy to not always be accessible. Currently renewable energy can be stored with solar batteries. They store excess energy produced by solar panels for later use. This may be ideal for residential solar panel installations, but solar batteries do not store enough energy to meet the demand of bigger facilities that utilize the solar panels. This problem can be solved with the creation of a device or a method that can efficiently store a large amount of renewable energy for different periods of time. If a method to accomplish this can be devised, then renewable energy can be used on a much larger scale in the future.

BY: Tauba Ashrafi

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