MODULE 2.1

2.1 What are renewable energies and how does it work? Renewable energies are generated from natural resources which are sustainable and can be easily replenished [1]. Compared to non-renewable energies such as fossil fuels, renewable energies produce much lower emissions which contribute to the effo...

2.1 What are renewable energies and how does it work? Renewable energies are generated from natural resources which are sustainable and can be easily replenished [1]. Compared to non-renewable energies such as fossil fuels, renewable energies produce much lower emissions which contribute to the effort to address the climate crisis. Renewable energy generation is considered low-cost compared to fossil generated energies in most countries [2]. Types of Renewable Energy Solar Energy Solar energy is a renewable energy generated from the sun that is converted to electrical and thermal energy [4]. It is the most abundant energy resource available for consumption [2]. The first use of solar energy happened when humans used shiny materials to redirect sunlight to make fire in the 7th century B.C. In 1883, Charles Fritts invented the first solar powered device that produces electricity using sunlight and was installed on a New York City rooftop [5]. In the modern days, solar energy can be used for electricity and heat generation for industrial, commercial, and domestic uses. Figure 1. Solar Panel Energy Conversion https://clipart-library.com To convert sunlight into electricity, it undergoes a process called Photovoltaic Process: 1. When a photon (light energy) of sunlight is absorbed by a solar panel made out of semiconductive materials such as silicon that produces electric charge (voltaic). 2. The photovoltaic charge then creates direct current (DC). 3. Through an inverter, the DC electricity is converted to alternating current (AC). 4. The AC current is connected to the electricity grid ready to use. [7] There are large areas where a large number of solar panels are installed. It is also known as solar farms. Solar farms are used to harvest massive amounts of solar energy. These large amounts of solar energy generation are created for large scale uses such as for commercial and industry uses. Figure 2. Tarlac Solar Farm https://www.solarphilippines.ph Wind Energy Wind energy is generated using wind by converting kinetic energy (energy in motion) of air into electricity [8]. The uneven heating by the sun through the atmosphere and the influence of mountains and valleys creates wind. With this, it can be drawn that wind energy is a byproduct of solar energy [9]. The first wind turbines (also known as windmills) were made from wood. Ancient Egyptians used wind energy to propel their boat when travelling the Nile River [12]. In the past, windmills were only used for grinding grains and pumping water. Today, wind turbines are made out of modern engineering materials and generate renewable and clean energy. Figure 3. Wind Turbines Energy Capture https://www.treehugger.com Wind turbines can be installed in various locations such as land, oceans, lakes, within cities, or remote plains. Wind turbines are used to convert wind into electricity under these processes: 1. The wind passes through the blades of the turbine creating energy in motion (kinetic energy) causing the blade to rotate transforming into mechanical energy. 2. The blade is connected to a generator with the use of a gearbox. As the gearbox spins, the generator turns mechanical energy into electricity [10]. 3. The electricity produced is then stored to a grid ready for distribution. Figure 4. Wind Farm Rizal https://www.thepoortraveler.net Hydropower Hydropower is the oldest renewable energy source [3]. It converts the movement of the natural flow of water into electricity [15]. moreover, it can also harness power from various bodies of water such as lakes, rivers, waterfalls, and streams Figure 5. Hydroelectric Dam https://mocomi.com Hydropower undergoes these processes: 1. In order to produce electricity from moving water, flowing water should have enough volume and speed in order for the turbine to spin. The increase in volume and speed for energy conversion is achieved by constructing dams. 2. The rapid flow of water creates mechanical energy from releasing water with enough speed. 3. The mechanical energy will then be converted into electrical energy using a generator. 4. The converted electricity will then be distributed to the users through power lines [16]. Figure 6. Angat Hydro Power Plant in San Lorenzo, Bulacan https://www.gamesaelectric.com Geothermal From the word “geo” (earth) and “thermal” (heat), geothermal energy is a renewable energy generated from the heat of earth [18]. It can be found in fluids and rocks below the earth’s surface. Figure 7. Geothermal Energy Capture https://www.hilaryallison.com/infographics Geothermal energy is generated through these processes: 1. Geothermal energy is generated when geothermal resources such as reservoirs of water were made below the surface of the earth and heated enough to form a hot steam. 2. The hot steam rotates the turbine, creating a mechanical energy which will operate a generator that produces electricity. 3. The hot steam will then be converted into water using a cooling tower and will be injected back to the reservoir, ready for another cycle. Figure 8. Makban Geothermal Power Plant https://www.thinkgeoenergy.com Biomass Energy Biomass is a renewable energy source generated from organic materials like crop waste, wood, animal waste, solid waste, etc [19]. Biomass energy can be transformed into a direct heat or electricity and biofuel [20]. Figure 9. Biomass Energy Mechanism https://informationq.com/about-the-biomass-energy/ Biomass energy is produced in different ways. Thermal conversion is the most common way of generating biomass energy[19]: 1. Organic materials such as wood or sawdust are gathered and burned to create steam. 2. The steam spins the turbine creating mechanical energy which is then converted into electricity by a generator [21]. Figure 10. Isabela Biomass Energy Corporation https://www.snapsandganaps.com