Lesson Notes By Weeks and Term v4 - SHS 1
RENEWABLE ENERGY SYSTEMS
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RENEWABLE ENERGY SYSTEMS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Engineering
Class: SHS 1
Term: 1st Term
Week: 20
Grade code: 1.2.2.LI.3
Strand code: 2
Sub-strand code: 2
Content standard code: 1.2.2.CS.1
Indicator code: 1.2.2.LI.3
Theme: ENE RGY SYSTEMS
Subtheme: RENEWABLE ENERGY SYSTEMS
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This lesson introduces the fascinating and crucial world of renewable energy. In Ghana, we are all familiar with the challenges of "dumsor" and the importance of a stable electricity supply for our homes, schools, and businesses. Our country is blessed with abundant natural resources like sunshine, water, wind, and organic materials. This lesson will explore how we can harness these gifts of nature to generate clean, sustainable electricity. We will move beyond just knowing the names of these sources to understanding the specific engineering principles that turn sunlight, flowing water, or even waste from a kenkey factory into the power that lights up our communities.
This section breaks down the "how" for each energy source. The key to understanding most of these methods is a simple but powerful principle. A. The Foundational Principle: The Turbine and The Generator
For many renewable sources (hydro, wind, biomass, biogas), the process follows a common pattern: Energy Source ➔ Turbine ➔ Generator ➔ Electricity Turbine: A turbine is essentially a machine with blades (like a fan or a propeller). When a force (like moving water, steam, or wind) pushes on the blades, it causes the turbine to spin very fast. This converts the energy of movement (kinetic energy) into rotational mechanical energy. Generator: The turbine is connected by a shaft to a generator. A generator works on the principle of electromagnetic induction. Inside the generator, large magnets are rotated inside coils of copper wire. As the magnets spin, their magnetic field "cuts" through the wire, forcing electrons in the wire to move. This flow of electrons is what we call an electric current. *Think of it this way:* The turbine's job is to spin the generator. The generator's job is to turn that spinning motion into electricity. The only thing that changes between hydro, wind, and biomass is *what* we use to spin the turbine. B. Hydropower (Water) Electricity Generation
Hydropower harnesses the energy of falling or flowing water. Ghana's biggest power plants, Akosombo and Bui, are hydropower dams.
Step-by-Step Process: Damming and Storing Water: A large dam is built across a river to create a reservoir (a large artificial lake). The water stored in the reservoir has a huge amount of Gravitational Potential Energy because of its height. Water Intake: At the bottom of the dam wall, there are large pipes called penstocks. When the gates (intake) are opened, water from the reservoir rushes down through these penstocks due to gravity. Its potential energy is converted into powerful Kinetic Energy. Spinning the Turbine: The high-pressure jet of water strikes the blades of a large turbine, causing it to spin at high speed. This converts the water's kinetic energy into Mechanical Energy. Generating Electricity: The spinning turbine is connected to a generator. As the turbine spins, so does the generator, producing electricity through electromagnetic induction. Transmission: The electricity is then sent to a transformer to increase its voltage for efficient long-distance travel through power lines to our towns and cities. Ghanaian Example: The Akosombo Dam holds back the Volta River to form Lake Volta. The water falls a great distance to spin massive turbines, generating a significant portion of Ghana's electricity. C. Wind Power Electricity Generation