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: 2nd Term
Week: 1
Grade code: 1.2.2.LI.4
Strand code: 2
Sub-strand code: 2
Content standard code: 1.2.2.CS.1
Indicator code: 1.2.2.LI.4
Theme: ENE RGY SYSTEMS
Subtheme: RENEWABLE ENERGY SYSTEMS
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Welcome, future engineers! We all know what it feels like when the lights go out – we call it "dumsor". This challenge highlights how important a steady supply of electricity is for our homes, schools, and businesses in Ghana. For many years, we have relied heavily on the Akosombo Dam. But what happens when the water level is low? We need other, more sustainable ways to generate power. This lesson explores the exciting world of renewable energy – sources that don't run out, like the sun, wind, and water. We will compare these different sources to understand which ones might be best for Ghana's future, considering our unique resources and needs.
A. What is Renewable Energy? Renewable energy is energy derived from natural sources that are replenished over a short period. Unlike fossil fuels (like crude oil or natural gas) which are finite and will eventually run out, renewable sources are virtually inexhaustible. Think of the sun that shines every day, the wind that blows, and the rivers that flow.
The main renewable energy sources we will focus on are: Solar Energy (from the sun) Hydropower (from moving water) Wind Energy (from the wind) Biomass Energy (from organic matter) B. How Each Source Generates Electricity Solar Energy Principle: Uses the Photovoltaic (PV) effect. Special materials, usually silicon, in solar panels can convert sunlight directly into Direct Current (DC) electricity. Process: Sunlight (photons) strikes the PV cells in a solar panel. This excites electrons in the silicon, causing them to flow, which creates DC electricity. An inverter is used to change the DC electricity into Alternating Current (AC) electricity, which is the type we use in our homes. Example in Ghana: Rooftop solar panels on houses in Accra, solar-powered streetlights, and the Navrongo Solar Power Station in the Upper East Region. Hydropower (Hydroelectric Energy) Principle: Uses the kinetic energy of flowing or falling water to generate electricity. Process: A dam is built across a large river to create a reservoir (a large artificial lake). Water is allowed to flow through tunnels in the dam. The force of the falling water turns a large wheel called a turbine. The turbine is connected to a generator. As the turbine spins, it makes the generator spin. The generator uses electromagnetic induction to convert the mechanical (spinning) energy into electrical energy. Example in Ghana: The Akosombo Dam and the Bui Dam are our primary sources of electricity. Wind Energy Principle: Uses the kinetic energy of wind to generate electricity. Process: The wind blows against the blades of a large wind turbine, causing them to rotate. The rotating blades are connected to a gearbox which increases the speed of rotation. This high-speed shaft is connected to a generator, which works just like in a hydropower plant, converting the mechanical energy of rotation into electricity. Example in Ghana: While not widespread yet, there are pilot projects and significant potential in coastal areas like Ada Foah and in the northern plains. Biomass Energy Principle: Uses organic material (plants, agricultural waste, animal manure) to generate energy. Process (Direct Combustion): Organic waste (like cocoa pods, sawdust, or cassava peels) is collected and dried. It is burned in a furnace to heat water, creating high-pressure steam. The steam is used to turn a turbine. The turbine spins a generator to produce electricity. Process (Biogas): Organic waste is put in a sealed container called a digester without oxygen. Bacteria break down the waste (anaerobic digestion), producing a flammable gas called methane (biogas). This biogas can be burned to heat water for a steam turbine or used in a gas engine to power a generator. Example in Ghana: Use of sawdust from timber mills for power; potential for using waste from cocoa, palm oil, and cassava processing. C. Comparison of Renewable Energy Sources in a Ghanaian Context
This table provides a detailed comparison based on the five key criteria mentioned in the NaCCA exemplar.
| Criterion | Solar Energy | Hydropower | Wind Energy | Biomass Energy | | :--- | :--- | :--- | :--- | :--- | | Availability of Resource | Excellent. Ghana has abundant sunshine all year round, especially in the Northern, Savannah, and Upper regions. | Good but Location-Specific. Depends on large rivers like the Volta. Prone to droughts and climate change affecting water levels. | Moderate and Location-Specific. Good potential along the coast (e.g., Ada, Ningo) and in some northern areas. Wind is not consistent everywhere or all the time. | Excellent. High availability of agricultural waste (cocoa pods, palm kernel shells, cassava peels) and municipal waste. | | Quantity of Electricity | Scalable. Can range from a single panel for a small home (low quantity) to a massive solar farm (high quantity, e.g., Navrongo). Output is intermittent (only during the day). | Very High. Large dams like Akosombo and Bui produce a huge, steady supply of electricity (baseload power). | Scalable but Intermittent. Can be large-scale wind farms. Depends heavily on wind speed, so output fluctuates. | Scalable (Small to Medium). Can power a small community or a factory. Not typically as large-scale as a major dam. Can provide a steady supply. | | Ease of Generation | Easy (for small scale). Installing rooftop solar is relatively simple. Large solar farms are more complex but straightforward. | Very Difficult. Requires massive civil engineering, geological surveys, and long construction times. Displaces communities. | Moderately Difficult. Requires land, technical expertise for installation, and connection to the grid. Turbine maintenance is specialised. | Moderately Difficult. Requires a system to collect, transport, and process the waste. Biogas digesters need careful management. | | Cost of Generation | High Initial Cost, Very Low Running Cost. Panels and inverters are expensive upfront, but sunlight is free. Prices are rapidly decreasing. | Extremely High Initial Cost, Very Low Running Cost. Building a dam costs billions of dollars, but water is free. | High Initial Cost, Low Running Cost. Turbines are expensive. Maintenance can also be costly. | Moderate Initial Cost, Moderate Running Cost. Building the plant is cheaper than a dam, but there are ongoing costs for collecting and transporting the biomass fuel. | | Availability of Technology | High. Solar panels, inverters, and batteries are widely available in Ghanaian markets. Many local technicians are trained in installation. | Low. The technology for building large dams is highly specialised and not locally manufactured. Requires foreign expertise. | Low to Moderate. Wind turbines are not made in Ghana and must be imported. Local expertise is still developing. | Moderate. Some components for smaller biogas systems can be made locally. Larger combustion plants require imported technology. |