CH:5 Towards Green Energy Solutions Class 10th | Towards Green Energy Questions And Answers SSC Class 10
Remake the table taking into account the relation between entries in three columns.
| I | II | III |
|---|---|---|
| Coal | Potential Energy | Wind electricity plant |
| Uranium | Kinetic Energy | Hydro electric plant |
| Water Reservoir | Nuclear Energy | Thermal plant |
| Wind | Thermal Energy | Nuclear power plant |
Solution Table:
| I | II | III |
|---|---|---|
| Coal | Chemical Energy | Thermal Power Plant |
| Uranium | Nuclear Energy | Nuclear Power Plant |
| Water Reservoir | Potential Energy | Hydroelectric Plant |
| Wind | Kinetic Energy | Wind Electricity Plant |
Which fuel is used in thermal power plant? What are the problems associated with this type of power generation?
Solution 1: Scientific and Written Exam Answer
In thermal power plants, coal, natural gas, and petroleum are primarily used as fuels. These fuels are burned to produce heat energy, which is then converted into electrical energy.
Problems associated with thermal power generation:
- Emission of greenhouse gases like CO2 and SO2, leading to air pollution and acid rain.
- Large consumption of fossil fuels, leading to resource depletion.
- Thermal power plants require a large amount of water for cooling, causing water resource depletion.
- Disposal of ash (fly ash) and other by-products causes environmental hazards.
- Land degradation due to extensive coal mining.
Solution 2: Simple and Understandable Answer
Thermal power plants use coal, natural gas, and petroleum as fuel to generate electricity. The heat produced from burning these fuels is used to convert water into steam, which drives a turbine connected to a generator.
Problems:
- Burning coal and gas pollutes the air.
- Fossil fuels are limited and will run out over time.
- Thermal plants use a lot of water, which can lead to shortages.
- Disposing of ash from burning coal is harmful to the environment.
Other than thermal power plant, which power plants use thermal energy for power generation? In what different ways is the thermal energy obtained?
Solution 1: Scientific and Written Exam Answer
Other than thermal power plants, the following power plants use thermal energy for power generation:
- Nuclear power plant: Uses heat from nuclear fission reactions.
- Geothermal power plant: Uses heat from the Earth's interior.
- Solar thermal power plant: Uses heat from solar radiation.
Different ways of obtaining thermal energy:
- Combustion of fossil fuels: Burning coal, petroleum, or natural gas releases heat.
- Nuclear reactions: Nuclear fission generates large amounts of heat.
- Geothermal energy: Heat from deep inside the Earth is harnessed.
- Solar energy: Concentrated solar panels focus sunlight to produce heat.
Solution 2: Simple and Understandable Answer
Besides thermal power plants, some other power plants also use heat to generate electricity:
- Nuclear power plants: Heat is created by splitting atoms.
- Geothermal power plants: Heat from inside the Earth is used.
- Solar thermal power plants: Heat from the Sun is collected and used.
Ways we get heat energy:
- Burning coal, gas, or oil.
- Splitting atoms in nuclear reactors.
- Using hot water or steam from inside the Earth.
- Focusing sunlight to produce heat.
Which type/types of power generation involve maximum number of steps of energy conversion? In which power generation is the number minimum?
Solution 1: Scientific and Written Exam Answer
The type of power generation that involves the maximum number of energy conversion steps is the thermal power plant. The steps of energy conversion in a coal-based thermal power plant are:
- Chemical Energy (in coal) → Thermal Energy (by burning coal)
- Thermal Energy → Kinetic Energy (steam rotates the turbine)
- Kinetic Energy → Mechanical Energy (turbine movement)
- Mechanical Energy → Electrical Energy (generator produces electricity)
Thus, a thermal power plant has multiple energy conversion steps.
The power generation method with the minimum number of energy conversion steps is the hydroelectric power plant. The conversion steps are:
- Potential Energy (stored water) → Kinetic Energy (flowing water)
- Kinetic Energy → Mechanical Energy (turbine movement)
- Mechanical Energy → Electrical Energy (generator produces electricity)
Since hydroelectric power plants have fewer steps, they are more efficient in energy conversion.
Solution 2: Simple and Understandable Answer
The thermal power plant has the most steps in energy conversion because it first burns coal to produce heat, then converts it into steam, moves a turbine, and finally generates electricity. The steps are:
- Coal has chemical energy → Burning coal makes heat
- Heat turns water into steam → Steam moves a turbine
- The turbine rotates a generator → Electricity is produced
The hydroelectric power plant has the fewest steps because it uses the movement of water to spin a turbine, which directly generates electricity. The steps are:
- Water stored in a dam has potential energy
- Water flows down and moves a turbine
- The turbine turns a generator → Electricity is made
Because hydroelectric power has fewer steps, it is more efficient than thermal power.
Solve the following crossword puzzle.
a. Maximum energy generation in India is done using..... energy.
Solution: Thermal
b. ...... energy is a renewable source of energy.
Solution: Solar
c. Solar energy can be called.... energy.
Solution: Radiant
d. .... energy of wind is used in windmills.
Solution: Kinetic
e. ..... energy of water in dams is used for generation of electricity.
Solution: Potential
Explain the difference between Conventional and Non-conventional sources of energy.
| Conventional Sources of Energy | Non-conventional Sources of Energy |
|---|---|
| These sources have been used for a long time. | These are modern sources and are being developed recently. |
| They are exhaustible and can deplete over time. | They are renewable and do not deplete. |
| Examples: Coal, petroleum, natural gas. | Examples: Solar energy, wind energy, tidal energy. |
| They cause environmental pollution. | They are eco-friendly and do not cause pollution. |
| They are mostly non-renewable resources. | They are renewable and sustainable. |
| Initial setup cost is low but operational costs are high. | Initial setup cost is high but operational costs are low. |
| Used in large-scale industries and power plants. | Can be used in remote areas and small-scale setups. |
Explain the difference between Thermal Electricity Generation and Solar Thermal Electricity Generation.
| Thermal Electricity Generation | Solar Thermal Electricity Generation |
|---|---|
| Uses fossil fuels like coal, oil, or natural gas to generate heat. | Uses solar energy to generate heat for electricity production. |
| Causes pollution due to the release of CO₂ and other gases. | Eco-friendly as it does not emit harmful gases. |
| Non-renewable source of energy. | Renewable source of energy. |
| Requires a continuous fuel supply, leading to high operational costs. | Sunlight is free, reducing operational costs. |
| Can generate electricity at all times, regardless of weather. | Depends on sunlight availability and is affected by cloudy weather. |
| Commonly used in large-scale power plants. | Used in solar farms and decentralized power production. |
| Contributes to global warming and climate change. | Helps in reducing carbon footprint and environmental damage. |
What is meant by green energy? Which energy sources can be called as green energy sources and why? Give examples.
Solution 1: Scientific and Written Exam Answer
Green energy refers to energy derived from natural and renewable sources that have minimal or no negative impact on the environment. These energy sources do not emit harmful greenhouse gases and are sustainable for long-term use.
Green energy sources:
- Solar Energy: It is obtained from sunlight using solar panels.
- Wind Energy: Generated using wind turbines that convert wind motion into electrical energy.
- Hydroelectric Energy: Uses the kinetic energy of flowing water to generate electricity.
- Geothermal Energy: Uses heat from the Earth's interior for electricity generation and heating.
- Biomass Energy: Produced from organic materials such as plant and animal waste.
Why are they called green energy sources?
These sources are called green energy because:
- They are renewable and inexhaustible.
- They do not produce harmful emissions like CO₂.
- They help reduce pollution and combat climate change.
- They promote sustainable energy solutions.
Examples: Solar panels for home electricity, wind farms for large-scale power, hydroelectric dams for electricity, and geothermal plants for heating.
Solution 2: Simple and Understandable Answer
Green energy means **clean energy** that comes from natural sources like the sun, wind, and water. It does not pollute the environment.
Green energy sources:
- Sunlight (Solar Energy): Solar panels capture sunlight to make electricity.
- Wind (Wind Energy): Windmills use the wind to generate electricity.
- Water (Hydroelectric Energy): Water in dams turns turbines to produce electricity.
- Earth’s Heat (Geothermal Energy): Heat from underground is used to generate power.
- Plants & Waste (Biomass Energy): Organic waste is burned to make electricity.
Why is it called green energy?
- It does not pollute the air or water.
- It is never-ending and will not run out.
- It helps fight climate change.
Examples: Solar panels on rooftops, wind farms, hydroelectric dams, and geothermal power plants.
Energy obtained from fossil fuels is not green energy.
Solution 1: Scientific and Written Exam Answer
Fossil fuels such as coal, petroleum, and natural gas are non-renewable energy sources formed from the remains of ancient plants and animals. These fuels undergo combustion to release energy, but they also produce harmful greenhouse gases like carbon dioxide (CO₂), sulfur dioxide (SO₂), and nitrogen oxides (NOₓ).
Reasons why fossil fuels are not green energy:
- Non-renewable: They take millions of years to form and cannot be replenished.
- Air pollution: Burning fossil fuels releases pollutants that contribute to acid rain and respiratory diseases.
- Climate change: CO₂ emissions from fossil fuels increase global warming.
- Environmental damage: Extraction methods like mining and drilling destroy ecosystems.
Formula for Carbon Emissions:
$$ C_xH_y + O_2 \rightarrow CO_2 + H_2O + Energy $$
Since fossil fuels pollute the environment and are not sustainable, they are not classified as green energy sources.
Solution 2: Simple and Understandable Answer
Fossil fuels like coal, petrol, and diesel are not green energy because they pollute the air and harm the environment. When burned, they release smoke and gases like carbon dioxide (CO₂), which causes global warming.
Why fossil fuels are bad for the environment?
- They will run out one day.
- They release harmful smoke that makes the air dirty.
- They make the Earth hotter by trapping heat.
- They damage nature and animals when mined or drilled.
Example: Cars running on petrol or diesel release smoke, but electric cars do not. That’s why electric energy is greener!
Saving energy is the need of the hour.
Solution 1: Scientific and Written Exam Answer
Energy conservation is essential due to the increasing demand for electricity and the depletion of fossil fuels. Efficient energy use helps in reducing power wastage and environmental damage.
Reasons why saving energy is crucial:
- Prevents resource depletion: Fossil fuels like coal and oil are limited.
- Reduces pollution: Less energy use means fewer emissions of CO₂ and other harmful gases.
- Cost savings: Energy-efficient appliances consume less electricity, lowering bills.
- Promotes sustainability: Using renewable energy and conserving power helps future generations.
Formula for Energy Efficiency:
$$ \text{Efficiency} = \left( \frac{\text{Useful Energy Output}}{\text{Total Energy Input}} \right) \times 100 $$
By reducing wastage and using energy-efficient devices, we can ensure a sustainable future.
Solution 2: Simple and Understandable Answer
Saving electricity is important because energy sources like coal and petrol will not last forever. Using less energy also helps reduce pollution and saves money.
Ways to save energy:
- Switch off lights and fans when not in use.
- Use LED bulbs instead of regular bulbs.
- Turn off mobile chargers after use.
- Prefer public transport or bicycles instead of cars.
- Use solar panels for electricity.
Example: If we leave lights on all day, it wastes electricity. But if we turn them off when not needed, we save power and money.
How can we get the required amount of energy by connecting solar panels?
Solution 1: Scientific and Written Exam Answer
Solar panels generate electricity by converting sunlight into electrical energy using photovoltaic (PV) cells. To obtain the required amount of energy, multiple solar panels can be connected in different configurations.
Methods of Connection:
- Series Connection: Increases voltage while keeping current constant.
- Parallel Connection: Increases current while keeping voltage constant.
- Hybrid Connection: Combines series and parallel to balance voltage and current.
Formula for Power Output:
$$ P = V \times I $$
where,
- P = Power (Watts)
- V = Voltage (Volts)
- I = Current (Amperes)
By choosing the right configuration, we can optimize power generation based on energy requirements.
Solution 2: Simple and Understandable Answer
Solar panels turn sunlight into electricity. If we need more energy, we can connect multiple panels in different ways.
Ways to connect solar panels:
- Series connection: Increases voltage (useful for high-power needs).
- Parallel connection: Increases current (useful for stable electricity supply).
- Combination: Uses both methods to balance power output.
Example: If one solar panel produces 12V, connecting two in series gives 24V, but connecting them in parallel keeps it at 12V while increasing power.
What are the advantages and limitations of solar energy?
Solution 1: Scientific and Written Exam Answer
Solar energy is a renewable and sustainable source of energy, but it also has some limitations.
Advantages of Solar Energy:
- Renewable Source: Sunlight is available in unlimited quantity.
- Eco-friendly: No greenhouse gas emissions during electricity production.
- Low Maintenance: Solar panels require minimal upkeep.
- Reduces Electricity Bills: Produces free energy once installed.
- Energy Independence: Reduces dependence on fossil fuels.
Limitations of Solar Energy:
- Weather Dependent: Energy production drops on cloudy days.
- High Initial Cost: Solar panel installation is expensive.
- Large Space Requirement: Needs a wide area for installation.
- Energy Storage Issues: Batteries are required for nighttime energy use.
Despite its limitations, solar energy is one of the most promising clean energy sources.
Solution 2: Simple and Understandable Answer
Solar energy is a great way to get electricity from the sun, but it has some good and bad points.
Good things about solar energy:
- It never runs out because the sun is always there.
- It does not pollute the air like coal or petrol.
- Once set up, it gives free electricity.
- It needs very little care or repairs.
Problems with solar energy:
- It doesn’t work well on rainy or cloudy days.
- It is expensive to install solar panels.
- It needs a big space to set up many panels.
- At night, we need batteries to store solar power.
Example: If you put solar panels on your roof, you can get free electricity during the day, but you might need batteries for night-time use.
Step-by-Step Energy Conversion in a Thermal Power Plant
A thermal power plant converts fuel energy into electricity through multiple stages:
1. Chemical Energy → Heat Energy (Boiler)
- Fuel (coal, oil, or gas) is burned in the boiler.
- Heat is produced, converting water into high-pressure steam.
2. Heat Energy → Kinetic Energy (Steam Turbine)
- Steam at high pressure enters the turbine.
- The turbine rotates, converting steam’s heat energy into motion.
3. Kinetic Energy → Mechanical Energy (Turbine Rotation)
- The rotating turbine shaft transfers mechanical energy to the generator.
4. Mechanical Energy → Electrical Energy (Generator)
- The generator converts mechanical energy into electricity using electromagnetic induction.
5. Cooling and Recycling (Condenser & Cooling Tower)
- Used steam is cooled in the condenser.
- Water is recycled back to the boiler for reuse.
Energy Conversion Summary:
🔥 Chemical Energy (Fuel) → Heat Energy (Boiler) → Kinetic Energy (Steam) → Mechanical Energy (Turbine) → Electrical Energy (Generator) 🔌
Schematic Diagram of Thermal Power Plant:
Step-by-Step Energy Conversion in a Nuclear Power Plant
A nuclear power plant generates electricity using nuclear reactions, primarily through the fission process:
1. Nuclear Energy → Thermal Energy (Nuclear Reactor)
- Uranium or Plutonium undergoes nuclear fission in the reactor core.
- The reaction releases a tremendous amount of heat.
2. Thermal Energy → Steam Generation (Boiler)
- The heat is transferred to water in the boiler.
- Water converts into high-pressure steam.
3. Steam Energy → Mechanical Energy (Turbine)
- The high-pressure steam flows to the turbine, causing it to rotate.
- This converts the steam's thermal energy into rotational mechanical energy.
4. Mechanical Energy → Electrical Energy (Generator)
- The turbine is connected to a generator.
- The generator converts rotational motion into electricity using electromagnetic induction.
5. Cooling and Steam Recycling (Condenser & Cooling Tower)
- Used steam is cooled in the condenser to form water again.
- The cooling tower expels excess heat, and water is sent back to the boiler.
Energy Conversion Summary:
⚛ Nuclear Energy (Fission) → Heat Energy (Boiler) → Kinetic Energy (Steam) → Mechanical Energy (Turbine) → Electrical Energy (Generator) 🔌
Step-by-Step Energy Conversion in a Solar Thermal Power Plant
A solar thermal power plant uses sunlight to generate electricity through the following steps:
1. Solar Energy → Thermal Energy (Solar Panel/Absorber)
- The solar panels/reflectors capture sunlight and focus it on an absorber.
- This heats up a working fluid, usually water or a heat transfer oil.
2. Thermal Energy → Steam Energy (Boiler)
- The heated fluid transfers its heat to water in a boiler.
- Water turns into high-pressure steam.
3. Steam Energy → Mechanical Energy (Turbine)
- The high-pressure steam flows into a turbine, causing it to rotate.
- This converts thermal energy into mechanical energy.
4. Mechanical Energy → Electrical Energy (Generator)
- The turbine is connected to a generator.
- The generator produces electricity through electromagnetic induction.
5. Cooling and Steam Recycling (Condenser & Cooling Tower)
- Used steam is cooled in a condenser to form water again.
- A cooling tower expels excess heat, and water is pumped back to the boiler.
Energy Conversion Summary:
☀️ Solar Energy → Heat Energy (Absorber) → Steam Energy (Boiler) → Mechanical Energy (Turbine) → Electrical Energy (Generator) 🔌
Explain with a diagram of step-by-step energy conversion in a Hydroelectric power plant.
Solution 1: Scientific and Written Exam Answer
A hydroelectric power plant converts the potential energy of stored water into electrical energy through a series of transformations. The step-by-step energy conversion process is as follows:
1. Potential Energy to Kinetic Energy: Water stored in the reservoir has high potential energy due to its elevated position. When released through sluice gates, it flows through the penstock, gaining kinetic energy.
2. Kinetic Energy to Mechanical Energy: The fast-moving water strikes the turbine blades, causing the turbine to rotate. This converts kinetic energy into mechanical energy.
3. Mechanical Energy to Electrical Energy: The turbine is connected to a generator, which operates on the principle of electromagnetic induction. The generator converts mechanical energy into electrical energy using the formula:
$$ P = VI $$
where,
P = Power (Watts)
V = Voltage (Volts)
I = Current (Amperes)
4. Power Transmission: The generated electricity is transmitted through power lines to homes, industries, and businesses.
5. Water Recycling: After passing through the turbine, the water is released back into the river, ensuring a continuous cycle.
Solution 2: Simple and Understandable Answer
A hydroelectric power plant produces electricity from flowing water. The process happens in five simple steps:
1. Storing Water: A large dam holds water in a reservoir at a high level.
2. Water Flow: When the gates open, water rushes down a pipe called the penstock, gaining speed.
3. Spinning the Turbine: The fast-moving water hits the blades of a turbine, making it spin.
4. Generating Electricity: The turbine is connected to a generator, which produces electricity.
5. Sending Electricity: The electricity travels through wires to homes and businesses.
Example: Think of a watermill! When water flows over its blades, it spins and generates energy to grind grains. Similarly, hydroelectric plants use water to spin a turbine and generate power.
Give scientific reason: The construction of turbine is different for different types of power plants.
Solution 1: Scientific and Written Exam Answer
The construction of turbines varies depending on the type of power plant because different energy sources provide different forms and intensities of energy. The main factors influencing turbine design are:
- Energy Source: Steam turbines are used in thermal and nuclear power plants, while hydraulic turbines are used in hydroelectric power plants.
- Working Fluid: Steam turbines handle high-temperature steam, while hydro turbines handle water at varying pressures.
- Speed and Efficiency: Gas turbines in thermal plants operate at higher speeds compared to hydro turbines, which require larger blades to harness water power efficiently.
- Operating Conditions: Wind turbines have aerodynamic blades designed to capture wind energy efficiently, unlike steam or hydraulic turbines.
Thus, turbines are constructed differently to optimize energy conversion efficiency based on the available energy source.
Solution 2: Simple and Understandable Answer
Different power plants use different types of turbines because the source of energy is different. For example:
- In thermal power plants, turbines run on steam.
- In hydroelectric power plants, turbines run on water flow.
- In wind power plants, turbines use wind energy.
Since each power plant uses a different type of energy, the turbine must be designed to work efficiently with that energy source.
Give scientific reason: It is absolutely necessary to control the fission reaction in nuclear power plants.
Solution 1: Scientific and Written Exam Answer
Nuclear fission reactions release a tremendous amount of energy. If these reactions are not controlled, they can lead to uncontrolled chain reactions, causing extreme heat and radiation hazards. The reasons for controlling the fission reaction are:
- Preventing Explosions: Uncontrolled fission reactions can cause nuclear explosions due to excessive energy release.
- Maintaining Reactor Safety: Proper control ensures that the reactor does not overheat, preventing damage to the core.
- Regulating Power Output: Control rods (made of boron or cadmium) absorb excess neutrons, ensuring a steady and safe power supply.
- Avoiding Radiation Leaks: Excessive reactions can increase radiation levels, posing health hazards.
Thus, nuclear power plants use control rods to regulate the fission reaction and ensure safe energy production.
Solution 2: Simple and Understandable Answer
In a nuclear power plant, fission reactions produce a lot of energy. If not controlled:
- It can cause extreme heat and damage the reactor.
- Too much energy release can lead to accidents.
- Harmful radiation can leak, affecting people and the environment.
To keep the reaction safe, nuclear plants use special rods to slow down the fission process.
Give a scientific reason: Hydroelectric energy, solar energy, and wind energy are called renewable energies.
Solution 1: Scientific and Written Exam Answer
Hydroelectric energy, solar energy, and wind energy are classified as renewable energies because they are naturally replenished and do not deplete over time. The scientific reasons are:
- Continuous Availability: These energy sources are derived from natural processes that occur continuously. Water cycles, sunlight, and wind are always present on Earth.
- Non-Exhaustible: Unlike fossil fuels, which have limited reserves, these energy sources will not run out as long as natural cycles continue.
- Environmentally Friendly: They do not produce harmful emissions or contribute to global warming, making them sustainable for long-term use.
- Self-Sustaining: Solar panels convert sunlight into electricity, wind turbines harness wind energy, and hydroelectric plants use flowing water, all without diminishing the resource itself.
Due to these reasons, hydroelectric, solar, and wind energy are termed renewable energy sources.
Solution 2: Simple and Understandable Answer
Hydroelectric, solar, and wind energy are called renewable because they never run out. Here’s why:
- Sunlight is available every day.
- Wind blows naturally and can be used anytime.
- Water keeps flowing in rivers and dams, making hydroelectric energy possible.
These energy sources are safe for the environment and will always be available, unlike coal and oil, which get used up.
Give a scientific reason: It is possible to produce energy from mW to MW using solar photovoltaic cells.
Solution 1: Scientific and Written Exam Answer
Solar photovoltaic (PV) cells generate electricity by converting sunlight into electrical energy using the photovoltaic effect. The amount of energy produced depends on the number of PV cells used and their efficiency. The reasons why energy can be produced from milliwatts (mW) to megawatts (MW) are:
- Scalability: Individual PV cells generate small amounts of electricity (in mW), but by connecting multiple cells in a panel, the power output can be increased.
- Modular Design: Solar panels can be combined to form large solar farms capable of producing MW-scale energy.
- High Efficiency: Modern PV cells have improved efficiency, allowing them to generate more power per unit area.
- Storage and Distribution: Solar energy can be stored in batteries and used efficiently in large-scale power grids.
Because of these factors, solar PV cells can be used for small devices (mW) as well as for large power plants (MW).
Solution 2: Simple and Understandable Answer
Solar PV cells can produce both small and large amounts of energy:
- A single solar cell makes very little electricity (mW), used in small devices like calculators.
- When many solar panels are connected, they produce enough power (MW) for homes, factories, and even entire cities.
- More solar panels = more electricity!
This is why solar energy can be used for both small and big needs.
Draw a schematic diagram of solar thermal electric energy generation.
Solution:
Give your opinion about whether hydroelectric plants are environment-friendly or not?
Solution:
Hydroelectric power plants are considered a renewable energy source because they use the natural water cycle to generate electricity. However, their impact on the environment has both positive and negative aspects.
Environment-Friendly Aspects:
- Renewable Energy: Hydroelectric power relies on the continuous water cycle, making it a sustainable energy source.
- No Air Pollution: Unlike thermal power plants, hydroelectric plants do not release greenhouse gases like CO2 or SO2.
- Efficient Energy Production: These plants have high energy conversion efficiency compared to fossil fuel plants.
- Water Storage Benefits: Reservoirs created by dams can be used for irrigation, drinking water supply, and flood control.
Environmental Concerns:
- Impact on Aquatic Life: Dams obstruct the natural flow of rivers, affecting fish migration and aquatic ecosystems.
- Displacement of Communities: Large hydro projects may require relocation of people living in dam-affected areas.
- Deforestation and Habitat Loss: Constructing a dam can lead to the destruction of forests and wildlife habitats.
- Emission of Methane: Decomposing organic matter in reservoirs can release methane, a potent greenhouse gas.
Conclusion:
Hydroelectric power is a clean and renewable energy source, but its environmental impact depends on careful planning and management. Small-scale hydro projects with minimal ecological disruption are more environmentally friendly compared to large dams.
Draw a neat and labelled diagram of Energy Transformation in Solar Thermal Electric Energy Generation.
Solution:
Draw a neat and labelled diagram.
One solar panel produces a potential difference of 18 V and a current of 3 A. Describe how you can obtain a potential difference of 72 Volts and a current of 9 A with a solar array using solar panels.
Solution:
To obtain a solar array with a total output of 72V and 9A using solar panels of 18V and 3A, we follow these steps:
- Step 1: Series Connection for Voltage - Connecting four solar panels in series adds up their voltages while keeping the current the same. Each panel provides 18V, so four panels in series will produce: $$ V_{total} = 18V + 18V + 18V + 18V = 72V $$
- Step 2: Parallel Connection for Current - Connecting three such series strings in parallel increases the total current while maintaining the same voltage. Each string provides 3A, so three parallel strings will result in: $$ I_{total} = 3A + 3A + 3A = 9A $$
Final Output: The solar array will provide a total voltage of 72V and a total current of 9A.
Neat and Labelled Diagram:
Conclusion: By arranging the solar panels in a combination of series and parallel connections, we achieve the required output of 72V and 9A efficiently.
Write a short note on Electrical energy generation and environment.
Solution 1: Scientific and Written Exam Answer
Electrical energy is generated using various sources such as thermal power plants, hydroelectric power plants, nuclear power plants, and renewable sources like solar and wind energy. The process of generating electricity has significant environmental impacts, depending on the source used.
1. Fossil Fuels and Thermal Power Plants: These plants burn coal, oil, or natural gas to produce steam, which drives turbines connected to generators. This process releases greenhouse gases (CO₂, SO₂, NOₓ) causing air pollution and global warming.
2. Hydroelectric Power Plants: These use the potential energy of stored water to generate electricity. Though they are renewable, dam construction can disrupt ecosystems, affect aquatic life, and displace human populations.
3. Nuclear Power Plants: These use controlled nuclear fission reactions to generate heat, which is used to produce steam. While they produce large amounts of energy with minimal CO₂ emissions, the disposal of radioactive waste poses serious environmental risks.
4. Renewable Energy Sources: Solar, wind, and tidal energy do not produce harmful emissions. However, manufacturing solar panels and wind turbines requires energy and raw materials, which have some environmental impact.
Conclusion: To minimize environmental damage, a shift toward cleaner and renewable energy sources is necessary. Adopting energy-efficient technologies and reducing fossil fuel dependency will help mitigate climate change.
Solution 2: Simple and Understandable Answer
Electricity is made using different methods, and each method affects the environment in different ways.
1. Thermal Power Plants: These use coal, oil, or gas to make electricity, but they release smoke and gases that cause pollution and global warming.
2. Hydroelectric Plants: These use water to generate electricity. They do not cause air pollution, but building dams can harm fish and wildlife.
3. Nuclear Power: This produces a lot of electricity without air pollution, but handling nuclear waste is dangerous.
4. Renewable Energy: Solar panels and wind turbines create clean electricity without pollution. However, making them requires materials and energy.
Conclusion: Using more renewable energy and less fossil fuel is better for the environment. Saving electricity also helps reduce pollution.