Grade 10 Q&A: Chapter 15: Towards Green Energy

Concept Questions

Q1: What is 'green energy'?

Answer: Green energy refers to energy derived from natural sources that are naturally replenished and cause minimal environmental impact, such as solar, wind, hydro, and geothermal energy.

Q2: What is the principle behind the generation of electrical energy in most power plants?

Answer: The principle behind the generation of electrical energy in most power plants is electromagnetic induction, where a conductor moves in a magnetic field or a magnetic field changes around a conductor, inducing an electric current.

Q3: Name the device used to convert mechanical energy into electrical energy.

Answer: The device used to convert mechanical energy into electrical energy is an electric generator.

Q4: What is the primary fuel used in a thermal energy-based electric power station?

Answer: The primary fuel used in a thermal energy-based electric power station is coal.

Q5: What are the main problems associated with thermal power generation?

Answer: The main problems associated with thermal power generation include air pollution due to burning coal (releasing CO₂, SO₂, NOₓ, soot), and the limited reserves of fossil fuels.

Q6: What fuel is used in a nuclear energy-based power plant?

Answer: Uranium or Plutonium (specifically U-235 or Pu-239) is the fuel used in a nuclear energy-based power plant.

Q7: What is a 'chain reaction' in the context of nuclear power?

Answer: A chain reaction in nuclear power is a self-sustaining series of nuclear fissions where neutrons released from one fission event cause further fission events in other atomic nuclei, releasing a large amount of energy.

Q8: Name two types of power plants based on renewable energy sources.

Answer: Two types of power plants based on renewable energy sources are hydroelectric power plants and wind energy power plants.

Q9: What are 'photovoltaic cells'?

Answer: Photovoltaic cells (solar cells) are devices that convert sunlight directly into electricity using the photovoltaic effect, typically made from semiconductor materials like silicon.

Q10: How is electricity generated in a hydroelectric power plant?

Answer: In a hydroelectric power plant, water stored at a height is released, its potential energy is converted into kinetic energy, which then rotates a turbine connected to a generator, producing electricity.

Q11: What is the main advantage of power generation from natural gas?

Answer: The main advantage of power generation from natural gas is that it causes less pollution compared to coal-based thermal power plants.

Q12: What is a 'solar thermal power plant'?

Answer: A solar thermal power plant uses concentrated sunlight to heat a fluid, which then produces steam to drive a turbine and generate electricity, rather than directly converting sunlight into electricity.

Q13: Why is 'energy conservation' important?

Answer: Energy conservation is important because it reduces reliance on finite fossil fuels, minimizes environmental pollution, lowers energy costs, and ensures sustainable energy availability for future generations.

Application-Based Questions

Q14: Explain how a wind turbine generates electricity.

Answer: A wind turbine generates electricity by converting the kinetic energy of wind into mechanical energy. The wind rotates the large blades of the turbine, which are connected to a shaft. This shaft then drives a generator, which produces electrical energy through electromagnetic induction.

Q15: Discuss the environmental benefits of using solar energy for electricity generation.

Answer: Using solar energy for electricity generation offers significant environmental benefits. It produces no greenhouse gas emissions (like CO₂, SO₂, NOₓ) during operation, thus reducing air pollution and mitigating climate change. It also minimizes reliance on fossil fuels, which are finite and contribute to environmental degradation through mining and drilling.

Q16: What are the challenges associated with nuclear power generation, despite its high energy output?

Answer: Despite its high energy output, nuclear power generation faces challenges such as the safe disposal of radioactive waste (which remains hazardous for thousands of years), the risk of accidents (like Chernobyl or Fukushima) that can release harmful radiation, and the potential for nuclear materials to be diverted for weapons proliferation.

Q17: How does the concept of a 'turbine' apply across different types of power plants?

Answer: The concept of a 'turbine' is central to most large-scale power generation. Whether it's a thermal, nuclear, hydroelectric, or wind power plant, the turbine acts as the intermediary device that converts the energy from a fluid (steam, water, or air) into mechanical rotational energy, which then drives the electric generator to produce electricity.

Q18: Why are fossil fuels considered 'non-renewable' sources of energy?

Answer: Fossil fuels (coal, petroleum, natural gas) are considered 'non-renewable' sources of energy because they are formed over millions of years from the decomposition of organic matter under intense heat and pressure. Their rate of formation is extremely slow compared to the rate at which humans consume them, meaning their reserves are finite and will eventually deplete.

Q19: Describe the process of electricity generation in a power plant based on the energy of natural gas.

Answer: In a natural gas power plant, natural gas is burned in a combustion turbine, which drives a generator to produce electricity. The hot exhaust gases from the turbine can also be used to produce steam, which then drives a second steam turbine to generate additional electricity in a combined cycle power plant, increasing efficiency.

Higher-Order Thinking Questions

Q20: "Electric energy generation and environment are closely related." Justify this statement.

Answer: The statement "Electric energy generation and environment are closely related" is profoundly true because almost every method of generating electricity has some impact on the environment. Fossil fuel-based power plants release greenhouse gases and pollutants, contributing to climate change and air pollution. Hydroelectric projects can alter ecosystems and displace communities. Nuclear power produces radioactive waste. Even renewable sources like wind and solar have environmental footprints (e.g., land use, material extraction, visual impact). Therefore, the choice of energy generation methods directly influences environmental health and sustainability, making their relationship inseparable.

Q21: Discuss the challenges in transitioning from fossil fuel-based energy to green energy sources on a global scale.

Answer: Transitioning to green energy globally faces significant challenges: 1. **Intermittency:** Renewable sources like solar and wind are intermittent (depend on weather), requiring robust energy storage solutions or backup systems. 2. **Infrastructure:** Building new green energy infrastructure (solar farms, wind farms, transmission lines) requires massive investment and land. 3. **Cost:** While costs are falling, initial capital investment for renewables can be high compared to established fossil fuel plants. 4. **Geographic Limitations:** Not all regions have optimal conditions for all types of green energy (e.g., consistent wind, abundant sunlight). 5. **Material Sourcing:** Production of renewable energy technologies requires specific raw materials, raising concerns about supply chains and environmental impact of mining. 6. **Political and Economic Inertia:** Resistance from industries reliant on fossil fuels and the need for international cooperation pose significant hurdles.

Q22: How can individuals contribute to the 'Towards Green Energy' movement in their daily lives?

Answer: Individuals can contribute significantly to the 'Towards Green Energy' movement by: 1. **Conserving Energy:** Reducing electricity consumption by switching off lights/appliances when not in use, using energy-efficient appliances, and optimizing heating/cooling. 2. **Adopting Renewable Energy:** Installing rooftop solar panels if feasible, or choosing electricity providers that offer green energy options. 3. **Sustainable Transportation:** Opting for public transport, cycling, walking, or electric vehicles instead of personal petrol/diesel cars. 4. **Reducing Waste:** Minimizing waste generation, recycling, and composting to reduce energy consumed in manufacturing new products and managing landfills. 5. **Supporting Green Policies:** Advocating for and supporting government policies that promote renewable energy and environmental protection. 6. **Educating Others:** Raising awareness among friends and family about the importance of green energy and sustainable practices.

Q23: Compare the efficiency of different electricity generation methods (e.g., thermal, nuclear, hydroelectric, solar) and explain factors affecting them.

Answer: * **Thermal (Coal/Gas):** Efficiency typically 35-45%. Factors: Carnot efficiency limits, heat loss in steam cycle, fuel quality. * **Nuclear:** Efficiency typically 30-40%. Factors: Similar to thermal, but limited by reactor design and safety considerations. * **Hydroelectric:** Very high efficiency, often 80-90%. Factors: Water availability, turbine design, head (height of water). * **Solar (Photovoltaic):** Cell efficiency 15-25% (commercial). Factors: Sunlight intensity, temperature, panel degradation, inverter efficiency. * **Wind:** Efficiency (capacity factor) 25-45%. Factors: Wind speed consistency, turbine design, blade length, hub height. Overall efficiency depends on conversion losses, fuel type, technology, and environmental factors.

Q24: Discuss the concept of 'energy security' and how a shift to green energy can impact it.

Answer: Energy security refers to the uninterrupted availability of energy sources at an affordable price. A shift to green energy can significantly impact energy security: 1. **Reduced Import Dependence:** Countries heavily reliant on imported fossil fuels can achieve greater energy independence by developing domestic renewable sources. 2. **Price Stability:** Renewable energy sources are not subject to the volatile price fluctuations of global fossil fuel markets. 3. **Diversification:** A diverse energy mix, including renewables, reduces vulnerability to disruptions in any single energy source. 4. **Decentralization:** Distributed renewable generation (e.g., rooftop solar) can enhance grid resilience and reduce reliance on large, centralized power plants, which are vulnerable to attacks or natural disasters. However, it also introduces new security challenges related to critical minerals for renewable technologies and cybersecurity for smart grids.

Q25: What is the role of 'energy storage' in making green energy sources more reliable?

Answer: Energy storage is crucial for making green energy sources more reliable because many renewables, like solar and wind, are intermittent; they only produce power when the sun shines or the wind blows. Energy storage systems (e.g., batteries, pumped-hydro, hydrogen) allow excess electricity generated during peak production times to be stored and then released when demand is high or renewable generation is low. This ensures a stable and continuous supply of power, balances the grid, and reduces the need for fossil fuel backup plants, thereby maximizing the integration and reliability of green energy.

References

1. MSBSHSE Class 10 Science and Technology Textbook Part 2 (2021-22 English) - Chapter 5: Towards Green Energy
2. Maharashtra State Board 10th Standard Science Syllabus 2025-26
3. Balbharati Science and Technology Part 2 Textbook
4. Shaalaa.com Balbharati solutions for Science and Technology 2