Generating Stations MCQ Quiz - Objective Question with Answer for Generating Stations - Download Free PDF

Explanation:

Francis Turbine Components and Flow Regulation

Definition: A Francis turbine is a type of reaction turbine used for hydropower generation, designed to operate efficiently under a wide range of head and flow conditions. It converts the potential energy of water into mechanical energy, which is then used to generate electricity through a connected generator. A key feature of the Francis turbine is its ability to dynamically regulate flow and optimize power output under varying load conditions.

Correct Option Analysis:

The correct answer is:

Option 1: Guide Vanes

The guide vanes play a critical role in regulating the flow rate and optimizing the power output of a Francis turbine. They are adjustable components located just before the turbine runner. By dynamically altering their angle, guide vanes control the amount of water entering the runner and the direction of the flow. This ensures that the turbine operates at peak efficiency under varying load conditions.

Working Principle of Guide Vanes:

• Flow Regulation: The guide vanes adjust their position to regulate the flow of water entering the runner. When the load on the turbine decreases, the guide vanes close slightly to reduce the flow rate, and when the load increases, they open to allow more water to flow through.
• Flow Direction: The guide vanes direct the water flow at an optimal angle to the runner blades. This ensures that the kinetic energy of the water is effectively transferred to the runner, maximizing the turbine's efficiency.
• Dynamic Response: Modern Francis turbines are equipped with servo mechanisms that allow the guide vanes to respond quickly to changes in load or flow conditions, maintaining stable operation and consistent power output.

Advantages of Guide Vanes:

• Enable precise control over the turbine's power output by dynamically adjusting the water flow.
• Improve the overall efficiency of the turbine by ensuring optimal flow direction and velocity.
• Help in maintaining stable operation during fluctuating load conditions.
• Reduce the risk of cavitation and mechanical stress on the turbine components by controlling flow conditions.

Conclusion: The guide vanes are essential components in a Francis turbine that dynamically adjust to regulate the flow rate and optimize power output under varying load conditions. Their ability to control both the quantity and direction of water entering the runner ensures efficient and reliable operation of the turbine.

Important Information

To further understand the analysis, let’s evaluate the other options:

Option 2: Spiral Casing

The spiral casing is the outer component of a Francis turbine that distributes the incoming water evenly to the guide vanes. It is designed to maintain a constant velocity of water around its circumference. However, it does not dynamically adjust to regulate the flow rate or optimize power output. Its primary function is to ensure uniform distribution of water, which is critical for the efficient operation of the turbine, but it does not have a direct role in dynamic regulation under varying load conditions.

Option 3: Draft Tube

The draft tube is a diverging passage located at the exit of the turbine runner. Its purpose is to recover the kinetic energy of the water leaving the runner and convert it into pressure energy, thereby increasing the overall efficiency of the turbine. While the draft tube plays a significant role in energy recovery, it does not dynamically adjust to regulate the flow rate or power output. Its function is passive rather than active in the context of flow regulation.

Option 4: Runner Blades

The runner blades are the primary moving components of a Francis turbine that convert the kinetic and potential energy of water into mechanical energy. While the shape and design of the runner blades are crucial for the turbine's efficiency, they do not dynamically adjust during operation. The runner blades are fixed in position and rely on the guide vanes to control the flow of water entering the runner.

Conclusion:

In a Francis turbine, the only component that dynamically adjusts to regulate the flow rate and optimize power output under varying load conditions is the guide vanes (Option 1). The spiral casing, draft tube, and runner blades, while essential for the turbine's operation, do not have the capability to dynamically adjust during operation. Understanding the distinct roles of these components is crucial for comprehending the operation and design of Francis turbines.

Explanation:

Solar Panels (Photovoltaic - PV) vs. Concentrating Solar Power (CSP):

Definition: Solar Panels (PV) and Concentrating Solar Power (CSP) are two prominent technologies used to harness solar energy. PV panels directly convert sunlight into electricity using semiconductor materials, while CSP systems use mirrors or lenses to concentrate sunlight onto a receiver to produce heat, which is then converted into electricity using a turbine or engine.

Correct Option Analysis:

The correct option is:

Option 2: They need costly batteries to store power for nighttime use.

This statement highlights one of the major challenges associated with Solar Panels (PV) compared to CSP systems. Solar Panels generate electricity during the daytime when sunlight is available, but they do not inherently have storage capabilities. To ensure a continuous power supply during nighttime or cloudy periods, it is necessary to pair PV systems with energy storage solutions, typically batteries.

While CSP systems often use thermal storage methods (e.g., molten salt) to store heat energy for later use, PV systems rely on batteries, which are expensive and can significantly increase the overall cost of the system. The integration of batteries into PV setups also presents challenges related to scalability, efficiency, and environmental concerns due to the mining and disposal of battery materials.

Detailed Explanation:

1. The Need for Energy Storage:

• Solar Panels (PV) produce electricity only when sunlight is available, meaning their output is intermittent and depends on the weather and time of day.
• To achieve a stable and reliable energy supply, PV systems often require batteries to store excess energy generated during the day for use during nighttime or cloudy periods.
• The cost of batteries, such as lithium-ion batteries, is a significant factor in the overall expense of a PV system. Additionally, battery lifespan and efficiency can impact the long-term viability of the system.

2. Cost Implications:

• Batteries are one of the most expensive components of a PV system. Their cost can rival or even exceed the cost of the solar panels themselves.
• The maintenance and replacement of batteries add to the operational costs, making PV systems less economically competitive compared to CSP in some cases.
• The environmental impact of battery production and disposal is another concern, as the extraction of materials like lithium and cobalt can cause ecological harm.

3. Comparison with CSP:

• CSP systems typically use thermal storage techniques, such as molten salt storage, which are more cost-effective and environmentally friendly compared to batteries.
• Thermal storage allows CSP systems to generate power even after sunset, providing a more consistent and reliable energy output.

4. Advances in Battery Technology:

• Research and development in battery technology, including solid-state batteries and flow batteries, aim to reduce costs and improve efficiency, which could make PV systems more competitive in the future.
• Despite these advancements, the current reliance on costly batteries remains a significant challenge for PV systems.

Conclusion:

Option 2 correctly identifies the major challenge of Solar Panels (PV) needing costly batteries for nighttime energy storage. This reliance on batteries increases the cost and complexity of PV systems compared to CSP systems, which often utilize more efficient and cost-effective thermal storage solutions.

Additional Information

Analysis of Other Options:

Option 1: They have lots of moving parts, making maintenance costly.

This statement is incorrect for Solar Panels (PV). PV systems have no moving parts, which is one of their advantages over CSP systems. CSP systems involve components like mirrors, tracking systems, and turbines, which require regular maintenance and have higher operational costs due to their mechanical complexity.

Option 3: They completely stop working on cloudy days.

This statement is misleading. While the efficiency of PV systems decreases on cloudy days due to reduced sunlight, they do not "completely stop working." Advanced PV panels can still generate some electricity under diffuse light conditions, although at a lower output. CSP systems, on the other hand, rely on direct sunlight for optimal performance and are more affected by cloudy weather.

Option 4: They need high-tech factories to be made.

This statement is partially correct but not unique to PV systems. Both PV and CSP technologies require specialized manufacturing facilities. PV panels involve semiconductor fabrication, which necessitates high-tech factories, but CSP systems also require precision engineering for mirrors, receivers, and tracking systems. Therefore, this challenge is not exclusive to PV systems.

Conclusion:

While all the options highlight challenges related to solar technologies, Option 2 accurately identifies the significant issue of costly batteries for energy storage in PV systems, making it the correct choice. Understanding these challenges is essential for selecting the appropriate solar technology based on specific needs and conditions.

Hydropower Plant Categories

Definition: Hydropower plants are categorized based on their installed capacity, which is the maximum amount of electricity they can generate under ideal conditions. These categories help classify hydropower projects for planning, design, and regulatory purposes. The primary classifications are Small hydro, Mini hydro, Medium hydro, and Large hydro. Each category is defined by specific capacity ranges, which can vary slightly depending on the country or organization.

Correct Option Analysis:

The correct option is:

Option 1: Small hydro

Why is this correct?

In most international classifications, a hydropower plant with an installed capacity between 1 MW and 25 MW is categorized as a Small hydro project. Since the given hydropower plant has an installed capacity of 10 MW, it falls squarely within this range. Small hydro projects are typically used to supply power to local communities or industries and often have a minimal environmental impact compared to larger projects.

Characteristics of Small Hydro Projects:

• Capacity Range: Typically between 1 MW and 25 MW.
• Applications: Often used for rural electrification, decentralized power generation, or small industrial purposes.
• Environmental Impact: Generally lower than larger hydropower projects due to their smaller scale and less invasive construction requirements.
• Advantages:
  • Can be developed in remote areas to provide localized power solutions.
  • Lower initial investment and shorter construction times compared to large hydropower projects.
  • Can often operate without the need for large dams, preserving local ecosystems.
• Disadvantages:
  • Limited capacity means it may not be suitable for regions with high power demands.
  • May be less efficient in terms of energy production compared to larger hydropower plants.

Conclusion: Since the given hydropower plant has an installed capacity of 10 MW, it falls into the category of Small hydro. This classification is widely recognized and aligns with international standards for hydropower categorization.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 2: Mini hydro

Mini hydro projects typically have an installed capacity of less than 1 MW (or sometimes up to 2 MW, depending on specific definitions). These systems are smaller than small hydro projects and are often used for localized, off-grid power generation in rural or isolated areas. Since the given plant has a capacity of 10 MW, it does not fall under this category.

Option 3: Medium hydro

Medium hydro projects generally have capacities ranging from 25 MW to 100 MW. These plants are larger than small hydro projects and are used to supply power to larger grids or industrial facilities. The 10 MW capacity of the given plant is significantly below this range, so it does not qualify as a medium hydro project.

Option 4: Large hydro

Large hydro projects have an installed capacity exceeding 100 MW. These are massive infrastructure projects that often involve significant dam construction and reservoir creation. They are used for large-scale power generation and contribute to national or regional grids. Since the given plant has a capacity of only 10 MW, it does not fall under this category.

Conclusion:

The classification of hydropower plants is essential for understanding their scale, applications, and potential impacts. The given plant, with an installed capacity of 10 MW, clearly falls under the category of Small hydro, as defined by widely accepted standards. This classification highlights the plant's suitability for localized power generation with minimal environmental disruption compared to larger hydropower projects.

Explanation:

Wind Turbine Blades Made of Glass Fibre Reinforced Polyester

Definition: Wind turbine blades are typically made of composite materials such as glass fibre reinforced polyester (GFRP) because these materials offer a combination of lightweight strength, durability, and flexibility, which are crucial for the efficient and safe operation of wind turbines. GFRP consists of fine glass fibres embedded in a polyester resin matrix, forming a composite material that exhibits superior mechanical properties compared to its individual components.

Correct Option Analysis:

The correct option is:

Option 2: To provide lightweight strength and durability.

Wind turbine blades must be lightweight to reduce the load on the turbine structure, including the tower and the nacelle, and to ensure that they can rotate efficiently even at low wind speeds. At the same time, they must be strong enough to withstand the forces exerted by high winds, as well as the fatigue caused by constant rotation and varying wind conditions.

Glass fibre reinforced polyester is ideal for this purpose because:

• Lightweight: Glass fibres are much lighter than metals or other traditional materials, making GFRP an excellent choice for reducing the overall weight of the blades.
• High Strength-to-Weight Ratio: GFRP exhibits a high strength-to-weight ratio, allowing the blades to be strong enough to endure extreme forces while remaining lightweight.
• Durability: The material is resistant to environmental factors such as corrosion, UV radiation, and temperature variations. This ensures that the blades can function effectively for decades without significant degradation.
• Flexibility: GFRP blades can flex slightly under high wind loads, which helps to dissipate energy and reduce the risk of structural failure.
• Ease of Manufacturing: GFRP can be molded into complex shapes, allowing for the aerodynamic designs required for efficient wind energy conversion.
• Cost-Effectiveness: Compared to other high-performance materials like carbon fibre, GFRP is more cost-effective, making it a practical choice for large-scale wind turbine production.

These properties make glass fibre reinforced polyester the most suitable material for wind turbine blades, balancing performance, durability, and cost-effectiveness.

Important Information:

To further understand the question, let’s evaluate the other options:

Option 1: To reduce cost.

While cost is an important factor in the selection of materials, it is not the primary reason for using glass fibre reinforced polyester in wind turbine blades. The performance characteristics, such as lightweight strength and durability, are more critical. Cost-effectiveness is a secondary benefit of using GFRP compared to other high-performance materials like carbon fibre.

Option 3: To increase the efficiency of power transmission.

This option is incorrect because the material of the blades does not directly influence the efficiency of power transmission. Power transmission efficiency is more related to the design and operation of the turbine’s generator and gearbox, as well as the quality of the electrical components. The material of the blades primarily affects the aerodynamic efficiency and structural integrity of the turbine.

Option 4: To make them heavier for stability.

This option is incorrect because heavier blades would increase the load on the turbine structure and reduce its efficiency. Lightweight materials like GFRP are preferred because they allow the blades to start rotating at lower wind speeds and reduce the stresses on the turbine components, enhancing the overall performance and lifespan of the system.

Conclusion:

Wind turbine blades are made of glass fibre reinforced polyester primarily to provide lightweight strength and durability, which are essential for their efficient and long-lasting operation. The properties of GFRP, including its high strength-to-weight ratio, resistance to environmental factors, and ease of manufacturing, make it the ideal material for this application. Understanding the requirements of wind turbine blades helps in appreciating the role of material selection in achieving optimal performance and cost-effectiveness in renewable energy systems.

Wind Power Density and Its Dependence on Wind Speed:

Definition: Wind Power Density (WPD) is a measure of the power available in the wind per unit area perpendicular to the wind direction. It is an important parameter for evaluating the potential of wind energy at a particular site and is given by the formula:

WPD = (1/2) × ρ × V³

Here:

• ρ is the air density (typically around 1.225 kg/m³ at sea level and standard atmospheric conditions).
• V is the wind speed in meters per second (m/s).
• The factor of 1/2 arises from the kinetic energy equation.

From the formula, it is evident that wind power density is directly proportional to the cube of the wind speed (V³), meaning that even a small increase in wind speed results in a significant increase in the power density.

Correct Option Analysis:

The question asks what happens to the wind power density when the wind speed doubles. Let us analyze this step-by-step:

WPD_initial = (1/2) × ρ × V³

WPD_new = (1/2) × ρ × (2V)³

WPD_new = (1/2) × ρ × 8V³

WPD_new = 8 × [(1/2) × ρ × V³]

• Let the initial wind speed be V.
• Substitute the initial wind speed into the formula for WPD:
• Now, if the wind speed doubles, the new wind speed becomes 2V.
• Substitute the doubled wind speed into the formula for WPD:
• Simplify the expression:
• From this, it is clear that the new wind power density is 8 times the initial wind power density.

Therefore, when the wind speed doubles, the wind power density increases by a factor of 8.

The correct answer is: Option 2 (8).

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: The wind power density increases by a factor of 6.

This option is incorrect because the relationship between wind power density and wind speed is cubic. A doubling of wind speed results in an 8-fold increase, not a 6-fold increase.

Option 3: The wind power density increases by a factor of 4.

This option is also incorrect. A 4-fold increase would imply that the wind power density is directly proportional to the square of the wind speed (V²), but in reality, it is proportional to the cube of the wind speed (V³).

Option 4: The wind power density increases by a factor of 2.

This option is incorrect because a doubling of wind speed does not result in a doubling of wind power density. Instead, the cubic relationship means the power density increases by a factor of 8.

Option 5: No option provided.

This option is not relevant to the question, as the correct answer has already been determined.

Conclusion:

Understanding the cubic relationship between wind speed and wind power density is crucial for evaluating the potential of wind energy. As demonstrated, doubling the wind speed leads to an 8-fold increase in wind power density, highlighting the significant impact of wind speed variations on energy generation. This principle is central to the design and optimization of wind energy systems, emphasizing the importance of selecting sites with consistently high wind speeds to maximize energy output.

Tarapur Atomic Power Station:

• Tarapur Atomic Power station is located in Tarapur, Maharashtra.
• It was the first commercial atomic power station of India commissioned on 28th October 1969.
• It was commissioned under 123 agreements signed between India, the United States and International Atomic Energy Agency. 
• The station is operated by the National power corporation of India.

About Tarapur Atomic Power Station:

• Tarapur Atomic Power station is located in Tarapur, Maharashtra.
• It was the first commercial atomic power station of India commissioned on 28th October 1969.
• It was commissioned under 123 agreements signed between India, the United States, and International Atomic Energy Agency. 
• The station is operated by the National power corporation of India.

​

Concept:

Load factor:

The load factor is the ratio of average energy consumed to maximum demand.

Load factor = average energy consumed / maximimum energy consumed

Calculation:

Given load factor = 0.5

Average energy consumed at 0.5 load factor = 600 kWh

Maximum energy consumed = \(\frac{{600}}{{0.5}}\) = 1200 kWh

Now maximum energy consumed is constant and load factor is increased to 0.8

Average energy consumed = load factor × maximum energy consumed

= 0.8 × 1200

CONCEPT:

Nuclear reactor:

• It is a device in which a nuclear reaction is initiated, maintained, and controlled.
• It works on the principle of controlled chain reaction and provides energy at a constant rate.

EXPLANATION:

• The moderator's function is to slow down the fast-moving secondary neutrons produced during the fission.
• The material of the moderator should be light and it should not absorb neutrons.
• Usually, heavy water, graphite, deuterium, and paraffin, etc. can act as moderators.
• These moderators are rich in protons. When fast-moving neutrons collide head-on with the protons of moderator substances, their energies are interchanged and thus the neutrons are slowed down.
• Such neutrons are called thermal neutrons which cause fission of U235 in the fuel. 

Economizer:

It is also known as a feedwater heater. It is a device in which the waste heat of the flue gases is utilized for heating the feed water.

In economizer, feed water is preheated by using flue gases to improve overall efficiency and only sensible heat transfer is taking place so feed water is heated without converting it into steam. Therefore, the economizer is placed after the superheater and located in the feeding water circuit.

Functions of economizer:

• Reduce fuel consumption
• Preheating a fluid (feed-water in case of steam boiler)
• Increases the efficiency of the power plant

Following are the advantages:

• There is about 15 to 20% of coal saving.
• It increases the steam raising capacity of a boiler because it shortens the time required to convert water into steam.
• It prevents the formation of scale in boiler water tubes.          

Explanation:

• A nuclear reactor is a cylindrical stout pressure vessel and houses fuel rods of Uranium, moderator, and control rods
• The fuel rods constitute the fission material and release a huge amount of energy when bombarded with slow-moving neutrons
• The moderator consists of graphite rods that enclose the fuel rods. The moderator slows down the neutrons before they bombard the fuel rods.
• The control rods are of cadmium and are inserted into the reactor. Cadmium is a strong neutron absorber and thus regulates the supply of neutrons for fission.

Concept:

Calorific values of fuel: The calorific value of fuel is the quantity of heat produced by its combustion at constant pressure and under normal conditions. Calorific value mention in kcal / kg.

The overall efficiency of the steam power station: The overall efficiency of the steam power station is defined as the ratio of the power available at the generator terminal to the rate of energy released by the combustion of fuel. It is given by,

\({\eta _{overall}} = \frac{{EO}}{{HC}}\)

Where EO is the Electrical output in the heat unit.

HC is Heat combustion.

Calculation: 

Given: Overall efficiency = 25 % , 0.5 kg coal burnt.

Let x cal /kg be the calorific value of the fuel.

Heat equivalent of 1 kWh = 860 kcal

\({\eta _{overall}} = \frac{{EO}}{{HC}}\)

\(0.25 = \frac{{860}}{{0.5x}}\)

\(x = \frac{{860000}}{{25 \times 5}}\)

\(x = 6880\;kcal/kg\)

​The correct answer is Storage and Dispersal.

• Major hazards of nuclear power generation:
  • Storage and disposal of spent or used fuels: This is because the uranium used decays into harmful subatomic particles radiations which are harmful to health. Further, there is a risk of accidental leakage of nuclear radiation.
  • Environmental contamination: improper nuclear-waste storage and disposal result in environmental contamination.
  • High cost of installation: nuclear power plants require a lot of money for their setup. moreover, the limited availability of uranium adds to the disadvantage of not making it an economic fuel.

Key Points

• Nuclear Power plant: