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

The correct answer is option 4.

A single large generating unit leads to higher generating costs per unit because:

• A single large generating unit may not be able to adjust its output efficiently when demand fluctuates, especially during periods of low demand. 
• A single, large generating unit can lead to higher per-unit generation costs due to lower utilization and higher fixed costs.
• A single unit, when forced offline, can result in a complete loss of power, making it less flexible and reliable compared to multiple smaller units. Also, the fixed costs (like depreciation, interest on capital, and operational costs) associated with a large plant are spread over a smaller number of generated units, increasing the cost per unit. 
• A single large unit is more vulnerable to outages. If the unit fails, the entire power supply could be disrupted, which can be costly in terms of lost production and consumer inconvenience. 

Use of a regenerative feedwater heating system

Modern steam power plants use regenerative feedwater heating systems primarily to improve thermal efficiency. This is because:

• By preheating the feedwater using steam extracted from intermediate stages of the turbine, the energy required in the boiler to convert water into steam is reduced.
• This reduces fuel consumption for the same power output, leading to better efficiency based on the Rankine cycle with regeneration.
• Regeneration increases the average temperature at which heat is added in the cycle, which directly boosts the cycle efficiency (per Carnot's principle).
• With improved efficiency, lower emissions per unit of electricity generated are achieved, making the plant more environmentally friendly.

String inverters handle groups of solar panels (strings) individually. If one string is affected by shading, dirt, or mismatch (like different panel orientations or aging), it only impacts that specific string, not the entire system.

In contrast, central inverters connect many strings together, and a problem in one string (like shading or a faulty panel) can drag down the performance of the whole system.

Thus, string inverters reduce power loss from partial shading or panel mismatch, increasing overall system efficiency and performance.

String Inverter Technology

• A string inverter connects a “string” of solar panels (typically 8–30 panels) to a single inverter. Each string is treated as an independent unit.
• DC power from each string is sent to a dedicated string inverter, which converts it to AC power. Multiple string inverters are used across a large system.

Central Inverter Technology

• A central inverter collects DC power from many strings (hundreds of panels), combined through DC combiner boxes, and converts all the power to AC in one large unit.
• DC strings feed into combiner boxes. Combiner boxes route the power to a single large inverter (hundreds of kW to MW). AC power is sent to the grid or a distribution system.

Given, Energy per fission = 200 MeV

Total energy per second =  3.204 × 10-11  Joules per fission

1 eV = 1.602 × 10^-19 joules

200 MeV = 200 × 10⁶ × 1.602 × 10-19 = 3.204 × 10^-11  J per fission

Fissions per second = \({Total \space  energy\space per\space second \over Energy \space per \space fission}\)

Fissions per second = \({3.2\times 10^{10} \over 3.204\times 10^{-11}}\)

Fissions per second = 1021

Concept:

In a biomass power plant, the combustion or gasification chamber is a critical component where biomass fuel is processed to produce usable energy. Combustion involves direct burning of biomass, while gasification converts it into syngas (a mixture of CO, H₂, and CH₄) for energy generation.

Calculation

The combustion/gasification chamber is where the actual conversion of biomass takes place. Biomass is either burned (in combustion) to produce heat or converted into syngas (in gasification), which is then used to drive turbines or engines for power generation.

Other options like cooling, storing biomass, or distributing electricity are handled by different components in the plant and are not the primary functions of this chamber.

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: