Question 1
Capacitors do not suffer from ________
A. dielectric breakdown
B. material dependence
C. excess electric potential
D. memory effect
View Answer
Answer: Option D
Explanation:
Capacitors store energy in the form of electric potential. They do not suffer memory effect as the energy is stored between two conducting plates. However, they do suffer from dielectric breakdown when excess electric potential is applied.
Answer: Option D
Explanation:
Capacitors store energy in the form of electric potential. They do not suffer memory effect as the energy is stored between two conducting plates. However, they do suffer from dielectric breakdown when excess electric potential is applied.
Question 2
Capacitors store energy in the form of ________
A. potential
B. AC voltage
C. thermal potential
D. electric potential
View Answer
Answer: Option D
Explanation:
Capacitors store energy in the form of electric potential. The energy is stored between two metallic plates. Neither AC voltage nor alternating current can be stored.
Answer: Option D
Explanation:
Capacitors store energy in the form of electric potential. The energy is stored between two metallic plates. Neither AC voltage nor alternating current can be stored.
Question 3
Efficiency of pumped hydro-electric storage is in the range of _________
A. 50% — 80%
B. 80% — 120%
C. 10% — 20%
D. 45% — 50%
View Answer
Answer: Option A
Explanation:
Efficiency of pumped hydro-electric storage is in the range of 50% — 80%. It has large power (>50MW) and storage capacity (>100MWh). The efficiency is further being improved using variable speed machines.
Answer: Option A
Explanation:
Efficiency of pumped hydro-electric storage is in the range of 50% — 80%. It has large power (>50MW) and storage capacity (>100MWh). The efficiency is further being improved using variable speed machines.
Question 4
Energy storage devices can manage power fluctuations.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
Energy storage devices can manage power fluctuations, particularly from renewable sources of energy – wind and solar. Thus, they enable such fluctuating and irregular technologies to cope with consumer’s demand.
Answer: Option A
Explanation:
Energy storage devices can manage power fluctuations, particularly from renewable sources of energy – wind and solar. Thus, they enable such fluctuating and irregular technologies to cope with consumer’s demand.
Question 5
Flywheels are an example of ________ energy storage.
A. potential
B. electric potential
C. thermal kinetic
D. kinetic
View Answer
Answer: Option D
Explanation:
Flywheels are an example of storing mechanical energy in the form of kinetic energy. The flywheel (or rotor) is accelerated to a high speed thus maintaining the energy. The energy is stored in the system in the form of rotational kinetic energy.
Answer: Option D
Explanation:
Flywheels are an example of storing mechanical energy in the form of kinetic energy. The flywheel (or rotor) is accelerated to a high speed thus maintaining the energy. The energy is stored in the system in the form of rotational kinetic energy.
Question 6
Flywheels are used in uninterrupted power supply (UPS).
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
The entire setup is mechanical, it can be repeatedly charged and discharged without much damage to the setup itself. Thus, flywheels are used in uninterrupted power supplies (UPS).
Answer: Option A
Explanation:
The entire setup is mechanical, it can be repeatedly charged and discharged without much damage to the setup itself. Thus, flywheels are used in uninterrupted power supplies (UPS).
Question 7
How does a flow battery energy storage work?
A. Electrolyte tanks → pumps → electrodes → current
B. Electrolyte tanks → pumps → current → electrodes
C. Electrolyte tanks → current → electrodes → pumps
D. Electrolyte tanks → electrodes → current → pumps
View Answer
Answer: Option A
Explanation:
FBES operate in a similar way. Two charged electrolytes are pumped to the cell stack where a chemical reaction occurs, allowing current to be obtained from the device when required. This current is then harnessed by sending it to a load.
Answer: Option A
Explanation:
FBES operate in a similar way. Two charged electrolytes are pumped to the cell stack where a chemical reaction occurs, allowing current to be obtained from the device when required. This current is then harnessed by sending it to a load.
Question 8
Pumped hydroelectric is an example of _________
A. Gravitational potential storage
B. Latent heat storage
C. Thermal storage
D. Hydroelectric power generation
View Answer
Answer: Option A
Explanation:
Pumped hydroelectric storage is an example of gravitational potential storage. It is the most mature storage technique and has the largest storage capacity. For optimization, the pump and the turbine are combined into a single device.
Answer: Option A
Explanation:
Pumped hydroelectric storage is an example of gravitational potential storage. It is the most mature storage technique and has the largest storage capacity. For optimization, the pump and the turbine are combined into a single device.
Question 9
The central shaft in a flywheel energy storage device rotates on two magnetic bearings.
A. FALSE
B. TRUE
View Answer
Answer: Option B
Explanation:
A flywheel energy storage (FES) consists of a central shaft. The shaft holds a rotor and a flywheel. The central shaft rotates on two magnetic bearings which considerably reduces friction losses. The entire setup is placed in vacuum to prevent drag losses.
Answer: Option B
Explanation:
A flywheel energy storage (FES) consists of a central shaft. The shaft holds a rotor and a flywheel. The central shaft rotates on two magnetic bearings which considerably reduces friction losses. The entire setup is placed in vacuum to prevent drag losses.
Question 10
What is a major disadvantage with pumped hydro-electric system?
A. No dependence on geographical locations
B. Small scale construction for effective functioning
C. Low initial costs of construction
D. Depends on specific geographical locations for the construction of the two reservoirs
View Answer
Answer: Option D
Explanation:
A major disadvantage with PHES is its dependence on specific geographical locations for the construction of the two reservoirs. It also demands that the two reservoirs be located in close proximity to reduce costs. This increases the initial costs of construction considerably.
Answer: Option D
Explanation:
A major disadvantage with PHES is its dependence on specific geographical locations for the construction of the two reservoirs. It also demands that the two reservoirs be located in close proximity to reduce costs. This increases the initial costs of construction considerably.
Question 11
What is an example of storing wind power electro-chemically?
A. Electro-hydrogen generation
B. Pumped storage
C. Batteries
D. Electric grid
View Answer
Answer: Option C
Explanation:
Storing energy in batteries is the most common and simplest method to store wind energy. An electric grid is an interconnected network for delivering power from suppliers to consumers.
Answer: Option C
Explanation:
Storing energy in batteries is the most common and simplest method to store wind energy. An electric grid is an interconnected network for delivering power from suppliers to consumers.
Question 12
What is charge-to-discharge ratio?
A. Time taken to charge the device
B. Ratio of time taken to charge the device relative to the time taken to discharge the device
C. Ratio of the amount of charge during charging cycle to the amount of charge during discharge cycle
D. Time taken to discharge the device
View Answer
Answer: Option B
Explanation:
Charge-to-discharge ratio is the ratio of time taken to charge the device relative to the time taken to discharge the device. For instance, if a device takes 2 times longer to charge than to discharge, it has a charge-to-discharge ratio of 2:1.
Answer: Option B
Explanation:
Charge-to-discharge ratio is the ratio of time taken to charge the device relative to the time taken to discharge the device. For instance, if a device takes 2 times longer to charge than to discharge, it has a charge-to-discharge ratio of 2:1.
Question 13
What is depth of discharge?
A. Percentage of the battery that is discharged during a cycle
B. Percentage of the battery that is discharged
C. Amount of charge discharged from a battery during a cycle
D. Amount of charge discharged from a battery
View Answer
Answer: Option A
Explanation:
Depth of discharge (DoD) is the percentage of the battery that is discharged during a cycle. It has a wider use because it indicates a percentage instead of an absolute value. Indicating the absolute value of the charge discharged is not practical as it is unique for every battery and cannot be generalized.
Answer: Option A
Explanation:
Depth of discharge (DoD) is the percentage of the battery that is discharged during a cycle. It has a wider use because it indicates a percentage instead of an absolute value. Indicating the absolute value of the charge discharged is not practical as it is unique for every battery and cannot be generalized.
Question 14
What is energy storage capacity?
A. Power stored
B. Amount of energy that can be drawn from a storage device
C. Amount of energy stored in a storage device
D. Amount of energy a storage device can store for a period of time
View Answer
Answer: Option D
Explanation:
Energy storage capacity is the amount of energy a storage device can store for a period of time. It is usually measured in kilowatt-hours (KWh) or megawatt-hours (MWh). It is not the same as amount of energy stored.
Answer: Option D
Explanation:
Energy storage capacity is the amount of energy a storage device can store for a period of time. It is usually measured in kilowatt-hours (KWh) or megawatt-hours (MWh). It is not the same as amount of energy stored.
Question 15
What is memory effect?
A. Electro-hydrogen generation
B. Pumped storage
C. Remembering a charging level
D. Electric grid
View Answer
Answer: Option C
Explanation:
Memory effect is mainly used to describe rechargeable batteries. If they are not fully charged for long periods of time then they ‘remember’ that charging level. Thus, they lose some of their capacity. The other options are storage techniques of wind energy.
Answer: Option C
Explanation:
Memory effect is mainly used to describe rechargeable batteries. If they are not fully charged for long periods of time then they ‘remember’ that charging level. Thus, they lose some of their capacity. The other options are storage techniques of wind energy.
Question 16
What type of materials are used for latent heat storage?
A. Materials with high stress
B. Phase-change materials
C. Materials with high stress/strain ratio
D. Elastic materials
View Answer
Answer: Option B
Explanation:
Phase change materials are used for latent heat storage. Stress and strain are used to describe a material’s deformation ability. Elastic materials are those which when deformed regain their original shape.
Answer: Option B
Explanation:
Phase change materials are used for latent heat storage. Stress and strain are used to describe a material’s deformation ability. Elastic materials are those which when deformed regain their original shape.
Question 17
When does a power conversion system act as a rectifier for an energy storing device?
A. When the device is being charged
B. When the device is being discharged
C. When the device stops working
D. When the power conversion system is being charged
View Answer
Answer: Option A
Explanation:
A power conversion system acts as a rectifier when the energy storing device is being charged. This is because any existing energy storage cannot store AC. Except for mechanical storage devices, it is necessary to convert alternating current (AC) to direct current (DC) and vice-versa.
Answer: Option A
Explanation:
A power conversion system acts as a rectifier when the energy storing device is being charged. This is because any existing energy storage cannot store AC. Except for mechanical storage devices, it is necessary to convert alternating current (AC) to direct current (DC) and vice-versa.
Question 18
When does a power conversion system act as an inverter for an energy storing device?
A. When the device is being charged
B. When the device is being discharged
C. When the device starts working
D. When the power conversion system is being discharged
View Answer
Answer: Option B
Explanation:
A power conversion system acts as an inverter when the energy storing device is being discharged. The converted AC current is then transported to the consumer. Transporting alternating currents reduces the amount of resistive losses.
Answer: Option B
Explanation:
A power conversion system acts as an inverter when the energy storing device is being discharged. The converted AC current is then transported to the consumer. Transporting alternating currents reduces the amount of resistive losses.
Question 19
Which of following is are parameters used to describe an energy storage device?
A. Power, energy, time, frequency, Young’s modulus
B. Power capacity, voltage, heat, angular speed, frequency
C. Power capacity, energy storage capacity, efficiency, response time, round-trip efficiency
D. Stress, strain, Young’s Modulus, elasticity, rigidity
View Answer
Answer: Option C
Explanation:
Power capacity, energy storage capacity, efficiency, response time and round-trip efficiency are generally used to describe an energy storage device. Stress, strain, Young’s modulus, elasticity and rigidity are used to describe a material. The other options are not used to describe ‘storage potential/capacity’.
Answer: Option C
Explanation:
Power capacity, energy storage capacity, efficiency, response time and round-trip efficiency are generally used to describe an energy storage device. Stress, strain, Young’s modulus, elasticity and rigidity are used to describe a material. The other options are not used to describe ‘storage potential/capacity’.
Question 20
Which of the following are used for large scale battery energy storage?
A. Li-ion batteries
B. Capacitors
C. Lead acid
D. Reservoirs
View Answer
Answer: Option C
Explanation:
Lead acid (LA) is used for large scale BES. Nickel-cadmium (NiCd) and sodium-sulphur (NaS) are also commonly used BES. Capacitors are not batteries. Li-ion is an upcoming technology and hasn’t been established as the industry standard yet. However, it is likely to take over the industry in the next decade.
Answer: Option C
Explanation:
Lead acid (LA) is used for large scale BES. Nickel-cadmium (NiCd) and sodium-sulphur (NaS) are also commonly used BES. Capacitors are not batteries. Li-ion is an upcoming technology and hasn’t been established as the industry standard yet. However, it is likely to take over the industry in the next decade.
Question 21
Which of the following best indicates the flow diagram of power generation mode in compressed air energy storage?
A. Storage → LPT → HPT → generator
B. Storage → HPT → LPT → generator
C. Storage → LPT → generator → HPT
D. HPT → Storage →LPT → generator
View Answer
Answer: Option B
Explanation:
In CAES, the compressed air is first sent from the storage tank to a high pressure turbine (HPT) which is in turn connected to a lower pressure turbine (LPT). Finally, the LPT is connected to an electric generator.
Answer: Option B
Explanation:
In CAES, the compressed air is first sent from the storage tank to a high pressure turbine (HPT) which is in turn connected to a lower pressure turbine (LPT). Finally, the LPT is connected to an electric generator.
Question 22
Which of the following best indicates the flow diagram of storage mode in compressed air energy storage?
A. Power from grid → motor → compressor → storage
B. Power from grid → motor → storage → compressor
C. Power from grid → compressor → motor → storage
D. Motor → power from grid → compressor → storage
View Answer
Answer: Option A
Explanation:
In CAES, power is drawn from the grid during off-peak hours to run a motor which in turn drives a compressor. Air passed into the compressor is then compressed and stored.
Answer: Option A
Explanation:
In CAES, power is drawn from the grid during off-peak hours to run a motor which in turn drives a compressor. Air passed into the compressor is then compressed and stored.
Question 23
Which of the following have large power (>50MW) and storage capacities (>100MWh)?
A. Memory effect
B. Battery energy storage (BES) and flow battery energy storage
C. Super capacitor energy storage and flywheel energy storage
D. Pumped hydro-electric storage and underground pumped hydro-electric storage
View Answer
Answer: Option D
Explanation:
Pumped hydro-electric storage (PHES) and underground pumped hydro-electric storage (UPHES) are grouped under the category of large power (>50MW) and storage capacity (>100MWh). Compressed air energy storage (CAES) is another example of this category. Memory effect is a parameter used to describe a rechargeable battery.
Answer: Option D
Explanation:
Pumped hydro-electric storage (PHES) and underground pumped hydro-electric storage (UPHES) are grouped under the category of large power (>50MW) and storage capacity (>100MWh). Compressed air energy storage (CAES) is another example of this category. Memory effect is a parameter used to describe a rechargeable battery.
Question 24
Which of the following is an application of pumped hydro-electric storage?
A. Energy source
B. Frequency regulation only in pumping mode
C. Frequency regulation in both pumping and generation modes
D. Absorbs power to increase the net expenses
View Answer
Answer: Option C
Explanation:
Pumped hydro-electric storage is used for frequency regulation in both pumping and generation modes. In fact, it absorbs power in a more cost-effective manner and boosts efficiency upto 3%.
Answer: Option C
Explanation:
Pumped hydro-electric storage is used for frequency regulation in both pumping and generation modes. In fact, it absorbs power in a more cost-effective manner and boosts efficiency upto 3%.
Question 25
Which of the following parameters are used to describe rechargeable batteries?
A. Power
B. Frequency
C. Charge-to-discharge ratio
D. Angular speed
View Answer
Answer: Option C
Explanation:
Charge-to-discharge ratio, depth of discharge (DoD) and memory effect are commonly used to describe rechargeable batteries. Power, frequency and angular speed are not used to describe any storage device’s characteristics.
Answer: Option C
Explanation:
Charge-to-discharge ratio, depth of discharge (DoD) and memory effect are commonly used to describe rechargeable batteries. Power, frequency and angular speed are not used to describe any storage device’s characteristics.
Question 26
Wind energy can be switched on ‘on demand’.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
Wind energy cannot be switched on ‘on demand’. It is inherently intermitted, variable and non-dispatchable. To match the supply with demand, it requires a backup to store the generated power.
Answer: Option B
Explanation:
Wind energy cannot be switched on ‘on demand’. It is inherently intermitted, variable and non-dispatchable. To match the supply with demand, it requires a backup to store the generated power.