Wind Energy Multiple Choice Questions on “Wind Energy Storage – 1”.
1. Which of the following is a reason for storing wind energy?
a) Wind power generation is not correlated to the demand cycle
b) Wind power generation is correlated to the demand cycle
c) Wind is a renewable resource
d) Wind power is guaranteed to be available during peak demands
Answer: a
Clarification: Most of the electricity produced from the plants is consumed immediately. Moreover, wind power generation is not correlated to the demand cycle. It is also not guaranteed to be available during peak demands. Thus, wind power storage is necessary.
2. Which of the following methods are used to store wind energy?
a) Glowing a bulb
b) Electro-chemical
c) Running a consumer electrical appliance
d) Turning off consumer electrical appliances when not in use
Answer: b
Clarification: Wind energy can be stored as electro-chemical energy in the form of batteries. Glowing a bulb and running a consumer electrical appliance consumes energy. While turning off an appliance when not in use saves energy, it doesn’t store energy.
3. What is an example of storing wind power electro-chemically?
a) Electro-hydrogen generation
b) Pumped storage
c) Batteries
d) Electric grid
Answer: c
Clarification: 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.
4. _________ is an example of storing wind energy chemically.
a) Flywheels
b) Pumped storage
c) Batteries
d) Electro-hydrogen generation
Answer: d
Clarification: Electro-hydrogen is an example of storing wind energy chemically. Batteries typically come under the category of electro-chemical storage. Flywheels come under the category of mechanical storage.
5. Wind energy can be switched on ‘on demand’.
a) True
b) False
Answer: b
Clarification: 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.
6. Energy storage devices can manage power fluctuations.
a) True
b) False
Answer: a
Clarification: 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.
7. 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
Answer: c
Clarification: 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’.
8. 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
Answer: d
Clarification: 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.
9. Pumped hydroelectric is an example of _________
a) Gravitational potential storage
b) Latent heat storage
c) Thermal storage
d) Hydroelectric power generation
Answer: a
Clarification: 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.
10. 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
Answer: b
Clarification: 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.
11. Flywheels are an example of ________ energy storage.
a) potential
b) electric potential
c) thermal kinetic
d) kinetic
Answer: d
Clarification: 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.
12. 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
Answer: a
Clarification: 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.
13. 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
Answer: b
Clarification: 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.
14. Which of the following parameters are used to describe rechargeable batteries?
a) Power
b) Frequency
c) Charge-to-discharge ratio
d) Angular speed
Answer: c
Clarification: 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.
15. Capacitors store energy in the form of ________
a) potential
b) AC voltage
c) thermal potential
d) electric potential
Answer: d
Clarification: 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.