Thermal and hydrogen storage – MCQs – EE

1. The primary purpose of a thermal energy storage (TES) system is:
(A) To convert electrical energy into chemical energy
(B) To store heat for later use
(C) To store hydrogen gas
(D) To produce electricity directly

2. Thermal energy can be stored as:
(A) Sensible heat, latent heat, or thermochemical energy
(B) Mechanical energy only
(C) Electrical energy
(D) Magnetic energy

3. In sensible heat storage, energy is stored by:
(A) Raising the temperature of a solid or liquid medium
(B) Phase change of material
(C) Chemical reactions
(D) Compressing a gas

4. Latent heat storage systems store energy through:
(A) Thermal conduction
(B) Change of phase (e.g., melting/freezing)
(C) Vibration of molecules
(D) Electromagnetic induction

5. A commonly used phase change material (PCM) for thermal storage is:
(A) Paraffin wax
(B) Water vapor
(C) Hydrogen gas
(D) Carbon dioxide

6. Molten salt is often used in thermal storage systems because:
(A) It has a high specific heat and melting point
(B) It is highly reactive
(C) It evaporates easily
(D) It is a conductor of electricity

7. The main advantage of thermal storage is:
(A) Low cost and high reliability
(B) Instant electricity generation
(C) High energy density
(D) No insulation required

8. Thermochemical storage relies on:
(A) Reversible chemical reactions
(B) Electric potential
(C) Kinetic energy
(D) Gravitational potential

9. A major application of thermal energy storage is in:
(A) Solar power plants
(B) Wind turbines
(C) Diesel engines
(D) Battery systems

10. Hydrogen energy storage primarily involves:
(A) Chemical storage of hydrogen as fuel
(B) Storing electrical charges
(C) Magnetic energy
(D) Compressed air

11. The main methods of hydrogen storage include:
(A) Compressed gas, liquid hydrogen, and solid-state storage
(B) Electrostatic and magnetic
(C) Thermal and optical
(D) Electrical and mechanical

12. Compressed hydrogen gas is typically stored at pressures of:
(A) 10–50 bar
(B) 100–200 bar
(C) 350–700 bar
(D) 1000 bar

13. Liquid hydrogen storage requires a temperature of approximately:
(A) 80°C
(B) 150°C
(C) 253°C
(D) 300°C

14. The main challenge of liquid hydrogen storage is:
(A) High temperature loss
(B) Boil-off losses and cryogenic handling
(C) Lack of availability
(D) Low energy density

15. Metal hydride storage systems store hydrogen by:
(A) Absorption in metals
(B) Compression
(C) Dissolving in water
(D) Freezing in solid ice

16. The main advantage of metal hydride hydrogen storage is:
(A) High safety and volumetric density
(B) High operating temperature
(C) Low efficiency
(D) Fast leakage

17. Ammonia and methane can be used as:
(A) Hydrogen carriers
(B) Oxidizers
(C) Solvents
(D) Thermal fluids

18. The energy density of hydrogen compared to gasoline is:
(A) Higher per unit mass but lower per unit volume
(B) Lower per unit mass and per volume
(C) Equal per unit volume
(D) Higher per unit volume

19. The main drawback of hydrogen storage is:
(A) Low volumetric energy density
(B) High toxicity
(C) Unavailability of hydrogen
(D) Low energy content

20. The round-trip efficiency of hydrogen storage systems is typically:
(A) 90–95%
(B) 60–70%
(C) 30–50%
(D) 10–20%

21. Hydrogen can be produced through electrolysis by:
(A) Splitting water using electricity
(B) Compressing air
(C) Burning natural gas
(D) Heating saltwater

22. In power-to-gas systems, excess renewable energy is used to produce:
(A) Hydrogen gas
(B) Methane
(C) Carbon dioxide
(D) Steam

23. The specific energy of hydrogen is approximately:
(A) 1 kWh/kg
(B) 10 kWh/kg
(C) 33 kWh/kg
(D) 100 kWh/kg

24. The main advantage of hydrogen storage is:
(A) Long-term energy storage potential
(B) High self-discharge rate
(C) Requires no energy input
(D) Low energy density

25. Thermal energy storage can improve the performance of:
(A) Concentrated solar power (CSP) plants
(B) Diesel generators
(C) Nuclear reactors
(D) Wind turbines

26. In phase change materials (PCMs), the most important property is:
(A) Latent heat of fusion
(B) Density
(C) Conductivity
(D) Specific gravity

27. Molten salt storage systems usually operate between:
(A) 50–150°C
(B) 150–250°C
(C) 250–600°C
(D) 600–1000°C

28. Thermochemical storage has the advantage of:
(A) Highest energy density among TES methods
(B) Lowest cost
(C) No chemical reaction
(D) Requires no insulation

29. Hydrogen storage is especially useful for:
(A) Seasonal renewable energy storage
(B) Short-term voltage regulation
(C) Low-voltage DC systems
(D) Capacitor charging

30. The combination of thermal and hydrogen storage in renewable systems helps to:
(A) Balance intermittent generation and ensure supply reliability
(B) Increase fossil fuel consumption
(C) Reduce system efficiency
(D) Eliminate energy conversion