Which of the following statements about non-conventional sources of energy and their improvements is correct?

Question

Which of the following statements about non-conventional sources of energy and their improvements is correct?

1. A. Commercial Solar panels can only convert 10-12% of sunlight into electricity.
2. B. Wind energy efficiency improves by using larger and more aerodynamically designed blades. (Correct answer)
3. C. Tidal energy cannot be harnessed effectively due to the predictability of tides.
4. D. Geothermal energy output is independent of drilling technology and heat extraction methods.

Correct Answer

Option B — Wind energy efficiency improves by using larger and more aerodynamically designed blades.

Detailed Solution & Explanation

The correct answer is Wind energy efficiency improves by using larger and more aerodynamically designed blades.

Key Points

• The power available to a wind turbine is:
  • $P = \frac{1}{2}\rho A v^3$
• where $A = \pi r^2$ is the swept area. Because power scales with the square of the blade length and the cube of the wind speed, longer blades capture disproportionately more energy. Improved aerofoil profiles further raise the coefficient of performance.
• Larger rotors also reach higher hub heights, where wind speeds are stronger and steadier.

Additional Information

• Why the other statements are wrong:
  • Option A — commercial silicon solar panels now routinely achieve 18–22% efficiency, well above the 10–12% claimed; laboratory perovskite–silicon tandem cells have exceeded 33%.
  • Option C — the predictability of tides is an advantage, not an obstacle. Tides follow the lunar cycle and can be forecast years ahead, which makes tidal power far more dependable than solar or wind. The real constraints are high capital cost and the limited number of sites with a sufficient tidal range.
  • Option D — geothermal output depends heavily on drilling technology; Enhanced Geothermal Systems (EGS) exist precisely to improve heat extraction from otherwise unproductive rock.
• Betz's limit: no wind turbine can convert more than 59.3% of the kinetic energy in the wind, since the air must retain some velocity to move away from the rotor. Modern turbines achieve 75–80% of this theoretical maximum.
• Non-conventional sources: solar, wind, tidal, geothermal, biomass, ocean thermal (OTEC) and small hydro. India's institutional home for these is the Ministry of New and Renewable Energy (MNRE).