Day 11 Wind Energy – ECET 2026 Mechanical

Why this topic is important for ECET

Energy resources like wind, solar, hydro are key areas in ECET because they are part of renewable energy & power generation. Wind energy is gaining global importance and questions are often asked on power equation, efficiency, applications, and advantages/disadvantages. Mastering this topic builds your scoring edge in ECET 2026.

📘 Concept Notes

🔹 Introduction

Wind energy is the process of converting the kinetic energy of moving air (wind) into mechanical energy or electrical energy using wind turbines. It is renewable, eco-friendly, and sustainable.

🔹 Working Principle

When wind strikes the turbine blades → blades rotate.
The rotation drives a shaft connected to a generator.
Generator converts mechanical energy → electrical energy.

🔹 Types of Wind Turbines

Horizontal Axis Wind Turbine (HAWT)
- Most common type.
- Blades rotate around a horizontal axis.
- High efficiency, widely used in wind farms.
Vertical Axis Wind Turbine (VAWT)
- Blades rotate around a vertical axis.
- Works in all wind directions.
- Less efficient but useful in urban areas.

🔹 Factors Affecting Wind Energy

Wind velocity (higher velocity → higher power).
Air density (higher density → more power).
Blade area (swept area) → Larger blades = more capture.
Turbine efficiency.

🔹 Advantages

Clean and renewable.
Reduces dependency on fossil fuels.
Low operating cost.

🔹 Disadvantages

Intermittent (depends on wind availability).
High initial cost.
Noise & environmental impact.

🔹 Applications

Electricity generation in wind farms.
Water pumping in rural areas.
Small wind turbines for household/industrial use.

⚙️ Formulas

Kinetic energy of wind per second (Power available):

$P_{wind} = \frac{1}{2} \rho A v^3$

where

$\rho$ = air density (kg/m³)
$A$ = swept area of blades (m²) = $\pi R^2$
$v$ = wind velocity (m/s)

Actual Power Extracted by turbine:

$P_{turbine} = C_p \times P_{wind}$

where

$C_p$ = power coefficient (Betz limit ≤ 0.593)

Efficiency:

$\eta = \frac{P_{output}}{P_{input}} \times 100$

🔟 10 MCQs

Q1. The power available in wind is proportional to:
a) v
b) v²
c) v³
d) 1/v

Q2. The maximum theoretical efficiency of a wind turbine (Betz limit) is:
a) 29.3%
b) 39.3%
c) 50%
d) 59.3%

Q3. If the wind speed doubles, the power available becomes:
a) 2 times
b) 4 times
c) 6 times
d) 8 times

Q4. The swept area of a wind turbine blade is given by:
a) $A = \pi D$
b) $A = \pi R^2$
c) $A = 2 \pi R$
d) $A = D^2$

Q5. A wind turbine operates at 25% efficiency with input wind power of 100 kW. The output is:
a) 10 kW
b) 15 kW
c) 20 kW
d) 25 kW

Q6. Which turbine can work in all wind directions?
a) HAWT
b) VAWT
c) Both
d) None

Q7. If air density is 1.2 kg/m³, swept area = 10 m², wind velocity = 5 m/s, power available = ?
a) 75 W
b) 375 W
c) 750 W
d) 3750 W

Q8. Wind energy is classified as:
a) Conventional source
b) Non-renewable source
c) Renewable source
d) Fossil fuel

Q9. The main drawback of wind energy is:
a) High operating cost
b) Intermittency of supply
c) Excessive fuel requirement
d) Noisy only in vertical turbines

Q10. If radius of turbine blade doubles, the power available increases by:
a) 2 times
b) 3 times
c) 4 times
d) 8 times

✅ Answer Key

Q	Ans
1	c
2	d
3	d
4	b
5	c
6	b
7	b
8	c
9	b
10	c

🧠 Explanations

Q1: Wind power $P \propto v^3$ → (c).
Q2: Betz limit = 59.3% → (d).
Q3: Doubling velocity → $(2^3 = 8)$ times → (d).
Q4: Swept area of blade $A = \pi R^2$ → (b).
Q5: $\eta = \frac{P_{out}}{P_{in}} ] → [latex] P_{out} = 0.25 \times 100 = 25 kW$ → (c).
Q6: VAWT can work in all wind directions → (b).
Q7: $P = 0.5 \times 1.2 \times 10 \times 5^3 = 375 W$ → (b).
Q8: Wind = Renewable energy → (c).
Q9: Main issue = Intermittency → (b).
Q10: Area ∝ R², so doubling R → 4 times area → 4 times power → (c).

🎯 Motivation / Why Practice Matters

Wind energy questions test your concept clarity + numerical accuracy.
In ECET 2026, solving these fast can give you an easy scoring advantage because formulas are simple but tricky in application.
👉 Regular practice improves calculation speed, accuracy, and confidence in exams.

📲 CTA

👉 Join our WHATSAPP group for ECET 2026 updates and discussions →
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Day 11 Wind Energy – ECET 2026 Mechanical

Why this topic is important for ECET