---
title: "Wind farm siting, layout and wake effect"
subject: "Energy Resources"
chapter: 4
key: "semester_6/energy_resources:wind-farm-siting-layout"
source: https://www.bctengineer.com/q/semester_6/energy_resources/wind-farm-siting-layout
site: BCT Engineering
---

# Wind farm siting, layout and wake effect

Energy Resources · Chapter 4: Wind energy

- Asked in: year not given, 5 marks
- Video: [4. DT - Wind Farm Design and Economic Evaluation  - April 2026 | RES | SNS Institutions](https://www.youtube.com/watch?v=hHSxCoEIXXo) — ASOKAN C SNS
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/energy_resources/wind-farm-siting-layout
- Whole chapter: https://www.bctengineer.com/md/semester_6/energy_resources/chapter-4

## Question

What is a wind farm? Discuss the factors considered in selecting a site and arranging the turbines in a wind farm. Explain the wake effect and how it is reduced.

## Short answer

A wind farm is a group of grid-connected turbines sharing infrastructure. Site factors: annual mean wind >6 m/s, open terrain, grid proximity, access, environment. Layout: rows across prevailing wind, spacing 3–5 rotor diameters crosswise, 5–10 along wind. Wake effect: lower wind speed behind a turbine reduces power by 5–15%; reduced by spacing, staggering, and wake models.

## Answer

A **wind farm** is a group of grid-connected wind turbines installed at one site to produce bulk electric power, sharing roads, substation and transmission line.

#### Site selection factors
1. **Wind resource:** annual mean speed above about 6 m/s at hub height from at least one year of measurement; wind rose, Weibull distribution and low turbulence.
2. **Terrain:** open land, ridges, hill tops or coast; avoid trees and buildings that cause turbulence and speed-down.
3. **Grid access:** nearness to a substation or line of enough capacity.
4. **Access and ground:** roads for heavy transport, firm soil for foundations.
5. **Environment and society:** noise (distance from houses), bird and bat routes, visual effect, shadow flicker, land cost and acceptance.
6. **Extreme conditions:** lightning, icing, high winds, earthquakes.

#### Layout
Turbines are placed in rows at right angles to the prevailing wind. Typical spacing is **3–5 rotor diameters (D)** between turbines crosswise and **5–10 D** along the wind.

```text
 wind -->   o     o     o     o   (row 1)
 
              o     o     o     o (row 2, staggered)
         <--- 5-10 D --->
```

#### Wake effect
Air behind a rotor has lower speed and higher turbulence. A turbine inside this wake produces less power and suffers higher fatigue loads. Power loss from wake is commonly 5–15 % of the farm output.

**Reduction:** adequate spacing, staggering of rows, laying rows across the dominant wind direction, use of wake models (e.g. Jensen) to optimise the layout, taller towers and control strategies that yaw turbines slightly off the wind.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is a typical minimum annual mean wind speed for a wind farm site at hub height?
   A. About 1 m/s
   B. About 6 m/s
   C. About 2 m/s
   D. About 20 m/s
   Answer: B. It should come from at least a year of measurement. (Key point: Wind resource)

2. What is the typical turbine spacing?
   A. 3-5 D crosswise and 5-10 D along the wind
   B. 0.5 D in all directions
   C. 20 D crosswise only
   D. 1 D along the wind
   Answer: A. Rows are at right angles to the prevailing wind. (Key point: Spacing)

3. What is the wake effect?
   A. Wind becomes faster behind a rotor
   B. Noise from the blades
   C. Reflection of light from blades
   D. Air behind a rotor has lower speed and higher turbulence, reducing downstream output and increasing fatigue
   Answer: D. Losses are 5-15% of farm output. (Key point: Wake effect)

4. Which measure reduces wake loss?
   A. Packing turbines closely
   B. Aligning all turbines in the wind direction
   C. Adequate spacing and staggered rows
   D. Using shorter towers
   Answer: C. Wake models also help optimise layout. (Key point: Wake reduction)

## Related in Energy Resources

- [Horizontal and vertical axis wind turbines](https://www.bctengineer.com/question.md?key=semester_6%2Fenergy_resources%3Ahawt-vawt-types-characteristics) — Energy Resources, chapter 4
- [Wind turbine power, tip speed ratio and energy](https://www.bctengineer.com/question.md?key=semester_6%2Fenergy_resources%3Awind-turbine-power-energy-numerical) — Energy Resources, chapter 4

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