L1: Intro and Wind Modelling I

Question 1

Define Renewable Energy

Answer 1

Energy flows which are replenished at the same rate as they are used

Question 2

Define Sustainable Energy

Answer 2

That which meets all the needs of the present without compromising the ability of future generations to meet their own needs

Question 3

Give two main reasons why offshore wind is appealing

Answer 3

• Offshore annual wind speeds are higher than onshore ones

- 40% world pop lives within 100km of coast

Question 4

Which industries are relevant to the “Blue Economy”? (6)

Answer 4

• Aquaculture
• Tourism
• Marine Renewable Energy
• Offshore Oil & Gas
• Pharmaceutical
• Shipping

Question 5

What two main challenges can the blue growth movement help respond to?

Answer 5

More energy and more food in a sustainable, safe and reliable way

Question 6

What does P in PESTLE represent?

Answer 6

Political

Question 7

What does the 1st E in PESTLE represent?

Answer 7

Economic

Question 8

What does S in PESTLE represent?

Answer 8

Social

Question 9

What does T in PESTLE represent?

Answer 9

Technological

Question 10

What does L in PESTLE represent?

Answer 10

Legal

Question 11

What does the 2nd E in PESTLE represent?

Answer 11

Environmental

Question 12

What is the basic origin of wind?

Answer 12

Solar radiation causing uneven heating of the Earth’s surface due to relative orientation of the surface and radiation. Results in pressure differences, so air moves from high to low pressure areas

Question 13

Where are the min and max areas of absorption of solar radiation on Earth?

Answer 13

Min: the poles (perpendicular)
Max: the equator (parallel)

Question 14

What are the space scale and the time scale of interest, for wind turbine design and single wind turbine dynamics modelling?

Answer 14

From 1 to ~100 meters and seconds (and fractions of seconds) to hours

Question 15

Give the names for the following time variations:

1. > 1 year
2. 1 year
3. Daily
4. Less than 10 minutes

Answer 15

1. Inter-annual
2. Annual
3. Diurnal
4. Short-term

Question 16

What is inter-annual wind variation useful for? How many years of data are required for a reliable annual wind speed?

Answer 16

Predicting long-term variation of energy produced by wind farms
5

Question 17

What information does annual wind speed data provide?

Answer 17

Seasonal and monthly changes

Question 18

How does wind speed vary seasonally in the northern hemisphere?

Answer 18

Usually the average monthly wind speed is higher in winter than in summer

Question 19

What causes variations in diurnal wind speeds?

Answer 19

Differential heating between night and day. Magnitude of effect depends on location - eg offshore, no earth to absorb heat so less pronounced effect

Question 20

What are statistically constant for around 10 minutes?

Answer 20

Average wind speed and its turbulence characteristics

Question 21

For how long are simulations carried out for onshore turbines?
What are wind speed variations over shorter time periods than this called?

Answer 21

10 minutes

Turbulence

Question 22

What do U, V, W and u, v, w represent?

Answer 22

U, V, W: 10-minute averages

u, v, w: fluctuating wind speeds with zero-mean (turbulence)

Question 23

What is turbulence intensity?

Answer 23

The parameter used to quantify the turbulence in the wind

Question 24

How is turbulence intensity defined?

Answer 24

The ratio between the standard deviation and mean of the wind speed

Question 25

How are wind power spectra used?

Answer 25

1. To model fluctuations of wind speed in time
2. To quantify and use variations of wind speed in time to:
   - quantify oscillating aerodynamic loads
   - estimate the variation of power produced

Question 26

How is the total energy in a wind signal obtained?

Answer 26

Integrate the power spectrum across the frequencies