L1: Intro and Wind Modelling I Flashcards
Define Renewable Energy
Energy flows which are replenished at the same rate as they are used
Define Sustainable Energy
That which meets all the needs of the present without compromising the ability of future generations to meet their own needs
Give two main reasons why offshore wind is appealing
- Offshore annual wind speeds are higher than onshore ones
- 40% world pop lives within 100km of coast
Which industries are relevant to the “Blue Economy”? (6)
- Aquaculture
- Tourism
- Marine Renewable Energy
- Offshore Oil & Gas
- Pharmaceutical
- Shipping
What two main challenges can the blue growth movement help respond to?
More energy and more food in a sustainable, safe and reliable way
What does P in PESTLE represent?
Political
What does the 1st E in PESTLE represent?
Economic
What does S in PESTLE represent?
Social
What does T in PESTLE represent?
Technological
What does L in PESTLE represent?
Legal
What does the 2nd E in PESTLE represent?
Environmental
What is the basic origin of wind?
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
Where are the min and max areas of absorption of solar radiation on Earth?
Min: the poles (perpendicular)
Max: the equator (parallel)
What are the space scale and the time scale of interest, for wind turbine design and single wind turbine dynamics modelling?
From 1 to ~100 meters and seconds (and fractions of seconds) to hours
Give the names for the following time variations:
- > 1 year
- 1 year
- Daily
- Less than 10 minutes
- Inter-annual
- Annual
- Diurnal
- Short-term
What is inter-annual wind variation useful for? How many years of data are required for a reliable annual wind speed?
Predicting long-term variation of energy produced by wind farms
5
What information does annual wind speed data provide?
Seasonal and monthly changes
How does wind speed vary seasonally in the northern hemisphere?
Usually the average monthly wind speed is higher in winter than in summer
What causes variations in diurnal wind speeds?
Differential heating between night and day. Magnitude of effect depends on location - eg offshore, no earth to absorb heat so less pronounced effect
What are statistically constant for around 10 minutes?
Average wind speed and its turbulence characteristics
For how long are simulations carried out for onshore turbines?
What are wind speed variations over shorter time periods than this called?
10 minutes
Turbulence
What do U, V, W and u, v, w represent?
U, V, W: 10-minute averages
u, v, w: fluctuating wind speeds with zero-mean (turbulence)
What is turbulence intensity?
The parameter used to quantify the turbulence in the wind
How is turbulence intensity defined?
The ratio between the standard deviation and mean of the wind speed
How are wind power spectra used?
- To model fluctuations of wind speed in time
- To quantify and use variations of wind speed in time to:
- quantify oscillating aerodynamic loads
- estimate the variation of power produced
How is the total energy in a wind signal obtained?
Integrate the power spectrum across the frequencies
