Ch7 Flashcards
What is one difference between Vertical Axis Wind Turbines (VAWT) and Horizontal Axis Wind Turbines (HAWT)?
VAWT can operate with wind in any direction, whereas HAWT must yaw to face into the wind.
This means VAWTs can harness wind energy regardless of its direction.
What is another difference between VAWT and HAWT?
VAWT can operate at low wind speeds, whereas HAWT requires higher wind speeds.
This makes VAWTs more versatile in varying wind conditions.
At what RPM do VAWTs typically rotate compared to HAWTs?
VAWT rotates at a low RPM, whereas HAWT rotates at higher RPM.
This difference affects the design and efficiency of the turbines.
How does noise production compare between VAWT and HAWT?
VAWT is less noisy than HAWT.
This can be an important consideration in urban or residential areas.
What is the rotor orientation for VAWT and HAWT?
VAWT has the rotor in a vertical direction; HAWT has the rotor in a horizontal direction.
This fundamental design difference impacts their efficiency and application.
What is the definition of Betz Limit?
The maximum amount of the wind’s kinetic energy that a HAWT can convert to mechanical energy turning a rotor; calculated at 59.3% of the kinetic energy from the wind.
Most modern turbines can convert only 35-45% of the wind’s energy to electricity.
What is rotor collected energy?
The energy in the wind utilized by the turbine blades.
This term is important for understanding the efficiency of wind turbines.
What factors can cause an energy shortfall between rotor collected energy and rated energy output?
- Energy losses through inefficiencies
- Limitations imposed by the size of the generator
These factors affect the overall efficiency and performance of wind turbines.
What is the relationship between power output and swept area in a HAWT?
The power output is directly proportional to the swept area.
This means larger swept areas capture more wind energy, increasing power output.
How does air density affect the power output of a wind turbine?
When air density is lower, the power output is less; when air density is higher, the power output increases.
This is because denser air carries more mass, contributing to greater energy conversion.
How does temperature impact the power output of a wind turbine?
When temperature is lower, the turbine power output is greater; when temperature is higher, the turbine power output reduces.
Cooler air is denser and thus more capable of producing energy.
What is the effect of increasing rotor diameter on turbine power output?
The power output will increase.
This is because a larger diameter means a larger swept area, capturing more wind energy.
True or False: The rated power output of a wind turbine is always equal to the rotor collected energy.
False.
The rated power output is often less than the rotor collected energy due to inefficiencies and equipment limitations.
What is the significance of the cut-in speed in a wind turbine power curve?
It is the wind speed at which the turbine begins to turn and generate electricity.
This speed is crucial for determining when a turbine becomes operational.
What is the relationship between wind speed and power production for a HAWT?
The power output increases with wind speed as Pout is directly proportional to v^3.
This means small increases in wind speed can lead to significant increases in power output.
What role does hub height play in determining wind turbine efficiency?
Hub height affects the wind resource assessment and potential energy capture; higher hub heights typically allow for greater energy capture from winds.
This factor includes considerations of local terrain and wind patterns.
What factors are considered in wind resource assessment?
Average windspeed, potential obstructions to wind flow, local environmental conditions, topography of the site
What is the significance of topography in wind turbine planning?
It affects wind flow and potential obstructions during a preliminary site assessment
How does the size of a turbine influence its performance?
Higher hub height allows for a larger swept area and greater power output
What visual impacts must be considered when installing a wind turbine?
Size of turbine/tower and topography of surrounding area
What is a full description in the context of planning permission responses?
Identifies a factor and explains its significance
What is a partial description in the context of planning permission responses?
Identifies a factor without explaining its significance
Why does increasing hub height improve wind turbine power output? (List two reasons)
- Wind speed is higher as height increases from ground level
- Larger hub height allows for a larger blade diameter, increasing swept area
What two critical factors must be considered when determining hub height for a wind turbine installation?
- Wind resource assessment of the site
- Topography of the site
