REP Wind Power Technologies 5 — Questions and Answers
Question 1: What is the primary environmental concern unique to offshore wind development compared to onshore?
- Greenhouse gas emissions during construction
- Impact on marine ecosystems, shipping lanes, and fisheries (Correct answer)
- Visual impact on residential communities
- Electromagnetic interference with broadcast signals
Correct answer: Impact on marine ecosystems, shipping lanes, and fisheries
Offshore wind projects must carefully assess impacts on marine habitats, fish populations, shipping navigation, and commercial fishing operations not present in onshore siting.
Question 2: Which federal agency has primary jurisdiction over offshore wind leasing in U.S. federal waters?
- Federal Energy Regulatory Commission (FERC)
- Bureau of Ocean Energy Management (BOEM) (Correct answer)
- Environmental Protection Agency (EPA)
- Army Corps of Engineers
Correct answer: Bureau of Ocean Energy Management (BOEM)
BOEM manages the leasing of the Outer Continental Shelf for offshore wind development, issuing leases, approving construction and operations plans, and overseeing environmental reviews.
Question 3: What is 'vortex-induced vibration' (VIV) a concern for in wind energy structures?
- Rotor blade flutter at high tip-speed ratios
- Oscillations in slender structures like towers caused by periodic shedding of wind vortices (Correct answer)
- Generator coil vibration at resonant electrical frequencies
- Foundation resonance during pile-driving installation
Correct answer: Oscillations in slender structures like towers caused by periodic shedding of wind vortices
VIV occurs when wind vortices shed alternately from a cylindrical structure at a frequency matching the structure's natural frequency, causing potentially destructive oscillations.
Question 4: In a doubly-fed induction generator (DFIG) wind turbine, what does the 'doubly-fed' refer to?
- Two independent gearboxes feeding the generator
- Electrical power fed to both the stator and rotor windings (Correct answer)
- Two separate generators sharing the same shaft
- Dual transformer connections to two grid circuits
Correct answer: Electrical power fed to both the stator and rotor windings
In a DFIG, electrical power is exchanged through both the stator (directly to grid) and the rotor (through a back-to-back power converter), enabling variable-speed operation.
Question 5: What is the primary purpose of a wind farm's collector system?
- Collect meteorological data from the turbines
- Aggregate power from individual turbines and step up voltage for transmission (Correct answer)
- Monitor blade condition and collect vibration data
- Collect and recycle gearbox lubricating oil
Correct answer: Aggregate power from individual turbines and step up voltage for transmission
The collector system consists of underground or submarine cables and a substation that aggregate each turbine's output and step up voltage for efficient transmission to the grid.
Question 6: What is 'sound power level' (Lw) used to characterize in wind turbine noise assessments?
- The noise level experienced by nearby residents
- The total acoustic power emitted by a turbine, independent of distance (Correct answer)
- The frequency spectrum of blade aerodynamic noise only
- Background noise levels used as a baseline for comparison
Correct answer: The total acoustic power emitted by a turbine, independent of distance
Sound power level is an intrinsic property of the turbine describing total emitted acoustic energy, allowing comparison between turbines regardless of measurement distance.
Question 7: Which wind speed metric is most useful for predicting annual energy production at a potential wind site?
- Maximum recorded wind speed
- Mean wind speed at hub height (Correct answer)
- Most frequently occurring wind speed
- Wind speed at 10-meter standard meteorological height
Correct answer: Mean wind speed at hub height
Mean wind speed at hub height is the most directly relevant metric for AEP estimates because it reflects the actual wind resource where the rotor will operate, weighted by wind speed distribution.
REP Wind Power Technologies 5
What is the primary environmental concern unique to offshore wind development compared to onshore?