Questions: Introduction to Renewable Energy Systems

Question 1

A wind turbine is rated at 2 MW but produces an average of 700 kW over a year. What is its capacity factor?

• A. 200%
• B. 70%
• C. 35%
• D. 28.6%

Answer: (C)

Capacity factor = average output / rated capacity = 700 kW / 2,000 kW = 0.35 = 35%. This means the turbine produces, on average, 35% of its maximum rated output due to variable wind speeds. This is typical for onshore wind turbines.

Question 2

Renewable energy sources produce power continuously without interruption.

• T. True
• F. False

Answer: False

Solar energy is unavailable at night and reduced on cloudy days. Wind energy varies with weather. Even hydroelectric can be affected by seasonal drought. This variability (called intermittency) is one of the primary engineering challenges of renewable energy systems.

Question 3

Why might a region with excellent solar resources still choose to install wind turbines instead of (or in addition to) solar panels?

Model answer: Wind and solar often complement each other -- wind may blow strongest at night or during storms when solar output is low. Combining both sources reduces overall variability and provides more consistent power. Additionally, wind may offer better economics at certain scales, the region may have limited suitable land for solar, or local regulations may favor one technology over the other.

This illustrates the engineering principle of diversification. Relying on a single intermittent source creates large gaps in supply. Combining multiple sources with different variability patterns produces a smoother, more reliable total output -- though it still does not eliminate the need for storage or backup.