Complex sentence: Wind farms are highly intermittent, due to the natural variability of the wind, but because a wind farm may have hundreds of widely spaced wind turbines, the farm as a whole tends to be robust against the failure of individual turbines.
Split into simpler sentences: Wind farms are variable, due to the natural variability of the wind. Because a wind farm may have hundreds of widely spaced wind turbines, the farm as a whole tends to be robust against the failure of individual turbines.