Complex sentence: A hydroelectricity plant may have a capacity factor lower than 100% due to scarcity of water, or its output may be regulated to match the current power need, conserving its stored water for later usage.
Split into simpler sentences: A hydroelectricity plant may have a capacity factor lower than 100% due to scarcity of water. However, its output may also simply be regulated to match the current power need, conserving its stored water for later usage.