Complex sentence: The Horse Hollow Wind Energy Center (735 MW) in Taylor and Nolan counties is the world's largest wind farm, but the Roscoe Wind Farm and Sherbino Wind Farm are under construction, and when completed, will be slightly larger than Horse Hollow.
Split into simpler sentences: The Horse Hollow Wind Energy Center (735 MW) in Taylor and Nolan counties is the world's largest wind farm. But the Roscoe Wind Farm and Sherbino Wind Farm are under construction and when completed will be slightly larger than Horse Hollow.