Complex sentence: For its first two decades, it operated ten wind turbines, built by Vestas, but in February 2011, an £11.8 million rebuilding of the facility was completed, which replaced the original ten with four new turbines, which are larger than the original ones.
Split into simpler sentences: For its first two decades, it operated ten wind turbines, built by Vestas. In February 2011, an £11.8 million rebuilding of the facility was completed, which replaced the original ten with four new turbines, which are larger than the original ones.