Complex sentence: It was divided into five units (Kiviõli, Küttejõu, Kohtla-Järve, Sillamäe, Kohtla), each consisting oil-shale mine and shale-oil plant, except Küttejõu, which did not have its own oil plant.
Split into simpler sentences: It was divided into five units (Kiviõli, Küttejõu, Kohtla-Järve, Sillamäe, and Kohtla). Each consisted of an oil shale mine and shale oil plant, except Küttejõu, which did not have an associated oil plant.