The transition from using wood as a primary source of energy to using coal was almost complete, and a second transition from coal to natural gas and oil was beginning.
(The transition from using wood as a primary source of energy to using coal; was; almost complete) (a second transition from coal to natural gas and oil; was beginning; )
The transition from using wood as a primary source of energy to using coal a second transition from coal to natural gas and oil
was was beginning
almost complete