DTE Energy Co. shared a Kumbaya moment with clean energy advocates in 2016 when utility CEO Gerry Anderson announced the Detroit-based company would shut down eight coal-fired units between 2020 and 2023 as part of a broader strategy to transition to cleaner energy sources. But the next phase of DTE's strategy — to replace most of the coal capacity with a $1 billion natural gas plant — has set off a bitter fight over the state's energy future.