The company said it reached that milestone Wednesday.
Chairman, President and CEO Anthony Wilson tells multiple members that move is a "substantial step forward for the project."
The company announced earlier this month it was completing maintenance on the plant's first gasifier, which followed six weeks of successful syngas production including generation of the plant's first electricity using syngas. That gasifier began generating electricity on Oct. 12.
The gasifiers run on synthesis gas, called syngas, which is made from lignite, a kind of coal.
The plant is more than $4 billion over its initial budget, and the start date has been pushed back several times. It is currently expected to be operational by Dec. 31.
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