Consumers Energy says a release of natural gas led to a compressor station fire that sparked concerns about keeping fuel flowing to millions of people during a bitter cold snap in January.
The Jackson-based utility said it submitted its report on the fire Friday to the Michigan Public Service Commission.
It said a plume of natural gas was released by a safety fire-gate system, mixed with air outside because of high winds, and was ignited by "extremely hot equipment" at the Ray Natural Gas Compressor Station in Macomb County.
Consumers says those were the findings of its two-month internal investigation and confirmed by a third-party consultant.
It says the fire "was precipitated by a safety venting fire-gate process that is proven safe and effective" but became hazardous in extreme weather.