A report from USC said Michigan utility companies Detroit Edison and Consumers Energy spent more than $1 billion in 2010 to import coal from states such as Wyoming and Kentucky. That year was most recent for which data were available from either company.
Jeff Deyette, the report's author, said coal prices have gone up about 80 percent in the past 10 years and much of that cost was transferred to consumers.
"If the utilities had instead invested in homegrown, renewable resources to produce electricity, like wind, solar and biopower, more of that money could have stayed in the local economy," he said in a statement from Chicago.
Michigan voters in November decide on a measure that would require the state to get 25 percent of its electricity from renewable energy resources by 2025. Legislation passed in Michigan in 2008 requires utility companies to get 10 percent of their electricity from renewable energy sources by 2015.
If approved, the measure would require amending the state's constitution.
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