CHARLOTTE, N.C. – Duke Energy is asking state regulators for a rate increase totaling $647 million, representing a 13.6 percent average rate increase for all groups of customers.

The company says much of the increase would be used for investments that would modernize the energy delivery system.

“We believe these investments are helping to shift our customers to a smarter energy future that we can all enjoy," said Duke Spokesperson Jeff Brooks. "That will move us away from older technologies and enable us to use energy in ways we haven’t been able to use before.”

The average increase for residential customers would be 16.7 percent.

In other words, a customer using 1,000-kilowatt hours a month would now pay $122.68, an average increase of $18 monthly.

The company says almost half of the increase would be used to cleanup and disposal of coal ash that is a byproduct of coal-fired plants.

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Some Duke customers say it is not fair for customers to pay those costs.

“I’m a little concerned that too much of these costs are passed on to actual consumers rather than company shareholders," said John Terrando, a customer.

But Brooks counters that every Duke customer benefits from energy from coal.

“A typical residential family actually generates more than 150 pounds of coal ash every year from the electricity that they consume," he said.

Other customers like Malria Everidge said Duke did not need any rate hike.

“I think that is absolutely crazy,” she said. “I can’t imagine that they can justify that per household. That’s a lot of money. What are they doing with it?”

Duke's rate-hike request will now be the subject of several hearings before the State Public Utilities Commission.