About 1.2 million customers of Ameren Missouri will see bigger bills for electricity, but the utility's largest customer will pay a lower rate.
The Missouri Public Service Commission approved a plan Wednesday to allow St. Louis-based Ameren to increase electric rates by $108 million.
An Ameren spokesman says the average residential consumer will pay an additional $7 per month.
But Noranda Aluminum would save about $17 million per year. Noranda operates a smelter in southeast Missouri that company officials had warned may shut down if it couldn't get lower electricity costs.
Commission chairman Robert Kenney says some of the costs of Noranda's lower rate are shifted to other consumers. But he says the increase is less than the amount other consumers would pay if Noranda shut down.