The Indiana Utility Regulatory Commission voted Wednesday to approve a request by Indianapolis Power and Light to spend 511-million dollars to upgrade power plants in Petersburg and Indianapolis to meet new federal mercury and toxic standards.
IPL says the upgrades will cut emissions by 80%.
The Indianapolis Star reports a rate increase to pay for the upgrades will raise typical household monthly electric bills 1.1 million dollars by 2014 and nearly nine-million dollars by 2017.
The Sierra Club and the Citizens Action Coalition fought the plan, saying IPL's 470-thousand customers shouldn't have to pay higher rates to upgrade outdated coal plants.
They want IPL to invest in clean, renewable energy sources.
Generating units at the two plants are 27 to 46 years old.
In addition to reducing emissions, the project will lead to new construction jobs for the next three years and will have a major economic impact on Petersburg and Pike County.
The project will create an estimated 350 to 400 jobs during the peak construction period, the majority of which will be local.