Georgia Power plans to retire coal- and oil-fired units at two power plants in the state and replace them with more power from new solar and other renewable power projects.

The utility also said it expects various efficiency programs to reduce customers’ peak electricity demand by about 12 percent from current levels by 2019.

The goals were outlined in the electric utility's 20-year energy plan, filed with state utility regulators Friday. The long-term plan is updated every three years, and subject to regulators' approval.

A utility spokesman did not elaborate on how much the various moves are expected to cost or how they will affect customers’ rates.

Past solar and wind-power projects “result in savings for customers,” said Georgia Power spokesman John Kraft. “We’re hoping that trend would continue.”

However, environmental groups were critical of Georgia Power’s plan, saying the utility plans to slow its investment in new solar and wind capacity and to keep operating some of its oldest coal-fired plants, which produce much more pollution than other types of plants.

“I hope the (state regulators) act to protect our health and our pocketbooks by putting these dirty, outdated coal plants, like Plant Hammond, on a schedule for retirement,” said Colleen Kiernan, director of Sierra Club’s Georgia Chapter.

In a joint statement, the Sierra Club and Southern Alliance for Clean Energy said the future projects boost Georgia Power’s renewable power capacity by about 1.5 percent annually in 2018 and 2019, well below the 3.9 percent increase slated this year.

If approved, Georgia Power plans to close 375 megawatts of coal and oil-fired plants. They are: one coal unit and two oil-fired units at Plant Mitchell near Albany, and an oil-fired unit at Plant Kraft, near Savannah. The utility also plans to sell its interest in a Florida oil-fired plant mostly owned by Duke Energy.

Meanwhile, Georgia Power said it plans to add 525 megawatts of generating capacity by 2019 from new renewable energy projects in Georgia.

Georgia Power currently projects that it will get almost 1,000 megawatts from solar projects by year-end, said Kraft.

The bulk of the new power — 425 megawatts — would come from large utility-scale solar, wind or biomass plants. The utility hopes to get the rest of the new power from long-term contracts with a mix of medium- and small-scale alternative power generators such as solar power installations on schools, parking lots, businesses and residences, he said.