INDIANAPOLIS (AP) _ Indianapolis Power & Light says it will build a $631 million natural gas turbine power plant in south-central Indiana as part of a push to meet tougher environmental regulations.
 
  The Indianapolis-based utility announced Wednesday it will begin building a combined-cycle gas turbine power station next year near Martinsville, pending regulatory approval.
 
  IPL says the 650-megawatt plant will be one of the cleanest of its kind in Indiana and be powered by two natural gas-fired turbines and one steam turbine driven by waste heat from the gas turbines. It will replace six coal-fired power units near Martinsville the company will close.
 
  IPL’s residential and business customers could see increases in their electric bills of 2 to 3 percent a year through 2018 to pay for the new plant and other upgrades.