LAKE FOREST, Ill. (AP) -- Cardboard box maker Packaging Corp. of America on Thursday received approval to spend $215 million on projects aimed at reducing energy use in two plants.

The company's board cleared plans to install new machinery and paper drying machine improvements at its Valdosta, Ga., mill, which will reduce fuel and electricity costs by 75 percent. When the work is done, the mill will generate all of its own electricity.

Rebuilding and upgrading machinery at its Counce, Tenn., mill, will cut fuel and electricity costs there by 50 percent.

The company said it will save about $80 million in maintenance costs by replacing old equipment, bringing its total investment to about $215 million. The after-tax return on the projects is expected to be 25 to 30 percent of the cost, based on proposed and potential tax incentives and benefits related to the production of green electricity and energy.

Both projects are expected to be completed by the end of 2011.

Packaging Corp. stock closed Thursday up 61 cents, or 3 percent, at $20.92. The stock has changed hands between $9.66 and $21.99 in the past 52 weeks, and is up more than 50 percent since the start of the year.