Raleigh, N.C. — Duke Energy and Progress Energy want to let customers purchase carbon credits through environmentally friendly programs administered by the nonprofit NC GreenPower.

The companies filed a letter with the North Carolina Utilities Commission Monday outlining their plans, which would expand renewable-energy programs run by NC GreenPower to include carbon credits, or offsets.

"While most people can reduce their energy use by improving the efficiency of their homes, buying cars that get better gas mileage and making other changes ... reducing their carbon footprint to zero through individual actions is nearly impossible," Duke Energy's letter read. "Carbon offsets are a cost effective way to reduce the remainder of one's carbon footprint."

Duke and Progress Energy customers could purchase carbon offsets through NC GreenPower.

Officials said the goal is to allow people to balance the carbon emissions produced through their energy-using activities with support of projects that reduce carbon dioxide. Such projects include renewable-energy, energy efficiency and reforestation ventures.

Currently, NC GreenPower – approved by the N.C. Utilities Commission and supported by all the state's utility companies – lets utility customers fund renewable-energy sources.

NC GreenPower officials will consider approving the plans by Duke and Progress Energy at their next meeting in late March.