Progress Energy is trying to gauge the public's interest in energy efficiency by discounting compact fluorescent light bulbs by $1 each.

The bulbs use 75 percent less energy than traditional bulbs and last up to 10 times longer, but they're more expensive. The discount can cut the cost of a compact fluorescent by more than half.

So far, the utility has sold 170,000 bulbs through local Home Depot stores. The goal is 200,000 by the end of the year.

Progress included an update of the program in its efficiency proposal filed Monday with the North Carolina Utilities Commission. If successful, it could be adopted long-term as part of a broader energy efficiency plan.

Progress officials say the efficiency programs could help customers reduce electricity consumption by as much as 15 percent.