The utilities commission held the hearing this week to review the accuracy of the utilities' energy demand forecasts. The utilities file the forecasts every year for planning purposes. Both companies are planning as many as four new nuclear reactors and other power plants in the Carolinas to meet customer demand.
Both Progress and Duke also are increasing conservation programs, as required by a new state law passed last year. But the advocates say it's not enough.
"The energy efficiency programs seem to be altogether too timid," said John Blackburn, a retired Duke University economist who testified for N.C. Waste Awareness and Reduction Network, a Durham group.
Conservation programs reverse the century-old logic of utility business operations, in which the companies generate their own power and sell it to customers. With conservation, the utilities try to persuade customers - by offering financial incentives - to upgrade appliances, lighting, insulation and home design to save power.
Duke is proposing to meet 1.6 percent of its energy demand through conservation programs in the next five years. Critics say that the company could meet 1 percent of power demand through conservation annually, up to 20 percent over two decades.
No one disputes that the conservation can dramatically cut household electricity use, by as much as 50 percent in some cases, but utility officials are reluctant to become dependent on the public for future planning. The concern is that even with financial incentives, customers may decide not to participate, which could wreak havoc with a region's power supply.
"Just because it's cost-effective doesn't mean that someone will do it," said Richard Stevie, Duke Energy's managing director of customer marketing analytics. "I have seen a lot of energy efficiency programs come and go."
The main drivers of energy demand are growing population and household income. The state is adding about 100,000 new electricity customer accounts a year, of which 75,000 are moving into territory served by Progress or Duke.
The Public Staff, the name of the state's consumer advocacy agency, told the utilities commission that the utility demand forecasts are reasonable.
The critics want the state to require the utilities to revise their forecasts by accounting for more efficiency programs.
The utilities commission is expected to rule on the request within a few months.