Virginia's power companies could soon reap larger financial rewards for saving energy than for selling it and their customers could share the bounty under a proposal endorsed yesterday by Gov. L. Douglas Wilder.

Wilder urged the State Corporation Commission, which approves new power plants and sets rates, to move "quickly and aggressively" on a study now underway of how to revamp state regulations to promote energy conservation. Changes are not expected for several months at least.

Virginia's secretary of natural resources, Elizabeth Haskell, said yesterday the idea is to "find other ways to deal with energy needs in Virginia aside from building new power plants. Some can be avoided."

If changes are made, customers could receive free energy-saving light bulbs or rebates for buying energy-efficient applicances. But energy experts said consumers may not see lower electric bills because utilities could raise their rates to pay for the costs of the new programs.

The state now allows utilities to include some energy-saving programs in their rates on an experimental basis, such as offering lower rates for large commercial customers who reduce power during peak-use hours. But Virginia Power recently yanked a proposal to give customers a $100 savings bond for installing a high-efficiency heat pump because utility officials said state rules prohibit it.

Virginia's action is a step into one of the newest areas of utility regulation. Several states allow power companies to claim higher profits for conserving energy than for producing it, and require new power plant applications to meet tougher standards in proving the need for the plant. Maryland and the District already have taken steps in that area.

The state's move was praised both by Virginia Power, the state's largest electric utility, and by environmentalists, who are protesting construction of new power plants they say will worsen pollution at Shenandoah National Park and other sites.

In a related action, Haskell wrote Environmental Protection Agency Administrator William K. Reilly yesterday urging tougher action to reduce the thousands of tons of sulfate pollution that blow into Virginia from out-of-state power plants. Her letter pointed out that the EPA issued rules to limit such pollution in 1987 that it never implemented. EPA spokesman David Ryan said the agency could not comment until it received the letter, but is studying additional action.

Virginia has 19 pending applications for new power plants, more than any other state. The state Air Pollution Control Board recently rejected efforts by environmentalists and the National Park Service to put coal-burning plant applications on hold until the state's air pollution is cleaned up.

"We're encouraged by the initiative taken by the governor and Secretary Haskell," said David Carr, a lawyer with the Southern Environmental Law Center. However, he said, "it does not address how Virginia is going to deal with the proliferation of new sources."

Virginia lags behind the District and Maryland in embracing energy conservation. The District ordered utilities in 1988 to engage in "least-cost planning" -- that is, compare the costs of energy conservation to the expense of a new plant, and implement the least expensive option.

Maryland took a similar step last year. Officials of the Potomac Electric Power Co., which serves suburban Maryland and the District, say they think the state will approve a plan to give the utility a higher profit if it meets a conservation target. Pepco's conservation programs now planned or underway are expected to save 685 megawatts in 1995, the equivalent of four small power plants.