Dominion Resources Inc. (D) third-quarter earnings rose 17% as the electricity utility and natural-gas provider reported surprise growth.

But it projected downbeat current-quarter earnings--55 cents to 65 cents a share compared with analysts' average estimate of 67 cents. Dominion said benefits from the gas-transmission business and lower tax rates would be offset by higher planned outage expenses, higher interest expense and lower volumes from its remaining petroleum exploration-and-production operations.

The power industry has experienced a slump in demand as consumers and industrial users cut back. Natural gas prices have fallen more than 60% from the highs hit in the summer of 2008 because of a glut of onshore U.S. production.

However, Dominion has recently seen strength at its utilities and higher margins at its merchant-power business, boosting the bottom line. And Friday, the company continued to forecast strength in its core businesses despite the cool summer. Competitors have had that weigh on results.

Dominion posted a profit of $594 million, or $1 a share, up from $508 million, or 87 cents a share, a year earlier. Operating earnings rose to 99 cents from 94 cents, above July's downbeat forecast of 88 cents to 93 cents.

Revenue decreased 16% to $3.65 billion. Analysts predicted $3.94 billion.

Earnings at Dominion Energy, which operates the oil and gas operation, rose 17%. Dominion's electricity-generation business had 2.2% earnings growth. Dominion Virginia Power, which serves Virginia and North Carolina, posted a 13% jump in profit.

Shares in Dominion Resources, which affirmed its 2009 and 2010 earnings views, closed Thursday at $34.63 and weren't active premarket. The stock, which has risen about one-quarter from a six-year low in March, remains down 3% so far this year.

-By Joan E. Solsman, Dow Jones Newswires; 212-416-2291; joan.solsman@dowjones.com