Potomac Electric Power co. soon will begin burning coal containing more sulfur at its Dickerson power plant, saving consumers $10 million a year in fuel bills, but adding to pollution.

The federal Environmental Protection Agency gave Pepco permission to switch types of coal at the Montogomery County power plant, Pepco announced yesterday.

Instead of burning coal with a one percent sulfur content as it has since last February, the plant will resume using 1.8-percent-sulfur coal, which it burned previously.

The switch will increase the sulfur dioxide emissions from the Dickerson plant by 40 percent, but the air around the facility still will meet all federal air quality standards, said William A. Foy, director of environmental affairs for Pepco.

"We don't think that any significant environmental change results" from the change in coal burned, he said.

The Maryland Department of Health and Mental Hygiene, which also regulates air pollution, approved the switch and asked federal regulators to do the same, Foy said.

Pepco officials contend the most important impact of the change will be a $10-million-a-year reduction in the fuel bills paid by the utility's customers. the higher-sulfur coal costs $9 a ton less than the lower-sulfur kind, and the plant burns 1.25 million tons of coal a year, the company estimated.

The Dickerson plant is the second in which Pepco has gotten persmission to burn coal with a higher sulfur content. Earlier this year, the EPA agreed to let the company continue using 2-percent-sulfur coal at its Chalk Point plant in Prince George's County. Pepco contended that switching to one-percent-sulfur coal would have increased the plant's fuel bills by more than $6 million a year, with little environmental benefit.

Pepco reported yesterday that its profits for the first 11 months of the year were a penny a share less than in the same period a year ago.

Pepco earned $65.4 million ($1.59 a share) during the period compared with $64.5 million ($1.60) a year earlier.Earnings per share decreased while total earnings increased because new stock has been issued in the past year.

Pepco's operating revenues for the 11 months increased to $693 million from $666 million.