Half the coal burned by Progress Energy's and Duke Energy's power plants would become illegal in North Carolina under legislation proposed Tuesday by state Rep. Pricey Harrison.

The Guilford County Democrat wants to outlaw importation of coal that has been extracted by a controversial form of strip mining known as mountaintop removal. The process involves blowing up several hundred feet of mountaintop to expose embedded veins of coal.

The state's power companies say Harrison's proposal would force utilities to buy more expensive coal and raise the cost of electricity for consumers. Coal mined from mountaintops is the cheapest coal available to Raleigh-based Progress and Charlotte-based Duke. North Carolina relies on coal for about 60 percent of its electricity.

Mountaintop coal removal is not practiced in North Carolina, but coal mined that way is imported from West Virginia, Kentucky and other Appalachian states. Critics say that mountaintop removal destroys habitats, leads to erosion and flooding, and releases toxins into waterways.

"Every time we turn on our lights, we're using energy derived from those destroyed mountains," Harrison said Tuesday at a news conference in Raleigh to discuss her proposal.

Progress and Duke import nearly all their coal from Appalachian coal mines. About half the coal -- about 15 million tons a year -- comes from mountaintop removal, while the rest comes from underground coal mines. North Carolina is one of the nation's top users of mountaintop coal.

But banning mountaintop coal would increase demand for other Appalachian coal and drive up prices for customers, utility officials warned.

"You'd basically cut our market in half where we can get our coal," said Duke spokeswoman Paige Sheehan. "And you would not stop mountaintop mining because there's such a global demand for coal."

Electric utilities buy coal and other fuels from competing vendors. Much of the fuel is bought on long-term contracts to lock in prices.

But coal prices have doubled in the past year, and Progress and Duke are seeking rate increases to pass costs on to their customers. Progress recently asked for a 6 percent rate increase in South Carolina and will file a request soon with state regulators in North Carolina. Duke is seeking a 4 percent increase.

Both companies say worldwide demand for coal is the main driver of the price increases.

Harrison said she was prompted to introduce legislation after recently seeing a documentary, "Mountain Top Removal," released this year by Pittsboro independent filmmaker Michael O'Connell. The documentary tracks two years of the life of a West Virginia family living at the edge of a mountaintop removal site.

Harrison acknowledges her proposed ban is controversial and may not get a public hearing this year. But she said she felt compelled to draw attention to the issue.

"I realize it's a difficult issue to move forward," Harrison said. "It's a pretty controversial issue."

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