Nearly six miles into a southwestern Pennsylvania coal mine, about 900 feet underground, two massive steel wheels ringed with carbide teeth chew chunks from a pitch-black wall.

But deregulation of the electricity market makes the battle relevant to all Pennsylvanians. It has given them more choice over who supplies their electricity, and how much of it – if any – they want to come from alternative sources such as solar and wind power.

Already, the coal industry considers itself threatened by federal regulations aimed at reducing pollution and global warming – measures that could force utilities to shutter coal-fired power plants rather than invest in upgrades to meet stricter standards for carbon-dioxide emissions.

A monstrous crusher smashes excavated rock – some pieces half the size of a car – under the white light of 12-volt halogen lights strung along the mine roof. More than 200 steel shields, each able to bear 975 tons, prop up that roof as the walls below it crumble.

High along some of the state’s forested ridges, meanwhile, wind turbines churn, their sleek, 150-foot-long fiberglass blades slicing through air in a mesmerizing rhythm.

And between earth and sky, atop rooftops or planted in rows on farmland, framed panels of silicon angle upward like sunning butterflies.

In the battle for energy supremacy in Pennsylvania, these forces of nature – coal, wind, and solar power – are the key combatants.

What that means for the state’s fledgling alternative-energy industries is not yet clear. But the stakes are high: energy-market share in a new era of electric deregulation and consumer choice and, as former Gov. Edward G. Rendell argued for years, Pennsylvania’s ability to reengineer its economy to one more dominant in clean technology.

Significant strides were made early in Rendell’s eight-year administration, with legislation mandating renewable alternative-energy use. But more recent efforts to build on that failed, largely because of resistance from the coal industry, the reigning source of power in Pennsylvania for more than 100 years.

Last week, the coal lobby gained what it considers a friend in the governor’s mansion: Tom Corbett, a native of Western Pennsylvania, where coal still pays the bills in thousands of households and underwrites community projects, and where a coal queen is crowned every year.