It's not that utilities are forsaking their least efficient power generators out of the goodness of their hearts. They are doing so because tougher regulations are occurring and will make retrofitting their coal-fired facilities prohibitively expensive. At the same time, natural gas - with half the carbon emissions of a coal plant -- has remained relatively cheap with no true signs that it will spike.

Consider Exelon Corp. It is closing three of its coal facilities in Pennsylvania in 2012 and is planning on replacing them with natural gas units. Ditto for Progress Energy, which said it would rather build new gas plants at a cost of $1.5 billion than to modify its older coal fleet at a price of $2 billion.

Typically, coal is at least half the cost of the natural gas. But now the price of coal is rising faster than other fuels, largely because of demand from China that has an inexhaustible need for cheap electricity to grow its economy. Meanwhile, newfound shale gas supplies have given the natural gas industry a second wind - one that many analysts are touting as the nation's bridge fuel until green energy takes root.

In fact, the U.S. Energy Information Administration says that coal-fired power will remain the dominate source of electricity in this country. But its share of the market will fall from around 50 percent today to about 45 percent in a decade or so. Natural gas, it continues, will be the primary benefactor, enabling it to grow its current 20 percent share.

Credit Suisse and Deutsche Bank, meanwhile, have issued separate reports drawing similar conclusions. The former says that tougher regulations on coal will reduce the demand for that product by as much as 30 percent while increasing that of gas by as much as 16 percent over a decade. Among the regulations: tougher rules for nitrogen oxide, sulfur dioxide and mercury. On the horizon: those involving disposal of coal ash and greenhouse gas emissions.

Altogether, the combined cost of all those new rules will total $70 billion over the next decade, according to the New York Times. The same story notes that about 10 utilities will permanently close around 36 older coal-fired plants by 2019.

As for Progress, it says that it is pursuing a three-pronged approach to reducing emissions and preparing itself for a new future: energy efficiency programs, renewable projects and state-of-the-art power systems that mean ditching coal and building gas plants. "We are involved in the full spectrum of activities from generating the power to delivering it to our customers - as well as providing solutions to help customers manage their energy use wisely," says Bill Johnson, chief executive of Progress.

Promising Options

To be sure, coal will remain of paramount importance to the nation's economy. And the thinking in some corners is that coal will not sit idle while other fuels vie for coal's share of the pie. The industry, in fact, is working feverishly with the utility sector to develop new technologies that they say will breathe new life into the sector while others are also cautioning that natural gas prices cannot be expected to stay so low.

Carbon capture could become commercial within 10-15 years, according to the Government Accountability Office. Meanwhile, more sophisticated forms of coal generation are looming. So-called ultra-supercritical and supercritical generation that substantially increases the efficiency is considered by many to be coal's saving grace - technologies that will also notably cut emissions levels.

That's what Duke Energy has chosen to do by building its 875-megawatt Cliffside plant in North Carolina. In this case, the company was forced to shut down some older and less efficient coal plants that generate 1,000 megawatts so that it could focus on this modern-era plant. Even though the total coal generation is less, the modern coal facility will burn less coal - increase efficiency -- and thereby be able to create more electricity.

Meanwhile, the Prairie State Energy Campus, which is a 1,600 coal-fired facility in Illinois, is expected to go on line by year-end 2012. Company officials say it will emit half the emissions of a typical coal plant.

"Instead of lamenting that coal will be in our energy mix for decades, I would suggest that we embrace that possibility, push forward on the new technologies and reap the benefits of the jobs and economic development that come with it," says Tom Wolf, executive director of the Illinois Chamber of Commerce Energy Council, in a release.

Companies, generally, are betting that restrictions on coal use will only increase. The most ominous of those is one that would limit carbon emissions, placing a price on each ton released. That would force companies to invest in best available coal technologies. But it may also cause them to seek less controversial fuel technologies. And the most notable of those is natural gas.

Indeed, Credit Suisse and Deutsche Bank say that if natural gas prices stay around $4-$6 a Btu, then utilities would be hard pressed to avoid this alternative. Prices have remained low for two years now, with the future price of natural gas projected to rise only nominally. That's all because of the gold rush to find shale gas and the modern drilling techniques that allow developers to access those deposits.

While many utilities had initially been skeptical of the changing landscape, most are now amendable to adjustments. All they are asking is for federal lawmakers to provide them with regulatory certainty. Those demands will require expensive new investments as well as extensive public outreach to convey the implications.