Environmentalists who decry the negative environmental effects of coal face a quandary: How else to meet the energy needs of a population that could reach 9 billion by midcentury, by which time scientists say we must also have cut carbon emissions in half? Nuclear energy faces opposition in the developed world and is often too expensive for countries with less built-in resistance. Wind and solar are growing fast, but currently provide only a small fraction of total supply.

The countries where population is expanding the fastest have been taking advantage of domestic coal reserves to add plants at a rapid clip. China, for example, has built as much new coal capacity in each of the past three years as Britain's total consumption. India has plans to add eight "ultra-mega" plants that will increase its current coal capacity by 50 percent.

The United States is not the only country that doesn't want to depend on imported oil, which is cleaner than coal -- Ukraine switched to domestic coal after Russia cut off gas supplies in a price dispute two years ago.

In Europe, an emissions trading scheme that penalizes carbon emissions has not stopped Germany from planning 16 new plants. And although both U.S. presidential candidates have indicated support for former Vice President Al Gore's call for the nation to run completely on renewable sources within 10 years, U.S. utilities are building 28 new coal-fired plants, with 66 in the early planning stages.

Carbon capture and sequestration, often thought of as a way to reap coal's energy while avoiding its emissions, has not been tested on a commercial scale and would add $1 billion to the cost of every new plant -- not including up to 25 percent efficiency losses and extra water for steam to compensate for lost power.