More States Ask Utilities to Factor In Ecology Costs : Energy: The price estimate of a plant should include environmental degradation, the governments say.

Power plants have long been recognized as a source of air pollution, but a growing number of states are attempting to put a price tag on environmental damage such as smog and acid rain.

Over the past few years, regulators in states such as Massachusetts, New York, California and Wisconsin have started forcing utilities to consider potential environmental costs when planning future resources.

While some utilities have balked, arguing that the cost estimates are far too high, experts say this system could tip the scales in favor of conservation and cleaner energy sources.

“What we’re saying is when you build a plant, you need to take in these other factors, what the real cost to society is,” said Barbara Kates-Garnick, a Massachusetts public utilities commissioner.

About a dozen states have adopted such plans or are considering them, experts say. Also, the Bonneville Power Authority in the Pacific Northwest incorporates environmental costs in its planning.

The typical method for tabulating the costs is to assign dollar values to certain pollutants. Here’s how it can work:

On the surface, one of the cheapest fuels is coal, but it also tends to emit bigger amounts of pollutants such as carbon dioxide and sulfur dioxide when burned to generate electricity.

A coal-fired plant that costs $60 million might have environmental costs totaling another $60 million, said Susan Tierney, the Massachusetts secretary of environmental affairs.

A natural gas-fired plant, which leaves less pollution, could cost $80 million and have environmental costs around $20 million.

Meanwhile, there would also be the option of using conservation methods such as extra-efficient light bulbs to curb energy demand rather than increase supplies. Such a program might cost $85 million and be most expensive in actual dollars, but theoretically would be cheapest overall since it would create no pollution, Tierney said.

These methods are already having an impact. In California, for example, utilities now plan to acquire more power from cleaner sources, such as geothermal energy, said Tom Thompson, a spokesman for the state Public Utilities Commission.

“Consumers do pay the cost of pollution. They pay a very high cost in terms of illnesses, damage to agriculture and damage to forests,” said Richard Ottinger, a professor specializing in energy law at Pace University in New York. “Avoiding those costs are a real value to consumers.”