The environmental mandate to ``think globally, act locally" gets tricky when it's your ``local.''

Nowhere is the conflict between virtue and practicality more vivid than in Tallahassee, Fla. -- capital of the nation's fourth-largest state -- where city officials are debating whether to build a new coal-fired power plant.

The question comes down to this:

Do officials seeking to diversify energy sources spend $400 million to buy into a new electricity-generating facility even though coal-fired power plants account for 33 percent of carbon dioxide emissions, the leading cause of global warming?

Or do they seek alternative sources of energy that require more imagination and demand a cultural shift?

Although a local issue, Tallahassee's struggle is universal as communities everywhere grapple with rising energy demands and the need to wean Americans from fossil fuels. Other eco-friendly energy sources, though available, aren't always as reliable in the short run.

More to the point, they require thinking in new ways and demand some degree of personal adjustment. It's hard for most of us to wrap our minds around the notion that buying an energy-saving refrigerator -- or swapping one type of light bulb for another -- in a place like Tallahassee is going to keep polar bears from drowning in the Arctic.

Tallahassee's dilemma is also richly ironic. The Democrats who run this town -- a tree-hugging Mecca whose city charter prohibits coal-fired plants -- are having a hard time sticking to the script as practicality clashes with ideology.

Not only is every commissioner a Democrat and professed environmentalist, but Mayor John Marks signed the U.S. Conference of Mayors agreement to reduce carbon emissions to pre-1990 levels. How does one reconcile that commitment with building a new coal-fired plant?

Marks says he wants to diversify to hedge against future high gas prices and insists that the new plant will be less polluting than older models. Practically speaking, his constituents are more interested in cutting their utility bills than in cutting C02 emissions, he told me.

Further complicating the moral issue, the plant is to be built in someone else's backyard -- two counties away in a community where hybrid vehicles are rare and bumper stickers are more likely to read: ``I'll give up my gun when they pry it from my cold dead fingers.''

The proposed plant has many dissenters in the environmental community, but only one on the city commission -- Allan Katz, a local attorney and Democratic National Committee member. Morally, Katz says he can't justify building something in someone else's backyard that he doesn't want in his own.

Moreover, he insists, the plant is unnecessary. He prefers buying power from other, cleaner coal-fired plants, combined with other alternative sources (burning wood and garbage, for instance) as well as what's called ``demand-side management'' -- bureaucratese for helping utilities and citizens make more efficient use of energy.

Swapping those light bulbs, for instance. It sounds silly, but it's not. In the current issue of Fast Company magazine, Charles Fishman (author of ``The Wal-Mart Effect'') writes about a tiny, energy-saving miracle called the compact fluorescent light bulb (CFL).

Improved, but not new, the CFL uses 75 percent to 80 percent less electricity than the classic incandescent bulb and lasts for about five years. Fishman predicts the CFL is about to change the world. Here's how: If all 110 million households in America replaced just one 60-watt bulb with a CFL, the energy saved would power a city of 1.5 million people.

Or save enough to shut down two power plants -- or skip building the next two.

What if Tallahassee handed out one free CFL to its approximately 80,000 households? I called Fishman to find out. He suggested giving 10 CFLs to each household at a cost of about $1 million. (CFLs cost slightly less than $3 each, but would sell for about $1 in such bulk, he figures.)

Given that one 60-watt bulb replaced saves 65.7 kilowatt-hours per year -- and a typical U.S. household uses 10,700 kilowatt-hours a year -- then Tallahassee would save enough power to light 4,881 homes. That's an energy savings of about 5 percent.

While 5 percent is a small savings in the grand scheme, it's a pretty good return on $1 million. Plus, that leaves plenty of saved money -- oh, about $399 million -- to direct toward other alternatives and innovations that don't involve producing more greenhouse gasses or polluting someone else's backyard.

Surely there's virtue -- and common sense -- in that.