A new interactive online database unveiled Wednesday provides maps, color-coded categories and detailed information about who is putting 10 billion tons of carbon dioxide into the atmosphere annually from power plants around the world — about a fourth of it from the United States. The Web site, which includes information from 4,000 utilities and 50,000 plants, shows not only the biggest CO2 emitters, but also the facilities and companies that are most green, releasing little if any carbon.

Using an array of information filters, a user can find out how much CO2 comes from electricity plants in a particular city or county, in a congressional district, from a specific company, or an individual plant. Dubbed the Carbon Monitoring for Action database, or CARMA ( www.carma.org ), it proclaims itself as “the world’s best place for power-plant voyeurism.”

[T]he United States has the most CO2 emissions (2.79 billion tons), followed by China (2.66 billion tons). China, which soon is expected to pass the United States, is home to three of the world’s five most CO2-polluting utilities. China’s Huaneng Power International leads all of the world’s power companies, releasing nearly 292 million tons of CO2 annually. That’s far more than Southern Co. and American Electric Power, the two biggest U.S. carbon emitters that each account for about 170 million tons a year, ranking sixth and seventh in the world.

With a click of the computer mouse, one can see a map showing the top CO2 producers in the world and then move in closer to find information about the individual utility bringing electricity into your home. Each emitter has a color code from green (the cleanest) to blue, yellow, orange and finally red (most polluting). The icons become larger the more CO2 a plant or company produces. A large red icon shows a plant producing a lot of electricity and a lot of carbon. A green one shows little if any carbon, often a nuclear power plant.

Click on American Electric Power, the Ohio-based utility that owns 25 coal-burning power plants, and one sees a large red icon. It is the country’s second largest emitter of CO2 at 169,000 tons a year. Southern Co., based in Atlanta, releases a little more CO2, but its code is a mix of red and orange because of its use of nuclear energy along with CO2-producing coal. Duke Energy, 12th on the list of worldwide CO2 emitters, nevertheless gets an orange icon, also reflecting its ownership of nuclear power plants.

But of most interest to consumers may be the “digging deeper” option that displays CO2 emissions by plants or companies in a region, state, congressional district, town or by ZIP code. The Ohio Valley, the Southeast and Texas rank high in CO2 emissions, reflecting heavy fossil fuel use, while the West Coast, where nuclear and hydroelectric power are in heavy use, has comparatively little CO2 pollution from power plants.