Carbon Monitoring for Action (CARMA), reveals the emissions of power plants and electric utilities across the world. Its database contains information on the carbon emissions of over 50,000 power plants and 4,000 power companies.

(CARMA is produced and financed by the Confronting Climate Change Initiative at the Center for Global Development, an independent and non-partisan think tank located in Washington, DC.)

You can search for your city, or your energy provider, and get a fairly straightforward impression of the carbon impact of electricity sources. The information is organized cleanly, so that a glance will show an energy source’s relative emissions and energy output, and you can drill down for details if you want.

The site uses worthwhile visual cues to indicate the intensity of emissions at a source; each energy source gets a simple icon that encapsulates emissions data and the amount of energy generation. The “clean-to-dirty” scale gets cued with color (yes, that’s right: it’s green to red), and the energy output changes the icon size.

The web interface also provides a potentially engaging Google Maps mashup showing the “dirtiest” and the “cleanest” plants, although I found that it doesn’t behave as I’d expect. I want to be able to zoom in on regions and reveal details according to my level of zoom. The zoom functionality on the maps aren’t built that way; you need to use the web site to navigate to a region (or energy provider), and the map on that page reveals corresponding information.

All in all, this looks like a stellar project, and I encourage you to play around with it for a little bit. To software people, one especially interesting aspect of the project will naturally be its API, which enables third parties to access the data and use it for unimagined uses, and essentially give users impressions of the information in new ways.