This is where you can find explanations of the terms used throughout CARMA.

% Fossil: The percentage of total electricity that is generated by the combustion of coal, oil, or natural gas.

% Hydro: The percentage of total electricity that is generated by hydroelectric power facilities.

% Nuclear: The percentage of total electricity that is generated by nuclear power facilities.

% Other Renewable: The percentage of total electricity that is generated by the use of wind, solar, biomass, geothermal, captured heat, or hydrogen energy.

Future: Data presented for the “Future” reflects planned plant construction, expansion, and retirement. We cannot reveal the precise timing of these changes, but most of those incorporated into CARMA will occur within the next decade.

Geographic regions: Regions refer to a host of geographic entities in CARMA. Emissions are aggregated at the level of countries and states or provinces as well as (in the U.S.) metro areas, counties, and Congressional districts. We also include emission totals for about 190,000 cities worldwide, calculated as the aggregate emissions of all power plants within a 15 mile (24km) radius of the city center.

Icons: Symbols used throughout CARMA to represent the type, size, and carbon intensity of plants, companies, and regions. For more information, learn All About Icons.

Intensity: Pounds of CO2 emitted per megawatt-hour of electricity produced.

MWh Energy: Annual megawatt-hours of electricity produced.

Operating Company: A company that directly owns or operates a plant.

Parent Company: A company that indirectly owns a plant through its subsidiary (operating) companies.

“Planned” Plants: Some of the plants in CARMA are not yet operational but are expected to be in the future. They are designating by the word “Planned” next to the facility’s name. In these cases, we estimate future emissions given information on the expected size, fuel source, and technology of the plant.

Power plant: A power plant is a site for electricity generation. This could be a massive facility with multiple boilers or solar panels on the local high school.

Power company: CARMA defines power companies as public or private utilities that own power plants. We also include information for thousands of non-utility companies that own power generation facilities — everything from automakers and paper manufacturers to hospitals and restaurants.

Tons CO2: Annual carbon dioxide (CO2) emissions. The units are “short” or “U.S.” tons. Multiply by 0.907 to get metric tons.

Total Power Plants: The total number of power plants currently in operation, under construction, or planned for the future.