This paper puts forward a concept of 'potential carbon' and gives a definition analogous to potential energy. Potential carbon explains: (1) what is the driving force of the difference of carbon emissions, and (2) what is the position in the force field. On the basis, an approach about potential carbon analysis is developed to investigate a physical mechanism of carbon-related balance between energy supply and demand. Especially, a derived evaluation parameter of critical carbon level (CCL), which depends on availability of local energy sources and energy use profile, can reflect a geographical feature of a zone or zones in carbon-related balance. The proposed methodology is applied in a case of Haidian North region, Beijing. The result shows that potential carbon analysis is able to assist in making decisions on energy source planning to meet energy demand within carbon emission constraints. (C) 2016 Elsevier Ltd. All rights reserved.