This viewpoint discusses the intra- and international distribution of energy consumption and their implications for intergenerational equity. For global development to be sustainable, the inequality of energy consumption must have ail upper limit. A graphic depiction of energy consumption distributions (intra- and international) shows that today's inequalities are large and it is argued that we may have already reached or perhaps even Surpassed the sustainability limit of energy consumption inequality. (c) 2004 Elsevier Ltd. All rights reserved.