Twenty years after the landmark United Nations Conference on Sustainable Development (UNCSD), which was held in Rio de Janeiro in 1992, the evidence of climate change, resource-intensive growth and persistent poverty in much of the developing word clearly demonstrate that the prevailing development paradigm is no longer sustainable. Although widely acknowledged in previous debates on sustainable development, energy is now widely recognized as one of the most critical enabling conditions for achieving sustainable development, low carbon growth and the Millennium Development Goals.