When sustainability is discussed among all the relevant groups and players, it is relatively easy for an agreement to be reached on the principles. However, there is often much resistance when it comes to moving from talk to action. Many political conflicts, from fuel price protests or the BSE (‘mad cow disease’) crisis in Europe to popular resistance against huge dams or pipeline projects in developing countries, are in fact conflicts about sustainable development – with huge vested interests trying to prevent moves towards sustainability while paying lip service to it. A major part of such conflicts about implementing sustainability is in fact related to energy. Energy is not only the fuel for economic development, its unsustainable use is also the main cause for many of the environmental problems associated with traditional economic development: from air pollution and global warming to oil spill disasters and nuclear waste. Within the last 200 years, the large-scale combustion of fossil fuels has already caused the highest atmospheric CO2 level in 160,000 years and the highest global average temperatures since measurements began. Conflicts about unsustainable energy policies gave birth to a major part of the environmental movements, and the question whether we will continue to use energy unsustainably will probably decide the future of the Kyoto Protocol and thus perhaps the entire Rio process.