Long-term scenarios for global energy supply

One motivation for this work is the Second Assessment Report of the UN Intergovernmental Climate Panel (suggesting the need for detailed energy scenarios for the 21st century, without significant carbon dioxide emissions). The lead author has been engaged in the IPPC work and a number of other precursor studies, investigating such energy scenarios on various levels and for various geographical regions (Danish Technology Council 1994, IEA Climate Programme 1995, and a EC APAS project 1996). The current project aims at investigating the detailed supply-demand matching in systems with fluctuating energy sources, as well as barriers to implementing energy systems substantially different from the current one (technological, economic and social factors). The demand analysis assumes that, except for certain buildings, all energy using equipment has been replaced at least once between now and the scenario year. This enables us to make assumptions on higher technological efficiency and on market choices based upon 'fair prices', i.e. prices including all social and environmental costs but excluding taxes that are not externality-related. Demand will be assessed glabally, by taking into account regional differences in development and climatic conditions. On the supply side, four basic scenarios are considered: 1) Clean fossil fuels, i.e. either gasified fuels such as hydrogen or fuels burned with carbon dioxide sequestration (and subsequent storage). 2) Safe nuclear energy, i.e.technologies free from potential diversion of weapon grade material, inherently safe against accidents with major radioactivity releases, and not entailing long-term custody of radioactive material. 3) Decentralised use of renewable energy, e.g. using solar panels integrated into rooftops or building facades, dispersed with turbines, and technologies based on integrated food and bioenergy production, as well as dedicated energy crops in suitable locations. 4) Centralized use of renewable energy, such as solar cell and wind farms placed on marginal land or off-shore, and requiring intercontinal energy transmission. In combining supply and demand structures, novel conversion technologies believed to become avaliable within the time horizon considered will be incorporated, e.g. reversible fuel cells of various sizes (down to units applicable to individual buildings or vehicles for the transportation sector). The base scenarios may become the basis for informed energy planning debate, also if the political implementations are likely to involve combinations of the 'pure' scenarios