Looking back over the past 30 years we have learned that energy and GDP growth do not necessarily proceed in lock step; that fears of physical shortages of oil were greatly exaggerated; that deregulation and privatization of the power sector has proved to be more difficult than envisaged; that market obstacles to renewable and energy efficiency remain strong; that technology can make a big difference but it is difficult to forecast which technologies will succeed: that the developing countries are a force to be reckoned with in world energy markets; that it is extremely difficult to bring energy services to the poor; and that unforeseen developments happen and they happen frequently. (c) 2005 Elsevier Ltd. All rights reserved.