There is a great temptation to think that there is an ideal blueprint for a secure and sustainable energy future, the role of each technology mapped out. But there are two problems. First, there is no agreement on an ideal blueprint. Exxon Mobil's long-term energy vision is very different from that of Greenpeace.
Second, there is much that we simply do not know. Can we build nuclear plants to time and cost? Will the costs of renewable energy fall fast enough so they can be weaned off subsidies?
Are members of the public up for changing their patterns of energy use? Will novel technologies work? Some uncertainties will be resolved through time and experience. Others we may have to live with for a long time.