The current discussion of climate change and energy problems is generally based on the assumption that technical solutions are possible and that the task is essentially to determine the most effective ways. This view relies heavily on the expectation that renewable energy sources can be substituted for fossil fuels. Australia is more favourably situated regarding renewable sources than almost any other country. This discussion attempts to estimate the investment cost that would be involved in deriving Australia's total energy supply from renewable sources. When provision is made for intermittency and plant redundancy it is concluded that the total investment cost is likely to be unaffordable. (C) 2012 Elsevier Ltd. All rights reserved.