Greenhouse gas mitigation strategies are generally considered costly with world leaders often engaging in debate concerning the costs of mitigation and the distribution of these costs between different countries. In this paper, the analyses and results of the design of a 100 per cent renewable energy system by the year 2050 are presented. Two short term transition target years in the process towards this goal are analysed for 2015 and 2030. The analyses reveal that implementing energy savings, renewable energy and more efficient conversion technologies can have positive socioeconomic effects, create employment and potentially lead to large earnings on exports. If externalities such as health effects etc. are included, even more benefits can be expected. 100 per cent renewable energy systems will be technically possible in the future, and may even be economically beneficial compared to the business-as-usual energy system. Hence the current debate between leaders should reflect a combination of these two main challenges.