The long-term impacts of climate change and the major role of the energy sector in causing emissions of greenhouse gases motivate a study of the diffusion of new carbon-free energy technologies. The purpose of the paper is to use the wind power example to illustrate important challenges to renewable energy technology diffusion in a modern society. In doing this we combine a quantitative analysis of innovation and diffusion in the European wind power sectors with an in-depth case study of the experiences of wind power development in Sweden. Overall the paper shows that the strength and the design of the different public support schemes for wind power can only to a limited extent explain important inter-country differentces in national wind power developments. It is shown that in Sweden, a country with a poor wind power diffusion record, the economics of wind power is instead negatively affected by: (a) the lack of policy stability; (b) criticism from local stakeholders; and (c) the legal provisions governing the assessment of the environmental impacts of wind mills and the planning procedures for mill location. While national and global energy policies as well as the general public typically point out wind power as particularly environmentally friendly, most of the objections to its expansion at the local level tend to have environmental origins. In Sweden the interests of those who object to wind mill installations gain strong legal protection, and the municipal territorial planning monopoly implies that it is hard to make national energy policy goals heard at the local implementation stage. This is in sharp contrast to the legal framework facing Danish wind projects. Compared to its competitors, wind power is one of the power technologies that tends to have the most to loose from the risk and uncertainties created by planning regulations that leaves much room for discretion on the part of local authorities.