Diffusion of renewable technologies are in the policy makers’ minds since the 1970s to deal with depleting resources and finding solutions to environmental concerns. Therefore, understanding the mechanisms behind a diffusion process becomes quite important for policy makers to manage the process effectively. A new understanding of innovation diffusion was introduced in the recent years, suggesting a dynamic understanding of the phenomenon. With this aim, this research used system dynamics modelling as a dynamic tool for modelling wind turbine diffusion. To be able to see to what extent system dynamics is able to capture the underlying mechanisms of diffusion processes, a known case of wind turbine diffusion in California and Denmark is chosen as a comparative case study. The results showed that Denmark was more successful with a higher diffusion rate due to various reasons; high oil prices, strong networks enabling knowledge share, and determination of the government. This research also showed that system dynamics is a promising approach for understanding innovation diffusion.