We study the transition between non-renewable and renewable energy sources with adjustment costs over the production capacity of renewable energy. Assuming constant variable marginal costs for both energy sources, convex adjustment costs and a more expensive renewable energy, we show the following. With sufficiently abundant non-renewable energy endowments, the dynamic equilibrium path is composed of a first time phase of only non-renewable energy use followed by a transition phase substituting progressively renewable energy to non-renewable energy before a last time phase of only renewable energy use. The investment into renewable energy may either begin before actual production of renewable energy or be delayed until the energy price achieves a sufficient gap with respect to the renewable energy cost. With an initially abundant non-renewable resource, the features of the transition between non-renewable and renewable energy do not depend upon the initial resource stock.