'This book is a path-breaking work. It is unique in the economic growth literature for its incorporation of diffusion theory into an economic growth model. In constructing the model, the author has drawn on both neo-classical and evolutionary growth theory. He uses the model to address the energy-efficiency paradox - why are efficient energy technologies often adopted so slowly? A significant, and counterintuitive, finding is that subsidies designed to speed-up the adoption of energy saving technologies in the short run may have an adverse effect in the longer run, due to the premature adoption of inferior technologies. Therefore, an important policy implication is that increased subsidies for energy saving technologies can be counterproductive.'