I have been using this book to teach students in energy science, for general aspects of energies and different approaches to an integrated view of energy. So, Exergy and Emergy comes as major players and for this second topic I did try this book, which is quite perfect, except that I realize that you need more material than the one is actually in the book. The model is clearly exposed, however to understand real life applications you need to go for extra help from on line web sites, focused on emergy, including excellent notes from the US EPA agency and other tutorials.
As a whole the book is amazing and gives you the idea of a refreshing approach to the integration of economy and science (particularly the ecology and energy driven ones). The book allows you to understand Odum's Ideas on how to use a different and clear tool to integrate problems like complete ecosystems or even countrywide problems into a common metric, which comes form the natural concept of looking at the total energy that comes into the planet biosphere, which is denoted as biogeosphere, as the reference. the emjoule and empower concepts are derived, so energy and the result of the changes associated with (the transformities) can be used to analyze large (or small) systems.
The book is quite enjoyable, easy to read and you get the sensation that it is necessary to read more about.
For anyone that wants to go into this analysis is better to start from the beginning (as usual), so go for the book of the same author "A prosperous way down", but you can read both at the same time if you like.
So, why not 5 stars?, just because I felt that a book like this one should capture you 100% giving you full capability of going into the subject without the need for extra stuff, so, it could be a 5 but as I did mention, I had to go for more, even I should say that perhaps you need, as a companion, from the same author too the book: "Environment, Power and Society for the Twenty-First Century: The Hierarchy of Energy", so that is why still I believe that 4 stars are ok.

