ABSTRACT
There is a clear need for indicators to assess sustainability, to be able to give a quantitative answer to the question: Is the proposed development of, for instance, a landscape sustainable? This chapter presents two indicators that could and should be used to answer this question quantitatively: eco-exergy (the work energy capacity) and a model for the complete carbon cycling in the landscape. To completely answer the question raised, in most cases, it is probably necessary to use supplementary indicators, but to be able to give a complete answer, the calculations of eco-exergy and the erection of a carbon cycling model is compulsory under all circumstances, because of the following:
1. Energy can be divided into exergy or work energy and anergy, which cannot do work. It is therefore crucial not only to set up an energy balance but also an exergy balance, because our focus is of course on the capacity to do work. We use energy in various forms because we want to perform work, for instance, by the use of vehicles for transportation and different machinery for various tasks in the industries. It is therefore important to know how much of the energy can be used to do work and how much is lost as anergy. By calculations of the work capacity (exergy), it will be possible to know how much work energy is available, which is the core question. So, exergy calculations will give
CONTENTS
11.1 Introduction ................................................................................................ 221 11.2 Exergy and Eco-Exergy .............................................................................222 11.3 Modeling the Carbon Cycling ..................................................................229 11.4 Conclusions ................................................................................................. 231 References ............................................................................................................. 232
us the ef‚ciency of our energy use. The exergy balance proposed will be able to indicate which energy applications have a low ef‚ciency, and therefore where it is possible to get more work energy out of the energy. Increased ef‚ciency means, of course, energy can be saved and that the corresponding emission of greenhouse gases is eliminated.
