A few blogs ago, I wrote about the life cycle analysis (LCA) of Compact Fluorescence Lamps (CFL’s,). CFL’s do “consume” during their life indeed about 5 times less electricity than incandescent light bulbs (and CFL’s live about 4 times longer). However, the manufacturing of CFL’s is much more complicated and therefore environmentally more demanding than classical bulbs and rightfully the question was raised that when you sum it all up would the environmental advantage still hold? After a careful and detailed LCA, a team of Australian researchers came with the answer: a big yes!
However, it was pointed out by the researchers at the University of Ghent, Belgium, that one needs to look not just at the environmental impact (for factors such as global warming, ozone depletion, toxics emission, acidification, etc.) of a certain product but also need to take into account resources such as organic and inorganic, fuel and feedstock, renewable and non-renewable, energy and materials. It is here where thermodynamics kicks in using the concept of entropy (as already suggested by Nicholas Georgescu-Roegen quite a while ago). Entropy, can be used to describe the degradation of resources during the manufacturing and actually usage of products. One can say, very roughly, that the faster and further away from equilibrium a certain production process is done, the more energy is degraded and made not-available anymore to do further work. This is described by an increase in entropy and is non-reversible, i.o.w. high quality energy (such as energy contained in fossil fuels for that matter) is turned into low quality energy (heat).
This sort of analysis is then used to study the environmental impact of bio-foods versus large scale agriculture produced foods. And sure enough you can find situations where bio-foods (because of their poor yields or their transport over large distances) have more negative impact on the environment than have traditional produced foods. It was found that if bio-beans are locally produced they are environmentally better than conventional produced beans. But when the beans needed to get transported from other areas to make it to our stores the balance can easily change and even reverse the situation! Bio-potatoes are always worse than conventional potatoes because they have such a lower yield per surface area land.
Therefore, before drawing conclusions on the impact of a given process or product on the environment or resources a careful evaluation (LCA) needs to be done. Such an evaluation is not a trivial matter at all and can only be done by qualified people.
© Copyright 2009, John Schmitz
 As a matter of fact a concept of « exergy » is used but it has a very close relationship to entropy