Promise and problems of emergy analysis

Solar Emergy is the available solar energy used up directly and indirectly to make a service or product. Although this basic concept is quite straightforward, its implications are potentially profound. H.T. Odum pioneered the development and use of emergy, and presented it as a way of understanding the behavior of self-organized systems, valuing ecological goods and services, and jointly analyzing ecological and economic systems. Unfortunately, like many groundbreaking ideas, emergy has encountered a lot of resistance and criticism, particularly from economists, physicists, and engineers. Some critics have focused on detailed practical aspects of the approach, while others have taken issue with specific parts of the theory and claims. This paper discusses the main features and criticisms of emergy and provides insight into the relationship between emergy and concepts from engineering thermodynamics, such as exergy and cumulative exergy consumption. This reveals the close link between emergy and ecological cumulative exergy consumption, and indicates that most of the criticisms of emergy are either common to all holistic approaches that account for ecosystems and other macrosystems within their systems boundaries, or a result of misunderstandings derived from a lack of communication between various disciplines, or are not relevant for engineering applications. By identifying the main points of criticisms of emergy, this paper attempts to clarify many of the common misconceptions about emergy, inform the community of emergy practitioners about the aspects that need to be communicated better or improved, and suggest solutions. Further research and interaction with other disciplines is essential to bring one of H.T. Odum's finest contributions into the mainstream to guide humanity on the prosperous way down. (C) 2003 Elsevier B.V. All rights reserved.