"Emergy" Analysis of the Cassava-Ethanol Production System in China

Researchers from the School of Chemistry and Chemical Engineering, South China University of Technology (China) report the use of "Emergy Analysis", for the assessment of the sustainability of cassava-based fuel ethanol (CFE) production in China. Emergy Analysis is considered to be a "valid approach to quantify both environmental and environmental costs" associated with a product, such as CFE. It could also help in the understanding of sustainability in a special way. "Emergy" (spelled with an "m") is described as a measure of the energy (of one kind) used in the past to make a product or service.

According to Howard Odum (URL to paper in related information below), "emergy" is a measure of energy used in the past and thus is different from a measure of energy now. The unit of emergy (past available energy use) is the emjoule. The unit of "emjoule" is distinguished from the unit of "joule", which is used for available energy remaining. The Chinese researchers mentioned that "emergy analysis considers both energy quality and energy used in the past, and compensates for the inability of money to value non-market inputs in an objective manner". Thus it can be considered as a common unit that allows all resources to be compared on a fair basis. Emergy indices for the CFE production system (in terms of transformity, emergy yield ratio (EYR), environmental loading ratio (ELR), renewable energy ratio (RER), and emergy sustainability index (ESR)) indicate that cassava ethanol has a better sustainability compared to wheat-ethanol or corn-ethanol.

From the perspective of sustainability, the researchers concluded that "CFE is a good alternative to substitute for oil". The full paper is published in the journal, Biomass and Bioenergy (URL above).

Related information of "Emergy Analysis" "Emergy Evaluation", by Howard Odum http://www.oilcrisis.com/emergy/EmergyEvaluation.pdf
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.115.7352&rep=rep1&type=pdf