An exergy-based environmental indicator for manufacturing systems

Suitable environmental indicators are a key for assessing and reducing the impact on the environment arising from manufacturing. While there are a number of environmental indicators, often they tend to be too complicated and there are a large number of them to deal with. Also, there are problems of weighting different aspects of environmental impacts into a single or a small set of indicators as general life cycle analysis does. To avoid these difficulties the concept of exergy is introduced to compute the eco-efficiency defined as the value of a product divided by its environmental impact over the whole life cycle. This concept computes the amount of useful work that is consumed in production for energy and materials and the work required for abatement of environmentally damaging emissions. Thus, exergy-based indicators avoid the problem of having to deal with a number of indicators and weighting. An Eco-efficiency indicator derived from this concept is developed and an application in the Australian aluminium industry is illustrated.