Quantifying the environmental support for dilution and abatement of process emissions - The case of electricity production

Strategies to deal with thermal and chemical emissions from electricity production processes are compared. Accounting for the environmental services required to dilute emissions is suggested as an unavoidable step towards correct evaluation of sustainability of processes. Calculations are performed in several case studies by means of the emergy accounting methodology. An emergy-based yield indicator decreases by 40-70% coupled to a parallel increase of a loading indicator, when the environmental services required for the dilution of pollutants are correctly accounted for. As a consequence of including environmental services, a lower sustainability is calculated for each investigated process when compared to evaluations that do not include them. Accounting for environmental services also provides a way to evaluate the carrying capacity of the environment in relation to human dominated processes. The requirement for environmental services to effectively recycle by-products at different space-time scales translates into the need for a suitable support area for the process under study. Two support areas are suggested, one using local constraints, and a second using global constraints. The former is suggested as a near term, regional carrying capacity, while the latter is a long term, global carrying capacity. (C) 2002 Elsevier Science Ltd. All rights reserved.