Exergetic pollution potential: Estimating the revocability of chemical pollution

Examination of the fate of carbon in waste management systems through statistical entropy and life cycle analysis

The statistical entropy (SE) function has been developed as a methodology to rapidly benchmark he effectiveness of different waste management systems by determining the level to which specific substances are either concentrated or diluted. Past usage of SE has been confined to metals. In this paper, this method is extended to account for carbon--a key substance of interest Accounting for carbon is complicated by the fact that reactions involving this substance are complex and their products are numerous. Through experiments on carbon-containing emissions from styrene-butadiene rubber (SBR), natural rubber (polyisoprene, IR), and waste tires we demonstrate that a knowledge of carbon-containing species accounting for 90% (by mass) of gaseous emissions is sufficient. Next, we develop an extended SE calculation methodology and apply it to compare carbon flows through two different systems for municipal solid waste (MSW) management (landfills) and waste-to-energy (WTE) facilities. Our results indicate that while landfills perform better on a cursory analysis, they are roughly equal to WTE when carbon flows related to energy generation are accounted for, and underperform by a factor of 3 when considering global warming potential.

Exergy: its potential and limitations in environmental science and technology

New technologies, either renewables-based or not, are confronted with both economic and technical constraints. Their development takes advantage of considering the basic laws of economics and thermodynamics. With respect to the latter, the exergy concept pops up. Although its fundamentals, that is, the Second Law of Thermodynamics, were already established in the 1800s, it is only in the last years that the exergy concept has gained a more widespread interest in process analysis, typically employed to identify inefficiencies. However, exergy analysis today is implemented far beyond technical analysis; it is also employed in environmental, (thermo)economic, and even sustainability analysis of industrial systems. Because natural ecosystems are also subjected to the basic laws of thermodynamics, it is another subject of exergy analysis. After an introduction on the concept itself, this review focuses on the potential and limitations of the exergy conceptin (1) ecosystem analysis, utilized to describe maximum storage and maximum dissipation of energy flows (2); industrial system analysis: from single process analysis to complete process chain analysis (3); (thermo)economic analysis, with extended exergy accounting; and (4) environmental impact assessment throughout the whole life cycle with quantification of the resource intake and emission effects. Apart from technical system analysis, it proves that exergy as a tool in environmental impact analysis may be the most mature field of application, particularly with respect to resource and efficiency accounting, one of the major challenges in the development of sustainable technology. Far less mature is the exergy analysis of natural ecosystems and the coupling with economic analysis, where a lively debate is presently going on about the actual merits of an exergy-based approach.