Evaluating Holistic Environmental Consequences of Brownfield Management Options Using Consequential Life Cycle Assessment for Different Perspectives

Brownfields are abandoned, idled, or underused sites whose reuse necessitates some sort of intervention. These sites are largely urban and are frequently contaminated. Brownfield management options can be associated with three types of environmental consequences: those resulting from changes in the site’s environmental quality (primary impacts); those resulting from the actual intervention stage (secondary impacts); and, if the vocation of the site changes, those resulting from effects on regional land use (tertiary impacts). Different stakeholders and decision-making contexts will place a different importance on each of these types of impacts. This article proposes a framework for comparing brownfield management options in regard to these three types of environmental impacts and for interpreting these results from different perspectives. The assessment framework is based on consequential life cycle assessment (LCA), which is shown to provide environmental information on the three types of impacts. The results for a case study are presented, where a “rehabilitation” option allowing residential redevelopment is compared to an “exposure minimization” option not resulting in the site being reused. Calculated primary and tertiary impacts are favorable to the rehabilitation option, whereas secondary impacts are favorable to the exposure minimization option. A ternary diagram presents the favorable option for different stereotypical perspectives. Tertiary impacts are much greater than secondary impacts, and consequently all perspectives that consider tertiary impacts favor rehabilitation. The perspective that considers primary and secondary impacts receives conflicting information. The ternary diagram, showing results for all perspectives, could possibly be useful for consensus-building among stakeholders.     

Life-cycle assessment of two sewage sludge-to-energy systems based on different sewage sludge characteristics: Energy balance and greenhouse gas-emission footprint analysis

Anaerobic digestion and incineration are widely used sewage sludge(SS) treatment and disposal approaches to recovering energy from SS, but it is difficult to select a suitable technical process from the various technologies. In this study, life-cycle assessments were adopted to compare the energy-and greenhouse gas-(GHG) emission footprints of two sludge-to-energy systems. One system uses a combination of AD with incineration(the AI system),whereas the other was simplified by direct incineration...     

Energy implications of mechanical and mechanical–biological treatment compared to direct waste-to-energy

Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical–biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation).The systems achieved net primary energy savings in a range between 34 and 140 MJ_primary/100 MJ_{input waste}, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3–9.5%, 1–18% and 1–8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS-based system achieved the highest savings, on the condition of SRF co-combustion. As a sensitivity scenario, alternative utilisation of SRF in cement kilns was modelled. It supported similar or higher net savings for all pre-treatment systems compared to mass combustion WtE, except when WtE CHP was possible in the first two background energy scenarios. Recovery of plastics for recycling before energy recovery increased net energy savings in most scenario variations, over those of full stream combustion. Sensitivity to assumptions regarding virgin plastic substitution was tested and was found to mostly favour plastic recovery.     

Happiness in the air: How does a dirty sky affect mental health and subjective well-being?

Previous studies evaluating the welfare cost of air pollution have not paid much attention to its potential effect on mental health and subjective well-being (SWB). This paper attempts to fill the gap by investigating the impact of air pollution on several key dimensions, including mental health status, depressive symptoms, moment-to-moment happiness, and evaluative happiness. We match a nationwide longitudinal survey in China with local air quality and rich weather conditions according to the exact time and place of survey. By making use of variations in exposure to air pollution for the same individuals over time, we show that air pollution reduces hedonic happiness and increases the rate of depressive symptoms, while life satisfaction has little to do with the immediate air quality. Our results shed light on air pollution as an important contributor to the Easterlin paradox that economic growth may not bring more happiness.     

Life cycle assessment of energy from waste via anaerobic digestion: A UK case study

Particularly in the UK, there is potential for use of large-scale anaerobic digestion (AD) plants to treat food waste, possibly along with other organic wastes, to produce biogas. This paper presents the results of a life cycle assessment to compare the environmental impacts of AD with energy and organic fertiliser production against two alternative approaches: incineration with energy production by CHP and landfill with electricity production. In particular the paper investigates the dependency of the results on some specific assumptions and key process parameters. The input Life Cycle Inventory data are specific to the Greater London area, UK. Anaerobic digestion emerges as the best treatment option in terms of total CO₂ and total SO₂ saved, when energy and organic fertiliser substitute non-renewable electricity, heat and inorganic fertiliser. For photochemical ozone and nutrient enrichment potentials, AD is the second option while incineration is shown to be the most environmentally friendly solution. The robustness of the model is investigated with a sensitivity analysis. The most critical assumption concerns the quantity and quality of the energy substituted by the biogas production. Two key issues affect the development and deployment of future anaerobic digestion plants: maximising the electricity produced by the CHP unit fuelled by biogas and to defining the future energy scenario in which the plant will be embedded.     

Eco-efficiency assessment of options for metal recovery from incineration residues: A conceptual framework

Residues from municipal solid waste (MSW) incineration in Switzerland have been a hot topic in recent years, both in the research and practice communities. Regarded by many as an economically and environmentally sound solution to this issue, technological retrofitting of existing grate incinerators has the dual purpose of enhancing the metal recovery of bottom and fly ashes and improving the inertization of residues to be landfilled. How does context influence the economic and environmental performance of this particular technological option? Under which conditions would this technological option be implemented nationwide in the future? What are stakeholders’ views on sustainable transitions of MSW incineration? We propose a three-stage methodological procedure to address these questions.