Waste LCA and the future.

Life cycle assessment (LCA) models quantifying the environmental aspects of waste management have become an integral part of waste management decision-making over the last two decades and have provided ample knowledge on both environmental benefits and drawbacks in the way we handle waste. Waste management and LCA modelling of waste management systems will soon be challenged by profound changes necessary in our societies and sectors to meet sustainable development goals. Foreseen changes in energy, material, and nutrient provision will directly and indirectly affect waste management in terms of its operation and goals. This study reflects on anticipated changes in society and industrial sectors and how these changes may affect waste management and LCA modelling of waste management systems in terms of waste input, the modelling of technologies and systems and exchanges of energy, materials, and nutrients, as well as how it may affect impact assessment and the interpretation of results. The study provides practical recommendations for LCA modelling of future waste management systems, which will hopefully lead to robust assessments that can support decision-making in an evolving society subject to great changes.

Life cycle assessment of air-pollution-control residues from waste incineration in Europe: Importance of composition, technology and long-term leaching.

Air pollution control residues (APCr) are hazardous materials generated from municipal solid waste incineration and require appropriate management. This life cycle assessment (LCA) study investigates the environmental impacts of current and alternative management options, considering the possibility of a cascading management of APCr, where one treatment technology is followed by another. In total, 14 base case scenarios and 30 sensitivity scenarios were evaluated. The effects of APCr composition, leaching, time horizon, and uncertainties were investigated. The APCr management options with the lowest environmental impacts and the smallest uncertainties were i) backfilling of underground salt mines and ii) neutralization treatment followed by backfilling (Langøya, Norway). These options were followed by iii) scenarios that included Zn extraction, iv) cement stabilization of fresh APCr followed by landfilling and v) production of cement aggregates made from carbonated APCr followed by their utilization in construction works. Recovery of salts from APCr required further performance optimizations before being environmentally competitive with other options. Long-term leaching emissions of Zn, Cr and As were among the largest contributors to toxicity-related impacts, emphasizing the need for management strategies that minimize their leaching. The investigated scenarios demonstrate that increased "processing" and cascading utilization of the residues, contribute with increased uncertainty of the results compared to landfilling and may not necessarily lead to decreased environmental impacts. LCA studies of APCr management should address the full management chain, rather than just the first treatment. Overall, the results of this study were found robust, also considering potential changes in the surrounding energy system.

Environmental assessment of amending the Amager Bakke incineration plant in Copenhagen with carbon capture and storage.

Amending municipal solid waste incineration with carbon capture and storage (CCS) is a new approach that can reduce the climate change impacts of waste incineration. This study provides a detailed analysis of the consequences of amending the new Amager Bakke incinerator in Copenhagen (capacity: 600,000 tonnes waste per year) with CCS as a post-combustion technology. Emphasis is on the changes in the energy flows and outputs as well as the environmental performance of the plant; the latter is assessed by life cycle assessment. Amending Amager Bakke with CCS of the chosen configuration reduces the electricity output by 50% due to steam use by the capture unit, but introducing post-capture flue gas condensation increases the heat output utilized in the Copenhagen district heating system by 20%. Thus, the overall net energy efficiency is not affected. The CCS amendment reduces the fossil CO2 emissions to 40 kg CO2 per tonne of incinerated waste and stores 530 kg biogenic CO2 per tonne of incinerated waste. Potential developments in the composition of the residual waste incinerated or in the energy systems that Amager Bakke interacts with, do not question the benefits of the CCS amendment. In terms of climate change impacts, considering different waste composition and energy system scenarios, introducing CCS reduces in average the impact of Amager Bakke by 850 kg CO2-equivalents per tonne of incinerated waste. CCS increases the environmental impacts in other categories, but not in the same order of magnitude as the savings introduced within climate change.

Application of LCA modelling in integrated waste management.

Life cycle assessment (LCA) has been used in waste management for the last two decades and hundreds of journal papers have been published. The use of LCA in waste management has provided a much-improved holistic view of waste management including waste flows and potential environmental impacts. Although much knowledge has been obtained from LCA studies, there is still a need to use LCA models in integrated waste management. This paper describes six areas where LCA is expected to play a role in waste management in the future: 1) understanding an existing waste management system; 2) improving existing waste management systems; 3) comparing alternative technologies/ technology performance; 4) technology development/prospective technologies; 5) policy development/strategic development; and 6) reporting. Illustrative examples are provided for each application area.