Examinando por Autor "Istrate, Ioan-Robert"

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Environmental life cycle assessment of the incorporation of recycled high-density polyethylene to polyethylene pipe grade resins
(Elsevier, 2021) Istrate, Ioan-Robert; Rafael Juan; Martin-Gamboa, Mario; Domínguez, Carlos; García-Muñoz, Rafael A.; Dufour, Javier
Plastic recycling involves a range of potential environmental benefits, from curbing landfill and incineration rates to the reduction of greenhouse gas emissions. However, the main challenge is to find applications where recycled plastic can successfully provide the same functionality as the replaced virgin plastic. Particularly, the incorporation of recycled high-density polyethylene (HDPE) to polyethylene (PE) pipe grade resins is a great challenge that is not currently being implemented in the manufacture of pressure pipes. In this study, life cycle assessment (LCA) is applied to quantitatively evaluate the potential environmental impacts from producing PE pipe grade resins from recycled HDPE blended with virgin HDPE. The LCA involves four HDPE waste feedstocks (crates/caps, packaging/detergency bottles, post-consumer industrial containers, and automobile fuel tanks) and two PE pipe grades (PE80 and PE100). Moreover, different allocation approaches that affect the LCA of plastic recycling, namely the cut-off approach and the Circular Footprint Formula, were investigated. The recycled content was found to largely determine the LCA results. In this regard, the production of PE80 quality from the pure HDPE waste feedstocks (such as automobile fuel tanks and post-consumer industrial containers) allows a higher recycled content, thus resulting in lower impacts. Compared with a 100 % virgin resin, these two sce- narios show 80 % and 53 % less carbon footprint if the waste feedstock is considered burdens free (cut-off allocation). These percentages however decrease to 32 % and 20 % if the impacts and benefits are shared ac- cording to the Circular Footprint Formula. These trends were similarly observed for most of the impact categories evaluated, such as, acidification and fossil resources. The robustness of these results is supported by error propagation via Monte Carlo simulation.
Waste-to-Energy in a Circular Economy: Assessing the Energy Recovery Potential and Economic and Environmental Optimal Pathways
(Universidad Rey Juan Carlos, 2022) Istrate, Ioan-Robert
The circular economy continues to gain traction in the political agenda for a competitive and climateneutral economy. In this context, the prevention, re-use, and recycling of municipal solid waste (MSW) are at the top of the waste policy. Meanwhile, energy recovery from MSW, or waste-to-energy (WTE), seems to have received rather scarce attention despite the dual benefit of avoiding landfilling and providing a domestic energy source. However, an increased circularity of materials will have broad implications on the WTE sector that remain poorly understood. The goal of this thesis is to assess the energy recovery potential of MSW and the economic and environmental optimal WTE pathways within the context of an increasingly circular economy. To achieve this goal, new tailored tools capable of tackling the complexity of MSW and anticipating system-wide consequences have been developed. First, a material flow analysis (MFA) model is applied to quantify the energy recovery potential of MSW under future scenarios of increased separate collection and recycling. Secondly, the MFA approach is combined with life cycle assessment (LCA) to quantitatively evaluate the potential environmental consequences of phasing-out MSW incineration. Finally, building on the previous tools and mathematical programming, a multi-period optimization framework is developed to determine time-dependent waste treatment capacities and flows according to economic and climate objectives and subject to waste availability and composition, system constraints and restrictions, and policy targets. Focusing on the case study of Madrid, it has been found that a higher separate collection and recycling of MSW do not compromise the energy recovery potential. This relatively low impact can be attributed to inefficiencies in separate collection and the limited efficiency of materials recovery at automatized sorting facilities. Overall, the future availability and characteristics of feedstocks are found adequate to sustain the operation of large-scale incineration and anaerobic digestion (AD) WTE facilities. Within this context, phasing-out the existing incineration facility in Madrid could reduce some of the environmental impacts, including climate change impacts, human toxicity, and ecotoxicity, at the expense of jeopardizing the realization of the 10% landfill target by 2035. In fact, the optimization results reveal that a more intensive use of incineration will be necessary to achieve this landfill target. Based on the work presented in this thesis, envisioning a future with a relevant role for WTE appears highly likely even within the context of an increasingly circular economy.