查看更多>>摘要：Existing electric power systems have been being faced with great concerns on climate change mitigation through the reduction of greenhouse gas emissions in recent decades. Small modular reactors (SMRs) are considered the next generation of power technologies, offering stable, safe, and environmental-friendly power. This research initially establishes a multi-stochastic SMR siting model (SSMRS) based on a dynamic mixed-integer left-handside chance-constrained multistage programming (DMLCM) method, aiming to provide solid bases for electric power system management to promote GHG mitigation under uncertainties and advance the practical application of SMRs in a regional electric power system. The model is applied to emission-intensive Saskatchewan power systems, which have a high reliance on fossil fuels. The commissioned coal-fired and gas-fired power plants in Saskatchewan are identified as potential sites for employing SMRs. A series of scenarios regarding technical development and carbon policies are analyzed to study the interrelationships among technological competition, policy efficiency, and system-failure risk. This is the first attempt to apply an optimization-based modeling approach for siting SMRs in Saskatchewan with detailed consideration of other new-emerging emission reduction technologies. We found that a carbon tax ranging from 30 to 40$/tonne might be reasonable in Saskatchewan after 2030 while the SMR would be partly commercially viable, occupying similar to >15% of total installed capacity. The solution obtained could provide scientific bases for decision-makers to determine optimal schemes for power supply, capacity expansions, and system costs under environmental targets, and particularly identify construction schemes for SMRs at specific sites in different periods under various risk levels.
查看更多>>摘要：A transition towards long-term sustainability in energy systems based on a low-carbon generation mix could mitigate growing global warming threats to human society. However, the optimal structure of future systems and potential transition paths are still open questions, especially for China's power generation sector dominated by fossil fuels. In this research, robust optimization-based dynamic generation expansion planning is proposed to describe the carbon-neutral transition path for China's power generation sector. The steps required to enable a realistic transition that prevents societal disruption, and the impact of pricing policies (i.e., carbon trading and tax) on neutrality are also discussed. Simulation results show that there exist multiple potential evolution paths for China's power generation system to reach carbon neutral. For the next decades-long journey, this radical transition will require steady but evolutionary changes. The low-share (under 10%) coal scheme is more likely a better option for the carbon-neutral transition of China's power generation sector. Under the low-coal scenario, the emissions peak would be seen by 2025 with around 4543 Mt (20% above the 2015 level) of CO2, and the milestone of neutrality would be reached in 2057. By 2060, wind and solar production could provide 63% of the electricity demand, and the share of non-fossil energy generation would approach 84%. The total cost of the low-coal plan is 14% lower than that under the 100% clean energy supply scenario.
查看更多>>摘要：The installed data storage capacity in the U.S. will reach 2.2 Zettabytes by 2025, generating about 50 million units of end-of-life (EOL) hard-disk drives (HDDs) per year. Due to data security concerns, most EOL HDDs are currently shredded (even when still functioning), representing an economic loss. Moreover, raw material extraction linked to the increased demand for storage causes environmental impacts. Besides mitigating the threat posed by sudden restrictions of raw materials, the circular economy (CE) offers to maximize value retention in the economy and reduce the environmental impacts of human activities. Common CE strategies are reusing and recycling products. However, the reuse of hard disk drives is currently burdened by the lack of trust HDD end-users have toward other non-physical means of data removal than shredding. Here, an agent-based modeling (ABM) approach is proposed to explore how techno-economic and social factors affect end-users' decisions to adopt EOL management practices other than shredding. The proposed method also accounts for data uncertainty by applying a semi-quantitative approach. Results demonstrate how increased green procurement and more robust standards could spur end-users' trust toward data-wiping technologies. Even when accounting for uncertainty, HDDs' reuse brings better environmental and economic benefits than HDD shredding followed by material recovery. The semi-quantitative approach proposed in this study could be more universally applied in future ABM, especially given the often-stochastic nature of such models. The developed ABM is also the first to represent several HDD industry stakeholders and demonstrate how the HDD shredding lock-in situation could be resolved.
查看更多>>摘要：Achieving sustainability is the key to a better future, which requires an accurate assessment of current and historic levels of sustainability at scales that can help targeted interventions. Yet, current assessments of sus-tainability are mostly focused at national and subnational levels that often fail to capture local and regional variations, especially in regions where management interventions are most needed. A grid-cell level analysis that can yield high-resolution maps of sustainability indices could address this challenge. This study aims to present the first high-resolution map of China's sustainability which integrates the social, economic, and environmental dimensions . The grid level sustainability maps reveal over 1.23 billion Chinese have been free from low sus-tainability area. There are large variations in sustainability across China with only 2.3% of the country in high sustainability zone and over 140 million, mostly in the northern and northeastern regions, inhabiting under low sustainability conditions. A lower sustainability index within each province is usually accompanied by higher variations of the index suggesting a lack of coordination and greater inequality between and within provinces. Our high-resolution maps of China's sustainability index provide valuable insights into the spatial distribution of sustainability in the country and could help policymakers identify regions to implement targeted interventions.
查看更多>>摘要：The prescribed buyback schemes as a part of the Extended Producer Responsibility (EPR) of companies are believed to be an effective practice to eliminate the landfill of packaging materials. The coercive measures include the reuse and recycling of plastic packaging material. The lack of awareness, motivation, concern and enforcement of rules are major concerns of the government in implementing the buyback schemes of plastic wastes in developing economies. In the present study, 11 barriers are identified and defined through an extensive literature review. The total interpretive structural modeling method (TISM) and MICMAC analysis are used for examining the interrelationship between the barriers by utilizing experts' opinions. A contextual relationship based structural model is developed by considering the direct relationships and transitivity links. The contextual model helps in identifying the influential barriers. Further, the MICMAC analysis segregates the barriers into four based on their dependence and driving influence. The result of this study indicates that the unclear and unstable policy is the most influential barrier which prevents the adoption of a buyback scheme for used plastic packaging material. The study further reveals that consumer motivation is the least influential and most dependent barrier which could be improved by establishing the infrastructure and minimizing the difficulty in availing the scheme.
Sanye-Mengual, EstherSala, SerenellaAmadei, Andrea Martino
13页
查看更多>>摘要：Despite plastic being one of the most used materials globally, information about plastic flows in value chains is generally lacking. The present study aims at estimating the European Union (EU) plastic footprint (including production and consumption flows) by combining different approaches, as well as at estimating marine littering potentials. Plastic flow estimates build on a literature review of studies on material flows analysis to gather available data. The review highlights the lack of complete and homogeneous estimates of EU plastic production and consumption, as well as detailed figures for specific sectors (e.g., fishing, healthcare, electrical and electronic equipment). Data retrieved from literature were compared with estimates based on consumption statistics (i.e., PRODCOM database). Estimates for 2014 based on literature equals to 84 kg/person, whilst results derived from PRODCOM for the 2014 equals to 129 kg/person (with an average of 112 kg/person for the period 2010-2019). Packaging contributes to 27.9% of the overall footprint in the case of the literature-based approach (23.6% in the case of PRODCOM results), which is dominated by three polymers (LDPE, PP and PET). Concerning the marine litter potential, beach litter rates-based on EU beach litter observations and plastic statistics-were in the order of 10000 part per million of the consumed plastic.. This study unveiled that methodological improvements in estimates of the EU plastic footprint together with plastic littering potential, as well as further data gathering, are fundamental steps for fulfilling the EU ambitions to assess and reduce the environmental impacts of plastics.
van Oorschot, JannekeSprecher, BenjaminRoelofs, Basvan der Horst, Judith...
11页
查看更多>>摘要：Despite many studies of the metal requirements for a transition towards low-carbon electricity system, the potential of the electricity system as a source for secondary material remains underexplored. We addressed this gap, the potential circularity of the electricity system, by analyzing the stocks and flows in that system towards 2050, including electricity generation, storage and transmission technologies, for both bulk metals and critical minor metals. Our model was applied to the Netherlands and was based upon detailed energy scenarios, presenting various governance structures for the Dutch energy transition. We show that the transition towards a low-carbon electricity system results in a strong growth of metal stocks and flows, both for bulk metals and for minor metals, especially for scenarios with higher levels of self-sufficiency in (renewable) electricity generation. These scenarios also show larger discrepancies between in and outflows. However, metal demand could decline substantially if material efficiencies improve, or when technologies with lower material intensities are chosen, especially for critical raw materials. While the potential for urban mining grows over time, at present a significant share of decommissioned components of the electricity system turns into hibernating stocks and remains unused, resulting in a missed opportunity for repurposing of valuable metals. National policies could therefore be aimed at maximizing collection of metals from the urban mine, together with the deployment of recycling capacity and stimulating material efficiency through technological development.
查看更多>>摘要：The recycling of polyhydroxybutyrate (PHB) via depolymerization-polymerization is here proposed and assessed for the first time. Effective depolymerization of PHB to crotonic acid through a thermolytic distillation at mild conditions (170 degrees C and 150 mbar), and without the need of any catalyst, gives a crotonic acid-enriched condensate (94% yield and 98% selectivity towards trans-crotonic acid) that was used without any further purification as a substrate for producing renewed PHB with a culture of Cupriavidus necator. The yield of PHB (0.6 g PHB per g of crotonic acid), final PHB content (63%), and PHB-molecular weight (1.5 MDa) confirmed the technical feasibility of this tandem approach, with a 55% overall yield. A preliminary evaluation of the energy consumption of various depolymerization approaches indicated that the thermolytic distillation consumes 20-25% less energy than previously reported methods; the energy requirement for producing crotonic acid from PHBwaste with 50% moisture has a still acceptable energy demand (4 MJ/kg(crotonic acid)), comparable to the energy required for obtaining fermentable sugars (4.4 MJ/kg(sugar)) to be used for feeding bacteria that accumulate PHB.
查看更多>>摘要：Sustainable building-demolition-waste management has become an important practice. Normally, three different methods of disposing of demolition waste should be considered: landfill, reuse, and recycling. The use of traditional documentation techniques for assessing the environmental impact of different disposal methods during the end-of-life (EOL) stage results in hundreds of detailed instruction sheets that need to be stored. In this study, a life-cycle assessment (LCA) framework is proposed for the evaluation and comparison of the environmental impacts of the three disposal strategies mentioned above in terms of factors such as the extraction of resources, loss of biodiversity, and effect on human health by using the information obtained with typical building information modeling (BIM). In the LCA framework, four environmental-impact-allocation types (namely, no, equal, mass, and economic allocations) are used to calculate the final impacts of the products to be shared by more than one product system. The results reveal that a particular disposal strategy should be investigated by considering an entire building to assess the effective reuse/recycling potential. In addition, a BIM-based plug-in (BIM-EF) is developed for the automatic appraisal of the environmental impact of buildings at the EOL stage by using Revit Add-in Manager. Two data libraries (the engineering quantity data library and environmental impact factor library) are created, and a coding system is established to connect the information stored in the BIM model and the two data libraries. Finally, the results of a case study are presented to illustrate the potential applications of the proposed method.
NSTL
Elsevier