Repair and recycling of PCBs and their components based on obsolescence index: a domestic electrical appliances case study.

Population expansion and improving living standards, particularly in developed nations, have led to an increase in the usage of domestic electrical equipment, worldwide energy consumption, and CO2 emissions per capita. To limit the usage of non-reusable components and the amount of garbage that must be transferred at the end of a product's life cycle, longer-lasting electrical domestic appliances are a pillar of the circular economy. In recent years, the complexity of printed circuit boards (PCBs) used in the manufacture of modern electrical devices has increased, leading to an increase in device failures. This study focuses on the maintenance and recycling of domestic electrical appliance components and printed circuit boards. The proposed methodology for PCB repair is defined as a sequential quadratic programming (SQP) problem implemented in MATLAB environment and successfully tested to a variety of domestic appliances such as refrigerator, dishwasher and washing machine. The possibility of recycling metal parts of electronic components, which were replaced after PCBs' repair was also studied. Metals' percentage concentration of PCB electronic components for three customer's budgets considering metals and valuable metals recovery as given from the corresponding average metal recovery and calculated from different recycling procedures presented in the literature. The results of the proposed procedure in terms of valuable metals gave 38.4078 ppm of silver. We also compared the suggested procedure with other works in terms of environmental perspective considering four measures, namely the gross energy requirement (GER), the global warming potential (GWP), the acidification potential (AP), and the solid waste burden (SWB). In terms of economic perspective and considering the existence of silver (Ag) in the electronic components, the recommended method gave comparable amount of money. Finally, a comparison of different recycling works from a technical viewpoint is also conducted. Moreover, a reparability index of domestic electrical appliances is introduced to further quantify the results of the proposed algorithm.

To dream or not to dream in Havana: multi-criteria decision-making for material and energy recovery from municipal solid wastes.

Currently, solid waste management strategies in Havana are outdated. This paper aimed to select the most suitable alternative for integrating material recovery facilities (MRF) with waste-to-energy technologies in the city of Havana, Cuba. Seven scenarios were considered: combustion, gasification, and hydrothermal carbonization (HTC) with and without carbon capture, and anaerobic digestion (AD). The selection was based on environmental, techno-economic, and social parameters using an analytic hierarchy process (AHP) as a multi-criteria decision-making tool (MCDM). The MCDM-AHP accounted for qualitative criteria (based on experts' judgments) and quantitative (based on Aspen Plus simulation models). From the MRF, 63% of the input recyclable materials were recovered, representing an energy saving of 256 kW-h/tMSW. The AHP results showed that environmental criteria had the highest priority, resulting in ~63% and ~73% higher than social and techno-economic criteria, respectively. Likewise, from the techno-economic, environmental, and social sub-criteria analysis, investment risk, pollution, and work safety had the major concern compared with the other sub-criteria levels. Overall, MRF+AD was the most suitable scenario (21% preference) for treating Havana's municipal solid waste (MSW), followed by combustion and gasification with carbon capture, respectively. This study confirms that AD is a preference option for emerging economies like Cuba, mainly due to low environmental pollution, high social acceptance, and financial stability in the long term.

A novel methodology for the estimation of failure behavior of "fair" smart meters and analysis of their circular economy chain.

Electric power utilities are striving to address critical challenges such as energy consumption, material recovery, e-waste, procurement, and supplier working conditions. Currently, they are converting their old infrastructure into smart grids. The installation of smart meters is a key step in this process. Since a smart meter is an intelligent and modern measuring device that includes computer-aided measurements while also allowing intelligent management and determination of residential and industrial users' energy consumption and supply, their deployment in smart grids is of major importance. In this study, considering that the estimated number of smart meter units will be 188.12 million units by 2025, five different types of smart meters are used to estimate their failure behavior. We adopted the probability of smart meters' survival, considering the number of the components included in their PCBs, while the influence of their components follows an exponential distribution for a given lifetime. The meaning of the "fair" smart meter is introduced to solve critical concerns such as energy use, material consumption, e-waste, supplier sourcing, and labor conditions. To achieve the above targets, a circular economy chain analysis is implemented by dismantling the existing smart meters, classifying their materials into five primary groups and weighing them to obtain average values. Moreover, we calculate the average cost of the components using their equivalent market value as provided by stock markets to get the average weight of each component in terms of material cost. Finally, we introduce the "remanufacturing index" and the "reusing index" indices as procedure metrics to further quantify the circular economy chain results. The results show that the percentage of the reusing procedure in the "fair" smart meter circular economy chain is greater than the corresponding percentage of the remanufacturing procedure, while the percentage of the recycling procedure is increased as the recycling cost per unit, is also increased.

Design of a Supraharmonic Monitoring System Based on an FPGA Device.

During the last few decades, the poor quality of produced electric power is a key factor that has affected the operation of critical electrical infrastructure such as high-voltage equipment. This type of equipment exhibits multiple different failures, which originate from the poor electric power quality. This phenomenon is basically due to the utilization of high-frequency switching devices that operate over modern electrical generation systems, such as PV inverters. The conduction of significant values of electric currents at high frequencies in the range of 2 to 150 kHz can be destructive for electrical and electronic equipment and should be measured. However, the measuring devices that have the ability of analyzing a signal in the frequency domain present the ability of analyzing up to 2.5 kHz-3 kHz, which are frequencies too low in comparison to the high switching frequencies that inverters, for example, work. Electric currents at 16 kHz were successfully measured on an 8 kWp roof PV generator. This paper presents a fast-developed modern measuring system, using a field programmable gate array, aiming to detect electric currents at high frequencies, with a capability for working up to 150 kHz. The system was tested in the laboratory, and the results are satisfactory.

Evaluating toxic element contamination sources in groundwater bodies of two Mediterranean sites.

The Driver-Pressure-State-Impact-Response (DPSIR) framework is applied for assessing the pressures and impacts on groundwater bodies of two Mediterranean sites (Megara and Oropos-Kalamos basins). The study areas present joint driving forces (drivers) and pressures. The main driving forces in the areas studied mainly include geology, agricultural activities, and urban development, while the main pressures mainly include the weathering of ultramafic rock masses, application of agrochemicals, and groundwater abstractions for irrigation and drinking uses. Hexavalent chromium (Cr+6), chromium total (Crtotal), manganese (Mn), and nitrate (NO3-) contamination of groundwater bodies are attributed to both anthropogenic and lithological sources. Elevated Crtotal (up to 70.3 µg L-1), Mn (up to 87.7 µg L-1), and NO3- (up to 411 mg L-1) contents are recorded for groundwater samples in Megara basin. High Crtotal (up to 34.3 µg L-1), Cr6+ (up to 27.9 µg L-1), Mn (up to 132.5 µg L-1), and NO3- (up to 30 mg L-1) are also observed for groundwater samples in the Oropos-Kalamos basin. The major response actions needed for the management options of groundwater bodies are discussed. Among the proposed remedial measures, the installation of a continuous groundwater monitoring network and the control in the usage of nitrogen fertilizers seems to be the most effective and tangible for immediate action.

A review on the requirements for environmentally friendly insulating oils used in high-voltage equipment under the eco design framework.

The advancements in electricity production and distribution, as well as the growing consumption of electrical energy, have made electrical equipment a vital part of the technological infrastructure. On the other hand, the necessity for environmentally safe and sustainable solutions is another requirement for electrical transformers, the same as for every technology and equipment nowadays. In this aspect, the main challenges in electrical transformers are the reduction in power losses, the use of construction materials with minimum environmental impact, and the elongation of their service life. All three challenges are related to the insulating oils that are used in the transformers which are exclusively mineral based and are products of crude oil. Mineral oils can almost be fully recyclable and can be regenerated with satisfactory results. However, they are not biodegradable, they are flammable, and they may present toxic properties for both humans and the environment. Bio-based lubricants are fully recyclable and can be regenerated, they have none of the hazardous properties of mineral oils, and are fully biodegradable. Furthermore, they are considered a sustainable solution, since they are not fossil-based but products of cultivation and the supplies can be considered indefinite. This paper tries to present an assessment of the environmental impact of vegetable-based insulating oils for electrical transformers, in the wider view of sustainability global efforts, considering additional environmental impact compared with the already used in related works. The assessment is executed for the whole life cycle of two product groups of transformers, as determined by the EU Eco Design Directive 2009/125/EC and the EU Regulation 548/2014 on eco design of requirements on transformers.

Recycling potential for low voltage and high voltage high rupturing capacity fuse links.

Low voltage and high voltage high-rupturing-capacity fuse links are used in LV and HV installations respectively, protecting mainly the LV and HV electricity distribution and transportation networks. The Waste Electrical and Electronic Equipment Directive (2002/96/EC) for "Waste of electrical and electronic equipment" is the main related legislation and as it concerns electrical and electronic equipment, it includes electric fuses. Although, the fuse links consist of recyclable materials, only small scale actions have been implemented for their recycling around Europe. This work presents the possibilities for material recovery from this specialized industrial waste for which there are only limited volume data. Furthermore, in order to present the huge possibilities and environmental benefits, it presents the potential for recycling of HRC fuses used by the Public Power Corporation of Greece, which is the major consumer for the country, but one of the smallest ones in Europe and globally, emphasizing in this way in the issue. According to the obtained results, fuse recycling could contribute to the effort for minimize the impacts on the environment through materials recovery and reduction of the wastes' volume disposed of in landfills.