• Energy Research
• 7. Clean energy close
• 13. Climate action close
• 15. Life on land close
• 6. Clean water close
• EC close

Currently, the pyrolysis process is an important technology for the final treatment of plastic waste worldwide. For this reason, knowing in detail the chemical process and the thermodynamics that accompany cracking reactions is of utmost importance. The present study aims to determine the thermodynamic parameters of the degradation process of conventional thermoplastics (polystyrene (PS), polyethylene terephthalate (PET), high-density polyethylene (HDPE), polypropylene (PP) and polyvinyl chloride (PVC)) from the study of their chemical kinetics by thermogravimetric analysis (TG). Non-isothermal thermogravimetry was performed at three heating rates from room temperature to 550 °C with an inert nitrogen atmosphere with a flow of 20 mL min−1. Once the TG data is obtained, an analysis is carried out with the isoconversional models of Friedman (FR), Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) in order to determine the one that best fits the experimental data, and with this, the calculation of the activation energy and the pre-exponential factor is performed. The validation of the model was carried out using the correlation factor, determining that the KAS model is the one that best adjusts for the post-consumer thermoplastic degradation process at the three heating rates. With the use of the kinetic parameters, the variation of the Gibbs free energy is determined in each of the cases, where it is necessary that for structures containing aromatic groups a lower energy is presented, which implies a relative ease of degradation compared to the linear structures.

This article describes the results of a study of Ecuador’s energy status, using the system dynamics methodology to model supply, demand and CO2 emissions scenarios for the year 2030. Primary energy production increased in the different projected scenarios, with oil as the most important source of energy. The increase observed in final energy consumption was mainly associated with the transport and industry sectors. A reduction in energy intensity was projected for the different scenarios, which could be associated with the projected economic growth. The results obtained were used to build a proposal for energy policies aimed at mitigating emissions. The proposed changes to the national energy matrix could be the factors that will contribute most to the achievement of carbon emission reductions projected by the different scenarios; changes in the energy matrix are mainly associated with the development of projects to replace fossil fuels with renewable energies, mainly hydropower.

The consumption of batteries and cooking oil have been increasing. Most used batteries are disposed of incorrectly, leading to health and environmental problems because of their composition. In a similar form, cooking oil, once used, is often released by the discharge reaching the wastewater, polluting soil, and water, which affects its treatment. In Ecuador, these environmental passives are recollected and stored without further treatment, which is a temporary and unsustainable solution. To address this issue, the circular economy concept has gained increasing attention. In this study, zinc oxide was prepared from discarded batteries using the hydrometallurgical method to use as a catalyst; it achieved 98.49% purity and 56.20% yield and 20.92% of particles presented a particle size of 1–10 nm. Furthermore, the catalyst morphology was investigated in an SEM, which showed that particle size ranged from 155.69 up to 490.15 nm and spherical shapes. Due to its characteristics, the obtained catalyst can be used in the industry instead of the zinc oxide obtained by mining processes. These processes are known to produce heavy contamination in the ecosystems and human health. Additionally, a zinc oxide lifecycle in the environment was analyzed through a material flow analysis (MFA), taking into consideration two paths, one assuming the disposal of used batteries and the other assuming the recycling of zinc. Biodiesel was produced with a heterogeneous catalyst. This took place with a transesterification reaction with used cooking oil, ethanol, and zinc oxide (ZnO) as catalysts. The biodiesel obtained had the following characteristics: 37.55 kJg−1 of heating power, 0.892 gcm−3 of density, 4.189 mm2/s of viscosity, 0.001% of water content, and a 70.91% yield. Furthermore, the energy consumption in biodiesel production was quantified, giving a total of 37.15 kWh. This kind of initiative prevents that waste from becoming environmental pollutants and potential health risks by giving them a second use as a resource. Moreover, turning waste into a valuable product makes the processes self-sustaining and attractive to be implemented.

Abstract The energy efficiency is one of the most important issues nowadays; the problem with the buildings heating is especially relevant for Ukraine. The aim of the paper is to develop a convenient tool building energy performance analysis based on regression model for internal air temperature prediction, depending on a number of internal and external influential factors. The external climatic factors, such as outside air temperature, wind speed and direction, solar heat gains depending on building fenestration surfaces orientation, are considered. Internal factors include heating load, number of floors, air exchange rate etc. In order to achieve the goal, a room dynamic simulation model is created in the EnergyPlus software. A number of simulations are carried out based on the created building energy model . The individual and aggregate selected factors influence on inside air temperature change is considered. The general structure of the multivariate nonlinear regression model for inside air temperature determination is analyzed and selected. Constant coefficients are obtained for each selected influencing factor, and verification of the received nonlinear regression model is performed based on simulation data using January climatic data from the IWEC file. The adequacy of the obtained regression model is estimated by the corrected determination coefficient (R 2 = 0.981) and Fisher's criterion (F = 1324.3), which indicates the high accuracy of the obtained multivariate nonlinear regression. The proposed approach for regression model creation can be used for other architectural and thermal properties of building envelope.

The correlations between perennials and the herbaceous productivity in patches occupied by them were previously studied and several descriptive models were defined. Yet these studies focused on either single or several species without analyzing higher numbers and ranking their effects. Here we describe a handy analytical methodology which allows separating the effects of each perennial species on herbaceous productivity at its respective patches from those of the others in a given area, even in case of complex patches containing several species. The described methodology also allows analysts to correlate the effect of perennials to their patch sizes and the respective herbaceous biomass. Additional mathematical analysis presented here succeeded in differentiating between the perennial species stand-alone presence effect on the herbaceous productivity and that attributed to the canopy size. In addition, the effects of location along the slope and its rockiness outlines were studied. As a case study, we chose representative sloped shrubland with rockiness outlines, located in Yattir farm, Northern Negev, Israel. Based on the described analyses we found that the species with the highest positive effects on the herbaceous productivity were Echinops polyceras, Echium angustifolium, and Salvia lanigera. Contradictory effects were observed in case of Thymelea hirsute, Anchusa ramosus, and Noaea mucronata. Collectively, the presented methodology could be an important management tool for monitoring the herbaceous biomass amounts in a given shrubland.

The incorporation of Energy Storage Systems (ESS) in an electrical power system is studied for the application of Energy Time Shift (ETS) or energy arbitrage, taking advantage of the turbinable energy discharged in hydroelectric plants. For this, three storage systems were selected: Lithium-Ion Batteries (LIB), Vanadium Redox Flow Battery (VRFB), and Hydrogen Storage Systems (H2SS). The spilled turbinable energy available at the Paute Integral hydropower complex in the Republic of Ecuador is taken as the case study. Based on real data from the operation of these plants, a distinctive element of the study, the performance of the selected energy storage systems was analyzed applying the Analytic Hierarchy of Process for decision-making, where technical, economic, and environmental criteria were considered. Electrical energy stored during the early morning seeks to displace the thermal generation during peak hours, close to the demand centers. The results show that all the storage systems analyzed satisfy the required demand, although VRFB is recommended for the ETS. From an economic point of view, LIB represents the best alternative. From a technical point of view, H2SS is slightly superior, while prioritizing environmental aspects, VRFB technology prevails. However, the selection of the best ESS alternative must be continually evaluated, due to permanent technological changes. It is concluded that ESS represent a viable alternative to improve the operational performance of hydroelectric plants, meet the variability of demand, improve the quality of the electrical energy delivered, and displace the pollution-generation plants. Ingeniería y Tecnología Digital

Analyzing plant phenology and plant–animal interaction networks can provide sensitive mechanistic indicators to understand the response of alpine plant communities to climate change. However, monitoring data to analyze these processes is scarce in alpine ecosystems, particularly in the highland tropics. The Andean páramos constitute the coldest biodiversity hotspot on Earth, and their species and ecosystems are among the most exposed and vulnerable to the effects of climate change. Here, we analyze for the first time baseline data for monitoring plant phenological dynamics and plant–pollinator networks along an elevation gradient between 4,200 and 4,600 m asl in three mountain summits of the Venezuelan Andes, which are part of the GLORIA monitoring network. We estimated the presence and density of plants with flowers in all the summits and in permanent plots, every month for 1 year. Additionally, we identified pollinators. We calculated a phenological overlap index between species. We summarized the plant–pollinator interactions as a bipartite matrix and represented a quantitative plant–pollinator network, calculating structural properties (grade, connectance, nestedness, and specialization). We also evaluated whether the overall network structure was influenced by differences in sampling effort, changes in species composition between summits, and phenology of the plant species. Finally, we characterized the pollination syndrome of all species. Flowering showed a marked seasonality, with a peak toward the end of the wet season. The overall phenological overlap index was low (0.32), suggesting little synchrony in flowering among species. Species richness of both plants and pollinators decreased along the elevation gradient. Flies, bumblebees, and hummingbirds were the most frequent pollinators in the network, while entomophily and anemophily were the prevailing pollination syndromes. The interaction network in all summits showed high connectance values, significant specialization (H2), and low nestedness. We did not find a significant effect of sampling effort, summit plant species composition, or plant phenology on network structure. Our results indicate that these high tropical alpine plant communities and their plant-pollination networks could be particularly vulnerable to the loss of species in climate change scenarios, given their low species richness and functional redundancy coupled with a high degree of specialization and endemism.

Abstract Exhaust aftertreatment systems are crucial to ensuring real-world NOx emission limits for motor vehicles. Operating conditions constrain the NOx reduction performance of aftertreatment devices. This study analysed real-world NOx emissions, tailpipe exhaust gas temperatures, and air-fuel ratios during cold start in a closed-loop urban route, followed by hot-start real driving emissions (RDE) tests. Five Euro-6b sport utility vehicles (SUV) were tested: two gasoline vehicles with three-way catalyst (TWC), namely, one gasoline direct injection (G-DI) and one hybrid electric vehicle (HEV); three diesel vehicles with different NOx control systems, namely, only exhaust gas recirculation (EGR), lean-burn NOx trap (LNT), and selective catalytic reduction (SCR). The only-EGR- and LNT-equipped diesel vehicles and the G-DI vehicle surpassed the NOx Euro 6 limits in all tested sections. For the same vehicles, the total RDE emission factors were 9.0, 7.4, and 5.0 times the Euro 6 limits, respectively. In contrast, the diesel vehicle with SCR had an RDE emission factor 1.0 times the limit, and the HEV exhibited very low emissions at approximately 2 mg NOx km−1. However, during the cold start phase (first 5 min), the emission levels of the SCR and HEV vehicles surpassed the Euro 6 limits by 2.7 and 1.1 times, respectively. Based on the measurements at the tailpipe, the results indicate that cold start, urban driving, and cooling conditions of aftertreatment devices can lead to a decrease in the NOx conversion efficiency of TWC and SCR systems. The air-fuel ratio was key for the NOx conversion in TWC aftertreatment. The large differences between G-DI and HEV vehicles were primarily attributed to the lean and rich operations of the G-DI and HEV engines, respectively. To comply with stringent future regulations, lean-burn engines would require diesel-like aftertreatment. SCR and hybrid vehicles would require a careful aftertreatment thermal management or heating to further exploit their potential for reducing emissions in urban areas.