Acercamiento a la producción más limpia como estrategia de gestión ambiental

In this paper a reflection on Cleaner Production as environmental management strategy and the advantages of it over the traditional approach of treatment at the end of the pro-cess. These advantages are mainly related to preventing pollu-tion rather than treat it to avoid its effect preventive approach. Some results of the implementation of this strategy in Cuba are relate

The temperature gradient of cereals as an optimization parameter of the milling process in hammermills

The wear degree of knives in hammermills strongly influences electricity consumption, productivity, and total operating costs. Currently, the timely replacement of the knives set is decided based on visual inspections, a feedstock load or a lifespan defined, the electric demand of the mill as compared to the limit of the motor driving it, or the vibrations of the hammermill. These approaches present different shortcomings. This study proposes the temperature gradient of the feedstock during the milling process as an indicator to monitor the wear degree of knives. The temperature gradient was implemented in a hammermill milling maize to compare two operating modes. In the conventional operating mode, the knives set mills with one edge during its lifespan, replacing the set once the electricity demand approaches the limit capacity of the electric motor driving the mill, or until the vibrations increase over safety limits. Moreover, in the proposed operating mode the temperature gradient is used to define the timely replacement/rotation of the knives edge. In this case, the four edges of the knives are used. The electricity consumption, productivity, and temperature gradient of the process were measured during the milling of ten maize loads of 2500 tons each. These data were used to characterize the performance of the hammermill, and the influence of the temperature gradient on its operational performance. As a result, a temperature gradient of 6.5 °C was defined as the optimal value to change the rotational direction or replacing the knives set in the hammermill assessed. As compared to the traditional operation approach, the use of the temperature gradient resulted in a reduction of the electricity consumption of 32%, and the greenhouse gas emissions by 37%, while reducing the total costs by 33%, and increasing productivity by 20%. Therefore, this approach stands as a significant opportunity to upgrade the operation of hammermills

Productive, Distributive, Dynamic, and Allocative Efficiency Improvement Model in Colombian Public Universities: Modelo de mejoramiento de la eficiencia Productiva, distributiva, de asignación y dinámica en las universidades públicas de Colombia

The measurement of efficiency in public universities has been a topic of interest for researchers and state officials in Colombia; this article presents a model that transcends the view of productive efficiency, and expands it by including aspects of equity with distributive efficiency, of acceptance by society in the allocative efficiency, and finally with the dynamic efficiency includes the time variable, with which the state can measure the stability of the indicators of interest. For the design of the model, multivariate statistical techniques and non-parametric techniques were used, such as Structural Equation Models, Principal Component Analysis, Data Envelopment Analysis, and the Balanced Scorecard. Different ranks are obtained with which university improvement plans were identified, emphasizing public institutions with high quality accreditation. A Balanced Scorecard is proposed with the indicators extracted from the sector databases that met the conditions of the techniques used. This technique suggests a causal relationship between the indicators of distributive, productive, and allocative efficiencies, where the perspective of inclusion forms the basis of the scorecard, affecting the perspective of education and research and the latter influencing the perspective of impact. Finally, it is concluded that the public university sector has great challenges in terms of inclusion and measurement of the satisfaction of society, as well as showing improvement trends in the measured aspects as reflected in the DEA Malmquist index. As a result, a model is obtained for university administrators to identify the aspects in which they must invest the public budget that guarantees the greater multidimensional efficiency of Colombian public universities

Productive, Distributive, Dynamic, and Allocative Efficiency Improvement Model in Colombian Public Universities: Modelo de mejoramiento de la eficiencia Productiva, distributiva, de asignación y dinámica en las universidades públicas de Colombia

The measurement of efficiency in public universities has been a topic of interest for researchers and state officials in Colombia; this article presents a model that transcends the view of productive efficiency, and expands it by including aspects of equity with distributive efficiency, of acceptance by society in the allocative efficiency, and finally with the dynamic efficiency includes the time variable, with which the state can measure the stability of the indicators of interest. For the design of the model, multivariate statistical techniques and non-parametric techniques were used, such as Structural Equation Models, Principal Component Analysis, Data Envelopment Analysis, and the Balanced Scorecard. Different ranks are obtained with which university improvement plans were identified, emphasizing public institutions with high quality accreditation. A Balanced Scorecard is proposed with the indicators extracted from the sector databases that met the conditions of the techniques used. This technique suggests a causal relationship between the indicators of distributive, productive, and allocative efficiencies, where the perspective of inclusion forms the basis of the scorecard, affecting the perspective of education and research and the latter influencing the perspective of impact. Finally, it is concluded that the public university sector has great challenges in terms of inclusion and measurement of the satisfaction of society, as well as showing improvement trends in the measured aspects as reflected in the DEA Malmquist index. As a result, a model is obtained for university administrators to identify the aspects in which they must invest the public budget that guarantees the greater multidimensional efficiency of Colombian public universities

Energy management of compressed air systems. Assessing the production and use of compressed air in industry

The use of compressed air in industry is an important and yet overlooked energy carrier. Although there are different energy-saving measures discussed in the specialized literature, there is little discussion on the energy performance of the production and use of compressed air. This study developed a new approach to assess the energy performance of compressed air systems based on a six-step local energy benchmarking methodology. The methodology includes an energy management procedure to monitor and control the electricity consumption and sustain the energy performance of compressed air systems in time. The procedure monitors the production and use of compressed at plant and at manufacturing section levels based on the real-time monitoring of relevant variables to calculate energy performance indicators, energy baselines, and CUSUM charts. Monitoring the consumption of compressed air at the section level in a case study reduced the demand between 11 and 47%. While electricity consumption to produce compressed air at the plant level reduced by an estimated 23%. This approach permits the rapid detection of inefficiencies in the production and demand sides of the compressed air system, highlighting inefficiencies that are frequently hidden in the total electricity consumption of manufacturing plant

Assessment of the energy efficiency estimation methods on induction motors considering real-time monitoring

Different methods have been developed to estimate the energy efficiency of induction motors. The accuracy of these methods vary with the load factor, the unbalanced voltage (UV) and harmonics. The feasibility of these methods for efficiency estimation in real-time were theoretically and experimentally assessed during the operation under different operational conditions (i.e. balanced sinusoidal voltage (BSV), harmonics, UV and harmonics with UV). Results show that for load factors over 80%, the air-gap method is applicable under any condition, while the slip method is only applicable under BSV or balanced harmonic voltage. Moreover, for load factors over 40%, the nameplate method is applicable under BSV. Other methods result in errors over 8% and optimization methods are not applicable for real-time monitoring. Electric systems generally operates with some degree of UV and harmonics, while induction motors mostly operate with load factors below 60%, limiting the use of these methods for real-time measurement

Wind and power density data of strategic offshore locations in the Colombian Caribbean coast

The high potential of wind speed in the Colombian Caribbean coast is an opportunity to develop offshore wind energy technology. This article contains the wind speed and wind power density in four strategic locations in Colombia (Cartagena, Barranquilla, Santa Marta and La Guajira) at different elevations. The dataset from this study is related to the research paper “Renewables energies in Colombia and the opportunity for the offshore wind technology published in Journal of Cleaner Production (Rueda-Bayona et al.) [1]. Reading and processing numerous files stored in databases could be challenging because it demands software programming to do so, what could difficult the access to valuable data for the community. Also, high compressed files such as NetCDF formats demand specialised software which is not easy obtaining and utilising because it requires skills in a programming language. Then, this study used the NARR-NOAA database [2] and generated local wind and power density data stored in Excel sheets to ease their utilisation

Eco-efficiency in urban freight transportation: A bibliometric and systematic literature review

Urban freight transport is currently of vital importance for the cities economic growth, but at the same time, it is one of the most representative sources of pollutant emissions. Although numerous models and approaches have been proposed that aim to improve the eco-efficiency of urban distribution, few have classified the available information by combining bibliometric and systematic analysis. The objective of this paper is to present a comprehensive science mapping analysis using a bibliometric analysis from 2004 to 2021 and a systematic review of the literature of the most relevant papers based on the identification of the attributes of the main investigations. In the systematic review, a search protocol was used to classify and index using a computer tool for the selection of keywords in the title and the abstract. The results showed that the first five most academica-lly productive countries are attributed 50% of the world’s academic production, in the same way, the five most cited countries concentrate 52% of the citations. The systematic review allowed us to identify: the lack of studies with validation with real field data, the trend of use of historical and real-time traffic records, and the prevalence of research towards optimizing operational logistics costs

The energy potential of agriculture, agroindustrial, livestock, and slaughterhouse biomass wastes through direct combustion and anaerobic digestion. The case of Colombia

In Colombia, agriculture and livestock production, and the processing agroindustry (including slaughterhouses) are a significant source of biomass wastes, which often generate significant environmental impacts. Waste-toenergy technologies, particularly direct combustion and anaerobic digestion systems are an alternative to revalorize these wastes as energy sources while reducing their environmental impacts. To this end, is necessary to identify the biomass-based energy potential from the available biomass wastes. It is additionally necessary to highlight potential applications of the biomass-based energy potential, to replace unsustainable energy sources like fossil fuels or cooking wood in the end-use energy mix. To this end, an inventory of the main crops and livestock produced in Colombia, and the share processed in agroindustry was developed to identify the available biomass wastes for energy applications. Based on the inventory, the biomass-based energy potential was calculated for the use of direct combustion and anaerobic digestion systems. The results show a bioenergy potential of 60,000 to 120,000 GWh per year, with higher potentialities for direct combustion systems than for anaerobic digestion. In particular, the biogas potential account for 90% of the use of natural gas and LPG. Moreover, using around half of the solid biomass available in direct combustion systems can potentially replace the use of solid fuels (i.e. wood and coal). In total, the combined use of direct combustion and anaerobic digestion can support from 50 to 97% of the use of gaseous and solid fuels. Using combined heat and power systems for heat and electricity production can increase the biomass share in the end-use energy mix up to 15 to 28%, including 27 to 53% of the 68,943 GWh of electricity produced in 2018