Energy

Organic Rankine Cycle (ORC) systems are capable of utilising low-enthalpy geothermal sources. The aim of the Above Ground Geothermal and Allied Technologies (AGGAT) research programme is the development of ORC systems within New Zealand. An experimental scale ORC system, known as ORC-B, was built at the University of Canterbury to assist with the research and development of the system design and component selection process. The unit is a 1 kW ORC consisting of four key components: evaporator, expander, condenser and pump. Selection of the working fluid was found to be a constraining factor in the design. A refrigerant mix known as HFC-M1 was selected due to its desirable performance, high safety and ease of availability in New Zealand. The heat source for the system is the exhaust of a Capstone gas turbine. Heat is transferred to the unit’s plate-type evaporator by a thermal oil extraction loop. Cooling is supplied to the plate-type condenser from the available water supply. A scrol...

This paper examines the functioning of energy efficiency standards and labeling policies for air conditioners in Japan. The results of our empirical analysis suggest that consumers respond more to label information, which benchmarks the energy efficiency performance of each product to a pre-specified target, than to direct performance measures. This finding provides justification for the setting, and regular updating, of target standards as well as their use in calculating relative performance measures. We also find, through graphical analysis, that air conditioner manufacturers face a tradeoff between energy efficiency and product compactness when they develop their products. This tradeoff, combined with the semi-regular upward revision of minimum energy efficiency standards, has led to the growth in indoor unit size of air conditioners in recent years. In the face of this phenomenon, regulatory rules were revised so that manufacturers could adhere to less stringent standards if th...

This paper aims to identify the magnitude of energy efficiency improvement, which has been promoted through energy efficiency labeling and the Minimum Energy Performance Standard, and to compare this against the increase in the number of products and the average increase in cooling capacity. Air conditioners (ACs) are one of the major contributors to energy consumption in a household. To assess the magnitude of this factor, we developed a formula to decompose total energy consumption from ACs into the number of ACs, their average cooling capacity, and energy efficiency. In the case of ACs in Thailand, energy efficiency improvement has offset the increase in the average AC cooling capacity. However, energy consumption from ACs increases with the number of ACs.

Статья* посвящена изучению феномена «бремени иностранца» (liability of foreignness — LOF) в процессе интернационализации российских компаний. Авторы оценивают степень воздействия эффекта страны происхождения как важнейшего проявления LOF на процесс интернационализации российских компаний и исследуют механизмы влияния этого эффекта на российские компании. Выявляются источники конкурентных преимуществ, способных помочь российским компаниям преодолеть эффект LOF. На примере крупнейшей российской энергетической компании «Интер РАО ЕЭС» в статье определяются факторы, препятствующие развитию и реализации компанией конкурентных преимуществ для зарубежных рынков, дается оценка потенциально привлекательных рынков с целью выбора наиболее подходящей стратегии для уменьшения негативных эффектов, связанных с «бременем иностранца», а также предлагаются рекомендации, связанные с выбором целевых рынков, основанные на минимизации эффекта страны происхождения для компании.

WSN consist of hundreds of thousands of small and cost effective sensor nodes. Sensor nodes are used to sense the environmental or physiological parameters like temperature, pressure, etc. For the connectivity of the sensor nodes, they use wireless transceiver to send and receive the inter-node signals. Sensor nodes, because connect their selves wirelessly, use routing process to route the packet to make them reach from source to destination. These sensor nodes run on batteries and they carry a limited battery life. Clustering is the process of creating virtual sub-groups of the sensor nodes, which helps the sensor nodes to lower routing computations and to lower the size routing data. There is a wide space available for the research on energy efficient clustering algorithms for the WSNs. LEACH, PEGASIS and HEED are the popular energy efficient clustering protocols for WSNs. In this research, we are working on the development of a hybrid model using LEACH based energy efficient and K-means based quick clustering algorithms to produce a new cluster scheme for WSNs with dynamic selection of the number of the clusters automatically. In the proposed method, finding an optimum "k" value is performed by Elbow method and clustering is done by k-means algorithm, hence routing protocol LEACH which is a traditional energy efficient protocol takes the work ahead of sending data from the cluster heads to the base station. The results of simulation show that at the end of some certain part of running the proposed algorithm, at some point the marginal gain will drop dramatically and gives an angle in the graph. The correct "k" i.e. number of clusters is chosen at this point, hence the "elbow criterion".

Europe's capacity to explore the envisaged pathways that achieve its near-and long-term energy and climate objectives needs to be significantly enhanced. In this perspective, we discuss how this capacity is supported by energy and climate-economy models, and how international modelling teams are organised within structured communication channels and consortia as well as coordinate multi-model analyses to provide robust scientific evidence. Noting the lack of such a dedicated channel for the highly active yet currently fragmented European modelling landscape, we highlight the importance of transparency of modelling capabilities and processes, harmonisation of modelling parameters, disclosure of input and output datasets, interlinkages among models of different geographic granularity, and employment of models that transcend the highly harmonised core of tools used in model intercomparisons. Finally, drawing from the COVID-19 pandemic, we discuss the need to expand the modelling comfort zone, by exploring extreme scenarios, disruptive innovations, and questions that transcend the energy and climate goals across the sustainability spectrum. A comprehensive and comprehensible multi-model framework offers a real example of "collective" science diplomacy, as an instrument to further support the ambitious goals of the EU Green Deal, in compliance with the EU claim to responsible research.

Efforts towards ensuring clean and affordable electricity for all have been progressing slowly in rural, off grid areas of developing countries. In this context, hybrid microgrids may offer reliable and potentially clean electricity for isolated locations. Nevertheless, the process of planning and operation of these systems faces several challenges, often due to the uncertainties related to the renewable resources and to the stochastic nature of electricity consumption in rural contexts. This paper tackles this problem and contributes to the literature in bridging the gap between field practices and two-stage stochastic modeling approaches by identifying an open-source modeling framework which is then applied to real local data. As reference case-study, we consider a microgrid built in 2015 in Bolivia. Overall, the optimal system results from a compromise between the Net Present Cost, the peak capacity installed and the flexibility (to balance variable generation). Different approaches to size isolated microgrids are tested, with the conclusion that methods accounting for the uncertainty in both demand and renewable generation may lead to a more robust configuration with little impacts on the final cost for the community.

Energy access projects in remote off-grid areas would benefit from the adoption of a multi-energy system perspective, addressing all energy needs -not only lighting and power appliances, but also waterheating and cooking -by means of a mix of energy vectors. However, multi-energy analyses in remote areas are hindered by a lack of models allowing for the generation of multi-energy load profiles based on interview-based information characterised by high uncertainty. This study proposes a novel opensource bottom-up stochastic model specifically conceived for the generation of multi-energy loads for systems located in remote areas. The model is tested and validated against data obtained from a real system, showing a very good approximation of measured profiles, with percentage errors consistently below 2% for all the selected indicators, and an improved accuracy compared to existing approaches. In particular, some innovative features -such as the possibility to define and modulate throughout the day appliances' duty cycles -seem to be determinant in marking a difference with previous approaches. This might arguably be even more beneficial for case studies characterised by a larger penetration of appliances that are subject to complex and unpredictable duty cycle behaviour.

This research analyzes proposed determinants of electricity consumption in Jordan during the period 1986-2015. For the upcoming years, Jordan's electricity consumption projections expected to exceed electricity generation capacities. Therefore, to understand electricity consumption key determinants, six independent variables were used: Gross Domestic Product (GDP), electricity prices, population, urbanization, structure of economy, and aggregate water consumption. A multivariate model was constructed using annual data to examine the influence of the independent variables on electricity demand. Johansen Cointegration test is used to examine the long-term relationships in the model, and Vector Error Correction Model (VECM) is utilized then. VECM regression results show that GDP, urbanization, structure of economy and aggregate water consumption are significant and positively related to electricity consumption, while electricity prices are significant and negatively related to electricity consumption. Population showed significant positive effect on electricity consumption in the short run. The result of VECM implies that there is a need to invest more in green energy projects, ban importing low efficiency electrical appliances and review refugee reception policy in place.

The combined economic/environmental dispatch treats the economic and environmental impact as competing objectives. This requires effective optimization algorithms to achieve a solution. The firefly algorithm and bat algorithm are the latest methods; they have already proven their effectiveness in several research areas. In this paper, we will use these two methods to optimize the production cost and the emission of NO x for three tests networks: three units systems, six units system and the last fourteen units systems, with variable transmission losses and different loads. Then the hybridization of these two Metaheuristics is developed and tested.

The combined economic/environmental dispatch treats the economic and environmental impact as competing objectives. This requires effective optimization algorithms to achieve a solution. The firefly algorithm and bat algorithm are the latest methods; they have already proven their effectiveness in several research areas. In this paper, we will use these two methods to optimize the production cost and the emission of NO x for three tests networks: three units systems, six units system and the last fourteen units systems, with variable transmission losses and different loads. Then the hybridization of these two Metaheuristics is developed and tested.

< We provided a 3D numerical model of a TEG module used in a waste heat recovery system. < The effects of temperature difference and waste gas heat transfer coefficients were investigated. < The power density for a TEG module is the objective function to be maximized. < The numerical data are in good agreement (within 8%) with the experimental data. < The optimum TEG module spacing and spreader thickness are strongly dependent on the waste gas heat transfer coefficient.

This paper investigates the three-dimensional turbulent flow in a chimney used for venting flue gas from either a boiler or stove. The thermoelectric generator (TEG) modules are embedded in the chimney walls. To understand the power output performance of the TEG module, three-dimensional numerical simulations combining convection and radiation effects, including the chimney tunnel, TEG modules, plate-fin heat sinks and cold plates, based on water cooling are developed and solved simultaneously. The effects of operational parameters such as the flue gas velocity (V in ¼ 3, 5 and 10 m/s) and flue gas temperatures (T gas ¼ 500, 600 and 700 K) on the flow and heat transfer are determined. The influences of the plate-fin height (H fin ) and number of fins (N), ranging from 0 mm < H fin < 100 mm and 4 < N < 8 respectively, on the power output and pressure drop are also described in detail. It is worthy of note that the net electric power (P net ) of the TEG module was obtained using the ideal electric power (P TEG ) minus the extra pumping power (P fan ). The numerical results for the power vs. current (PeI) curve are in good agreement with the experimental data within an error of 9%.

The relationship between renewable energy sources and economic growth has attracted the interest of researchers in recent years. However, the analysis has focused mostly on measuring the impact of renewable energy consumption on economic performance (such as economic growth) that does not reflect the quality of standards of living. We employ a different approach measuring the impact of renewable energy consumption on the Human Development Index (HDI) that considers these qualitative characteristics associated with better health and educational standards along with income performance. Additionally, we develop a simultaneous equation system approach that describes the interrelations between economic variables, renewable energy and pollution emissions with feedback effect tendencies. We provide robust evidence using panel data for a set of 28 OECD countries over the period 2004-2015. The system of equations is estimated by 3sls considering a static and dynamic specification of the model. It is shown that renewable energy consumption along with human and physical capital are important factors for explaining the sustainable development level of the countries considered. Renewable energy consumption is mostly determined by higher levels of human capital, the R&D spending and the stage of countries' development. Factors like the stage of development, total energy consumption, renewable energy consumption and standard levels of education are important elements for explaining environmental pollution (measured by CO2 emissions per capita). It is also established a non-linear relationship between the countries` stage of development and carbon emissions.

In Ground Source Heat Pump Systems (GSHPS), distance between boreholes is a very important parameter for reliability, long life time and performance of the whole system. In large scale applications of GSHPS, more than one borehole is needed and determination of the optimal distance between boreholes becomes an important issue. In this study, the effect of distance between boreholes on heat transfer rate per unit borehole length (unit HTR value) is computationally investigated. Four different configurations consisting of 2, 3, 5 and 9 boreholes are considered. 3 and 6 months averaged unit HTR value of the most critical borehole in each configuration is compared with that of single borehole to determine the performance loss. Variations of performance loss due to thermal interactions of boreholes with both time and distance are analyzed. Furthermore, the effects of thermal conductivity of ground on temperature distributions around borehole is also examined. Results can be used to deter...

The European Union (EU) and Azerbaijan have cultivated a dynamic energy partnership that reflects the evolving demands of global energy security, sustainability, and geopolitical realities. This article explores how Azerbaijan has transitioned from being a key hydrocarbon supplier through initiatives like the Southern Gas Corridor (SGC) to becoming a vital player in Europe’s renewable energy landscape. Transformative projects such as the Black Sea Undersea Cable and the Caspian Green Energy Corridor highlight Azerbaijan’s emerging role as a leader in renewable energy integration, aligning with EU objectives under the Green Deal and REPowerEU Plan. Key challenges, including infrastructure vulnerabilities, regulatory alignment, and geopolitical risks, are critically examined alongside opportunities for economic diversification and innovation. Azerbaijan’s investments in renewable technologies, green hydrogen production, and regional energy cooperation underscore its commitment to fostering a sustainable energy future. The study concludes that the EU-Azerbaijan partnership serves as a model for balancing immediate energy security needs with long-term decarbonization goals, offering a pathway for resilience and innovation in a rapidly changing energy landscape.

In Jan. 2003 we monitored explosions at Santiaguito Volcano (Guatemala) with thermal, infrasonic, and seismic sensors. Thermal data from 2 infrared thermometers allowed computation of plume rise speeds, which ranged from 8 to 20 m/s. Rise rates correlated with cumulative thermal radiance, indicating that faster rising plumes correspond to explosions with greater thermal flux. The relationship between rise speeds and elastic energy is less clear. Seismic radiation may not scale well with thermal output and/or rise speed because some of the thermal component may be associated with passive degassing, which does not induce significant seismicity. But non‐impulsive gas release is still able to produce a high thermal flux, which is the primary control on buoyant rise speed.

Informal settlements are pervasive in urban areas of developing countries. They dominate a greater percent of the cities and are characterized by poor infrastructure supply, degraded environment and poverty. Most revitalization efforts ignored informality and so fail. Yet the essence of informality speaks of the indomitable will and perseverance of the urban poor to partake in formality in the face of lack of infrastructure, services and amenities. Within this essence of informality is contained some design elements that have been used as catalyst to trigger change in place-making in some parts of the world. These elements, though untested in developing countries, have been found to work as facilitators of change in developed countries. Place-making is a concept where social and political processes are used to create value and meaning in a particular setting. This paper therefore explores the existing principles of informality found in African settlements, and compares them to urban...

This paper reports on the development of a two-dimensional, fully nonlinear Computational Fluid Dynamics (CFD) model to analyse the efficiency of fixed Oscillating Water Column (OWC) Wave Energy Conversion (WEC) devices with linear power take off systems. The model was validated against previous experimental, analytical and numerical results of others. In particular, the simulation results show excellent agreement with the analytical results obtained by Sarmento and Falcão for linear waves in a 2D channel and with previous experiments by others on the interaction between nonlinear waves and a fixed barge. Results are presented for linear waves on the influence of the seaward wall draft and thickness of the OWC device on the resonant frequency and the capture efficiency of the OWC. The key outcome of the present work is that for fully nonlinear waves a substantial decrease in the hydrodynamic capture efficiency of the OWC device was observed with increasing wave height, which represents a significant departure from the linear wave case. The optimal pneumatic damping coefficient for the OWC was also found to be dependent on the wave height. By analysing the magnitude of the first and higher order components of the incident nonlinear waves and the response of the OWC it was found that the first order capture efficiency decreases with increasing wave height, which in turn implies that the OWC hydrodynamic system is fully nonlinear and that the behaviour of an OWC in a nonlinear wave train cannot be accurately represented by the superposition of the linear response to a number of component linear waves. These results have significant implications for the design and operation of practical OWC systems.

Farms of wave energy convertors are more likely to be deployed than widely separated individual devices so as to harness maximum available power and to facilitate installation and electrical power transmission. In this paper, the theory of the interaction between oscillating systems, developed by , is for the first time applied and extended to an explicit study of the dynamic and energetic performance of a finite array of fixed OWC devices. The interactions between devices and air compressibility are taken into account. Following the method, a FEM model is applied to the study of a single OWC device and three different array configurations. It is demonstrated that the inner properties and the interaction between OWC devices are strongly dependent on the position of the devices in the array and should be taken into account when determining the optimum device parameters so as to increase the maximum power extraction of the system or the overall frequency power-capture bandwidth.

Prior research on wave energy devices such as Oscillating Water Column (OWC) systems has revealed the complex nature of the interactions between ocean waves and these systems. This is especially true when such devices are arranged in arrays. Within these arrays, the multiple scattered waves produced by each device interact and can lead to unexpected fluctuations of the power captured by each individual OWC. In the present study, a finite element model based on linear wave theory has been developed to study scattered waves around single and multiple oscillating water column wave energy conversion devices. The power capture efficiency of a single cylindrical OWC deduced from the finite element model is compared with the numerical approximation used by . The efficiency of the single OWC is then compared with that of an array of OWCs of the same dimensions, as a function of array spacing, pneumatic damping and direction of the incident waves. It is found that the presence of neighboring OWCs has a significant influence on the power capture efficiency of individual devices, even for large separations, and that the optimal pneumatic damping for OWCs in an array may differ from that of an isolated OWC of the same dimensions.

The study of floating oscillating water column (OWC) wave energy conversion (WEC) device performance includes analysis of the dynamic coupling of the water column and the floating structure. In the present investigation, a mechanical oscillator model was proposed in order to examine this relationship for the heave motion of a floating wave energy conversion device. Characterisation of the dynamic system optimal behaviour was performed by examining the effect of relative OWC and floating structure natural frequencies, the phase relationships of the various system components and the optimal power take-off damping of the system. It was determined that separation of the natural frequencies results in significant increases in maximum power capture. When the OWC and structure natural frequencies are coincident the motions are essentially in phase and limited power capture is achieved. For optimal power capture the separation of the natural frequencies should be such that the floating structure has the lower natural frequency. This should also generally result in improved alignment of the system resonant response with the available wave power. The model also provides evidence of the capacity of power take-off damping control to improve the nonresonant performance ofthe OWC WEC device in a spectrally distributed wave environment.

The development of tidal energy in Australia is still a challenge with few studies performed on the characterisation of the resource, due to the difficulty to acquire data and uncertainties about the influence of this anthropogenic activity on the marine environment. Changes in flow could lead to alterations in sediment transport and have further influence on the marine habitat. A case study in a promising area, Banks Strait (Australia), was created using high resolution 2D and 3D models validated against in situ data to investigate changes to hydrodynamic conditions with two scenarios of tidal farms (100 and 300 turbines). Comparison between 2D and 3D is performed to find the best compromise between model accuracy and computational time for preliminary assessment. Changes to current speed and bed shear stress over a 35 day period were found to be localised around the tidal farms and did not extent more than 7 km from the farm (300 turbines) for both 2D and 3D. The results showed th...

The study of floating oscillating water column (OWC) wave energy conversion (WEC) device performance includes analysis of the dynamic coupling of the water column and the floating structure. In the present investigation, a mechanical oscillator model was proposed in order to examine this relationship for the heave motion of a floating wave energy conversion device. Characterisation of the dynamic system optimal behaviour was performed by examining the effect of relative OWC and floating structure natural frequencies, the phase relationships of the various system components and the optimal power take-off damping of the system. It was determined that separation of the natural frequencies results in significant increases in maximum power capture. When the OWC and structure natural frequencies are coincident the motions are essentially in phase and limited power capture is achieved. For optimal power capture the separation of the natural frequencies should be such that the floating structure has the lower natural frequency. This should also generally result in improved alignment of the system resonant response with the available wave power. The model also provides evidence of the capacity of power take-off damping control to improve the nonresonant performance ofthe OWC WEC device in a spectrally distributed wave environment.

Farms of wave energy convertors are more likely to be deployed than widely separated individual devices so as to harness maximum available power and to facilitate installation and electrical power transmission. In this paper, the theory of the interaction between oscillating systems, developed by , is for the first time applied and extended to an explicit study of the dynamic and energetic performance of a finite array of fixed OWC devices. The interactions between devices and air compressibility are taken into account. Following the method, a FEM model is applied to the study of a single OWC device and three different array configurations. It is demonstrated that the inner properties and the interaction between OWC devices are strongly dependent on the position of the devices in the array and should be taken into account when determining the optimum device parameters so as to increase the maximum power extraction of the system or the overall frequency power-capture bandwidth.

This paper reports on the development of a two-dimensional, fully nonlinear Computational Fluid Dynamics (CFD) model to analyse the efficiency of fixed Oscillating Water Column (OWC) Wave Energy Conversion (WEC) devices with linear power take off systems. The model was validated against previous experimental, analytical and numerical results of others. In particular, the simulation results show excellent agreement with the analytical results obtained by Sarmento and Falcão for linear waves in a 2D channel and with previous experiments by others on the interaction between nonlinear waves and a fixed barge. Results are presented for linear waves on the influence of the seaward wall draft and thickness of the OWC device on the resonant frequency and the capture efficiency of the OWC. The key outcome of the present work is that for fully nonlinear waves a substantial decrease in the hydrodynamic capture efficiency of the OWC device was observed with increasing wave height, which represents a significant departure from the linear wave case. The optimal pneumatic damping coefficient for the OWC was also found to be dependent on the wave height. By analysing the magnitude of the first and higher order components of the incident nonlinear waves and the response of the OWC it was found that the first order capture efficiency decreases with increasing wave height, which in turn implies that the OWC hydrodynamic system is fully nonlinear and that the behaviour of an OWC in a nonlinear wave train cannot be accurately represented by the superposition of the linear response to a number of component linear waves. These results have significant implications for the design and operation of practical OWC systems.

Prior research on wave energy devices such as Oscillating Water Column (OWC) systems has revealed the complex nature of the interactions between ocean waves and these systems. This is especially true when such devices are arranged in arrays. Within these arrays, the multiple scattered waves produced by each device interact and can lead to unexpected fluctuations of the power captured by each individual OWC. In the present study, a finite element model based on linear wave theory has been developed to study scattered waves around single and multiple oscillating water column wave energy conversion devices. The power capture efficiency of a single cylindrical OWC deduced from the finite element model is compared with the numerical approximation used by . The efficiency of the single OWC is then compared with that of an array of OWCs of the same dimensions, as a function of array spacing, pneumatic damping and direction of the incident waves. It is found that the presence of neighboring OWCs has a significant influence on the power capture efficiency of individual devices, even for large separations, and that the optimal pneumatic damping for OWCs in an array may differ from that of an isolated OWC of the same dimensions.

Temporal variability in renewable energy presents a major challenge for electrical grid systems. Tides are considered predictable due to their regular periodicity; however, the persistence and quality of tidal-stream generated electricity is unknown. This paper is the first study that attempts to address this knowledge gap through direct measurements of rotor-shaft power and shore-side voltage from a 1MW, rated at grid-connection, tidal turbine (Orkney Islands, UK). Tidal asymmetry in turbulence parameters, flow speed and power variability were observed. Variability in the power at 0.5Hz, associated with the 10-minute running mean, was low (standard deviation 10-12% of rated power), with lower variability associated with higher flow speed and reduced turbulence intensity. Variability of shore-side measured voltage was well within acceptable levels (~0.3% at 0.5Hz). Variability in turbine power had <1% difference in energy yield calculation, even with a skewed power variability distribution. Finally, using a "t-location" distribution of observed fine-scale power variability, in combination with an idealised power curve, a synthetic power variability model reliably downscaled 30 minute tidal velocity simulations to power at 0.5Hz (R 2 = 85% and ~14% error). Therefore, the predictability and quality of tidal-stream energy may be undervalued in a future, high-penetration renewable energy, electricity grid.

The problem of water scarcity is nowadays one of the themes under discussion around the world. Currently arise increasingly prevention measures, as well as have been developed and improved systems of production, treatment and storage of water. Based on this serious problem lived by a considerable part of the world&#39;s population, the present work proposes the use of a simple dehumidification system to obtain water from a renewable source of water, the Earth&#39;s atmosphere. Results will be presented concerning the capacity and costs of this type of equipment to produce water. Although the extracted water, from the atmospheric air by condensation of water vapour, in vapour compression refrigeration systems, require treatment and to be mineralized, this equipment can be used in any house as a source of drinking water. The work includes conducting experimental studies, in a climatic test chamber, using a commercial equipment with a dehumidifying capacity of 20 l/day, for values of 3...

Direct methanol alkaline fuel cell (DMAFC) using a cation exchange membrane (CEM) was operated in passive condition and compared to passive direct methanol fuel cell (DMFC). A polymer electrolyte membrane for passive DMAFC was prepared by immersing Nafion117 membrane into KOH solution at temperature of 80 C. The prepared membrane (potassium-doped Nafion117) exhibited higher mechanical properties and thermal stability than Nafion117. Ionic conductivity of K þ form Nafion117 membrane was measured to be lower than that for pristine Nafion117. Single cell in alkaline condition (passive DMAFC) exhibited better cell performance than that in the cell using Nafion117 in acidic condition (passive DMFC). The open circuit voltage (OCV) of passive DMAFC reached to about 1 V which was considerably higher than that for passive DMFC (0.45 V). The methanol crossover rate through membranes was also measured and the results implied that the potassium-doped Nafion117 membrane had lower permeability to methanol.

Facing global climate change and the oncoming shortage of fossil resources, it is neces-sary to reduce overall primary energy consumption. There is a strong need for action concerning car traffic as a main originator of greenhouse gas emissions by use of fossil energy. For a strong mitigation effect, the technological improvement of today&#39;s petrol and diesel engines has to be accompanied by the promotion of alternative vehicles, still being sparsely represented in most carfleets. The spread of one or more new drivetrain tech-nologies throughout the transportation sector represents an innovation diffusion process, which is needed in order to achieve long-term climate and energy policy goals. How-ever, there exist no adequate innovation diffusion models that accurately explain the main driving forces between competing alternative drivetrain technologies and their diffusion rate. This work contributes to the understanding of the fundamental diffusion processes by developing, analys...

Strategic measures for global ecology and security of energy supply particularly affect road traffic, as a main originator of greenhouse gas emissions by use of fossil energy. The introduction of several alternative, eco-friendly drive-train technologies in the automotive fleet leads to a competition with the existing petrol and diesel engines as well as with each other. A system dynamics model is developed to understand the fundamental competing forces driving the market penetration of the new technologies, and to derive policy implica-tions and strategies potentially contributing to their successful introduction. A conceptual model is presented to examine different diffusion patterns between competing technolo-gies. First results show, that reaching a critical market share in time is a decisive factor. This is demonstrated for the case of Switzerland, that represents a demand driven market without an autonomous automotive industry.

Exergy method of optimization for the geometrical parameters of an air conditioning precooling air reheater with turbulent flow is developed in this paper. The method is based on exergy, economic analysis and optimization theory. As there are humid air streams involved in the heat transfer process, then there are irreversibilities or exergy destruction, which is due to pressure losses, temperature difference and specific humidity gradient. These principle components of total irreversibility are not independent and there is a trade-off between them. Therefore, the purpose of this research paper is to study the effect of the geometry and the specific humidity of the two streams on the irreversibilities of a crossflow precooling air reheater dehumidifier. Also, the optimum balance between the three components of irreversibility is determined thereby giving the optimum solution for heat exchanger area. The total cost function is expressed on an annualized basis of the sum of the precooler capital cost and the running cost attributable to the precooler irreversibility. This total cost function is optimized in this paper according to the optimum heat transfer area and the total irreversibilities. Two optimum heat transfer areas were found for minimum total irreversibility and minimum total annual cost for a specific example. Finally, the relations between the typical operational variables such as heat transfer area, Reynolds numbers and the total annual cost for the precooler is developed and presented in graphs, which allow the calculation of the optimal heat transfer area, which gives the optimum irreversibility and minimum total annual cost.

Recently, the environment has been negatively impacted by the excessive CO2 emissions caused by the wide usage of fossil fuels in electricity generation. If this continued, it is predicted that the temperature of the atmosphere would rise, causing an increase in storms, hurricanes, droughts, dust, and floods. Therefore, as renewable energy produces little to no emissions, there is an urgent need to adapt it in recent times. Meanwhile, The PV sector has experienced rapid growth in recent years. The PV sector is embracing new technology, and the cell efficiency has been rising rapidly like Silicon Hetero- junction technology HJT which has offered additional benefits: It offers a well-suited application to reach efficiencies above 23% with process temperatures below 200°C. HJT solar panels have &gt;90% module bifaciality and a low temperature coefficient (-0.3 %/C°), and provide additional benefit to the Levelized Cost of Energy LCOE and output power for PV systems. This study intends ...

Det är de stora företagen som skapar de små företagens villkor och som avgör vilken typ av företag som kan överleva på marknaden, skriver Elisabeth Sundin. "Småforetak i et stordrifssamfunn" var titeln på den del av den norska maktutredningen som behandlade små och medelstora företag. Den publicerades för mer än 20 år sedan (1980) men skulle kunna sättas som rubrik också över detta kapitel som behandlar Sverige idag -och kanske också i framtiden. En utgångspunkt för framställningen är den stora positiva betydelse som nu tillskrivs små och medelstora företag (SMF) på snart sagt alla offentliga arenor. Politiker från alla partier betonar vikten av små-och medelstora företag och menar att deras verksamhet bör underlättas. Vidare har småföretag och entreprenörskap blivit ett etablerat forskningsområde. Professurer i ämnet finns runt om i landet och vid alla universitet och högskolor ges specialkurser i entreprenörskap. 1 Småföretagaren, och alldeles särskilt då nyföretagaren, ses som vår tids hjälte. Men vad är ett litet företag? Vad är en entreprenör? Och varför är just små företag stödvärda och positiva? Svaren, eller snarare föreställningarna om svaren, på den sist nämnda frågan rör sig både på samhällelig, organisatorisk och individuell nivå. Det brukar ofta anföras att små företag svarar för en stor del av sysselsättningen, cirka en tredjedel, av dem som finns i arbete idag. Vidare betonas att småföretagen utgör en stödtrupp till storföretagen genom att fungera som underleverantörer och stå för en del av den flexibilitet som de stora organisationerna anses sakna. Små företag anses vara innovativa och förnyande. Hos dem utvecklas nya produkter och tjänster som prövas förhållandevis lätt och snabbt på marknaden efter-

The purpose of this paper is to carry out an updated energy Life-Cycle Assessment of soybean biodiesel produced in the Pampean region of Argentina and to analyze the influence of different tillage systems on the Energy Return on Investment (EROI). It aims to identify the processes, materials and methodological aspects that significantly affect biofuel EROI. The procedure considers the main processes and operations of both the agriculture and industrial stages of biofuel production system, but the main novelty of this study is linking EROI with farming and conservation practices and not in the chemical processing of the oil. The results obtained represent the current average energetic performance of soy-based biodiesel produced in the considered region. The EROI values are very encouraging, demonstrating that this biodiesel provides a net energy gain. The results also show that conservation agriculture and the implementation of practices that improve crop yield do not always determine better energetic performance. Sensitivity analysis confirms that EROI values of soybean biodiesel are more responsive to methodological choices such as the system's boundary definition and the choice of the allocation method rather than to the physical aspects of the productive system such as tillage and water management practices.

The study examines the challenges of ethnicity and social work interventions in Nigeria. The cultural and religious background of the nation is prune to multi-ethnic and cultural diverse society with conflictogenic challenges. These challenges arose due to complex cultural diversity with socio-cultural differences which anchored on the historical antecedent of Nigerian federalism. It has been observed that National integration in Nigeria and the attempt to foster unity-in-diversity tend to create diverse conflicts and poses obstacles to unification and peaceful co-existence of the people of Nigeria. In other words, ethnicity took the center stage in the political, social, economic and cultural life of the people with pathogenic consequences. In view of the fact that all efforts made to eradicate ethnicity and its negative influence in the body polity of Nigeria were futile, social work intervention becomes imperative and quintessential.  That is, the application of social work as a ...

With the increasing adoption of solar energy, the disposal of end-of-life photovoltaic modules has become a growing environmental concern. As crystalline silicon has significant potential as an anode material for lithium-ion batteries, this study investigates recycling waste solar cell material into batteries using 3D printing. An open-source toolchain is developed to ensure accessible replication including a ball mill for grinding the waste silicon, a bottle roller for synthesizing novel stereolithography (SLA) resins and an SLA 3D printer for geometric control of the deposition of the materials. The materials were characterized at each step using spectrometry analysis, differential thermal analysis and thermogravimetric analysis of the polymer resin, optical microscopy on the printed parts, as well as scanning electron microscopy, energydispersive X-ray spectroscopy, and X-ray diffraction on the pyrolyzed parts. Electrochemical characterization, including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, was performed on the assembled batteries. A mixture of 12% ground silicon solar cells with SLA resin was used for 3D printing the anodes and the samples were pyrolyzed at 1400 °C. The electrochemical tests from the anodes demonstrated a specific capacity of around 400 mA h g-1 with 89% capacity retention and coulombic efficiency more than 100% over 200 cycles. This study presents a promising sustainable solution by integrating recycled solar cell waste into lithium-ion battery anode production, which can address both waste management and energy storage challenges. Sustainability spotlight The growing amount of solar photovoltaic module waste poses signicant environmental and economic concerns. This research addresses the challenge through fabrication of anodes for lithium-ion batteries through the recycling of silicon from discarded solar cells. Additionally, the integration of 3D printing techniques enables precise engineering of complex anode structures, enhancing battery performance by increasing energy density without sacrificing power density. This innovative approach represents a promising step toward improving the performance of sustainable and cost-effective energy storage devices as well as improving the end of life of photovoltaic systems. The batteries assembled with the recycled anode showed better performance than commercial graphite anode-based batteries showing the promise to provide lower cost batteries while enabling green end-of-use recycling for solar cells.

como la gasificación subterránea del carbón (GSC) para la producción de syngas (gas sintético). Las tecnologías GSC han sido probadas exitosamente en diversos países tanto para la obtención de energía eléctrica como para la generación de combustibles y productos químicos tales como fertilizantes nitrogenados. Los trabajos exploratorios realizados por YCF en la década del setenta permitieron identificar tres mantos de lignito en el área del Río Coyle y curso Medio del Río Santa Cruz (Cuenca Austral). En los últimos años, el conocimiento de las nuevas tecnologías de aprovechamiento de este combustible fósil, alentó la realización de tareas de exploración en estas áreas, incluyendo una perforación de 700 m en el sector del Río Coyle. En este trabajo se presentan las principales características geológicas de superficie y subsuelo de estos sectores, se describe la tecnología GSC que facilitaría su aprovechamiento y se analizan las posibilidades de producción de fertilizantes nitrogenados.

We present in this work the quantitative and qualitative study of the flow in the stepped spillways. The experimental measurement is realized on the reduced model. Different flow configurations on a spillway are described. New experimental results linked to the flow aspect and to the energy dissipation after the passage over the spillway are presented. The experimental results relative to the energy dissipation are analysed. They are compared thereafter to the results of the experiences and models found in other research works.

Paper mill sludge (PMS) can be efficiently utilized to produce fuels and chemicals. However, wastewater is usually generated during the de-ashing step of the PMS for fibrous materials recovery. Per process requirements, the wastewater stream must be treated which results in an increase in the overall process production cost. Therefore, this research aims at reusing the wastewater produced during the de-ashing step as a substitute for freshwater addition during the conversion of PMS into ethanol. The advantages of this approach include reducing the amount of wastewater produced and enhancing the overall efficiency of the process. It will contribute to the circular economy of zero waste discharges. The results showed that 30% of the process wastewater can be recycled without affecting the enzymatic hydrolysis and ethanol fermentation. Hence, the amount of wastewater that needs to be treated is reduced by 30% resulting in a cost reduction of 22.5%. The results also showed that wastewater recycling minimized the energy demands in the distillation and evaporation units by 1206 kJ/kg. The energy reduction is due to the increase of metals and total soluble solids in the broth stream after fermentation. This process configuration enhanced the process economy, saved energy and managed waste streams.

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This paper models the economic feasibility of growing the oilseed crop Camelina sativa ("camelina") in the western United States to produce value-added protein feed supplement and an SVO-based biofuel. Modeled in eastern Colorado, this study demonstrates that camelina can be grown profitably both as a commodity and as an energy biofuel. These findings, along with the stochastic crop rotation budget and profitability sensitivity analysis, reflect unique contributions to the literature. The study's stochastic break-even analysis demonstrates a 0.51 probability of growing camelina profitably when diesel prices reach 1.15 $ L À1 . Results also show that the sale of camelina meal has the greatest impact on profitability. Yet once the price of diesel fuel exceeds 0.90 $ L À1 , the farmer generates more revenue from the ability to offset diesel fuel purchases than the revenues generated from the sale of camelina meal. A risk analysis using second degree stochastic dominance demonstrates that a risk-averse farmer would choose to grow camelina if the price of diesel equals or exceeds 1.31 $ L À1 . The article concludes that camelina can offset on-farm diesel use, making it economically feasible for farmers to grow their own fuel. As a result, camelina production may increase farm income, diversify rural economic development, and contribute to the attainment of energy policy goals.

The maize-wheat-mungbean (MWMb) cropping system is being advocated as an alternative to the traditional rice-based cropping systems of north-western Indo-Gangetic Plains (IGP) to address the issues of energy and nutritional scarcity, residue burning, decline in biomass productivity and water tables. In semi-arid regions, the climate-change-induced variability in rainfall and temperature may have an impact on phenological responses of cereals and pulses which in turn would affect biomass production, economic yield and energy and water-use efficiency (WUE) of the crops. Henceforth, quantification of bioequivalent yields, energy requirement, economics and WUE of MWMb system is essentially required owing to have better understanding of this cropping system. Following a 4-year study was conducted under different tillage and nutrient management. ZT and PB plots had significantly higher pooled average (17.2e20.3%) biomass productivity, (34.4e39.8%) net returns and (49.8e66.2%) biomass water-use efficiency with lesser (8.5e16.1%) water-use than the CT plots. Significantly higher pooled bioenergetic yields (21.7e35.2%), net returns (31.4e37.8%) and biomass water-use efficiency (30.1e35.2%) was observed in SSNM/Ad-hoc plots compared with FFP plots. The total pooled energy input in ZT/PB and SSNM/Ad-hoc plots was significant (P < 0.05) higher than CT and FFP plots, respectively, with greater net energy output, energy productivity and energy efficiency. The interactions between tillage and nutrient management practices on pooled input energy and energy productivity of MWMb system was significant (P < 0.05). Thus, adoption of conservation tillage (ZT/PB) practices with improved nutrient management (SSNM/Ad-hoc) could be a viable option for achieving higher biomass productivity, water and energy-use efficiency and profitability in MWMb system.