Electrical Energy Requirements Research Articles

Microclimate Effect on Cooling Energy for Buildings in Hot, Humid Climates: A Comparative Analysis of Shaded and Unshaded Environments

This paper explores the influence of microclimates on changes in air temperature and the often-overlooked aspect of their effect on energy savings across varying microclimatic conditions. The study compares the cooling energy requirements of two identical single-story buildings in distinct microclimates: one characterized by concrete ground devoid of shade and the other featuring soil ground with tree shade. Climatic environmental data were collected over 15 days in the concrete-exposed field and shaded area beneath the trees to conduct the investigation. These datasets were input into EnergyPlus 9.6 to model the energy demands and consumption of buildings subject to the specified climatic conditions. The validation of the simulated model against actual energy demand data from a classroom building demonstrated agreement. The findings reveal notable differences in air temperature, with the shaded area experiencing temperatures 0.8°C to 8.0°C lower than the concrete-exposed monitoring location. The building in the tree-shaded microclimate exhibited a lower peak cooling load than its concrete-exposed counterpart, resulting in a 35% reduction in the electrical energy requirements for the air-conditioning system. The study recommends implementing 0.08-m polyurethane insulation for the building walls and roof to equalize the energy demand and consumption of the concrete-exposed building with that of its shaded counterpart. Furthermore, building design in shaded areas can maximize the window glass area while consuming less energy than buildings on concrete-exposed grounds. The study advocates leveraging the microclimate associated with surrounding buildings in the design process to enhance the overall energy savings.

Study of the Management of the Electrical Energy Production and Distribution System Within the National School of Teachers of Mamou, Guinea

With the energy transition, marked essentially by the mass integration of energy production based on renewable resources, the missions and challenges of electrical energy distribution networks are evolving. This study is part of this dynamic, its objective is the study of the management of the production and distribution system of electrical energy within the National School of Teachers of Mamou. It emerges from this study that the supply of electrical energy to the National School of Teachers of Mamou is ensured by a hybrid system of three power sources: photovoltaic solar fields, Generator Group and Electricity of Guinea. The current electrical energy requirements of the Mamou NST are 40 kW. The total power of the installed photovoltaic solar fields is 70 kWp; the Generator used has a power of 10 kVA; the site’s Electricity of Guinea network is made up of transformers, cabin substations and protective equipment. The electricity distribution network is characterized by: Four (4) 250 A circuit breakers; a 32 A circuit breaker for the departure of lamps, sockets and fans; a 10 A circuit breaker for the lamps; a 10 A circuit breaker for the fans; a 16 A circuit breaker for the sockets and an 800 A mechanical inverter. The study shows that the power of photovoltaic solar fields is largely sufficient to cover the current electrical energy needs of the National School of Teachers of Mamou.

Microwave-induced dual-responsive spinel (CoxMn1-xFe2O4) target-triggered non-radical pathways of peroxymonosulfate: Superexchange interaction and synergistic mechanism

The efficient activation of peroxymonosulfate (PMS) and the directional selection of oxidation pathways are crucial for achieving efficient pollutant removal in advanced oxidation processes (AOPs). A composite activation method of a microwave-induced dual-responsive catalyst (Co0.4Mn0.6Fe2O4) with both dielectric and catalytic properties is proposed to successfully trigger the non-radical pathway of PMS for 100 % removal of pharmaceutical pollutant (diatrizoate, DTZ) in 6 min, which shows good resistance to environmental interference and cyclic stability, and lower electrical energy requirement. 1O2 and surface-bound reactive oxygen species (ROS) are the main ROSs responsible for non-radical oxidation, with a total contribution of 98 %. The superexchange effect of Co-Mn (Mn3++Co3+→Mn4++Co2+) induces the electron delocalization of Mn site, which promotes the adsorption of PMS, interfacial charge transfer, and surface-bound ROS generation. The "thermal and non-thermal" effects of microwaves accelerate electron transfer and 1O2 generation to further trigger non-radical pathways. This work provides new strategies for bifunctional catalyst design and directional triggering of non-radical pathways of PMS-AOPs.

Dynamic-based artificial intelligence model for simulation and optimization of the single chamber anode brush microbial electrolysis cell

Microbial electrolysis cells (MECs) have become more attractive because they can produce hydrogen (H2) from various organic sources with a low input electrical energy requirement. In this study, a dynamic model for the single-chamber anode brush MEC with acetic acid as a carbon source was developed for the first time. The dynamic model was calibrated and validated using both experimental and literature data, with a high coefficient of determination (R2) of 0.87–0.99, a high Pearson correlation coefficient (PCC) of 0.93–0.99, and a low normalized root mean squared error (NRMSE) of 0.221–0.078. For rapid simulation and optimization, the validated dynamic model was reproduced using an artificial neural network (ANN), and particle swarm optimization (PSO) was then applied to optimize the fitness functions derived from this ANN model (i.e., hydrogen production yield, hydrogen production rate, hydrogen fraction in biogas, and total energy recovery). As a result, the proposed method took about 3 s with an absolute error of <3.5 %. The optimization results revealed that an optimal condition (including applied voltage, operating temperature, substrate concentration, and reactor working volume) cannot exist to obtain the maximum values of all performance parameters simultaneously. Under the same importance, the co-optimal condition was determined at an applied voltage of 0.9 V, temperature of 36.2 °C, substrate concentration of 0.87 g/L, and reactor working volume of 0.05 L. At such co-optimal conditions, MEC achieved an H2 yield of 1168.6 ± 13.3 mL/g with a production rate of 185.6 ± 2.7 mL/L/h, an H2 fraction of 63.6 ± 0.2 %, and a total energy recovery (including electrical, substrate, heat, and mixing input energies) of 16.7 ± 0.2 %. Although these performances increased 1.5–2.3 times compared to non-optimal conditions, the low energy efficiency indicates the need for further investigation into combining MEC with sustainable energy sources, such as solar, wind and osmosis.

Green hydrogen, electricity, and heat multigeneration via using solar, wind and hybrid RE systems: Comprehensive case studies in Arabian Peninsula Countries

This paper aims to assess the impact of solar and wind renewable energy (RE) potentials on the performance and economics of different RE systems located in Saudi Arabia and the rest of the Arabian Peninsula Countries (APC) to meet hydrogen, electrical, and thermal energy requirements. Techno-economic studies were carried out to evaluate the performance of a solar Photovoltaics (PV), a wind turbine (WT), and a hybrid solar/wind (PV/WT) system. The performance of different configurations of the considered systems are simulated and optimized in hourly basis at various locations in the APC region using a developed MATLAB computer code. The findings showed that the hybrid PV/WT system is more effective than PV or WT systems. In Riyadh, for the hybrid PV/WT system, Net Present Cost (NPC), Cost of Electricity (COE) and Cost of Hydrogen (COH) are 97.792 K$, 0.137 $/kWh and 2.01 $/kg, respectively. However, for the PV system, the findings showed that NPC, COE and COH increased by 30, 27 and 32%, respectively. For a standalone WT system NPC, COE and COH values increased by 53, 52, and 54%, respectively. In Saudi Arabia, it is obsereved that the minimum costs of both electricity and hydrogen productions are achieved for the hybrid standalone PV/WT system in Neom City with values of COE = 0.128 $/kWh and COH = 1.881 $/kg. For the APC region, the most cost-effective hybrid standalone PV/WT system is found in Kuwait City with COE = 0.120 $/kWh and COH = 1.765 $/kg. Furthermore, COE and COH contours of PV, WT, and PV/WT systems economics are developed which give the decision makers a full vision about solar and wind potentials in the region and identify the locations that minimize the cost of production.

Electrochemical mechanism and kinetics of electrodissolution-coupled hafnium alkoxide synthesis in tetraethylammonium-chloride-based anhydrous system

Electrodissolution-coupled hafnium alkoxide synthesis (EHS) is a promising pathway for efficient electro- synthesis. It employs simultaneous heterogeneous reactions of Hf dissolution and ethanol dehydrogenation, and spontaneous solution-based combination reaction between Hf4+ cations and alkoxy anions. To elucidate the mechanism and kinetics of EHS process, the electrochemical behaviors of anodic Hf dissolution and cathodic ethanol dehydrogenation were explored through electrochemical measurements, SEM observations, gas chromatography, and micro-kinetics modeling. The results indicated the supporting electrolytes of tetraethylammonium chloride (Et4NCl) to be preferable, which facilitated a passive-film-punctured pitting mechanism for Hf dissolution and a two-stage dehydrogenation mechanism. Three indicators related to passive rate, sensitivity towards puncture of the passive film, and pitting rate were extracted to quantify the kinetics of passive puncture and Hf corrosion. Micro-kinetics models were developed to evaluate the Et4NCl-based EHS process, which achieved electric energy requirements of 1.53–1.83 kW·h/kg Hf(OC2H5)4.

Effect of gangue on CO2 emission for different decarbonisation pathways

At present, iron and steelmaking industry worldwide is going through the transition of decarbonisation to meet its goal of reaching net zero by 2050. In addition, Australian iron and steelmaking industry is facing its own challenge of processing lower grade ores with increasing gangue content. Two major pathways are direct reduction of iron – electric arc furnace pathway (DRI-EAF) and direct reduction of iron – electric smelter-BOF (DRI-electric smelter-BOF) pathway. In the present work, a mass and energy balance model of basic oxygen furnace (BOF) and electric arc furnace (EAF) have been developed using thermodynamic software. The EAF model showed that with 100 wt-% cold DRI, the specific electric energy requirement varied between 514 and 651 kWh/tls whereas in case of hot DRI, it varied between 399 kWh/tls and 510 kWh/tls. As the gangue content increased from 10.7 wt-% to 19.1 wt-%, yield decreased from 88 wt-% to 75.5 wt-% and slag weight increased from about 200 kg/tls to 630 kg/tls. The BOF model showed that the slag produced in a BOF varied between 63 kg/tls and 73 kg/tls for lower to higher grade ores reflecting different hot metal chemistry (P, Mn) coming from different ores. The results indicated that electric smelter-BOF is more compatible to process lower grade ores than EAF where quantity of slag and loss of yield are very high with increasing gangue content. CO2 emissions from H2DRI-EAF and H2DRI-electric smelter-BOF pathway for different types of ores increased with the increasing gangue content. For H2DRI-EAF pathway, as gangue content increases from 10.7 wt-% to 19.1 wt-%, CO2 emission rises from 0.10 t/tls to 0.19 t/tls as more limestone is needed to remove the gangue which also increases the production of CO2. In case of H2DRI-electric smelter-BOF pathway, CO2 emission increases from 0.12 t/tls to 0.19 t/tls with increasing gangue content. CO2 emissions from both pathways are significantly lower than the current BF-BOF pathway.

Global Warming Potential from the Life Cycle of Fischer-Tropsch Fuel from Carbon Capture for Passenger Cars in Jakarta

Measures to mitigate the impacts of climate change in the form of carbon capture and storage have not been implemented in Indonesia, especially because there are carbon transportation and storage processes that do not provide added value. The Fischer-Tropsch process is a technology that can produce products that can be processed from CO2 and processed to become value-added commodities in the form of motor vehicle fuel. Using the openLCA application, a life cycle analysis was carried out of the synthesis of FT fuel for use in conventional gasoline vehicles in Jakarta from the capture of CO2 sourced from a coal fired power plant’s exhaust gas, which was compared with the life cycle of electrical energy for battery electric vehicles and conventional fuel for internal combustion engine vehicles. The life cycle impact method used is global warming potential which is expressed in kg CO2-eq. An alternative scenario is created as a comparison for analysis regarding life cycle impacts and parameter sensitivity. It is gathered that FT Fuel synthesis from carbon capture has a higher GWP impact than electrical energy for BEVs and conventional gasoline for ICEVs, due to the high electrical energy requirements from FT Fuel synthesis and the energy mix of the Java-Bali electric power system which is still dominated by fossil-fueled power plants. With alternative scenarios, the GWP impact from FT Fuel synthesis could be equivalent to or lower than electrical energy for BEVs and conventional gasoline for ICEVs.

Designing and simulation of a grid-connected solar plant in Mathura city region employing PVsyst

Existing electricity generation methods are ecologically unsustainable due to the industrial revolution's massive population growth and digitalization. The photovoltaic (PV) simulation tool is crucial for forecasting the solar system's energy output. The objective of this research is to simulate the feasibility of establishing a PV system isolated with batteries in Mathura, India, where the research is taking place to measure solar radiation and examine the technical and economic components of the PV system for generating domestic electrical energy requirements. The program has been implemented by PVsyst software. The amount of electricity that is added to the grid is 100.95 MWh. In the intended location, the Si-poly (polycrystalline silicon) PV system's typical performance ratio is 72.35%. From March to October, the most electrical energy was generated. The temperature of the solar field, which was 7.69%, was the primary cause of the losses observed in the research.

PERANCANGAN SISTEM INFORMASI PENCATATAN DAN PERHITUNGAN TAGIHAN KWH METER LISTRIK PASCA BAYAR DI PT. MAHIZA KARYA MANDIRI

Electrical energy requirements have increased in line with economic growth and social welfare. Every month, meter recording officers come to record customers' electricity kwh usage. Problems often occur in the recording process using the ACMT application such as errors in inputting the booth meter numbers or the customer's kwh meter as recorded by the officer. The main problem of this research is how to design a system for recording and calculating postpaid electricity kwh meter bills to produce a report that is fast, accurate, and optimal. This research aims to design a postpaid electricity meter recording system that will provide bill estimates for the customers, and reduce complaints and spikes in customer bills due to recording errors. The design created was tested using the White Box and Black Box Testing method as the results worked according to its function defined.

Optimizing electrocoagulation pre-treatment efficiency during simultaneous treatment of different produced water streams in a FO-MD hybrid system

In this study, the electrocoagulation (EC) process was explored and optimized for the pre-treatment of key contaminants present in hyper-saline produced water (PW) streams before their treatment through forward osmosis-membrane distillation (FO-MD) hybrid system. Due to their hyper-saline nature and the associated high temperatures, PW streams can be treated cost-effectively and sustainably using low-pressure dual membrane filtration systems like FO-MD hybrids. Desalter effluent (DE) stream was used as the FO feed solution, and WOSEP outlet (WO) stream served simultaneously as the FO draw solution and MD feed solution. The key foulants were identified in the WO and DE streams. Silicon, calcium, and sulfur were found as the key elements contributing towards FO and MD membrane fouling in the form of CaSO4, SiO2, and CaSiO3. Applying EC for 10 min with 100 mA current (7 mA/cm2 current density) at a neutral pH of 7 demonstrated the highest removal efficiencies for silicon (97 %), calcium (3.6 %), and sulfur (12.2 %) with only 0.023 kWh/m3 electric energy requirement. FO-MD hybrid efficiency was re-assessed with pre-treated WO and DE streams. The FO flux showed more stability and increased by 32.5 % and MD by 28.9 %, with a 10 % reduction in specific reverse solute flux. EC is thus a robust and effective process for hyper-saline hazardous PW pre-treatment and can substantially improve the FO-MD hybrid system efficiency.

Performance Test, Noise, and Economic Analysis of Coffee Roasting Machines Rotating Cylinder

The roasting process carried out in this study was at the medium roast level, using a rotating cylindrical coffee roasting machine that used an electric heat source. This research aims to determine the performance and economic analysis of a rotating cylinder coffee roasting machine. Descriptive analysis in this study includes coffee roasting machine performance data (roasting temperature, moisture content, electrical energy requirements and noise) and economic performance data (NPV, IRR and BCR). The results of observing the performance of the machine obtained a roasting temperature of 205°C and a moisture content of 4.42%, in accordance with the Indonesian national standard (SNI) and the need for electrical energy in the heater was 3.18 kWh and in the motor of electric was 1.17 kWh. In this study, the noise analysis obtained showed the number 90 dB, which means it is less effective for operators in that environment. Meanwhile, the results of the economic analysis were obtained NPV, IRR and BCR respectively are IDR 225,363,266; 21.6 %; 5.18.

Efficient Removal of Chromium and Lead from Tanneries Effluent of Korangi Industrial Area Karachi Using Rotating Disk Mesh as Anode Electrode Electrocoagulation

The aim of this study was to examine the best electrode design for the electrocoagulation process with the best removal performance, reduced passivation on the electrode surface, and lower energy consumption requirements for removing Chromium (Cr) and Lead (Pb) from leather tannery effluent. Three different electrodes were compared: non-rotating disk electrode (NRDE), rotating disk electrode (RDE) and rotating disk mesh electrode (RDME). All electrodes were used to observe a reduction in passivation on the electrode surface and its effects on the removal performance of Cr and Pb. The material used for the electrodes was iron. The maximum removal efficiency obtained was Cr = 87.9% and Pb = 97.5% under the following operating conditions: pH = 7, treatment time = 90 min, current density = 6.57 mA/cm², and RPM = 80. The results show that the electrical energy requirement for treating chromium and lead using RDME was 4.5 kWh/m³, which was found to be lower than the energy requirement observed in various other studies for treating tannery effluent. According to the results, RDME shows the highest removal performance with lower specific energy consumption compared to NRDE and RDE. RDME can be efficiently employed at a larger scale for treating leather tannery effluent.

Temperature-dependent dynamics of electrokinetic conservative and reactive transport in porous media: A model-based analysis

Electrokinetic techniques employ direct current electric fields to enhance the transport of amendments in low permeability porous media and have been demonstrated effective for in situ remediation of both organic contaminants and heavy metals. The application of electric potential gradients give rise to coupled chemical, hydraulic and electric fluxes, which are at the basis of the main transport mechanisms: electromigration and electroosmosis. Previous research has highlighted the significant impacts of charge interactions and fluid composition, including temperature-dependent properties such as electrolyte conductivity and density, on these transport phenomena. However, current models of electrokinetic applications often assume isothermal conditions and overlook the production of heat resulting from Joule heating.This study provides a detailed model-based investigation, systematically exploring the effects of temperature on electrokinetic conservative and reactive transport in porous media. By incorporating temperature-dependent material properties and progressively investigating the impact of temperature on each transport mechanism, we analyze the effects of temperature variations in both 1D and 2D systems. The study reveals how temperature dynamically influences the physical, chemical and electrostatic processes controlling electrokinetic transport. A temperature increase results in a higher speed of amendments delivery by both electromigration and electroosmosis and increases the kinetics of degradation reactions. The simulations also reveal a feedback mechanism in which higher aqueous conductivity results in increased Joule heating, leading to a faster temperature rise and, subsequently, to higher electrolyte conductivity. Finally, we estimate the electric energy requirements of the system at varying temperatures and show how these changes impact the rate of contaminant removal.

Evaluation of the Optional Wideband Accuracy of Inductive Current Transformers in Accordance with the Standard IEC 61869-1 Ed.2

This paper presents the evaluation of tested inductive CTs’ accuracy for distorted current harmonics in accordance with the optional accuracy class WB1 introduced by the new edition of the standard IEC 61869-1 published in the year 2023. The tests were performed in compliance with the interpretation sheet IEC 61869-2:2012/ISH1:2022. Therefore, the resistive and the resistive–inductive loads of the secondary winding of tested inductive CTs were used, as this was required for the given test conditions. The results indicate that the units designed for the transformation of a sinusoidal current of a frequency of 50 Hz ensure the high wideband transformation accuracy of the distorted current harmonics, as demanded by the power quality monitoring and distorted electrical power and energy requirements. The key to this is proper design using modern magnetic material(s) for the magnetic core and its oversizing in relation to the requirements for a given accuracy class defined for the transformation of sinusoidal currents with a rated frequency. Both tested inductive CTs with a rated primary current RMS value equal to 300 A, class 0.2 and 0.5, ensured compliance with the requirements of the WB1 wideband accuracy class.

Energy and Stochastic Economic Assessments of Photovoltaic Systems in the East Midlands

This study implements techno-economic evaluations of different photovoltaic (PV) systems in the East Midlands of the UK. Three application case studies, including an office building, a domestic building, and a poultry shed, are achieved. The building electricity consumption is obtained according to hourly automatic meter readings, and the PV electricity production is predicted based on the Engineering Equation Solver 8.4 software. Meanwhile, the 25-years’ complete economic profitability investigations of the three PV systems are conducted on the basis of the Monte Carlo method; the sensitivity analyses of payback period and net present value are also carried out by using the @RISK 8 software. Furthermore, the payback period and yearly savings are investigated and compared between the Smart Export Guarantee (SEG) and feed-in tariff (FiT) schemes. Technical investigation outcomes conclude that the three PV systems are able to satisfy electrical energy requirements in summer, and the additional electricity could be exported to the grid in this period. In winter, however, the systems have less electricity output resulting in power shortage and input from the grid. Economic study results exhibit that the net present values of the office building, domestic building, and poultry shed are £9108.4, £1717.91, and £7275.86, respectively, corresponding to the payback periods of 6.15 years, 9.12 years, and 9.41 years. This implies that there is an acceptable payback period (&lt;10 years) for the PV system installation; meanwhile, the FiT scheme has the shorter payback period compared with the SGE scheme.

Hybrid multi power sources PEMFC/battery/supercapacitor real time setup energy conversion system

&lt;span lang="EN-US"&gt;This paper presents an energy management system with multiple sources. The proton exchange membrane fuel cell as the main power drive source is used when needed. However, because of its slow rate it is combined with a battery and supercapacitor racks as secondary sources. The proposed energy conversion system ensures the energy demand of an electric vehicle. The storage system, which includes a battery and a supercapacitor, provides a high level of performance in both autonomy and availability of power. The battery as a primary storage source, feeds the whole system during cruse processes. At needs and during accelerations phases, the supercapacitor, takes over and reacts to supply the load. This topology keeps the fuel cell disconnected from the bus supply, until the battery reaches a critical voltage level. At this time, the fuel cell kicks in and charges the battery rack. The entire system was initially tested using MATLAB/Simulink environment and the outcome findings were subsequently analyzed. The simulated results have been corroborated experimentally using a test rig based on dSPACE real time interface. Experimental results indicate that the suggested approach is capable of meeting the electric vehicle energy requirements.&lt;/span&gt;

Degradation of emerging per- and polyfluoroalkyl substances (PFAS) using an electrochemical plug flow reactor

In recent years, shorter-chain fluorinated compounds have been manufactured as alternatives to legacy per- and polyfluoroalkyl substances (PFAS) after a global ban on some long-chain PFAS. This study is the first to investigate the degradability of emerging PFAS by an electrochemical plug flow reactor (EPFR). Ten different emerging PFAS, representing classes of fluorotelomer alcohol, perfluoroalkyl ether carboxylate, polyfluoroalkyl ethersulfonic acids, perfluoroalkyl ether/polyether carboxylates, perfluoroether sulfonate, N-alkyl perfluoroalkylsulfonamido carboxylate, fluoroalkyl phosphonic acid, and perfluoro alkane sulfonamide were investigated. The process kinetics was performed. The degradation of parent compounds increased with increasing retention time (RT). At 45.2 min of RT, the degradation of parent compounds ranged between 68%−100% with a current density of 17.2 mA/cm2. A linear increase in pseudo-first order rate constants was observed for all PFAS with increasing current density from 5.7 to 28.7 mA/cm2 (R2 > 0.91). The effect of pH, natural organic matter, and bicarbonate on the degradation, defluorination, and fluorine mass balance are reported. Alkaline pH (11) caused a decrease in degradation for all PFAS. While the presence of natural organic matter (NOM) significantly decreased the degradation and defluorination processes, the presence of bicarbonate at all studied concentrations (25, 50, and 100 mg/L) did not affect the process efficiency. The defluorination reduced to 34% from 81% with 15 mg/L NOM. The unknown/undetected fluorine fraction also increased in the presence of 15 mg/L NOM indicating the formation of NOM-PFAS complexes. Additionally, C2-C8 perfluoro carboxylic acids (PFCAs), one perfluoro sulfonic acid (PFSA), two H-PFCAs, and 4:2 fluorotelomer sulfonate (FTS) were identified as degradation byproducts in suspect screening. The electrical energy per order for PFAS ranged between 1.8 and 19.4 kWh/m3. This study demonstrates that emerging types of PFAS can potentially be degraded using an EPFR with relatively low electrical energy requirements.

Modeling, simulation and performance evaluation of a PVT system for the Kenyan manufacturing sector

Manufacturing is an end-use sector that uses the most delivered energy, accounting for around 50% of all transported fuel globally and 40% of carbon dioxide emissions worldwide. Solar photovoltaic-thermal (PVT) energy can substitute the transported energy to meet thermal and electrical energy requirements, mitigating high energy costs and climatic problems. This research aimed to develop, simulate, and evaluate the capabilities of a solar photovoltaic-thermal system for potential use in Kenya's manufacturing sector. A multistage cluster sampling technique was used in the study to characterize the manufacturing industry. Additionally, a PVT system was simulated using MATLAB Simulink to ascertain the relationship of temperature and the PV electrical efficiency. The impact of incorporating a thermal collector into the PV system on electrical, thermal, and overall system efficiency, and also the system's potential for use in thermal processes in manufacturing, were assessed. From the characterization results, the agro-processing sector dominates with 35% representation, and the small-scale thermal energy category dominates at 80%. The simulation findings show that a small temperature increase leads to a small increment in short circuit current but a significant decline in open circuit voltage. As a consequence, the maximum power (Pmax) of the PV decreases, lowering its electrical efficiency. However, the integration of PV with thermal collector improved the electrical, thermal, and the entire system efficiencies by, 16.01%, 20%, and 36.13%, respectively. More than 75% of the electrical and thermal energy processes fall in the small energy category. Hence, the PVT system is suitable for small-scale low-to-medium heat thermal energy categories or as a substitute system for higher temperature processes to raise feed water temperatures and reduction of thermal energy cost. This study gives a new approach of the application of PVT system for thermal industrial applications.

Selective butyric acid production from CO2 and its upgrade to butanol in microbial electrosynthesis cells

Microbial electrosynthesis (MES) is a promising carbon utilization technology, but the low-value products (i.e., acetate or methane) and the high electric power demand hinder its industrial adoption. In this study, electrically efficient MES cells with a low ohmic resistance of 15.7 mΩ m2 were operated galvanostatically in fed-batch mode, alternating periods of high CO2 and H2 availability. This promoted acetic acid and ethanol production, ultimately triggering selective (78% on a carbon basis) butyric acid production via chain elongation. An average production rate of 14.5 g m−2 d−1 was obtained at an applied current of 1.0 or 1.5 mA cm−2, being Megasphaera sp. the key chain elongating player. Inoculating a second cell with the catholyte containing the enriched community resulted in butyric acid production at the same rate as the previous cell, but the lag phase was reduced by 82%. Furthermore, interrupting the CO2 feeding and setting a constant pH2 of 1.7–1.8 atm in the cathode compartment triggered solventogenic butanol production at a pH below 4.8. The efficient cell design resulted in average cell voltages of 2.6–2.8 V and a remarkably low electric energy requirement of 34.6 kWhel kg−1 of butyric acid produced, despite coulombic efficiencies being restricted to 45% due to the cross-over of O2 and H2 through the membrane. In conclusion, this study revealed the optimal operating conditions to achieve energy-efficient butyric acid production from CO2 and suggested a strategy to further upgrade it to valuable butanol.