Payback Period Research Articles

Sweet Bread Teaching Factory's Feasibility Projection at Banyuwangi State Polytechnic

This study aims to provide an overview of sweet bread production as an alternative in planning and developing teaching factories based on business feasibility projection analysis. A quantitative technique was applied in this research. Survey techniques and statistical tests were used to examine the hypotheses. To demonstrate that an institution can and should continue its sweet bread business, several variables were measured, including the Internal Rate of Return (IRR), Net Present Value (NPV), Return on Investment (ROI), Benefit–Cost Ratio (B/C ratio), Payback Period (PBP), and Break Event Point (BEP), providing further information for Business Model Canvas analysis of a business model. Based on the BMC, the value propositions are a variety of sweet bread, ease of access, affordable prices, quality, and taste. Key activities include sweetbread production, stock management, marketing and promotion, and customer service. Customer segmentation involves students, lecturers, staff, and institutional visitors. An analysis of financial projections reveals that business is feasible. This can be seen from IRR = 53,19%; the NPV > 0 is equal to IDR 85,222,327; ROI = 216.69%; B/C ratio =1.07; BCR > 1; PBP = 41 months; and BEP = IDR 5,528,669.25. Keywords: teaching factory, sweet bread production, business feasibility, financial projection

Solid Minerals as Alternate means of Nigeria’s Economy Recovery Using Artificial Intelligence

Nigeria is one of the nations blessed with vast number of mineral resources which can make its economy one of best in the world. However, very little attention is directed to this sector as the sector contributes less than 10% to the country's Gross Domestic Product (GDP). Therefore, this study evaluates the economic potentials of Nigeria mineral resources as means of liberating the country from its current economic woes. Data obtained from the existing company, internet sources, U.S. Geological Survey, Nigeria Geological Survey Agency among others were used to form the bases for the analyses. The economic indicators were first computed to determine the dependency of Nigeria mineral demands on the import and forecasting was also done using the moving average method and forecast command. The obtained import reliance and self-sufficiency indicated that Nigeria still depend largely on the importation to meet its mineral requirements and hence not self- sufficient. The Net Profit Value (NBP), Internal Rate of Return (IRR) and Payback Period (PBP) revealed that the minerals investigated are economically viable. To enhance the easy assessment of the NPV, artificial intelligence approach, Artificial Neural Network (ANN) was used to develop models for barite and iron ore. The model was validated, and the validation results are compared with the actual values. They were found to be very close to the actual NPV and can be used for the NPV predictions. Therefore, ANN model was transformed through the weights and biases to mathematical form. Hence, the study has revealed the dependency of Nigeria on import and the economic viability of the minerals in Nigeria.

Techno-economic optimization of a geothermal multi-product layout composed of a CO2 trans-critical Rankine-LNG system integrated with ejector cooling system and HDH desalination unit

This current research introduces and examines a new multi-product configuration based on geothermal energy, using energy, exergy, and exergy-economic perspectives. The configuration under consideration aims to maximize the use of geothermal energy. A cascading trans-critical CO2 Rankine cycle (TCRC)/LNG subsystem functions as the primary system, and a cascading ejector cooling system (ECS)/humidification-dehumidification (HDH) desalination unit functions as the secondary system. The LNG subsystem's output power is transferred to an alkaline electrolyzer for the manufacture of hydrogen once the output power is retrieved from the TCRC. The HDH system and ECS provide the necessary cooling and freshwater. Thus, the suggested plan is transformed into a poly-generation scheme. The addressed research gap lies in the integration of these subsystems to create a novel poly-generation arrangement that simultaneously produces electricity, hydrogen, cooling, and freshwater using geothermal energy—a configuration not yet explored in existing studies. The novelty of this work lies in optimizing this unique system through a comprehensive exergy-economic approach. In the parametric analysis section, geothermal heat source temperature, the hot side temperature difference of TCRC heater, upper pressure of TCRC, and lower temperature in the TCRC are chosen for sensitivity analysis. In conclusion, when taking into account exergy efficiency and the payback period as two opposing objective functions, they are determined to be 16.99 % and 0.616years, respectively, in the optimization process. At this stage, the suggested configuration is capable of generating 435.9 kW of power, 251.5 kW of cooling, 3.68 kg/h of hydrogen, and 0.0493 kg/s of freshwater.

A hazai gyermekvédelmi rendszer fejlesztésében rejlő potenciális gazdasági hasznok

The study approaches child protection involvement from an economic perspective, and is thus a niche study in the Hungarian literature. It seeks to quantify the social benefits to society of mitigating the negative impact of involvement in the provision of child protection, and the maximum return on investment in the child protection system for a given payback period and discount rate. As in international research, the evaluation of the project is based on a cost-benefit analysis of the increase in educational attainment. The social benefit is estimated by determining the number of people affected and the social benefit per person affected, and the social discount rate is determined using two types of elasticity estimates. The results suggest that a greater allocation of public resources to child protection provision not only benefits the individuals concerned, but can also result in a positive net present value investment for society as a whole.

Feasibility Study of an Integrated Waste Management Technology System for a Circular Economy in the Philippines

Increasing population and rapid economic growth result in waste management problems in the Municipality of Bay, Laguna. In response, the municipality is planning to invest in an Integrated Waste Management Technology System (IWMTS) that aims to generate public revenue. Key informant interviews, surveys, and focus group discussions were utilized for data collection. Results showed that respondents lack knowledge about IWMTS but perceive positive impacts on waste volume reduction and municipal waste management and little to no negative impacts on health, livelihood, and accessibility. Meanwhile, economic analysis showed that it is estimated to generate an annual revenue of PHP 11.986 million (USD 214,036) with yearly expenses of PHP 3.7 million (USD 66,071). These cash flows are expected to recover the overall capital outlay of PHP 48.14 million (USD 859,642). A net present value (NPV) of PHP 3.164 million (USD 56,500) and a 5.77-year payback period (PBP) were calculated through cost-benefit analysis. The environmental analysis revealed positive impacts on reducing the volume of wastes, water resources, and quality, odor and air quality, and soil and nutrients. Considering these, the study provided recommendations on project implementation to achieve sustainable waste management and circular economy in the municipality.

Potential site evaluation of fifth-generation district heating and cooling networks under uncertain energy market conditions: A two-step robust design analysis approach

In a fifth-generation district heating and cooling (5GDHC) network, energy demands are satisfied without using fossil fuel-based sources, rather by sharing participants’ energy loads through decentralized consumption and production. However, finding such locations where the complementary energy demands of participants are matched is difficult. The problem becomes more complicated due to uncertain energy markets (equipment investment and operational costs). These uncertain market trends make it difficult to decide whether to build the network. Finding the feasible network temperatures for the 5GDHC network is challenging due to the conflicting participants, as at one-time instance some need cooling and others need heating. The sensitivity analysis using Sobol’ indices is performed to find the most influencing input parameters. Then, a techno-economical assessment of the considered location is performed against influencing inputs. Two different sites Diest and Alpha Cloud (Flanders, Belgium) are evaluated. The systematic techno-economic analysis under the influence of an uncertain energy market and network operating temperatures reveals that building a network might be not feasible due to the high payback period. The methodology offers greater flexibility in identifying key uncertain input parameters and evaluating the robustness of critical performance indicators, overcoming the limitations of current GIS-based approaches. This improved capability assists decision-makers in more accurately determining feasibility.

An updated multi-criteria decision-making method for the sustainable renovation of buildings including environmental, economic and social life-cycle metrics

The ambitious targets of carbon emission reduction set worldwide for the coming years entail the commitment of structural engineers towards the sustainable renovation of existing buildings. The life cycle thinking (LCT) approach offers a holistic perspective for the design of sustainable retrofitting strategies. It envisages the reduction of the environmental impact at all building life cycle phases, while also addressing economic and social issues. Multi-criteria decision-making (MCDM) approaches support the choice of optimal retrofitting solutions, thus being relevant tools for boosting the actual adoption of LCT in current practices. In this study, a previously proposed MCDM approach is enriched with additional LCT-inspired decision parameters (module D beyond-life impacts, environmental payback period, invasiveness), and is then scrutinised and discussed through its application to a case-study building. Four integrated retrofitting scenarios are investigated using state-of-art seismic loss and energy performance assessment methods, including four different types of exoskeletons, made of timber, steel, and concrete. The end-to-end integrated assessment shows that the inclusion of additional LCT-inspired decision criteria effectively favours LCT-based retrofitting interventions over more traditional ones.

Techno-economic assessment of co-production of biodiesel and epoxy fatty acid methyl ester as renewable fuel and plasticizer from waste cooking oil

Diversifying waste cooking oil (WCO)-based biodiesel production towards epoxy fatty acid methyl esters (EFAMEs) offers a double gain, boosting revenue channels in the biodiesel sector and driving the development of sustainable phthalate plasticizer alternatives. This study explored the techno-economic feasibility of co-derived biodiesel and EFAMEs from WCO using a three-step process involving enzymatic transesterification, urea complexation, and performic acid epoxidation. The result shows that a plant processing 61,300 tonnes/year of WCO, may produce ∼27,770 tonnes/year of biodiesel and ∼30,180 tonnes/year of EFAMEs, with a total heating duty of 1,124 kW and annual electricity consumption of 34.9 million kWh. The initial capital investment of the plant in China amounts to 136.8 MM CNY, with an annual manufacturing cost of 460 MM CNY in 2022. Techno-economic evaluation demonstrats a net present value (NPV) of 421.9 MM CNY at a 10 % discount rate, an internal rate of return (IRR) of 37.69 %, and discounted payback period of 2.37 years. The break-even point (BEP) is estimated at an annual sales volume of total products of 27,101 tonnes/year, including 12,790, 11,769, 2,542, and 2,390 tonnes/year of epoxy plasticizers, biodiesel, glycerol, and polymeric grease, respectively, collectively utilizing 42.38 % of the processing capacity. Monte Carlo simulation indicates minimal risk of the project, with probabilities of 98.5 % for IRR > 10 % and 97.8 % for a positive NPV. This study affirms the economic viability of co-producing biodiesel and EFAMEs from WCO for industrial application.

A CFD and experimental analysis of a double-slope solar still with channel integration

Freshwater scarcity is a critical global issue, particularly in arid regions. Solar stills provide a sustainable solution for water desalination using solar energy, yet traditional designs often exhibit limited efficiency. This study examines the performance of a Double Slope Solar Still (DSSS) integrated with a square-shaped conventional channel (CCDSSS) to enhance water evaporation and production. Experiments were conducted in Chengalpattu, Kattankulathur (latitude 12.8° N, longitude 80.03° E) along with three-dimensional simulations using Computational Fluid Dynamics (CFD) and were validated against literature and experimental data. The CCDSSS system achieved a water productivity of 3.084 lm−2day−1, which is 25.67 % higher than the DSSS system’s 2.454 lm−2day−1. It also keeps a uniform temperature within still and enhances vapor velocities, resulting in higher evaporation rates and productivity. Optimal performance was observed with a 10 mm water depth, showing a 24.41 % increase in yield compared to a 30 mm depth. Despite higher initial costs, the CCDSSS system offers a shorter payback period of 238 days compared to 289 days for the DSSS system. This study provides detailed insights on the effect of channel attachment in DSSS highlighting significant improvements in both solar still efficiency and economic performance.

Design and performance evaluation of a solar-assisted biogas and air-source heat pump hybrid system for radiant heating applications

Energy and environmental crises have become critical challenges, making the efficient use of clean energy a focus of public attention. Although emerging clean energies have high economic and environmental values, these single energy sources are not well-developed. In colder climates, maintaining a stable fermentation temperature can be difficult, leading to the idling of many biogas digesters. Furthermore, despite extensive research on solar-assisted air-source heat pumps, these systems perform poorly in cold climates with low solar irradiance. To address these issues, this study investigates the integration of a solar-assisted biogas and air-source heat pump hybrid heating system (SBHP-HHS) for capillary radiant heating in rural North China, specifically adapted to local conditions. The system aims to utilize the combined benefits of various clean energy sources to improve system reliability in harsh climates. By combining experimental analysis with TRNSYS simulation, the system performance during the heating season in rural northern China was evaluated. Experimental results show that the hybrid system, utilizing the radiant capillary terminal, is capable of maintaining room temperatures above 20 °C, demonstrating its effectiveness. Simulation results show that the air-source heat pump achieves a coefficient of performance (COP) of 4.6. This efficiency level is generally favorable, ensuring stable operation. Additionally, the system achieves a solar-biogas hybrid utilization rate exceeding 75 % and a primary energy-saving rate of 78 %. Economically, the system offers an 8.23-year dynamic payback period and annual cost savings of 3055 CNY. Environmentally, it reduces CO2 emissions by 4263.6 kg annually. This study provides a solid experimental foundation for further research, offering empirical evidence to optimize system performance.

Investigating the performance of a gas turbine system combined with steam methane reforming as a thermochemical recuperator in a power, cooling, freshwater, and hydrogen production multigeneration system

Depletion of fossil fuel resources at a high speed and increasing demand for energy supply for various purposes in today's life integrated with industry has led to collective contemplation for the optimal and maximum utilization of fossil fuels through the implementation of multigeneration systems. In the presented study, a multigeneration system for cooling, power, freshwater, and Hydrogen production is proposed and investigated from exergy, energy, and economic viewpoints through a specific scenario. A case study is performed, revealing that the system can deliver a net output power of 16,251.8 kW, a cooling load of 15,905.0 kW, produce freshwater at a rate of 3.891 kg/s, and generate hydrogen at 0.284 kg/h. The energy and exergy efficiencies of the system are 60.48 % and 32.55 %, respectively. An economic analysis shows a payback period of 0.474 years. A parametric evaluation is performed to perceive the system operation in various conditions. Subsequently, a multi-objective optimization using the MOPSO-LINMAP method is conducted to identify the optimal operating conditions for the system. The optimization results are compared with the case study findings, demonstrating further improvements in performance metrics. The optimized system achieves a slightly higher energy efficiency of 61.62 % and a lower payback period of 0.40 years, underscoring the benefits of the optimization process. This study highlights the potential of the proposed system to efficiently and economically meet the demands for power, hydrogen, cooling, and freshwater in various applications.

Using geothermal energy in enhancing all-air HVAC system performance - Case study, thermal analysis and economic insights

The background is the same for addressing the twin challenges of attaining thermal comfort and concurrently reducing energy use and CO2 emissions. As a safeguard against worsening contamination, combining geothermal energy with an All-Air Heating, Ventilating, and Air Conditioning system (HVAC) with 100 % fresh air intake is also crucial in the context of the lessons learned from the COVID-19 pandemic. As a result, this study suggests using geothermal energy as a backup source to run a typical All-Air centralized HVAC system. The resulting system is referred to as a combined system from now on, and its primary goals are to lower the amount of operating energy needed while being environmentally and financially sound. In this context, the creative way of combining the suggested geothermal duct with the All-Air HVAC system possesses various insights, as demonstrated by the thorough thermal analysis and related design. Strong conclusions were derived from a thorough case study focused on Lebanon: adding 100 % fresh air intake leads to an astounding yearly energy savings of 67 %, whereas configurations with 10 % and 30 % fresh air produced energy savings of 52 % and 36 %, respectively. In the study, a geothermal multi-duct system was also suggested and looked at. The research revealed that the 311-m length of the single geothermal duct connected to a pressure of 7000 Pa was reduced to 210 m and the pressure drop was lowered to 140 Pa when a geothermal multi-duct system was employed. Furthermore, as the computed payback period makes clear, the integrated system presents an appealing chance to drastically cut resource usage during energy consumption, lower CO2 emissions, and provide 100 % fresh air circulation.

Low carbon solar-based sustainable energy system planning for residential buildings

Demand-side policy support has a significant role in energy systems. System profitability will widely hinge on planning and programming under conventional systems with no support. On the other hand, in smart grids, buildings are no longer passive consumers, but they can be used for demand-side energy management. In this study, two energy systems are assumed for an on-grid smart building. The power grid and PV panels are the first system’s electricity suppliers, and the thermal load is fulfilled by an electric boiler, Solar Collector (SC), and thermal storage in this system. The second energy system, instead of an electric boiler, is equipped with a gas boiler. As a consequence of investigating this system as an energy hub, the best combination and optimized size of each design are achieved using the Particle Swarm Optimization heuristic method (PSO) via MATLAB software based on technical and economic benchmarks. The payback period for the system equipped with a gas boiler is equal to 3.3 years, compared to 4.3 years of the electric boiler system payback and their net present value is 4633.9$ and 3909.5$ respectively. The results of optimization inditated that the PV panels should be 15 m2 in size, the solar collector should have a size of 2.68 m2, and the gas boiler should be 3.09 kW in capacity. The optimization results indicate that the solar collector is not beneficial in the system with the gas boiler, so all of the thermal loads have been provided with a gas boiler in this system.

Assessment of a mixed-mode vertical solar dryer for experimental turmeric drying

Solar drying, an eco-friendly and sustainable approach harnesses solar radiations to remove moisture from a drying commodity, thereby preventing its spoilage and extending shelf life. Turmeric (Curcuma longa), a popular herb is being used for centuries in Ayurveda as a traditional medicine. Since, fresh turmeric contains 80–90 % moisture content, therefore, it is quite difficult to store for a longer period. An innovative and compact mixed-mode vertical solar dryer (MVSD) with a circular solar collector (solar tracking geometry) is developed and tested for turmeric slices drying under partial and fully loaded conditions. Turmeric samples of 2, 3 and 4 mm slices thicknesses were used for experimentation under partial loading condition. The thickness of the turmeric slices was observed to affect the performance of the MVSD. The drying rate and thermal efficiency were observed to be highest for 3 mm thick turmeric slices sample under partially loaded condition. The MVSD was further tested with full loading capacity for 3 mm thick turmeric slices drying under natural and forced convection (NC and FC), respectively modes. The drying behavior of turmeric slices was well described by Midilii-Kucuk model. Heat transfer coefficients and efficiency (thermal and exergy) were observed to be higher under FC mode. Embodied energy and energy payback time were observed as 554.44 and 585.53 kWh; and 4.39 and 4.55 years under NC and FC modes, respectively. Annualised cost and payback period were observed to be desirable for NC mode.

An MINLP-based decision-making tool to help microbreweries improve energy efficiency and reduce carbon footprint through retrofits

Microbreweries have greater production costs per litre of beer compared to large breweries, as well as higher carbon footprints. Due to the range of different retrofit technologies available and the different capacities and configurations of microbreweries, it is not always clear what retrofits will improve operations. Therefore, this work proposes a novel mixed-integer nonlinear programming decision-making tool to be used by any microbrewery, that determines the technoeconomic feasibility and sizing of energy efficiency-improving retrofits, including solar and wind power, battery storage, anaerobic digestion, boiler type selection, heat integration by heat storage, and carbon capture via dual-function materials. The model was demonstrated on a real UK microbrewery case study. The model gave an optimal configuration of a 10 m3 anaerobic digester, 30 solar panels outputting 380 W each, an 800 W wind turbine and a 2.3 m3 heat storage tank, reducing annual operating costs by 62.9 % and carbon dioxide emissions by 77.1 % with a payback period of 8 years. The tool is designed to be flexible for use by any microbrewery in any location with any brewing recipe and allow the owner(s) to develop more profitable and sustainable microbreweries.Tweetable abstractMicrobreweries can implement mathematically optimised renewable energy, heat integration and anaerobic digestion to reduce operating costs by 62.9 % and carbon emissions by 77.1 %.

Driving industrial symbiosis: Evaluating policy intervention effects on waste heat utilization in local district heating networks

This study aims to quantitatively assess the required policy support level to ensure economic viability for all stakeholders in the context of using industrial waste heat as source of local district heating (DH). Additionally, the research explores the potential of industrial symbiosis to support district-level energy transition in the context of Positive Energy Districts and Smart Cities. The proposed approach combines energy modelling tools, namely the Multi Energy System Simulator (MESS) model and financial concepts (i.e. Cash Flow Analysis, Net Present Value Evaluation) typical of industry’s project evaluation. It is then tested in the area of Bolzano, Italy. The study examines various policy scenarios, including financial incentives and the involvement of district heating operators (DHOs). Initial findings indicate that district heating offers significant cost advantages (up to –23%) over electrified systems. However, industries face challenges meeting standard payback periods without policy intervention in the context of projects using waste heat as a source of DH. A combined scenario involving DHOs handling connection costs with a 60% incentive and industries receiving a 15% Feed-In Premium shows promising results in achieving economic feasibility. The results underscore the critical role of policy support in overcoming barriers. Consequently, it is possible to strengthen cooperation between industries and districts fostering local energy transition. Nonetheless, the achievement of positive energy balance requires a stronger presence of RES particularly on the electricity side. The study highlights the broader implications for similar projects in other regions and the essential role of policy interventions in facilitating such industrial symbiosis.

Waste to hydrogen: Investigation of different loads of diesel engine exhaust gas

In this study, green hydrogen production by utilizing diesel engine exhaust gas waste heat in steam and organic Rankine with internal heat exchanger with two thermoelectric generators and proton exchange membrane electrolyzer combined system under different load conditions is investigated. Thermo-economic, enviro-economic and exergo-environmental analyses of the maximum hydrogen production point determined for different waste heat conditions are carried out. Total and specific investment cost and levelized cost of hydrogen determined under different loads are compared. Simple and dynamic payback period, profit ratio of investment and net present value of the combined system at different selling prices of hydrogen are determined and their feasibility is analyzed. Carbon reduction and carbon credit gain amount due to green hydrogen produced in line with zero emission targets are compared under different waste heat conditions. Exergetic sustainability index of the system were determined within the scope of exergo-environmental analysis. In terms of economic and environmental performance, a hydrogen cost of 2.04 $/kg was obtained under 100% load and a carbon saving of 7211 $ was achieved depending on the hydrogen produced. Dynamic payback period and net present value were found to be 4.467 years and 404,696 $, respectively, if the hydrogen selling price was 5 $/kg under 100% load. It is found that a 50% load reduction leads to an increase in dynamic payback period and levelized cost of hydrogen by 18.6% and 13.72%, respectively, and a decrease in net present value and profit ratio of investment by 54.39% and 12.39%, respectively. On the other hand, since the exergy destruction decreases with the decrease in the load, exergo-environmental index is found to decrease by 2.03%.

Multistage data center cooling system for temperature gradation and matching

A prototype of a multistage cooling system with a cooling capacity of 20 kW is assembled and studied. The traditional single-stage system is split into two sub-systems according to the temperature level, which reduces the temperature difference and irreversible heat transfer loss, and further improves the system's energy efficiency. The system mainly features three modes including free-air cooling, refrigeration-based cooling and waste heat recovery, which can achieve efficient cooling while capable of recovering the waste heat to the surrounding heat users. The efficiency of the proposed cooling and heat recovery system was assessed by measuring its energy reuse effectiveness (ERE). The energy savings and environmental benefits of the system were analyzed across five cities in China, each representing different climates. Results indicate that the system achieved an ERE of 0.91 in Beijing, 38.9 % lower than the national average of the city. Additionally, an economic analysis showed a payback period of less than two years for the proposed system across all climates considered, which is 30 % shorter than that of a single-stage cooling system.

Energy and enviro‐economic (3E) assessment of greenhouse solar dryer (GHSD) for drying and quality evaluation of medicinal Ocimum sanctum leaves: A sustainable path for preservation

AbstractThis article presents an experimental analysis of greenhouse solar dryer (GHSD) under natural and forced convection for shelf storage of Tulsi (Ocimum sanctum) leaves, and the obtained results are compared with conventional open sun drying and shade drying to determine the optimal drying method. The GHSD, being capable of raising the interior temperature 15–25 °C higher than the ambient temperature, took only 2.5 and 2.0 h for drying of 100 gm Tulsi under natural and forced convection mode compared to 5.0 and 7.0 h in open sun and shade drying, respectively. The peak drying rate under natural and forced convection GHSD drying was 0.57 and 0.70 gm of water per gram of dry solid, while dryer efficiencies were estimated as 14% and 16%, respectively. The findings revealed a reduction in drying time by 50% and 60% compared to open sun drying, and by 64% and 71% compared to shade drying under natural and forced convection, respectively. The calculated energy payback time (EPBT) was 0.78 years with earned carbon credit of US$ 60.22 for 10 years of intended life span while the economic payback period was 1.3 years associated with potential saving of Rs 1,11,916. In quality evaluation, total phenolic and flavonoid content (73.39 mg GAE/g and 5.09 mg QE/g) along with antioxidant potential (IC50 value: 55.09 μg/mL) have been recorded higher for the leaves dried in GHSD compared to open sun drying. The findings established a sustainable, eco‐friendly and economical path for the blooming herbal medicine industry.Practical applicationGreenhouse solar dryer is an eco‐friendly, sustainable, clean and hygienic way to dry herbs and medicinal plants. The greenhouse solar dryer can shorten the drying time by 50%–60% compared to natural stand in the sun (OSD), improve the quality of dried herbs and medicinal plants, and reduce the decay rate of the dried products. These leaves can be best suited for Ayurveda medicine industries for herbal powder (Churna). Being economically advantageous, greenhouse solar dryers improve the shelf life of the dried leaves, reduce their density, and lower transportation costs, boosting farmers' income in herbal farming and nutritional security.

Solar methanol production from carbon dioxide and water using NaA zeolitic membrane reactor with pressurized solid oxide electrolysis cell

Solar-driven methanol synthesis coupled with water electrolysis can achieve carbon-negative methanol production. In this study, a solar methanol production system using water-conduction membrane reactor coupled with pressurized solid oxide electrolysis cell is proposed. A methanol synthesis membrane reactor model and a solar-driven pressurized solid oxide electrolysis cell model are developed and validated. Under the specified conditions, the conversion efficiency of the membrane reactor is found to be twice as high as that of a conventional reactor. A thermodynamic model is developed to simulate the system's performance. Using this model, the energy flows within the system are visually represented through a Sankey diagram, providing a clear illustration of energy distribution and losses. Additionally, effects of the solid oxide electrolysis cell temperature, current density, methanol synthesis temperature and pressure on the system performance are investigated parametrically. An optimum solar-to-methanol efficiency of 7.3 % is obtained. Furthermore, the economic analysis shows the levelized cost of methanol close to 1.40 Euro/kg and the payback period is around 4.5 years. This study proposed a novel efficient solar methanol production system.