The paper aims to assess the performance of three different Organic Rankine Cycle (ORC) configurations from thermodynamic and economic standpoints. The examined configurations include: Basic ORC ...(B-ORC), Reheating ORC (RH-ORC) and Regenerative ORC with an open feed-heater (REG-ORC). Four different working fluids R123, R245fa, Isobutane and R152a were assessed energetically, exergetically and economically. Key factors that affect thermal efficiency, exergy efficiency, payback period (PP) and levelized cost of energy (LCOE) are discussed in detail. The results demonstrate that the REG-ORC shows better energy efficiency among the analyzed ORCs. It is higher by about 13% than the basic ORC for the same working conditions, whereas the thermal efficiencies of the basic and reheat ORC are so close to each other. Furthermore, the exergy destruction of the REG-ORC is the smallest, 44% less than that of the B-ORC. Economic evaluation based on the calculation of the payback period and LCOE showed a close similarity for the examined ORC configurations. Taking the three criteria together, it seems that the REG-ORC is the recommended system independently of working fluid category. Finally a sensitivity analysis was conducted to determine the economic parameters that mostly influence the economics of the system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The development of novel grid-connected integrated renewable energy systems for sustainable residential buildings is vital. The aim of this paper is to analyze the energy, economic and environmental ...performance of a novel grid-connected renewable energy system consisting of solar hybrid PV-Thermal collectors, wind turbine and sensible heat storage. The new integrated system serves concurrently hot water and electricity loads to a single-family building located in Laayoune, Morocco. The system adopts a stratified thermal storage and an auxiliary back-up to satisfy continuously the thermal load. Energy interaction between the examined system, load and grid is predicted at regular time intervals of 0.25 h. For a wind capacity of 1.2 kW, PV-T thermal collectors with a total area of 2.84 m2 and a storage tank of 0.3 m3, the system was able to satisfy 43.08% and 64.8% of the electric and heat demand, respectively. Compared to three other power supply scenarios, the economic assessment of the proposed configuration revealed that its Net Present Cost (NPC) is lower by 20.7%, 10.7% and 11.5% compared to grid only, PV-T only and wind only scenarios, respectively. As such, the novel system presents promising development perspectives especially that it allows additionally a reduction of up to 54% in the annual CO2 emissions compared to the conventional energy supply mode relying entirely on the electric grid.
•A novel hybrid PV-T/Wind system with thermal storage for electricity and heat generation•Self-consumption and self-sufficiency ratios are 90.25% and 43.08%, respectively.•Net present Cost of the proposed system is significantly lower than other options•The system can achieve an annual CO2 emission reduction of 54%
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, a new multi-objective optimization approach is introduced to optimize economically and environmentally the implementation of solar photovoltaic systems for self-consumption under the ...scenario of zero export injection. Such a scenario is encountered in several developing countries, but up to the author’s knowledge, no previous study dealt with its detailed assessment and optimization. The problem formulation considers using the levelized cost of electricity (LCOE) and the cumulative environmental benefit (CEB) as two life-cycle conflicting objective functions. First, a multiple linear regression technique was developed to predict accurately the PV power generation under a time resolution of 15 min as recommended for PV-self consumption studies. A new mathematical expression was as well derived to calculate more accurately the CEB considering both the degradation of the PV productivity over the project lifetime and the dynamic evolution of the electricity mix of the country with respect to time. A Genetic algorithm (GA) is used to identify Pareto frontiers and Technique for Order Preference by Similarity to Ideal Solution “TOPSIS” decision-making method is employed to select the final optimum. The followed approach was applied for a large Moroccan commercial structure with an annual electric load of 2.932 GWh. It was found that the recommended optimum PV installed capacity is 847.4 kWp. This optimized design leads to the best compromise between economic and environmental aspects and the LCOE is 15.12 c$/kWh while the CEB is 7.89 tonnes CO2. The corresponding self-sufficiency and self-consumption ratios were estimated at 41.41% and 79.14%, respectively.
•Optimal integration of solar photovoltaic systems under the scenario of zero export injection.•Multi-objective optimization approach based on two life cycle environmental and financial criteria.•Building a simple multiple linear regression model to predict AC photovoltaic power.•New mathematical expression to estimate the environmental benefit considering the evolution of national energy mix.•Optimum PV capacities in terms of LCOE and CEB are given for six cities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper emphasizes the conceptualization and techno-economic-environmental analysis of a novel power-to-heat system based on the excess energy from solar photovoltaic (PV) plants and open-loop ...geothermal heat pumps (GHPs). This integrated energy system is engineered to supply simultaneously the electric load in a residential community and the heat demand in a primary school. The solar PV plant was optimized in a way to maximize the project net present value (NPV). Environmental accounting was as well introduced by estimating the total environmental penalty cost saving (TEPCS) for various carbon prices. Several scenarios were investigated, and corresponding optimum designs were determined. For annual electric and heat demand of 207.46 MWhele and 13.67 MWhth in the residential community and the primary school, respectively, the optimum PV capacity to be installed is 26 kWp when no inflation of the grid electricity cost is considered. For this optimum PV capacity, the NPV is about 19.41 k$. The annual savings and discounted payback period for this case are calculated as 4.88 k$/year and 14.45 years, respectively. Including carbon prices enhanced the economic attractiveness of the concept. For a carbon cost of 40 $/tCO2, the recommended PV capacity is 36.4 kWp giving rise to a TCS of 33.8 k$.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This review reports the most recent developments of solar thermoelectric generators and their promising integration options within various solar thermal collectors and processes. These combined ...structures provide thermal energy with additional electric power which implies better harnessing of solar irradiation. First, fundamentals of combined solar thermal conversion systems including thermoelectric generators are presented along with a basic mathematical formulation of the physical problem. The main assessment indexes used to evaluate the performance of such systems are as well summarized. Recent investigations related to the utilization of thermoelectric generators in the various solar thermal stationary and concentrating collectors and processes are reviewed and analyzed. A deep analysis of the major technical, operational and financial challenges is provided as well as research directions related to the development of high-efficiency solar thermoelectric hybrid configurations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper assesses energetically and economically the power-to-hydrogen concept by exploring the excess power resulting from the mismatch between the photovoltaic (PV) generation and the electric ...demand of a medium-size commercial structure located in Morocco. The variability in the building electric load is considered and the power flows from the PV field to the building are predicted using Artificial Neural Networks for a time-resolution of 15 min. A MATLAB code was implemented to estimate the instantaneous hydrogen production based on a semi-empirical mathematical formulation of an Alkaline type electrolyzer with a nominal capacity of 15 kW. These combined approaches are for the first time adopted to evaluate the feasibility of integrated PV hydrogen systems under the Moroccan context. Using a set of 5 electrolyzers coupled to the 104 kWp currently installed solar PV field, it was possible to generate about 18,622 Nm3/year of hydrogen by exploring the PV excess power. The overall efficiency of the integrated system ranged from 9.5% (in March) to 10.1% (in May). Such an approach allowed enhancing the effective efficiency and capacity factor to values of 9.873% and 26.87%, respectively compared to 6.325% and 10.163% for the base case scenario without hydrogen systems. From an economic perspective, it was found that the integrated PV-hydrogen plant engendered levelized cost of electricity and hydrogen of 12.56 c$/kWh and 21.55 $/kg, respectively.
•Managing excess PV energy via the power-o-hydrogen concept.•ANNs are used to predict AC power from PV field.•Variable building load with sub-hourly values is considered.•Excess PV power can generate a yearly hydrogen production of 18 622 Nm3.•Integrated PV-hydrogen system improved considerably the effective capacity factor.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This work focuses on the design and optimization of a hybrid renewable energy system (HRES) consisting of solar photovoltaic (PV), wind turbine with battery storage to support a run-of-river ...micro-hydropower plant. The objective is to provide clean and reliable electricity for Ouenskra, a rural site in Morocco. The main objective is to enhance energy access and promote sustainable development in the region. Furthermore, a part of electricity generated from the HRES was employed to provide clean hydrogen required by fuel cell bikes to serve as a green transportation technique. The total daily electric load requirement for local community in Ouenskra was determined to be in the range of 400 kWh. The optimized HRES demonstrated cost-effectiveness for rural electrification, with a Net Present Cost (NPC) of 473.6 k$ and a Cost of Electricity (COE) of 0.147 $/kWh. The HRES configuration ensured reliable electricity generation, with solar energy contributing 60 % of the total electricity generated and the micro-hydropower plant contributing 40 %. The HRES was also able to satisfy a hydrogen load of 0.2 kg/h for about 69 daily charging sessions to power fuel cell bikes. Sensitivity analysis indicated that higher solar energy potential, as indicated by increased Global Horizontal Irradiance (GHI), resulted in reduced NPC and COE values, as well as decreased PV capacity requirements. Furthermore, the variability of wind resources had limited impact on the HRES configuration and overall profitability, with wind speeds below 7 m/s showing no significant changes in NPC and COE. The study's findings align with Morocco's sustainable development goals, offering practical and tangible solutions for addressing the energy and transportation needs of rural communities, and promoting a greener and more environmentally friendly energy sector.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The objective of this paper is to assess the potential of machine learning algorithms in predicting the indoor air temperature in a greenhouse using the outdoor data. A dataset gathering the main ...weather data and the indoor air temperature of a greenhouse located in Agadir, Morocco was used for this purpose. Machine learning models including support vector machine based-regression, ensemble trees and Gaussian process regression are compared against multiple linear regression models. This comparison was carried out on the basis of a 5-fold cross validation framework and across unseen data. The results show that all predictive models are capable of describing the indoor air temperature of the greenhouse and perform well (R2 > 0.9), with only 10% fraction of the dataset as training data. The Gaussian process regression outperforms all models, with R2 = 0.94 in the 5-fold cross validation test. However, the computational time related to the training of Gaussian process regression model is slightly higher than other machine learning models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Solar heat is an attractive alternative in industrial processes. However, the intermittent and stochastic nature of solar energy necessitates the use of heat storage systems to bridge the gap between ...heat production and demand. This study introduces a validated numerical analysis approach to investigate the performance of latent storage tanks filled with spherical phase-change materials. A 1D thermal model is developed to describe the charging processes of adipic acid as PCM. The study examines the performance characteristics of latent heat storage in terms of stored energy and duration through parametric investigations. For mass flow rates ranging from 600 to 1000 kg/h, storage durations were found to vary from 440 to 582 min. The storage duration decreased significantly from approximately 1150 min at a charging temperature of 160 °C to 470 min at a charging temperature of 240 °C. The bed porosity affected the storage process, with a porosity of 0.5 achieving a thermal energy storage of around 344 MJ but requiring a longer charging time of about 610 min. Higher heating rates allowed for lower storage durations, with storage durations of approximately 460 min for a heating rate of 3 °C/min, compared to 660 min, for a heating rate of 0.5 °C/min.
Protected crop production is rapidly expanding in the Mediterranean Basin, and particularly in Morocco. Increased local and overseas demand for these products led to a rapid development in greenhouse ...usage encouraged by government policies. The aim of this study is to investigate key design parameters that affect the thermal behavior and the heating/cooling energy need of a greenhouse situated in Agadir (Morocco). The parameters include the cladding material characteristics, shape, orientation, and air change rate. The greenhouse is modeled by a developed thermal model using TRNSYS software. The model considers the presence of the plants inside the greenhouse by adding the heat and humidity gain into the heat and water balance of the greenhouse using an evapotranspiration sub-model. The effect of evapotranspiration on the greenhouse thermal behavior was also examined in this study. A validation of the current TRNSYS simulation and evapotranspiration model was made using previous studies from the literature, and the comparison showed fair agreement. The relative error of the annually heating demand obtained by this model is 1.66%, and the evapotranspiration model used in this study shows relative deviation less than 6.5%. The results of this study indicate that the East-West greenhouse orientation is the optimum orientation as it can reduce the annual cost of air-conditioning of the greenhouse by 9.28% compared to North-South orientation. Quonset shape is the optimum greenhouse shape in Morocco as it can save 14.44% of annual cost of air-conditioning instead of the Even-span shape.
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