Theoretical work for concentrated solar-operated green hydrogen production system using compound parabolic
concentrator (CPC) integrated with solar photovoltaic (PV) cells driving proton membrane electrolysis (PME)
was developed, analysed, and evaluated under winter and summer conditions. Mathematical models for the
system components, including the CPC-PV integrated unit and the electrolyzer, were developed and solved. Key
system performance parameters were also evaluated. The system of equations was solved using MATLAB. Results
of the mathematical model show that for 1 m2 of the PV panel, the hydrogen production flowrate reaches a peak
on 0.0175 kg/h in summer and 0.0144 kg/h in winter, while the CPC-PV system power output can reach up to
607 W in summer and 590 W in winter. The PV efficiency in the CPC-PV system increases to about 14.75 % in
both seasons. Additionally, the overall system shows a summer and winter efficiency of nearly 13 % with a slight
variation between both seasons. The minimum achieved cost of hydrogen production of the system during
summer and winter is $0.17/kg and $0.271/kg, respectively at concentration ratio of 5. The system shows
promising performance under operation of different concentration ratios provided by CPC-PV system, highlighting
the system ability to enhance the production of green hydrogen gas cost effectively.

Electric and hybrid electric vehicles are promising alternatives to tackle environmental impact and greenhouse
gas emissions associated with internal combustion engine vehicles. Electric vehicles have fueled the need for an
efficient energy storage system to provide high power output, maximum energy density, and rapid charging.
Lithium-ion batteries are a viable alternative as their high power density and energy capacity make them stand
out from their long lifespan and quick charging capabilities. However, thermal energy generated during charging
and discharging can cause safety concerns. In this regard, an experimental study was conducted to assess cooling
performance using four distinct phase-change-materials (PCM): PARA-Block, RT-54 HC, RT-44 HC and RT-35 HC
were tested in a cyclic test, which showed a reduction in the battery's maximum temperature to 59.6 
C, 50.9 ◦ C, 51.9  ◦C respectively, compared to 76.4  C with natural convection cooling. For further modification to
achieve the cell's optimum operating temperature and shape stabilized material, various weight percentages of
expanded graphite (EG) (3 %, 6 %, 12 %, 15 %) were added to obtain composite stable phase change material
(CPCM). The results showed that the battery's highest temperature decreased by almost 55 % by adding 12 % EG
to PCM RT 35 HC compared to natural cooling. In addition, the best conditions were applied for a four-battery
pack.

Passive cooling of photovoltaic systems has been demonstrated to enhance their electrical performance at costeffective
methods. Among passive mechanisms, evaporative cooling stands out, particularly when utilizing
water-saturated porous structures. This study explores the parametric analysis of a porous clay structure as an
evaporative cooler for building integrated photovoltaic (BIPV) systems. It examines key parameters such as water
saturation levels and meteorological conditions, including wind velocity and relative humidity, assessing their
influence on system’s cooling performance. A numerical heat and mass transport model, along with the evaporation
model based on energy balance principle were presented and solved for this purpose. Further, experimental
evaluation of material variations was conducted utilizing hollow porous clay and traditional hollow red
brick structures, concurrently validating the numerical model. The experimental results highlight significant
improvements, with a 6 % reduction in peak PV temperature observed when using a porous clay structure
compared to conventional red bricks. The parametric study further revealed a maximum 9.7 % reduction in peak
PV temperature at higher water saturation levels. Notably, PV electrical efficiency and output power showed
peak enhancements of 0.93 % and 1.6 %, respectively, when humidity levels were halved rather than doubled.
Additionally, doubling wind velocity led to a 1.13 % decrease in indoor room temperature compared to halved
velocity values, demonstrating the effectiveness of these parameters in optimizing building cooling and PV
performance. Moreover, water evaporation rates reached a maximum of 6.07 L/h.m
2 and a minimum of 2.4 L/h. m 2 when the wind velocity and humidity values were doubled. Moreover, the system attained its highest water consumption rate of 10.19 L/h.m 2 when wind velocity values were doubled. Hence, these findings offer essential insights, underscoring the considerable impact that different operational conditions have on the effectiveness of evaporative cooling systems.

Solar energy electricity generation with concentrated photovoltaic (CPV) panels delivering substantially higher
power output than non-concentrated panels. However, CPVs suffer from excessive heat accumulation and non-
uniform temperature distribution, both of which severely impact electrical efficiency and shorten the panels’
lifespan. This study explores the implementation of a passive evaporative cooling strategy coupled with heat pipe
to mitigate CPV temperature rise. To address this challenge, a novel dual-function mechanism is proposed,
enabling efficient CPV cooling while simultaneously capturing and condensing fresh water to minimize evaporative
cooling losses. The study evaluates the proposed water harvesting indirect cooling mechanism
(WH-ICM) against two alternative cooling strategies: the direct cooling mechanism (DCM),
where the evaporative structure is directly attached to the panel’s backside, and the indirect cooling mechanism
(ICM),b which incorporates a heat pipe. The findings revealed that the ICM attained the highest average PV temperature reduction of 45.2 C, representing a 45.3 % improvement over the conventional PV system. Meanwhile, the WH-ICM followed closely with a 42.3  C reduction, marking a 42.4 % enhancement. Furthermore, WH-ICM boosted the average PV output power by 36.8 % and improved average efficiency by 30 % compared to the standard PV system. It also harvested
2.87 kg/day.m ◦2 of water, with a consumption of 25.36 kg/day.m2, recovering around 11.3 % of the total water
used. Notably, integrating WH-ICM increased the system’s daily average overall efficiency to 19.43 %, reflecting
a 36.26 % improvement over the conventional PV system, and a 7.7 % and 3.1 % raise compared to the DCM and
ICM, respectively.

This study evaluates the performance of a new standalone integrated system for independent hydrogen production combining waste heat recovery (WHR) via thermoelectric generators, humidification-dehumidification
(HDH), and a proton exchange membrane (PEM) electrolyzer. The system’s behavior is analyzed at varying
steam inlet temperatures and qualities to identify the best configuration for power generation. A complete
mathematical model of the whole system unit is constructed, programmed inside Matlab, solved, and validated.
Four configurations are studied for the thermoelectric generator unit distributions [100 × 100], [50 × 200],
[25 × 400], and [12 × 833]. Configuration 4 (12 ×833 TEG arrangement) outperforms others, generating
36.88 kW at 160 ◦C and 0.97 steam inlet quality, a 130 % increase compared to 100 C. This configuration extracts 337 kW from steam, enabling a hydrogen production rate of 15.5 kg/day with PEM efficiency peaking 73.65 % (declining to 68.94 % at 160 ◦◦C due to overpotentials). The HDH unit is operating at a GOR of 1.892. The system efficiency increased from 4.45 % at 100 ◦C to 4.95 % at 160 C, driven by enhanced TEG power generation. Economic analysis reveals a levelized hydrogen cost (LCOH) of 2.22–2.22–2.96/kg, competitive with blue hydrogen markets. Net Present Value (NPV) analysis shows profitability at 3–5 $/kg hydrogen, with breakeven 10–20 years for 3 $/kg and 4–5 years for 5 $/kg. Excess water utilization in the PEM electrolyzer reaches near-zero at 160 ◦ C, contrasting with 55 % excess at 100 ◦◦C. Trade-offs between steam quality and hydrogen yield are quantified: increasing quality from 0.05 to 0.97 at 100 C raises hydrogen production by 0.45 % (6.97–7.01 kg/day), while higher temperatures prioritize power over electrolyzer efficiency.

This study investigates the gasification of tea waste biomass in a fluidized bed reactor, with a focus on optimizing
syngas composition and energy content. A lab-scale hot flow fluidization bed reactor is designed, fabricated and
installed. The impact of fluidization parameters, velocity and gasification temperature on the quality of syngas
products is investigated. The effect of these parameters on the CO and H
percentages and calorific value of the produced syngas is studied. The results show that increasing air injection velocity enhances carbon monoxide (CO) production and reduces carbon dioxide (CO2) levels, with an optimal air injection velocity of 15 m/s for maximizing syngas calorific value. Furthermore, a gasification temperature of around 400  C is found to be optimal for producing syngas with high calorific value, balancing CO and hydrogen (H) production while minimizing CO2 . A higher CO/CO ratio is closely linked to increased syngas energy content, while the methane to hydrogen ratio also influences calorific value, though its impact is less predictable.

To achieve affordable and clean energy as part of the sustainable development goals, a techno-enviro-economic
performance of solar Photovoltaics (PV) and Vertical Axis Wind Turbines (VAWT) hybrid system for street
lighting load of New Borg El-Arab city, Egypt is presented. The system is designed for both standalone battery
storage and grid-connected at different ratios of energy sources “PV 100%”, “VAWT 100%”, “PV 50% and VAWT
50%”, “PV 33.3%, and VAWT 66.7%” and “PV 66.7% and VAWT 33.3%”. The physical model was created in
Autodesk INVENTOR, the spacing of the wind turbine was simulated on ANSYS FLUENT, the spacing of the solar
photovoltaic panels was simulated in Autodesk REVIT, the mathematical model was solved in MATLAB and
Microsoft EXCEL. The study outcomes reveal that the energy system distribution for the grid-connected and
standalone systems are about the same achieving smaller turbine numbers, PV panels, and land space in the case
of grid-connected systems. The minimum capital and payback period are achieved by the grid-connected system
with a land ratio of “PV 100%”. It has a payback period of 12 years while using a land area of 139 m
. It used 30 Solar PV panels to supply a total energy of 20,829 kWh for 1 year. This resulted in a levelized cost of electricity of 0.0096 $/kWh and 450 tonnes of CO emission savings. This shows 100% PVs grid-connected system is more economically viable than the hybrid system.

This study focuses on enhancing the efficiency of vertical axis Savonius Hydrokinetic turbines designed for
marine applications, historically characterized by a power coefficient below 0.1. Prior efforts aimed at improving
rotor performance have primarily involved modifications to blade designs. In this article, a new approach is
introduced, incorporating twisted blades inspired by the Archimedes screw turbine. Utilizing a 3D incompressible
flow analysis based on the Navier-Stokes equation, this research explores and compares the turbine’s
effectiveness with varying screw pitches (0.5, 0.75, 1). The system of equations is solved numerically using
ANSYS 2020 R2 fluid fluent. The performance assessment involves contrasting each proposed rotor against a
pitchless semi-circle rotor. An innovative aspect of this work involves investigating the impact of asymmetry
using two different ratios (2:1 and 3:1). Specifically, the lower half of the optimal pitch screw remains constant,
while the upper half varies based on these ratios. To understand performance trends, the study employs visualizations
of pressure, velocity contours, and streamlines to grasp the flow field and its underlying principles.
Turbulent kinetic energy and eddy viscosity are also visualized. The results reveal an 18.25 % improvement in
performance with the proposed rotor featuring a pitch screw of 0.5. Notably, the asymmetric rotor with a 2:1
ratio demonstrates the highest performance. According to the ANN, the optimum pitch screw value is determined
to be 0.6, achieving a power coefficient of 0.1938. This investigation employs novel design modifications and
asymmetrical configurations, offering valuable insights into significantly enhancing the performance of Savonius
turbines for marine applications.

As the adoption of renewable energy is on the rise all around the world, the use of wind and solar energy is
increasing rapidly. Most wind or solar farms only use a single energy resource for generation on a specific area of
land. So, this study presents a techno-enviro-economic evaluation of using both horizontal axis wind turbines and
photovoltaic panels on the same land area to increase land utilisation, it is presented on the map of Egypt as a
case study. The area of the wind turbine shadows on the solar photovoltaic panels are estimated using new
technique of image processing with Python code. An energy model was developed on MATLAB Simulink to
analyse the yield energy generation. The dual use of land is compared to cases using solar only, and wind only for
wind turbines ranging from 0.75 MW to 3 MW. The results demonstrate that the dual use land produces the
highest amount of energy yearly in 41 % of the governorates when using the 0.75 MW turbine. Then, the dual use
land produces the highest amount of energy in 100 % of the governorates when using the 1.5 MW and 3 MW
wind turbines. This shows that the bigger the size of the turbines, the lesser the effect of the shadows on the
overall energy being produced. In terms of economic viability, the best performing case used solar photovoltaic
only in Aswan governorate with a total energy generation of 594,856 MWh and total CO
emission reduction of 10,351 tonnes over the 25 years project lifetime. It has an LCOE of 0.01050 $/kWh, a payback period of 8.96 years, and a capital cost of $3,391,956. In conclusion, the study results show that dual-use land can improve the economic viability of projects using only wind turbines for energy generation in Egypt.