• Energy Research

The effect of Phosphotungstic acid (PWA) on the proton conductivity and morphology of zirconium phosphate (ZrP), porous polytetrafluoethylene (PTFE), glycerol (GLY) composite membrane was investigated in this work. The composite membranes were synthesized using two approaches: (1) Phosphotungstic acid (PWA) added to phosphoric acid and, (2) PWA + silicic acid were added to phosphoric acid. ZrP was formed inside the pores of PTFE via the in situ precipitation. The membranes were evaluated for their morphology and proton conductivity. The proton conductivity of PWA–ZrP/PTFE/GLY membrane was 0.003 S cm−1. When PWA was combined with silicic acid, the proton conductivity increased from 0.003 to 0.059 S cm−1 (became about 60% of Nafion’s). This conductivity is higher than the proton conductivity of Nafion–silica–PWA membranes reported in the literature. The SEM results showed a porous structure for the modified membranes. The porous structure combined with this reasonable proton conductivity would make these membranes suitable as the electrolyte component in the catalyst layer for direct hydrocarbon fuel cell applications.

Nanofluids, comprising nanoparticles and a base fluid, have captured substantial interest due to remarkable enhancements in thermal conductivity and other crucial thermophysical properties. These advancements facilitate diverse applications across various industrial processes, including biomedical and drug research. This review centers on non-Newtonian nanofluids, which diverge from Newton's law of viscosity, rendering them more adaptable and versatile. Through a comprehensive examination of the latest research, preparation methods, including both one-step and two-step techniques, and their formulations in oil-based, water-based, and ethylene glycol-based solutions are systematically explored. The study synthesizes findings that highlight significant improvements in heat transfer efficiency and introduces novel applications in sectors, such as biomedical engineering and energy systems. Furthermore, an in-depth characterization of non-Newtonian nanofluids is provided, covering their rheological, dispersion, transport, magnetic, optical, and radiative properties. These fluids are increasingly utilized in heat exchangers, automotive radiators, engines, solar collectors, and electronic coolants, demonstrating their broad spectrum of practical applications. This review shows that the ongoing challenges are primarily centered on the preparation, stability, and commercialization of non-Newtonian nanofluids. Conclusively, the paper underscores the potential of non-Newtonian nanofluids to revolutionize various technological areas and advocates for continued research to develop more stable and efficient formulations, paving the way for innovative industrial and scientific applications.

Thermal energy storage systems are extensively investigated because of their fundamental role in the storage of renewable energy and in the recovery of useful heat generated from various systems. The three mechanisms of thermal energy storage are discussed herein: sensible heat storage (QS,stor), latent heat storage (QL,stor), and sorption heat storage (QSP,stor). Various materials were evaluated in the literature for their potential as heat storage mediums in thermal storage systems. The evaluation criteria include their heat storage capacity, thermal conductivity, and cyclic stability for long-term usage. This work offers a comprehensive review of the recent advances in materials employed for thermal energy storage. It presents the various materials that have been synthesized in recent years to optimize the thermal performance of QS,stor, QL,stor, and QSP,stor systems, along with the challenges associated with thermal energy storage materials. The paper concludes that latent heat storage systems via the use of inorganic phase change materials (PCMs) would be ideal for high-temperature applications.

Abstract The world's first fuel cell described in the early 1800's was fueled with hydrogen. While hydrogen is still the most common fuel, hydrocarbon fuels offer several advantages including availability at a lower cost, higher storage density and existing infrastructure. This paper provides an overview for the significant potential benefits of using hydrocarbon fuels directly in a fuel cell system. Their use leads to a reduction in the capital cost due to the elimination of the fuel processor unit. The fundamentals, advantages, types of direct hydrocarbon fuel cells (DHFC), challenges and applications are discussed in this paper. The past and current status of research and development activities are addressed with emphasis on efficiency and exergy analyses. In spite of their high theoretical energy efficiency, technical challenges remain unsolved in DHFC systems. In high temperature hydrocarbon fueled operation, the deposition of carbon-based material leads to fuel cell degradation. In lower temperature fuel cells, electrode (mainly the anode) over-potentials and fuel crossover are still challenging. Therefore, the improvement and commercialization of these types of fuel cells will probably require the development of less or non-noble catalysts and reasonably functioning membranes.

This work evaluates date palm waste as a cheap and available biomass feedstock in UAE for the production of biofuels. The thermochemical and biochemical routes including pyrolysis, gasification, and fermentation were investigated. Simulations were done to produce biofuels from biomass via Aspen Plus v.10. The simulation results showed that for a tonne of biomass feed, gasification produced 56 kg of hydrogen and fermentation yielded 233 kg of ethanol. Process energy requirements, however, proved to offset the bioethanol product value. For 1 tonne of biomass feed, the net duty for pyrolysis was 37 kJ, for gasification was 725 kJ, and for fermentation was 7481.5 kJ. Furthermore, for 1 tonne of date palm waste feed, pyrolysis generated a returned USD $768, gasification generated USD 166, but fermentation required an expenditure of USD 763, rendering it unfeasible. The fermentation economic analysis showed that reducing the system’s net duty to 6500 kJ/tonne biomass and converting 30% hemicellulose along with the cellulose content will result in a breakeven bioethanol fuel price of 1.85 USD/L. This fuel price falls within the acceptable 0.8–2.4 USD/L commercial feasibility range and is competitive with bioethanol produced in other processes. The economic analysis indicated that pyrolysis and gasification are economically more feasible than fermentation. To maximize profits, the wasted hemicellulose and lignin from fermentation are proposed to be used in thermochemical processes for further fuel production.

This mini review discusses the sustainability aspects of various fuels for proton exchange membrane fuel cells (PEMFCs). PEMFCs operate by converting the chemical energy in a fuel into electrical energy. The most crucial parameters in the operation process are the temperature, pressure, relative humidity, and air stoichiometry ratio, as presented in this work. The classical structure of a PEMFC consists of a proton exchange membrane, anode electrode, cathode electrode, catalyst layers (CLs), microporous layer (MPLs), gas diffusion layers (GDLs), two bipolar plates (BPs), and gas flow channels (GFCs). The mechanical behavior and the conductivity of the protons are highly dependent on the structure of the MEAs. This review discusses the various fuels and their production paths from sustainable sources. For the fuel production process to be renewable and sustainable, a hydrogen electrolyzer could be powered from solar energy, wind energy, geothermal energy, or hydroelectric energy, to produce hydrogen, which in turn could be fed into the fuel cell. This paper also reviews biomass-based routes for sustainable fuel production.

This study presents a case study of a novel hybrid solar chimney power plant (HSCPP) design’s performance in the city of Doha, Qatar. The HSCPP construction is similar to the traditional solar chimney power plant (SCPP) but with the addition of water sprinklers installed at the top of the chimney. This allowed the solar chimney (SC) to operate as a cooling tower (CT) during the nighttime and operate as an SC during the daytime, hence providing a continuous 24-h operation. The results showed that the HSCPP produced ~633 MWh of electrical energy per year, compared to ~380 MWh of energy produced by the traditional SCPP. The results also showed that the HSCPP was able to produce 139,000 tons/year of freshwater, compared to 90,000 tons/year produced by the traditional SCPP. The estimated CO2 emission reduction (~600 tons/year) from the HSCPP is twice that of the traditional SCPP (~300 tons/year). The results clearly show that the HSCPP outperformed the traditional SCPP.

Biological plants such as algae have a great potential of fixating CO2 from flue gases or atmospheric air and converting it into useful biomass. This is because CO2 is part of their photosynthesis ...

The present work involves a new and novel upgrading design to the classical solar chimney power plant (SCPP) structure. The SCPP design was modified by adding a co-centric secondary external chimney to the SCPP structure to enhance energy production. In the new improved design, named the solar double-chimney power plant (SDCPP), the internal chimney, operates like a traditional SCPP to produce electricity during the daytime whereas the secondary external chimney operates as 10 cooling towers (CT) in a series. Each CT is equipped with a turbine and water sprinklers for further energy production. The new design offers the operation of the SCPP during the day and the continuous operation of the CT (day-and-night). A mathematical model that includes the energy and mass balance equations of the system was built using MATLAB. The SDCPP system produced up to 993 MWh of electrical energy, which is 2.6 times higher than the traditional SCPP (377 MWh). The new design configuration achieved a percentage of thermal efficiency (%ηth) of 1.6%, which is 200 times greater than the SCPP. The economic assessment of the new system revealed a 50% reduction in the localized cost of energy (LCOE) compared with traditional SCPP. The key advantage of the new design is related to the use of low-cost material in constructing the secondary chimney to reduce the fixed capital cost and prompt the economic feasibility of the system. Overall, the proposed SDCPP offers a feasible and economic solution to produce electricity and to potentially reduce greenhouse gas emissions.