Open Access

Review

Article ID: 3842

Effect of different pretreatments and their parameters on biogas production performance: A review

by Himan Khodkam

Energy Storage and Conversion, Vol.3, No.4, 2025;

Energy supply is fundamental to modern society, yet its current reliance on fossil fuels is a major contributor to global warming. A transition to renewable energy is therefore critical, offering both climate mitigation and economic opportunities. Biogas is a particularly effective renewable source, addressing energy needs and waste management simultaneously by converting organic matter into clean fuel. Production occurs through a four-stage anaerobic digestion process, influenced by parameters such as temperature, pH, C/N ratio, retention time, mixing, and moisture. Pretreatment methods can significantly enhance efficiency and yield. For lignocellulosic materials, sodium hydroxide is a common chemical choice, while biological pretreatment offers a low-energy alternative. Among additives, zero-valent iron nanoparticles have shown considerable promise. This article aims to identify optimal conditions to make biogas production more cost-effective. Synthesized studies indicate that maximum biogas yield is achieved by: reducing feedstock particle size, maintaining an inlet concentration near 8%, applying a ratio of 25, ensuring neutral pH, and operating at mesophilic temperatures. A key finding is that pretreatment effectiveness is not universal; it is highly dependent on the specific feedstock and digestion conditions. In conclusion, biogas exemplifies the potential of renewables to create a more sustainable and resilient energy system. By optimizing its production, we can advance toward a greener future that reduces environmental impact while supporting economic growth.

Open Access

Article

Article ID: 3933

Hybrid energy storage system integrating lithium-ion batteries and supercapacitors for enhanced electric vehicle performance

by Ashiq Hussain, Muhammad Fasih Aamir

Energy Storage and Conversion, Vol.3, No.4, 2025;

The increasing adoption of electric vehicles (EVs) has highlighted persistent challenges related to battery efficiency, limited lifespan and performance fluctuations during highly dynamic driving conditions. To address such issues, this study proposes a novel Hybrid Energy Storage System (HESS) that strategically combines lithium-ion batteries and supercapacitors to take advantage of the high energy density of batteries and the rapid charge-discharge characteristics of supercapacitors. The hybrid configuration is governed by an Arduino-based control unit equipped with an intelligent power management algorithm, which tracks real-time acceleration profiles and dynamically allocates power to the appropriate energy source. During steady-state operation, the batteries supply the required power, while peak loads during sudden acceleration or regenerative braking are effectively handled by the supercapacitors. Extensive simulations and laboratory experiments demonstrate that this strategy significantly reduces battery stress, mitigates thermal effects, and increases overall cycle life. Additionally, a dedicated mobile application enables real-time monitoring of key operating parameters, including SOC, vehicle speed and overall system status, thereby improving user interaction and enabling proactive maintenance decisions. Overall, the proposed HESS substantially improves energy efficiency and operational stability, representing a practical and scalable solution for achieving long-term sustainability and high performance in next-generation electric vehicle technologies.

Open Access

Editorial

Article ID: 3975

More patience—a plea for longer stability testing and systematic data reporting

by Rudolf Holze

Energy Storage and Conversion, Vol.3, No.4, 2025;

A brief look at publications in this journal, as well as many other journals covering materials and systems for electrochemical energy conversion and storage, confirms the impression that mostly electrochemical materials science in terms of electrode materials, sometimes electrolytes and electrocatalysts, is at work. Once a study of a newly developed material for a battery or supercapacitor electrode is (barely) completed, the authors rush to report. In their enthusiastic excitement, they frequently calculate energy and power density for a single electrode, apparently happily clueless about the absence of single-electrode batteries and capacitors. Reporting charge densities with specification of the explored electrode potential range would be fine [1], and stating explicitly whether only the active material, or the complete electrode material including binder and conductive additives, even the support and current collector, has been included in calculating said charge density would be fine! In case of a complete cell (the terms full cell or full battery are hardly helpful because they commonly refer to the state of charge), the same applies. Setting up a Ragone plot for a single electrode (material) is obviously baseless, too, but very popular. Disappointed authors afraid to lose their chance to demonstrate the high current capabilities of their electrode have a popular and well-established option: display the capacity, i.e., charge storage capability, retention as a function of applied current!

Open Access

Article

Article ID: 3891

Comparative evaluation of green hydrogen production methods using the Pugh matrix technique

by Afrin, Adeel H. Suhail, Fiseha M. Guangul, Abdalellah Mohmmed, Abdul Nazeer

Energy Storage and Conversion, Vol.3, No.4, 2025;

Hydrogen plays a vital role as an energy carrier in the global effort to combat climate change, with significant applications in sectors such as transportation and ammonia production. However, traditional hydrogen production methods are heavily carbon-intensive, with over 98% of hydrogen derived from fossil fuels. This primarily occurs through steam methane reforming (76%) and coal gasification (22%). While steam methane reforming is cost-effective, it generates approximately 9 kg of CO₂ per kg of hydrogen. Consequently, advancing green hydrogen production methods has become a critical area of research. This study explores and compares various green hydrogen production techniques powered by renewable energy sources, including solar, wind, hydro, biomass, and hybrid systems. Production methods such as electrolysis, thermal, chemical, photonic, and biological processes are evaluated using a Pugh matrix, accounting for factors including efficiency, hydrogen yield, resource availability, operating conditions, cost, and greenhouse gas emissions. The findings indicate that alkaline electrolysis currently represents the most viable option for green hydrogen production. These findings affirm alkaline electrolysis as the most appropriate near-term technology for large-scale green hydrogen implementation in Oman and the GCC, while also advocating for the ongoing development of PEM and emerging pathways to ensure long-term diversification. Ultimately, this study provides a clear and practical decision-support framework for the strategic selection of hydrogen technologies in renewable-rich arid regions.

Open Access

Article

Article ID: 3850

Comparative evaluation of solar photovoltaic cell technologies across Türkiye’s climatic regions: A PVsyst simulation-based analysis

by Muhammed Fatih Saltuk

Energy Storage and Conversion, Vol.3, No.4, 2025;

Over the past fifteen years, solar photovoltaic (PV) technologies have become a part of the global energy transition, primarily driven by sustained reductions in capital costs. This rapid deployment has intensified the need for robust, technology-specific performance assessments under diverse climatic conditions. This study presents a comparative evaluation of three crystalline silicon PV cell technologies, which are Passivated Emitter and Rear Contact (PERC), Tunnel Oxide Passivated Contact (TOPCon), and Silicon Heterojunction (SHJ/HJT), across Türkiye’s climatically heterogeneous regions using PVsyst simulation software. A rigorously controlled modelling framework was employed, in which all system-level parameters, including irradiance data, thermal behaviour, array configuration, and loss assumptions, were held constant across simulations, thereby isolating the impact of cell architecture on energy yield. The results demonstrate clear performance differentiation among the examined technologies. SHJ modules exhibit superior energy output under high temperature conditions due to favourable temperature coefficients, whereas TOPCon modules show enhanced robustness under harsh operating environments and improved resistance to lifetime degradation. PERC technology, despite its maturity, remains competitive in regions characterised by moderate climatic stress. These findings indicate that PV technology selection should extend beyond nominal efficiency metrics to incorporate thermal sensitivity, degradation behaviour, and low irradiance performance. Consequently, informed PV investment and deployment strategies must align cell technological attributes with specific environmental conditions. While controlled PVsyst simulations provide a consistent comparative baseline, their practical relevance depends on careful contextualisation to real-world operating environments.

Open Access

Review

Article ID: 3826

Ammonia synthesis and decomposition mediated by hydrides, imides, and amides

by Muhammad Anis Aslam, Sajad Hussain, Ismat Ullah Khan

Energy Storage and Conversion, Vol.3, No.4, 2025;

Ammonia is used for global fertilizer production and is increasingly viewed as a viable carrier for renewable hydrogen and long-duration energy storage. Realizing this potential requires catalysts and process architectures that enable both N₂-to-NH₃ synthesis and NH₃-to-H₂ decomposition at substantially reduced temperature and pressure. This review surveys recent advances in which alkali- and alkaline-earth metal hydrides, amides, and imides act as dynamic redox and hydrogen/nitrogen-transfer media, undergoing reversible interconversion with N₂, H₂, and NH₃. We summarize thermocatalytic systems where hydridic H⁻ and electron-rich lattices promote N₂ activation, heterolytic H₂ cleavage, and N–H bond formation, including composite catalysts that exploit cooperative interfaces with transition metals and complex or mixed-anion hydrides that relax constraints imposed by conventional metal-only surfaces. We also discuss photo-assisted routes that leverage defect-stabilized charge carriers in hydrides to drive nitrogen conversion under illumination, and chemical-looping strategies that decouple nitrogen fixation from hydrogenation (or hydrogen release) to tune thermodynamics and mitigate competitive adsorption. Across these platforms, recurring motifs include lattice-mediated hydride/proton shuttling, interfacial electron donation, and reversible nitride–imide–amide formation that can be engineered to balance activity, selectivity, and stability. Finally, we outline key barriers to practical deployment, air/moisture sensitivity, carrier volatility, phase segregation, and limited operando understanding and highlight design priorities for stabilizing reactive phases and integrating reactors compatible with renewable heat, photons, or electricity, thereby enabling scalable and decentralized ammonia and hydrogen technologies.