Applications & Pathways
Hybrid Renewable Energy Systems for Off-Grid Electrification: A Comprehensive Review of Storage Technologies, Metaheuristic Optimization Approaches and Key Challenges
Nov 2025
Publication
Hybrid Renewable Energy Systems (HRESs) are a practical solution for providing reliable low-carbon electricity to off-grid and remote communities. This review examines the role of energy storage within HRESs by systematically comparing electrochemical mechanical thermal and hydrogen-based technologies in terms of technical performance lifecycle cost operational constraints and environmental impact. We synthesize findings from implemented off-grid projects across multiple countries to evaluate real-world performance metrics including renewable fraction expected energy not supplied (EENS) lifecycle cost and operation & maintenance burdens. Special attention is given to the emerging role of hydrogen as a long-term and cross-sector energy carrier addressing its technical regulatory and financial barriers to widespread deployment. In addition the paper reviews real-world implementations of off-grid HRES in various countries summarizing practical outcomes and lessons for system design and policy. The discussion also includes recent advances in metaheuristic optimization algorithms which have improved planning efficiency system reliability and cost-effectiveness. By combining technological operational and policy perspectives this review identifies current challenges and future directions for developing sustainable resilient and economically viable HRES that can accelerate equitable electrification in remote areas. Finally the review outlines key limitations and future directions calling for more systematic quantitative studies long-term field validation of emerging technologies and the development of intelligent Artificial Intelligence (AI)-driven energy management systems within broader socio-techno-economic frameworks. Overall this work offers concise insights to guide researchers and policymakers in advancing the practical deployment of sustainable and resilient HRES.
Hydrogen Blending as a Transitional Solution for Decarbonizing the Jordanian Electricity Generation Sector
Nov 2025
Publication
While renewable energy deployment has accelerated in recent years fossil fuels continue to play a dominant role in electricity generation worldwide. This necessitates the development of transitional strategies to mitigate greenhouse gas emissions from this sector while gradually reducing reliance on fossil fuels. This study investigates the potential of blending green hydrogen with natural gas as a transitional solution to decarbonize Jordan’s electricity sector. The research presents a comprehensive techno-economic and environmental assessment evaluating the compatibility of the Arab Gas Pipeline and major power plants with hydrogen–natural gas mixtures considering blending limits energy needs environmental impacts and economic feasibility under Jordan’s 2030 energy scenario. The findings reveal that hydrogen blending between 5 and 20 percent can be technically achieved without major infrastructure modifications. The total hydrogen demand is estimated at 24.75 million kilograms per year with a reduction of 152.7 thousand tons of carbon dioxide per annum. This requires 296980 cubic meters of water per year equivalent to only 0.1 percent of the National Water Carrier’s capacity indicating a negligible impact on national water resources. Although technically and environmentally feasible the project remains economically constrained requiring a carbon price of $1835.8 per ton of carbon dioxide for economic neutrality.
Green Hydrogen as a Decarbonization Pathway for Steel Industry in Pakistan
Nov 2025
Publication
The global steel industry emits 1.92 tons of CO2 per ton of output and faces urgent pressure to decarbonize. In Pakistan the sector accounts for 0.29 tons of CO2 per ton of output with limited mitigation frameworks in place. Green hydrogen (GH2)-based steelmaking offers a strategic pathway toward decarbonization. However realizing its potential depends on access to renewable energy. Despite Pakistan’s substantial technical wind potential of 340 GW grid limitations currently restrict wind power to only 4% of national electricity generation. This study explores GH2 production through sector coupling and power wheeling repurposing curtailed wind energy from Sindh to supply Karachi’s steel industry and proposing a phased roadmap for GH enabling fossil fuel substitution industrial resilience and alignment with global carbon-border regulations.
Techno-economic Assessment of Retrofitted Combined-cycles for Power-to-hydrogen-to-power Systems in European Electricity Markets
Oct 2025
Publication
This paper investigates the performance and economic viability of Combined Cycle Gas Turbines (CCGT) operating on natural gas (NG) and hydrogen within the context of evolving electricity markets. The study is structured into several sections beginning with a benchmark analysis to establish baseline performance metrics including break-even prices and price margins for CCGTs running on NG. The research then explores various base cases and sensitivity analyses focusing on different CCGT capacity factors and the uncertainties surrounding key parameters. The study also compares the performance of CCGTs across different European countries highlighting the impact of increased price fluctuations in forecasted electricity markets. Additionally the paper examines Power-to-X-to-Power (P2X2P) configurations assessing the economic feasibility of hydrogen production and its integration into CCGT operations. The analysis considers scenarios where hydrogen is sourced externally or produced on-site using renewable energy or grid electricity during off-peak hours. The results provide insights into the competitiveness and adaptability of CCGTs in a transitioning energy landscape emphasizing the potential role of hydrogen as a flexible and sustainable energy carrier.
Applied Simulation Study of a Metal Hydride Refrigeration System for Fuel Cell Trucks
Oct 2025
Publication
Refrigeration units in semi-trucks or rigged-body trucks have an energy demand of 8.2–12.4 MWh/y and emit 524.26 kt CO2e/y in Germany. Electrification with fuel cell systems reduces the CO2 emission but an increase of efficiency is necessary because of rapidly increasing hydrogen costs. A metal hydride refrigeration system can increase the efficiency. Even though it was already demonstrated in lab scale with 900 W this power is not sufficient to support a truck refrigeration system and the power output of the lab system was not controllable. Here we show the design and validation of a MATLAB© Simulink model of this metal hydride refrigeration system and its suitability for high power applications with a scaled-up reactor. It was scaled up to rated power of 5 kW and efficiency improvements with an advanced valve switching as well as a controlled cooling pump were implemented. Two application-relevant use cases with hydrogen mass flows from hydrogen fuel cell truck systems were analyzed. The simulation results of these use cases provide an average cooling power of 4.2 and 6.1 kW. Additionally the control of the coolant mass flow at different temperature levels a controlled hydrogen mass flow with a bypass system and an advanced valve switching mechanism increased the system efficiency of the total refrigeration system by 30 % overall.
Energy Management of Hybrid Energy System Considering a Demand-Side Management Strategy and Hydrogen Storage System
Oct 2025
Publication
A hybrid energy system (HES) integrates various energy resources to attain synchronized energy output. However HES faces significant challenges due to rising energy consumption the expenses of using multiple sources increased emissions due to non-renewable energy resources etc. This study aims to develop an energy management strategy for distribution grids (DGs) by incorporating a hydrogen storage system (HSS) and demand-side management strategy (DSM) through the design of a multi-objective optimization technique. The primary focus is on optimizing operational costs and reducing pollution. These are approached as minimization problems while also addressing the challenge of achieving a high penetration of renewable energy resources framed as a maximization problem. The third objective function is introduced through the implementation of the demand-side management strategy aiming to minimize the energy gap between initial demand and consumption. This DSM strategy is designed around consumers with three types of loads: sheddable loads non-sheddable loads and shiftable loads. To establish a bidirectional communication link between the grid and consumers by utilizing a distribution grid operator (DGO). Additionally the uncertain behavior of wind solar and demand is modeled using probability distribution functions: Weibull for wind PDF beta for solar and Gaussian PDF for demand. To tackle this tri-objective optimization problem this work proposes a hybrid approach that combines well-known techniques namely the non-dominated sorting genetic algorithm II and multi-objective particle swarm optimization (Hybrid-NSGA-II-MOPSO). Simulation results demonstrate the effectiveness of the proposed model in optimizing the tri-objective problem while considering various constraints.
Decarbonising Sustainable Aviation Fuel (SAF) Pathways: Emerging Perspectives on Hydrogen Integration
Oct 2025
Publication
The growing demand for air connectivity coupled with the forecasted increase in passengers by 2040 implies an exigency in the aviation sector to adopt sustainable approaches for net zero emission by 2050. Sustainable Aviation Fuel (SAF) is currently the most promising short-term solution; however ensuring its overall sustainability depends on reducing the life cycle carbon footprints. A key challenge prevails in hydrogen usage as a reactant for the approved ASTM routes of SAF. The processing conversion and refinement of feed entailing hydrodeoxygenation (HDO) decarboxylation hydrogenation isomerisation and hydrocracking requires substantial hydrogen input. This hydrogen is sourced either in situ or ex situ with the supply chain encompassing renewables or non-renewables origins. Addressing this hydrogen usage and recognising the emission implications thereof has therefore become a novel research priority. Aside from the preferred adoption of renewable water electrolysis to generate hydrogen other promising pathways encompass hydrothermal gasification biomass gasification (with or without carbon capture) and biomethane with steam methane reforming (with or without carbon capture) owing to the lower greenhouse emissions the convincing status of the technology readiness level and the lower acidification potential. Equally imperative are measures for reducing hydrogen demand in SAF pathways. Strategies involve identifying the appropriate catalyst (monometallic and bimetallic sulphide catalyst) increasing the catalyst life in the deoxygenation process deploying low-cost iso-propanol (hydrogen donor) developing the aerobic fermentation of sugar to 14 dimethyl cyclooctane with the intermediate formation of isoprene and advancing aqueous phase reforming or single-stage hydro processing. Other supportive alternatives include implementing the catalytic and co-pyrolysis of waste oil with solid feedstocks and selecting highly saturated feedstock. Thus future progress demands coordinated innovation and research endeavours to bolster the seamless integration of the cutting-edge hydrogen production processes with the SAF infrastructure. Rigorous technoeconomic and life cycle assessments alongside technological breakthroughs and biomass characterisation are indispensable for ensuring scalability and sustainability
Coordinated Control Strategy for Island Power Generation System with Photovoltaic, Hydrogen-Fueled Gas Turbine and Hybrid Energy Storage
Oct 2025
Publication
Marine and island power systems usually incorporate various forms of energy supply which poses challenges to the coordinated control of the system under diverse irregular and complex load operation modes. To improve the stability and self-sufficiency of island-isolated microgrids with high penetration of renewable energy this study proposes a coordinated control strategy for an island microgrid with PV HGT and HESS combining primary power allocation via low-pass filtering with a fuzzy logic-based secondary correction. The fuzzy controller dynamically adjusts power distribution based on the states of charge of the battery and supercapacitor following a set of predefined rules. A comprehensive system model is developed in Matlab R2023b integrating PV generation an electrolyzer HGT and a battery–supercapacitor HESS. Simulation results across four operational cases demonstrate that the proposed strategy reduces DC bus voltage fluctuations to a maximum of 4.71% (compared to 5.63% without correction) with stability improvements between 0.96% and 1.55%. The HESS avoids overcharging and over-discharging by initiating priority charging at low SOC levels thereby extending service life. This work provides a scalable control framework for enhancing the resilience of marine and island microgrids with high renewable energy penetration.
Analysis of Fuel Cell Electric Vehicle Performance Under Standard Electric Vehicle Driving Protocol
Nov 2025
Publication
The paper studies and analyzes electric vehicle engines powered by hydrogen under the WLTP standard driving protocol. The driving range extension is estimated using a specific protocol developed for FCEV compared with the standard value for battery electric vehicles. The driving range is extended by 10 km averaging over the four protocols with a maximum of 11.6 km for the FTP-75 and a minimum of 7.7 km for the WLTP. This driving range extension represents a 1.8% driving range improvement on average. Applying the FCEV current weight the driving range is extended to 18.9 km and 20.4 km on average when using power source energy capacity standards for BEVs and FCEVs.
Enhancing Power-to-Hydrogen Flexibility Through Optimal Bidding in Nordic Energy Activation Market with Wind Integration
Oct 2025
Publication
The recent updates to the Single Day-Ahead Coupling (SDAC) framework in the European energy market along with new rules for providing manual frequency restoration reserve (mFRR) products in the Nordic Energy Activation Market (EAM) have introduced a finer Market Time Unit (MTU) resolution. These developments underscore the growing importance of flexible assets such as power-to-hydrogen (PtH) facilities in delivering system flexibility. However to successfully participate in such markets well-designed and accurate bidding strategies are essential. To fulfill this aim this paper proposes a Mixed Integer Linear Programming (MILP) model to determine the optimal bidding strategies for a typical PtH facility accounting for both the technical characteristics of the involved technologies and the specific participation requirements of the mFRR EAM. The study also explores the economic viability of sourcing electricity from nearby wind turbines (WTs) under a Power Purchase Agreement (PPA). The simulation is conducted using a case study of a planned PtH facility at the Port of Hirtshals Denmark. Results demonstrate that participation in the mFRR EAM particularly through the provision of downward regulation can yield significant economic benefits. Moreover involvement in the mFRR market reduces power intake from the nearby WTs as capacity must be reserved for downward services. Finally the findings highlight the necessity of clearly defined business models for such facilities considering both technical and economic aspects.
Design of Hydrogen-Powered Mobile Emergency Power Vehicle with Soft Open Point and Appropriate Energy Management Strategy
Oct 2025
Publication
Mobile emergency power supply vehicles (MEPSVs) powered by diesel engines or lithiumion batteries (LIBs) have become a viable tool for emergency power supply. However diesel-powered MEPSVs generate noise and environmental pollution while LIB-powered vehicles suffer from limited power supply duration. To overcome these limitations a hydrogen-powered MEPSV incorporating a soft open point (SOP) was developed in this study. We analyzed widely used operating scenarios for the SOP-equipped MEPSV and determined important parameters including vehicle body structure load capacity driving speed and power generation capability for the driving motor hydrogen fuel cell (FC) module auxiliary LIB module and SOP equipment. Subsequently we constructed an energy management strategy for the model for MEPSV which uses multiple energy sources of hydrogen fuel cells and lithium-ion batteries. Through simulations an optimal hydrogen consumption rate in various control strategies was validated using a predefined load curve to optimize the energy consumption minimization strategy and achieve the highest efficiency.
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