Publications

The purpose of this study is to analyze and compare the techno-economic performance of grid-connected Hybrid Energy Systems (HES) consisting of Photovoltaic (PV) and Reformer Fuel-Cell (RF-FC) using different types of solar PV tracking techniques to supply electricity to a small location in the City of Chlef Algeria. The PV tracking systems considered in this study include fixed facing south at four different angles (32◦ 34◦ 36◦ 38◦) horizontal-axis with continuous adjustment vertical-axis with continuous adjustment and a two-axis tracking system. The software tool HOMER Pro (Hybrid Optimization of Multiple Energy Resources) is used to simulate and analyze the technical feasibility and life-cycle cost of these different configurations. The meteorological data consisting of global solar radiation and air temperature used in this study was collected from the geographical area of the City of Chlef during the year 2020. This study has shown that the optimal design of a grid-connected hybrid PV/RF-FC energy system with Vertical Single Axis Tracker (VSAT) leads to the best economic perfor mance with low values of Net Present Cost (NPC) Cost of Energy (COE) with a Positive Return on Investment (ROI) and the shortest Simple Payback (SP) period. In addition from the simulation results obtained it can be concluded that the Horizontal and Vertical Single-Axis Trackers (HSAT and VSAT) as well as the Dual-Axis Tracker (DAT) are not always cost effective compared to the Fixed Tilt System (FTS). Therefore it is neces sary to carefully analyze the use of each tracker to assess whether the energy gain achieved outweighs the overall shortcomings of the tracker.

This paper investigates the circularity of green hydrogen and resource recovery from brine using an integrated approach based on alkaline water electrolysis (AWE). Traditional AWE employs highly alkaline electrolytes which can lead to electrode corrosion undesirable side reactions and gas cross-over issues. Conversely indirect brine electrolysis requires pre-treatment steps which negatively impact both techno-economics and environmental sustainability. In response this study proposes an innovative brine electrolysis process utilizing solid electrolytes (SELs). The process includes an on-site brine treatment facility leveraging a self-driven phase transition technique and incorporates a hydrophobic membrane as part of a membrane distillation (MD) system to facilitate the gas pathway. Polyvinyl alcohol (PVA) and tetraethylammonium hydroxide (TEAOH)-based electrolytes combined with potassium hydroxide (KOH) at various concentrations function as a self-wetted electrolyte (SWE). This design partially disperses water vapor while effectively preventing the intrusion of contaminated ions into the SWE and electrode-catalyst interfaces. PVA-TEAOH-KOH-30 wt% SWE demonstrated the highest ion conductivity (112.4 mScm−1) and excellent performance with a current density of 375 mAcm−2. Long-term electrolysis confirmed with a nine-fold brine in volume concentration factor (VCF) demonstrated stable performance without MD membrane wetting. The Cl−/ClO− and Br− concentrations in the SWE were reduced by five orders of magnitude compared to the original brine. This electrolyzer supports the circular use of resources with hydrogen as an energy carrier and concentrated brine and oxygen as valuable by-products aligning with the sustainable development goals (SDGs) and net-zero emissions by 2050.

The growing penetration of renewable energy sources requires resilient microgrids capable of providing stable and continuous operation. Hybrid energy storage systems (HESS) which integrate hydrogen-based storage systems (HBSS) battery storage systems (BSS) and supercapacitor banks (SCB) are essential to ensuring the flexibility and robustness of these microgrids. Accurate modelling of these microgrids is crucial for analysis controller design and performance optimization but the complexity of HESS poses a significant challenge: simplified linear models fail to capture the inherent nonlinear dynamics while nonlinear approaches often require excessive computational effort for real-time control applications. To address this challenge this study presents a novel state space model with linear variable parameters (LPV) which effectively balances accuracy in capturing the nonlinear dynamics of the microgrid and computational efficiency. The research focuses on a high-voltage DC bus microgrid architecture in which the BSS and SCB are connected directly in parallel to provide passive DC bus stabilization a configuration that improves system resilience but has received limited attention in the existing literature. The proposed LPV framework employs recursive linearisation around variable operating points generating a time-varying linear representation that accurately captures the nonlinear behaviour of the system. By relying exclusively on directly measurable state variables the model eliminates the need for observers facilitating its practical implementation. The developed model has been compared with a reference model validated in the literature and the results have been excellent with average errors MAE RAE and RMSE values remaining below 1.2% for all critical variables including state-of-charge DC bus voltage and hydrogen level. At the same time the model maintains remarkable computational efficiency completing a 24-h simulation in just 1.49 s more than twice as fast as its benchmark counterpart. This optimal combination of precision and efficiency makes the developed LPV model particularly suitable for advanced model-based control strategies including real-time energy management systems (EMS) that use model predictive control (MPC). The developed model represents a significant advance in microgrid modelling as it provides a general control-oriented approach that enables the design and operation of more resilient efficient and scalable renewable energy microgrids.

The reliance on fossil fuels for electricity production in insular regions creates critical environmental economic and logistical challenges particularly for ecologically fragile islands. Transitioning to renewable energy is essential to mitigate these impacts enhance energy security and preserve unique ecosystems. This systematic review addresses key research questions: what practical strategies have proven effective in reducing fossil fuel dependency in island contexts and what barriers hinder their widespread adoption? By applying the PRISMA methodology this study examines a decade (2014–2024) of research on renewable energy systems highlighting successful initiatives such as the integration of solar and wind systems in Hawaii energy storage advancements in La Graciosa hybrid renewable grids in the Galápagos Islands and others. Specific barriers include high upfront costs regulatory challenges and technical limitations such as grid instability due to renewable energy intermittency. This review contributes by synthesizing lessons from diverse case studies and identifying innovative approaches like hydrogen storage predictive control systems and community-driven renewable projects. The findings offer actionable insights for policymakers and researchers to accelerate the transition towards sustainable energy systems in island environments.

This study explores the potential of solar tracking technologies to enhance South Africa’s energy transition focusing on their role in supporting green hydrogen production for domestic use and export. Using the Global Energy System Model (GENeSYS-MOD) it evaluates four solar tracking technologies — horizontal axis tilted horizontal axis vertical axis and dual-axis — across six scenarios: tracking and non-tracking versions of a Business-as-Usual (BAU) scenario a 2 ◦C scenario and a high hydrogen demand and export (HighH2) scenario. The results identify horizontal axis tracking as the most cost-effective option followed by tilted horizontal axis tracking which is particularly prominent in the HighH2 scenario. Tracking systems enhance hydrogen production by extending power output and increasing electrolyzer full-load hours. In the HighH2 scenario they reduce hydrogen production costs in 2050 from 1.47 e/kg to 1.34 e/kg and system cost by 0.66% positioning South Africa competitively in the global hydrogen market. By integrating tracking technologies South Africa can align hydrogen production ambitions with renewable energy growth while mitigating grid and financial challenges. The research underscores the need for targeted energy investments and policies to maximize renewable energy and hydrogen potential ensuring a just energy transition that supports export opportunities domestic energy security and equitable socio-economic growth.

Hydrogen production is increasingly vital for global decarbonization but remains a waterand energy-intensive process especially in arid regions. Despite growing attention to its climate benefits limited research has addressed the environmental impacts of water sourcing. This study employs a life cycle assessment (LCA) approach to evaluate three water supply strategies for hydrogen production: (1) seawater desalination without brine treatment (BT) (2) desalination with partial BT and (3) freshwater purification. Scenarios are modeled for the United Arab Emirates (UAE) Australia and Spain representing diverse electricity mixes and water stress conditions. Both electrolysis and steam methane reforming (SMR) are evaluated as hydrogen production methods. Results show that desalination scenarios contribute substantially to human health and ecosystem impacts due to high energy use and brine discharge. Although partial BT aims to reduce direct marine discharge impacts its substantial energy demand can offset these benefits by increasing other environmental burdens such as marine eutrophication especially in regions reliant on carbon-intensive electricity grids. Freshwater scenarios offer lower environmental impact overall but raise water availability concerns. Across all regions feedwater for SMR shows nearly 50% lower impacts than for electrolysis. This study focuses solely on the environmental impacts associated with water sourcing and treatment for hydrogen production excluding the downstream impacts of the hydrogen generation process itself. This study highlights the trade-offs between water sourcing brine treatment and freshwater purification for hydrogen production offering insights for optimizing sustainable hydrogen systems in water-stressed regions.

The European Union promotes decarbonization in energy-intensive industries like glass manufacturing. Collaboration between industry and researchers focuses on reducing CO2 emissions through hydrogen (H2) integration as a natural gas substitute. However to the best of the authors’ knowledge no updated real-world case studies are available in the literature that consider the on-site implementation of an electrolyzer for autonomous hydrogen production capable of meeting the needs of a glass manufacturing plant within current technological constraints. This study examines a representative hollow glass plant and develops various decarbonization scenarios through detailed process simulations in Aspen Plus. The models provide consistent mass and energy balances enabling the quantification of energy demand and key cost drivers associated with H2 integration. These results form the basis for a scenario-specific techno-economic assessment including both on-grid and off-grid configurations. Subsequently the analysis estimates the levelized costs of hydrogen (LCOH) for each scenario and compares them to current and projected benchmarks. The study also highlights ongoing research projects and technological advancements in the transition from natural gas to H2 in the glass sector. Finally potential barriers to large-scale implementation are discussed along with policy and infrastructure recommendations to foster industrial adoption. These findings suggest that hybrid configurations represent the most promising path toward industrial H2 adoption in glass manufacturing.

With the accelerating global transition to clean energy underground hydrogen storage (UHS) has gained significant attention as a flexible and renewable energy storage technology. Ontario Canada as a pioneer in energy transition offers substantial underground storage potential with its geological conditions of salt limestone and sandstone providing diverse options for hydrogen storage. However the hydrogen transport characteristics of different rock media significantly affect the feasibility and safety of energy storage projects warranting in-depth research. This study simulates the hydrogen flow and transport characteristics in typical energy storage digital rock core models (salt rock limestone and sandstone) from Ontario using the improved quartet structure generation set (I-QSGS) and the lattice Boltzmann method (LBM). The study systematically investigates the distribution of flow velocity fields directional characteristics and permeability differences covering the impact of hydraulic changes on storage capacity and the mesoscopic flow behavior of hydrogen in porous media. The results show that salt rock due to its dense structure has the lowest permeability and airtightness with extremely low hydrogen transport velocity that is minimally affected by pressure differences. The microfracture structure of limestone provides uneven transport pathways exhibiting moderate permeability and fracture-dominated transport characteristics. Sandstone with its higher porosity and good connectivity has a significantly higher transport rate compared to the other two media showing local high-velocity preferential flow paths. Directional analysis reveals that salt rock and sandstone exhibit significant anisotropy while limestone’s transport characteristics are more uniform. Based on these findings salt rock with its superior sealing ability demonstrates the best hydrogen storage performance while limestone and sandstone also exhibit potential for storage under specific conditions though further optimization and validation are required. This study provides a theoretical basis for site selection and operational parameter optimization for underground hydrogen storage in Ontario and offers valuable insights for energy storage projects in similar geological settings globally.

The combustion of pure H2 in engines is still troublesome needing further research and development. Using H2 and diesel in a dual-fuel compression ignition engine appears as a more feasible approach. Here we report an experimental assessment of performance and emissions for a single-cylinder four-stroke air-cooled compression ignition engine operating with neat diesel and H2-diesel dual-fuel. Previous studies typically show the performance and emissions for a specific operation condition (i.e. a fixed engine speed and torque) or a limited operating range. Our experiments covered engine speeds of 3000 and 3600 rpm and torque levels of 3 and 7 Nm. An in-house designed and built alkaline cell generated the H2 used for the partial substitution of diesel. Compared with neat diesel the results indicate that adding H2 decreased the air-fuel equivalence ratio and the Brake Specific Diesel Fuel Consumption Efficiency by around 14–29 % and 4–31 %. In contrast adding H2 increased the Brake Fuel Conversion Efficiency by around 3–36 %. In addition the Brake Thermal Efficiency increased in the presence of H2 in the range of 3–37 % for the lower engine speed and 27–43 % for the higher engine speed compared with neat diesel. The dual-fuel mode resulted in lower CO and CO2 emissions for the same power output. The emissions of hydrocarbons decreased with H2 addition except for the lower engine speed and the higher torque. However the dual-fuel operation resulted in higher NOx emissions than neat diesel with 2–6 % and 19–48 % increments for the lower and higher engine speeds. H2 emerges as a versatile energy carrier with the potential to tackle current energy and emissions challenges; however the dual-fuel strategy requires careful management of NOx emissions.

Underground hydrogen storage is critical for supporting the transition to renewable energy systems addressing the intermittent nature of solar and wind power. Despite its promise as a carbon-neutral energy carrier there remains limited understanding of the geomechanical behavior of subsurface reservoirs under hydrogen storage conditions. This knowledge gap is particularly significant for fast-cycling operations which have yet to be implemented on a large scale. This review evaluates current knowledge on the geomechanics of underground hydrogen storage focusing on risks and challenges in geological formations such as salt caverns depleted hydrocarbon reservoirs saline aquifers and lined rock caverns. Laboratory experiments field studies and numerical simulations are synthesized to examine cyclic pressurization induced seismicity thermal stresses and hydrogen-rock interactions. Notable challenges include degradation of rock properties fault reactivation micro-seismic activity in porous reservoirs and mineral dissolution/precipitation caused by hydrogen exposure. While salt caverns are effective for low-frequency hydrogen storage their behavior under fast-cyclic loading requires further investigation. Similarly the mechanical evolution of porous and fractured reservoirs remains poorly understood. Key findings highlight the need for comprehensive geomechanical studies to mitigate risks and enhance hydrogen storage feasibility. Research priorities include quantifying cyclic loading effects on rock integrity understanding hydrogen-rock chemical interactions and refining operational strategies. Addressing these uncertainties is essential for enabling large-scale hydrogen integration into global energy systems and advancing sustainable energy solutions. This work systematically focuses on the geomechanical implications of hydrogen injection into subsurface formations offering a critical evaluation of current studies and proposing a unified research agenda.

The maritime sector’s transition to sustainable energy is critical for achieving global carbon neutrality with container terminals representing a key focus due to their high energy consumption and emissions. This study explores the potential of hydrogen energy as a decarbonization solution for port operations using the Chuanshan Port Area of Ningbo Zhoushan Port (CPANZP) as a case study. Through a comprehensive analysis of hydrogen production storage refueling and consumption technologies we demonstrate the feasibility and benefits of integrating hydrogen systems into port infrastructure. Our findings highlight the successful deployment of a hybrid “wind-solar-hydrogen-storage” energy system at CPANZP which achieves 49.67% renewable energy contribution and an annual reduction of 22000 tons in carbon emissions. Key advancements include alkaline water electrolysis with 64.48% efficiency multi-tier hydrogen storage systems and fuel cell applications for vehicles and power generation. Despite these achievements challenges such as high production costs infrastructure scalability and data integration gaps persist. The study underscores the importance of policy support technological innovation and international collaboration to overcome these barriers and accelerate the adoption of hydrogen energy in ports worldwide. This research provides actionable insights for port operators and policymakers aiming to balance operational efficiency with sustainability goals.

This study evaluates and compares physical chemical and dual activation methods for preparing activated carbons from spent coffee grounds to optimize their porosity for hydrogen storage. Activation processes including both one-step and two-step chemical and physical methods were investigated incorporating a novel dual activation process that combines chemical and physical activation. The findings indicate that the two-step chemical activation yields superior results producing activated carbons with a high specific surface area of 1680 m2 /g and a micropore volume of 0.616 cm3 /g. These characteristics lead to impressive hydrogen uptake capacities of 2.65 wt% and 3.66 wt% at 77 K under pressures of 1 and 70 bar respectively. The study highlights the potential of spent coffee grounds as a cost-effective precursor for producing high-performance activated carbons.

This study evaluates the effects of adding a hydrogen gaseous mixture (HGM) to primary fuel in a single cylinder research engine (SCRE). Storage and transportation of high-purity hydrogen limit the application of this gas. With the development of fuel reforming methods using hydrogenenriched mixtures in spark-ignited internal combustion engines is a convenient option to fossil fuels. Ethanol and gasoline were used as primary fuel by direct injection (DI) and gaseous mixture was added by fumigation system (FS). The experimental analysis was developed in Spark Ignition (SI) four-stroke engine 4 valves and 0.45 L of cubic capacity. For each operation condition and primary fuel spark timing and amount of HGM were adjusted in order to keep air-fuel ratio stochiometric (λ = 100). However the spark timing and the percentage of gas varied aiming to evaluate the behavior of the air-fuel mixture. It was evaluated the specific fuel consumption and the evolution of the combustion process. The results showed that the addition of reformed gas promotes acceleration of the combustion process ethanol and gasoline. Results were expressive when using ethanol. A reduction in fuel-specific consumption - for this fuel - with combustion centralized which did not occur when gasoline was employed.

To enable a sustainable and socially accepted hydrogen and methanol economy it is crucial to prioritize green and water-conscious production. In this review we reveal that there is a significant research gap regarding comprehensive assessments of such production methods. We present an innovative process chain consisting of adsorption-based direct air capture solid oxide electrolysis and methanol synthesis to address this issue. To allow future comprehensive techno-economic assessments we perform a systematic literature review and harmonization of the techno-economic parameters of the process chain’s technologies. Based on the conducted literature review we find that the long-term median specific energy demand of adsorption-based direct air capture is expected to decrease to 204 kWhel/tCO2 and 1257 kWhth/tCO2 while the capture cost is expected to decrease to 162 €2024/tCO2 with a relative high uncertainty. The evaluated sources expect a future increase in system efficiency of solid oxide electrolysis to 80% while the purchase equipment costs are expected to decrease significantly. Finally we demonstrate the feasibility of the process chain from a technoeconomic perspective and show a potential reduction in external heat demand of the DAC unit of up to 34% when integrated in the process chain.

This paper deals with proton exchange membrane (PEM) electrolyzers directly coupled with a photovoltaic source. It proposes a method to increase the energy delivered to the electrolyzer by reconfiguring the electrical connection of the arrays according to solar radiation. Unlike the design criterion proposed by the literature the suggested approach considers a source obtained by connecting arrays in parallel depending on solar radiation based on a fixed photovoltaic configuration. This method allows for the optimization of the operating point at medium or low solar radiation where the fixed configuration gives poor results. The analysis is performed on a low-power plant (400 W). It is based on a commercial photovoltaic cell whose equivalent model is retrieved from data provided by the manufacturer. An equivalent model of the PEM electrolyzer is also derived. Two comparisons are proposed: the former considers a photovoltaic source designed according to the traditional approach i.e. a fixed configuration; in the latter a DC/DC converter as interface is adopted. The role of the converter is discussed to highlight the pros and cons. The optimal set point of the converter is calculated using an analytical equation that takes into account the electrolyzer model. In the proposed study an increase of 17% 62% and 93% of the delivered energy has been obtained in three characteristic days summer spring/autumn and winter respectively compared to the fixed PV configuration. These results are also better than those achieved using the converter. Results show that the proposed direct coupling technique applied to PEM electrolyzers in low-power plants is a good trade-off between a fixed photovoltaic source configuration and the use of a DC/DC converter.

The H2STORE collaborative project investigates potential geohydraulic petrophysical mineralogical microbiological and geochemical interactions induced by the injection of hydrogen into depleted gas reservoirs and CO2- and town gas storage sites. In this context the University of Jena performs mineralogical and geochemical investigations on reservoir and cap rocks to evaluate the relevance of preferential sedimentological features which will control fluid (hydrogen) pathways thus provoking fluid-rock interactions and related variations in porosity and permeability. Thereby reservoir sand- and sealing mudstones of different composition sampled from distinct depths (different: pressure/temperature conditions) of five German locations are analysed. In combination with laboratory experiments the results will enable the characterization of specific mineral reactions at different physico-chemical conditions and geological settings.

Chemical looping hydrogen generation (CLHG) from biomass is a promising technology for producing carbonnegative hydrogen. However achieving autothermal operation without sacrificing hydrogen yield presents a significant thermodynamic challenge. This study proposes and evaluates a novel thermal management strategy that enables a self-sustaining process by balancing the system’s heat load with its internal exothermic reactions. A comprehensive analysis was conducted using process simulation to assess the system’s thermodynamic performance identify key sources of inefficiency through exergy analysis and determine its economic viability via a detailed techno-economic assessment. The results show that a 200 MWth CLHG plant can produce 2.06 t-H2/h with a hydrogen production efficiency and exergy efficiency of 34.46 % and 44.4 % respectively. The exergy analysis identified the fuel reactor as the largest source of thermodynamic inefficiency accounting for 66.4 % of the total exergy destruction. The techno-economic analysis yielded a base-case minimum selling price (MSP) of hydrogen of 2.63 USD/kg a rate competitive with other carbon-capture-enabled hydrogen production methods. Sensitivity analysis confirmed that the MSP is most influenced by biomass price and discount rate. Crucially the system’s carbon-negative nature allows it to leverage carbon pricing schemes which can significantly improve its economic performance. Under the EU’s current carbon price the MSP falls to 0.98 USD/kg-H2 and it can become negative in regions with higher carbon taxes suggesting profitability from carbon credits alone. This study demonstrates that the proposed CLHG system is a technically robust and economically compelling pathway for clean hydrogen production particularly in regulatory environments that incentivize carbon capture.

Hydrogen-enriched compressed natural gas (HCNG) holds significant promise for renewable energy absorption and hydrogen utilization while also increasing the complexity of Integrated Energy System (IES) structures which presents challenges for optimal HCNG-IES operation. Energy inertia provides IES with potential operational flexibility. However existing HCNG-IES optimization technologies inadequately account for hydrogen and thermal inertia leaving significant opportunities to enhance system performance. In this study we begin with a comprehensive analysis and modeling of the hydrogen-thermal multi-energy inertia (HTMEI) processes which encompass the hydrogen inertia of HCNG loads and hydrogen storage tanks as well as the thermal inertia of thermal storage tanks and buildings. Following this we develop an optimization model for the operation of HCNG-IES that incorporates HTMEI to optimize the system's overall performance in terms of economic environmental and energy efficiency criteria. The resulting optimal scheduling scheme integrates the outputs of energy devices and multi-energy inertia processes. Case studies validate the efficacy of the proposed operational optimization method. The results indicate that in comparison with an operational optimization method that does not consider energy inertia the proposed approach reduces operational costs by 34.79% carbon emissions by 32.93% electricity purchased from the grid by 95.37% and natural gas consumption by 11.8%. Furthermore the analysis has verified the mutual enhancement between hydrogen inertia and thermal inertia along with their positive individual impacts on operational performance of the HCNGIES.

Ammonia (NH3) has emerged as a promising hydrogen carrier due to its high hydrogen content favourable storage and transport properties and carbon-free utilisation. Its ability to be stored as a liquid under relatively mild conditions and its compatibility with existing industrial infrastructure make it an efficient and scalable solution for hydrogen distribution. This study conducts a detailed investigation into the kinetics of ammonia decomposition over rutheniumbased catalysts which are known for their high catalytic activity for ammonia cracking. Experimental data across a wide range of operating conditions are used to validate the proposed models with a promising catalyst (0.5 wt.% Ru/Al2O3). The study employs kinetic models based on different theoretical frameworks such as the Langmuir isotherm the Temkin-Pyzhev approach and the microkinetic model focusing on evaluating various rate-determining steps. A comparison of these models shows that those that consider nitrogen desorption a ratedetermining step provide the best predictions of NH3 conversion effectively capturing the dependencies on temperature and feed molar fractions of reactants and products. This multifaceted approach integrates experimental data with proposed kinetic models contributing to a better understanding of NH3 decomposition through parameter optimisation. The findings provide valuable insights for modelling catalytic reactors optimising conditions and enhancing catalyst performance for efficient hydrogen production from ammonia.

Energy management in hybrid fuel cell ship systems faces the dual challenges of optimizing hydrogen consumption and ensuring power quality. This study proposes an Improved Weighted Antlion Optimization (IW-ALO) algorithm for multi-objective problems. The method incorporates a dynamic weight adjustment mechanism and an elite-guided strategy which significantly enhance global search capability and convergence performance. By integrating IW-ALO with the Equivalent Consumption Minimization Strategy (ECMS) an improved weighted ECMS (IW-ECMS) is developed enabling real-time optimization of the equivalence factor and ensuring efficient energy sharing between the fuel cell and the lithium-ion battery. To validate the proposed strategy a system simulation model is established in Matlab/Simulink 2017b. Compared with the rule-based state machine control and optimization-based ECMS methods over a representative 300 s ferry operating cycle the IW-ECMS achieves a hydrogen consumption reduction of 43.4% and 42.6% respectively corresponding to a minimum total usage of 166.6 g under the specified load profile while maintaining real-time system responsiveness. These reductions reflect the scenario tested characterized by frequent load variations. Nonetheless the results highlight the potential of IW-ECMS to enhance the economic performance of ship power systems and offer a novel approach for multi-objective cooperative optimization in complex energy systems.

Green H2 production using electrolyzer technology is an emerging method in the current mandate using renewable-based power sources integrated with electrolyzer technology. Prior research has been extensively studied to understand the effects of intermittent power sources on the hydrogen production output. However in this context the characteristics of the working electrolyzer behave differently under system-level operation. In this paper we investigated a 25 kW alkaline electrolyzer for its stack performance in terms of stack efficiency the stack current vs. stack voltage and the relationship between the H2 flow rate and stack current. It was found that the current of 52 A produces the best system efficiency of 64% under full load operation for 1 h. The H2 flow rate behaves in an exponential asymptotic pattern and it is also found that the ramp-up time for hydrogen generation by the electrolyzer is significantly low thus marking it as an efficient option for producing green hydrogen with the input of a hybrid grid and renewable PV-based power sources. Hydrogen production techno-economic analysis has been conducted and the LCOH is found to be on the higher side for the current electrolyzer under investigation.

Alkaline water electrolysis (AWE) is the most mature electrochemical technology for hydrogen production from renewable electricity. Thus its mathematical modeling is an important tool to provide new perspectives for the design and optimization of energy storage and decarbonization systems. However current models rely on numerous empirical parameters and neglect variations of temperature and concentration alongside the electrolysis cell which can impact the application and reliability of the simulation results. Thus this study proposes a simple four-parameter semi-empirical model for AWE system analysis which relies on minimal fitting data while providing reliable extrapolation results. In addition the effect of model dimensionality (i.e. 0D 1/2D and 1D) are carefully assessed in the optimization of an AWE system. The results indicate that the proposed model can accurately reproduce literature data from four previous works (R 2 ≥ 0.98) as well as new experimental data. In the system optimization the trade-offs existing in the lye cooling sizing highlight that maintaining a low temperature difference in AWE stacks (76-80°C) leads to higher efficiencies and lower hydrogen costs.

This article examines the growing potential of low-emission hydrogen as an innovative solution supporting the decarbonization of the agricultural sector. It discusses its potential applications on farms including as an energy source for powering agricultural machinery producing fertilizers and storing energy from renewable sources. Within the European context it considers actions arising from the European Green Deal and the “Fit for 55” strategy which promote the development of hydrogen infrastructure and support research into low-emission technologies. The article also discusses global initiatives and trends in the development of the hydrogen economy pointing to international cooperation investment and the need for technology standardization. It highlights the challenges related to cost infrastructure and scalability as well as the opportunities hydrogen offers for a sustainable and energy-efficient agriculture of the future.

As the global demand for energy increases and the transition to renewable and clean sources accelerates microgrid (MG) has emerged as a promising solution. Hydrogen fuel cell vehicles (HFCVs) offer significant advantages over gasoline vehicles in terms of reducing carbon dioxide emissions. However the development of HFCVs is hindered by the substantial up-front costs of hydrogen refueling stations (HRSs) coupled with the high cost of hydrogen transportation and the limitations of the hydrogen supply chain. This research proposes a multimicrogrid (MMG) system that integrates hydrogen energy and utilizes it as the HRS for fuel vehicle refueling. An adaptive hydrogen energy management method is employed for fuel cell vehicles to optimize the coupling between the transportation network and the power system. An integrated transportation state assessment model is developed and a smart MMG system is deployed to receive information from the transportation network. Building on this foundation an adaptive hydrogen scheduling model is developed. HFCVs are influenced by the hydrogen price adjustments leading them to travel to different MGs for refueling which in turn regulates the unit output of the MMG system. The MMG system is then integrated with the IEEE 33 bus distribution system to analyze the daily load balance. This integrated approach results in reduced traffic congestion lower MG costs and optimized power distribution network load balance.

The power-to-methanol (PtMeOH) will play a crucial role as a form of renewable chemical energy storage. In this paper PtMeOH techno-economics are assessed using the promising configuration from the previous work (Mbatha et al. [1]). This study evaluated the effect of parameters such as the CO2 emission tax electricity price and CAPEX reduction on the product methanol economic parity with respect to a reference case. Superior to previous economic studies a scenario where an existing methanol synthesis infrastructure is 100 % retrofitted with the promising electrolyser is assessed in terms of its economics and the associated economic parity. The volatile South African electricity market is considered as a case study. The sensitivity of the PtMeOH and green H2 profitability are checked. Grid-connected and standalone renewable energy PtMeOH scenarios are assessed. Foremost generalisable effect trends of these parameters on the net present value (NPV) and the levelized cost of methanol(LCOMeOH) and H2 (LCOH2) are discussed. The results show that economic parity of H2 (LCOH2 = current selling price = 4.06 €/kg) can be reached with an electricity price of 30 €/MWh and 70 % of the CAPEX. While the LCOMeOH will still be above 2 €/kg at 80 % of the CAPEX and electricity price of 20 €/MWh. This indicates that even if the CAPEX reduces to 20 % of its original in this study and the electricity price reduces to about 20 €/MWh the LCOMEOH will still not reach economic parity (LCOMeOH > current selling price = 0.44 €/kg). The results show that to make the retrofitted plant with a minimum of 20 years of life span profitable a feasible reduction in the electricity price to below 10 €/MWh along with favourable incentives such as CO2 credit and reduction in CAPEX particularly that of the electrolyser and treatment of the PtMeOH as a multiproduct plant will be required.