Publications

We consider a profit-maximizing renewable energy producer operating in a rural area with limited electricity distribution capacity to the grid. While maximizing profits the energy producer is responsible for the electricity supply of a local community that aims to be self-sufficient. Energy storage is required to deal with the energy productions' uncertain and intermittent character. A promising new solution is to use strategic hydrogen reserves. This provides a long-term storage option to deal with seasonal mismatches in energy production and the local community's demand. Using a Markov decision process we provide a model that determines optimal daily decisions on how much energy to store as hydrogen and buy or sell from the power grid. We explicitly consider the seasonality and uncertainty of production demand and electricity prices. We show that ignoring seasonal demand and production patterns is suboptimal and that introducing hydrogen storage transforms loss-making operations into profitable ones. Extensive numerical experiments show that the distribution capacity should not be too small to prevent local grid congestion. A higher storage capacity increases the number of buying actions from the grid thereby causing more congestion which is problematic for the grid operator. We conclude that a profit-maximizing hydrogen storage operation alone is not an alternative to grid expansion to solve congestion which is essential knowledge for policy-makers and grid operators.

Hydrogen and electricity derived from renewable sources present feasible alternative energy options for the decarbonisation of the transportation and power sectors. This study presents the utilisation of hydrogen generated from solar and wind energy resources as a clean fuel for mobility and backup storage for stationary applications under economic and environmental uncertainties. This is achieved by developing a detailed technoeconomic model of an integrated system consisting of a hydrogen refuelling station and an electric power generation system using Mixed Integer Quadratic Constrained Programming (MIQCP) which is further relaxed to Mixed Integer Linear Programming (MILP). The model is implemented in the Advanced Interactive Multidi mensional Modelling Software (AIMMS) and considering the inherent uncertainties in the wind resource solar resource costs and discount rate the total cost of the three configurations (Hybrid PV-Wind Standalone PV and Standalone wind energy system) was minimised using robust optimisation technique and the corresponding optimal sizes of the components levelised cost of energy (LCOE) excess energy greenhouse emission avoided and carbon tax were evaluated. The levelised cost of the deterministic optimisation solution for all the config uration ranges between 0.0702 $/kWh to 0.0786 $/kWh while the levelised cost of the robust optimisation solution ranges between 0.07188 $/kWh to 0.1125 $/kWh. The proposed integration has the advantages of affordable hydrogen and electricity prices minimisation of carbon emissions and grid export of excess energy.

Acceleration of the hydrogen economy is being observed on a global scale. It is considered to be a potential solution to the problems with high-carbon energy industry and transport systems. The potential of production cost-competitiveness and opportunities are currently being investigated to provide insights to policymakers researchers and industry. In this context this study makes a quantitative assessment of the competitiveness of hydrogen storage compared to Li-ion batteries based on price arbitrage in the day-ahead market. Two scenarios that form the boundaries of rational decision-making regarding the charging and discharging of energy storage are considered. The first one assumes the charging and discharging of energy storage facilities over the same hours throughout the entire year. The selection of these hours is based on historical electricity prices. The second scenario assumes charge and discharge during historical daily minimum and maximum prices. The results show that NPV is below zero for both technologies when current values of investment expenditure are assumed. The outcomes of sensitivity analysis indicate that only a substantial reduction of investment expenditure could improve the financial results of the Li-ion batteries (NPV>0). The investigation also shows that even simplified charge and discharge over the same hours allows one to achieve 47% (hydrogen) and 70% (Li-ion batteries) of the maximum operating profit when the perfect foresight of prices is applied. In each case NPV for Li-ion technology is significantly higher than for hydrogen; for example for a 1 MWh and 1 MWout storage system NPV is EUR -4.85 million in the case of hydrogen and with Li-ion NPV is EUR -0.23 million. Consequently the application of expensive decision support systems in small systems may be unprofitable. The increase in profits may not cover the cost of developing and introducing such a system.

T The large-scale implementation of solar hydrogen production requires an optimal combination of photovoltaic systems with suitably-designed electrochemical cells possibly avoiding power electronics for DC-DC conversion to decrease costs. Here a stable solar-driven water splitting system is presented obtained through the direct connection of a state-of-the-art proton exchange membrane (PEM) electrolyzer to a bifacial silicon hetero junction (SHJ) solar module of three cells in series with total area of 730 cm2 . The bifaciality of the solar module has been optimized through modeling in terms of the number of cells module height and inclination. During outdoor operation in the standard monofacial configuration the system is able to produce 3.7 gr of H2 h 1 m 2 with an irradiation of 1000 W m 2 and a solar-to-hydrogen efficiency (STH) of 11.55%. The same system operating in bifacial mode gives rise to a higher H2 flux and STH efficiency reaching values of 4.2 gr of H2 h 1 m 2 and STH of 13.5%. Such a noticeable difference is achieved through the collection of albedo radiation from the ground by the bifacial PV system. The system has been tested outdoors for more than 55 h exhibiting very good endurance with no appreciable change in production and eff

This scientific article presents a developed model for optimising the scheduling of hydrogen production processes addressing the growing demand for efficient and sustainable energy sources. The study focuses on the integration of advanced scheduling techniques to improve the overall performance of the hydrogen electrolyser. The proposed model leverages constraint programming and satisfiability (CP-SAT) techniques to systematically analyse complex production schedules considering factors such as production unit capacities resource availability and energy costs. By incorporating real-world constraints such as fluctuating energy prices and the availability of renewable energy the optimisation model aims to improve overall operational efficiency and reduce production costs. The CP-SAT was applied to achieve more efficient control of the electrolysis process. The optimisation of the scheduling task was set for a 24 h time period with time resolutions of 1 h and 15 min. The performance of the proposed CP-SAT model in this study was then compared with the Monte Carlo Tree Search (MCTS)-based model (developed in our previous work). The CP-SAT was proven to perform better but has several limitations. The model response to the input parameter change has been analysed.

The synergy between hydrogen and water is crucial in moving towards a sustainable energy future. This study explores the integration of geothermal energy with desalination and hydrogen production systems to address water and clean energy demands. Two configurations one using multi-effect distillation (MED) and the other reverse osmosis (RO) were designed and compared. Both configurations utilized geothermal energy with MED directly using geothermal heat and RO converting geothermal energy into electricity to power desalination. The systems are evaluated based on various performance indicators including net power output desalinated water production hydrogen production exergy efficiency and levelized costs. Multi-objective optimization using an artificial neural network (ANN) and genetic algorithm (GA) was conducted to identify optimal operational conditions. Results highlighted that the RO-based system demonstrated higher water production efficiency achieving a broader range of optimal solutions and lower levelized costs of water (LCOW) and hydrogen production while the MED-based system offered economic advantages under specific conditions. A case study focused on Canada illustrated the potential benefits of these systems in supporting hydrogen-powered vehicles and residential water needs emphasizing the significant impact of using high-quality desalinated water to enhance the longevity and efficiency of proton exchange membrane electrolyzers (PEME). This research provides valuable insights into the optimal use of geothermal energy for sustainable water and hydrogen production.

This study explores the performance and emissions characteristics of a dual-fuel internal combustion engine operating on a blend of hydrogen and gasoline. This research began with a baseline simulation of a conventional gasoline engine which was subsequently validated through experimental testing on an AVL testbed. The simulation results closely matched the testbed data confirming the accuracy of the model with deviations within 5%. Building on this validated model a hydrogen–gasoline dual-fuel engine simulation was developed. The predictive simulation revealed an approximately 5% increase in overall engine efficiency at the optimal operating point primarily due to hydrogen’s combustion properties. Additionally the injected gasoline mass and CO2 emissions were reduced by around 30% across the RPM range. However the introduction of hydrogen also resulted in a slight reduction (~10%) in torque attributed to the lower volumetric efficiency caused by hydrogen displacing intake air. While CO emissions were significantly reduced NOx emissions nearly doubled due to the higher combustion temperatures associated with hydrogen. This research demonstrates the potential of hydrogen–gasoline dual-fuel systems in reducing carbon emissions while highlighting the need for further optimization to balance performance with environmental impact.

A series of unconfined hydrogen detonation bench-mark experiments are analyzed with respect to CFD code validation and safety measures development. 1-Dimensional in-house code COM1D was applied for validation against experimental data for unconfined detonation of a hemispherical envelope of about 3- and 5-m radius with hydrogen-air mixtures from 20 to 30% hydrogen in air. The code demonstrates a very good agreement with experimental data and allows an adequate simulation of the unconfined hydrogen detonation. All calculated data were scaled in Sachs coordinates to compare with experimental data and to approximate the data for practical evaluation of safety distances. Numerical experiments with different hydrogen inventories from 50 g to 50 kg and different sizes of the cloud from 1 to 2 m radius of the same amount of hydrogen 50g were carried out to clarify the problem of energy of gaseous explosion responsible for the strength of blast wave. Additionally a comparison of hydrogen-air explosion pressure with blast wave properties from the hypothetical cloud of hot compressed combustion products (P=Picc; T=Ticc) and simply a hot air of the same initial pressure and temperature as combustion products showed very good agreement of shock wave strength at far distances beyond the cloud. This confirms the governing role of energy of combustion on blast wave propagation and its ability to scale the strength of blast waves. The dynamics of the explosion process and combustion product expansion were also analyzed experimentally and numerically to evaluate the dimension of the heat radiation zone and heat flux from combustion products. To demonstrate the capability of tested COM1D code the modeling and analysis of high-pressure hydrogen tanks rupture at 350 and 700 bar were conducted to investigate blast wave strength and evaluate the safety distances.

Hydrogen is a versatile energy vector for a plethora of applications; nevertheless its production from waste/residues is often overlooked. Gasification and subsequent conversion of the raw synthesis gas to hydrogen are an attractive alternative to produce renewable hydrogen. In this paper recent developments in R&D on waste gasification (municipal solid waste tires plastic waste) are summarised and an overview about suitable gasification processes is given. A literature survey indicated that a broad span of hydrogen relates to productivity depending on the feedstock ranging from 15 to 300 g H2/kg of feedstock. Suitable gas treatment (upgrading and separation) is also covered presenting both direct and indirect (chemical looping) concepts. Hydrogen production via gasification offers a high productivity potential. However regulations like frame conditions or subsidies are necessary to bring the technology into the market.

During the last two decades Gulf Cooperation Council (GCC) countries have seen their population economies and energy production growing steeply with a substantial increase in Gross Domestic Product. As a result of this growth GCC consumption-based carbon dioxide (CO2) emissions increased from 540.79 Metric tons of CO2 equivalent (MtCO2) in 2003 to 1090.93 MtCO2 in 2020. The assumptions and strategies that have driven energy production in the past are now being recast to achieve a more sustainable economic development. The aim of this study is to review and analyze ongoing energy transition strategies that characterize this change to identify challenges and opportunities for bolstering the effectiveness of current strategic orientations. The ensuing analysis shows that since COP26 GCC countries have been pursuing a transition away from carbon-based energy policies largely characterized by the adoption of solar PV with other emerging technologies including energy storage carbon capture and hydrogen generation and storage. While as of 2022 renewable energy adoption in the GCC only represented 0.15 % of global installed capacity GCC countries are making strong efforts to achieve their declared 2030 energy targets that average about 26 % with peaks of 50 % in Saudi Arabia and 30 % in the UAE and Oman. With reference to solar energy plans are afoot to add 42.1 GW of solar photovoltaics and concentrated solar power which will increase 8-fold the current installed renewable capacity (5.1 GW). At the same time oil and gas production rates remain stable and fossil fuel subsidies have grown in the last few years. Also there is a marked preference for the deployment of CCUS and utility-scale solar energy technology vs. distributed solar energy energy efficiency and nature-based solutions. The pursuit of energy transition in the GCC will require increased efforts in the latter and other overlooked strategic endeavors to achieve a more balanced portfolio of sustainable energy solutions with stronger emphasis on energy efficiency (as long as rebound effects are mitigated) and nature-based solutions. Increased efforts are also needed in promoting governance practices aimed to institutionalize regulatory frameworks incentives and cooperation activities that promote the reduction of fossil fuel subsidies and the transition away from fossil fuels.