Publications

Due to the high cost of hydrogen utilization and the uncertainties in renewable energy generation and load demand significant challenges are posed for the operation optimization of hydrogen-containing integrated energy systems (IESs). In this study a robust operational model for an electric–heat–gas IES (EHG-IES) is proposed considering the hydrogen energy system heat recovery (HESHR) and multiple uncertainties. Firstly a heat recovery model for the hydrogen system is established based on thermodynamic equations and reaction principles; secondly through the constructed adjustable robust optimization (ARO) model the optimal solution of the system under the worst-case scenario is obtained; lastly the original problem is decomposed based on the column and constraint generation method and strong duality theory resulting in the formulation of a master problem and subproblem with mixed-integer linear characteristics. These problems are solved through alternating iterations ultimately obtaining the corresponding optimal scheduling scheme. The simulation results demonstrate that our model and method can effectively reduce the operation and maintenance costs of HESHR-EHG-IES while being resilient to uncertainties on both the supply and demand sides. In summary this study provides a novel approach for the diversified utilization and flexible operation of energy in HESHR-EHG-IES contributing to the safe controllable and economically efficient development of the energy market. It holds significant value for engineering practice.

This review article provides a comprehensive overview of the pivotal role that nanomaterials particularly graphene and its derivatives play in advancing hydrogen energy technologies with a focus on storage production and transport. As the quest for sustainable energy solutions intensifies the use of nanoscale materials to store hydrogen in solid form emerges as a promising strategy toward mitigate challenges related to traditional storage methods. We begin by summarizing standard methods for producing modified graphene derivatives at the nanoscale and their impact on structural characteristics and properties. The article highlights recent advancements in hydrogen storage capacities achieved through innovative nanocomposite architectures for example multi-level porous graphene structures containing embedded nickel particles at nanoscale dimensions. The discussion covers the distinctive characteristics of these nanomaterials particularly their expansive surface area and the hydrogen spillover effect which enhance their effectiveness in energy storage applications including supercapacitors and batteries. In addition to storage capabilities this review explores the role of nanomaterials as efficient catalysts in the hydrogen evolution reaction (HER) emphasizing the potential of metal oxides and other composites to boost hydrogen production. The integration of nanomaterials in hydrogen transport systems is also examined showcasing innovations that enhance safety and efficiency. As we move toward a hydrogen economy the review underscores the urgent need for continued research aimed at optimizing existing materials and developing novel nanostructured systems. Addressing the primary challenges and potential future directions this article aims to serve as a roadmap to enable scientists and industry experts to maximize the capabilities of nanomaterials for transforming hydrogen-based energy systems thus contributing significantly to global sustainability efforts.

Renewable Energy Sources (RESs) are characterized by high unevenness cyclicality and seasonality of energy production. Due to the trends in the production of electricity itself and the utilization of hydrogen distributed generation systems are preferred. They can be connected to the energy distribution network or operate without its participation (off-grid). However in both cases such distributed energy sources should be balanced in terms of power generation. According to the authors it is worth combining different RESs to ensure the stability of energy production from such a mix. Within the mix the sources can complement and replace each other. According to the authors an effective system for generating energy from RESs should contain at least two different sources and energy storage. The purpose of the analyses and calculations performed is to determine the characteristics of energy generation from a photovoltaic system and a wind turbine with a specific power and geographical location in the Lublin region in Poland. Another important goal is to determine the substitutability of the sources studied. Probabilistic analysis will be used to determine the share of given energy sources in the energy mix and will allow us to estimate the size of the stationary energy storage. The objective of these procedures is to strive for the highest possible share of renewable energy in the total energy required to charge electric vehicle fleets and to produce low-emission hydrogen for transportation. The article proves that the appropriately selected components of the photovoltaic and wind energy mix located in the right place lead to the self-balancing of the local energy network using a small energy storage. The conclusions drawn from the conducted research can be used by RES developers who intend to invest in new sources of power generation to produce low-emission hydrogen. This is in line with the current policy of the European Union aimed at climate and energy transformation of many companies using green hydrogen.

Due to concerns regarding fossil greenhouse gas emissions biogenic material such as forest residues is viewed nowadays as a valuable source of carbon atoms to produce syngas that can be used to synthesise biofuels such as methanol. A great challenge in using gasified biomass for methanol production is the large excess of carbon in the syngas as compared to the H2 content. The water–gas shift (WGS) reaction is often used to add H2 and balance the syngas. CO2 is also produced by this reaction. Some of the CO2 has to be removed from the gaseous mixture thus decreasing the process carbon yield and maintaining CO2 emissions. The WGS reaction also decreases the overall process heat output. This paper demonstrates the usefulness of using an extra source of renewable H2 from steam electrolysis instead of relying on the WGS reaction for a much higher performance of syngas production from gasification of wood in a simple system with a fixed-bed gasifier. A commercial process simulation software is employed to predict that this approach will be more efficient (overall energy efficiency of about 67%) and productive (carbon conversion yield of about 75%) than relying on the WGS reaction. The outlook for this process that includes the use of the solid oxide electrolyser technology appears to be very promising because the electrolyser has the dual function of providing all of the supplemental H2 required for syngas balancing and all the O2 required for the production of a suitable hot raw syngas. This process is conducive to biomethanol production in dispersed small plants using local biomass for end-users from the same geographical area thus contributing to regional sustainability.

The adoption of low-carbon fuels in maritime propulsion requires operational autonomy material suitability and compliance with safety standards making liquid fuels like LNG and LH2 the most viable options. LNG is widely used for reducing GHG NOx and SOx emissions while LH2 though new to the maritime sector leverages aerospace experience. This paper explores the operational requirements and challenges of LH2 cryogenic handling systems using LNG practices as a reference. Key comparisons are made between LNG and LH2 supply systems focusing on cryogenic materials hydrogen embrittlement and structural integrity under maritime conditions. Most maritime-approved materials are suitable for cryogenic use and hydrogen embrittlement is less critical at cryogenic temperatures due to reduced atomic mobility. Risk assessments suggest LH2’s safety record stems from limited operational data rather than superior inherent safety. The paper also addresses crucial safety and regulatory considerations for both fuels underscoring the need for strict adherence to standards to ensure the safe and compliant integration of LH2 in the maritime industry.

Chemical hydrogen storage is a key step for establishing hydrogen as a main energy vector. For this purpose liquid organic hydrogen carriers (LOHCs) present the outstanding advantage of allowing a safe efficient and high-density hydrogen storage being also highly compatible with existing transport infrastructures. Typical LOHCs are organic compounds able to be hydrogenated and dehydrogenated at mild conditions enabling the hydrogen storage and release respectively. In addition the physical properties of these chemicals are also critical for practical implementation. In this work key properties of potential LOHCs of three different chemical families (homoaromatics and Nand O-heteroaromatics) are estimated using molecular simulations. Thus density viscosity vapour pressure octanol-water coefficient melting point flash point dehydrogenation enthalpy and hydrogen content are estimated using the programs COSMO-RS and HYSYS. In addition we have also evaluated the performance of several binary mixtures as LOHCs using these methodologies. Considering the hydrogen content characteristic temperatures and previous experimental results of the cyclic process; our simulation results suggest that 1-methylnaphthalene/1-methyldecahydronaftalene and methylbenzylpyridine/perhydromethylbenzylpyridine pairs are appropriate candidates for chemical hydrogen storage. Binary mixtures of LOHCs are also relevant alternatives since substances with a great potential can be used as LOHCS when dissolved. That is the case of naphthalene and 1-methyl-naphthalene mixtures or indoles dissolved in benzene or benzylbenzene. Concerning O-compounds although several pairs could be used as LOHCs thermodynamic and kinetic feasibility of the hydrogenation/dehydrogenation cycles must be better studied.

This paper proposes a novel dual-fuel dual-mode dual-thermodynamic cycle aviation propulsion system for the first time and conducts theoretical research on it based on a moderately simplified mathematical model. It is specifically designed to significantly reduce carbon emissions for wide-body aircraft. A comprehensive thermodynamic model is developed for this hybrid power system which integrates a high-temperature proton exchange membrane fuel cell with a dual-rotor turbofan engine. The matching characteristics between aircraft and engine performance are analyzed by systematically varying the fuselage length of the dual-fuel aircraft configuration. Results show that the specific fuel consumption of the proposed engine is decreased by 12.6% compared with that of the traditional turbofan engine as the Mach number increases. Conversely as the relative physical rotational speed decreases the thrust of the novel engine is increased by 10%. With a 20 % extension in fuselage length the dual-fuel aircraft operating on 100 % hydrogen fuel can achieve an endurance exceeding 17 h representing a 20 % endurance improvement over conventional aviation kerosene-powered aircraft. In this case the aircraft weight can be reduced by 96.79 tons and CO2 emissions can be decreased by 301.65 tons.

This paper presents the results of the H2SAREA project which focuses on integrating hydrogen (H2) into the existing natural gas (NG) distribution network with blends of up to 20%. A key component of the project was the H2Loop testing platform built using ex-service materials and components to realistically assess the impact of hydrogen on current systems and components. The investigation covered several critical areas including gas injection and blending network capacity leak detection gas pressure regulation station (GPRS) performance valve and meter functionality materials compatibility permeation testing and gas deblending. Results show the feasibility of safely injecting up to 20% hydrogen into the existing system offering valuable insights to guide the transition of gas distribution networks toward a hydrogen-based energy future.

In the coming years as a result of changing climate policies and finite fossil fuel resources energy producers will be compelled to introduce new fuels with lower carbon footprints. One of the solutions is hydrogen which can be burned or co-fired with methane in energy generation systems. Therefore this study presents a thermodynamic and emission analysis of a gas turbine fueled by a mixture of CH4 and H2 as well as pure hydrogen. Numerical studies were conducted for the actual operating parameters of the LM6000 gas turbine in both simple and combined cycles. Aspen Hysys and Chemkin-Pro 2023R1 commercial software were used for the calculations. It was demonstrated that with a constant turbine inlet temperature set at 1723 K the thermal efficiency increased from 39.4% to 40.2% for the gas turbine cycle and from 49% to 49.4% for the combined cycle gas turbine. Nitrogen oxides emissions were calculated using the reactor network revealing that an increase in H2 content above 20%vol. in the fuel leads to a significant rise in nitric oxides emissions. In the case of pure H2 emissions are more than three times higher than for CH4 . The main reason for this increase in emissions was identified as the greater presence of H O and OH radicals in the reaction zone causing an acceleration in the formation of nitric oxides.

Reducing greenhouse gas emissions in the transport sector is known to be an important contribution to climate change mitigation. Some parts of the transport sector are particularly difficult to decarbonize; this includes the heavy-duty vehicle sector which is considered one of the “hardto-abate” sectors of the economy. Transitioning from diesel trucks to hydrogen fuel cell trucks has been identified as a potential way to decarbonize the sector. However the current and future costs and efficiencies of the enabling technologies remain unclear. In light of these uncertainties this paper investigates the investments required to decarbonize New Zealand’s heavy-duty vehicle sector with green hydrogen. By combining system dynamics modelling literature and hydrogen transition modelling literature a customized methodology is developed for modelling hydrogen transitions with system dynamics modelling. Results are presented in terms of the investments required to purchase the hydrogen production capacity and the investments required to supply electricity to the hydrogen production systems. Production capacity investments are found to range between 1.59 and 2.58 billion New Zealand Dollars and marginal electricity investments are found to range between 4.14 and 7.65 billion New Zealand Dollars. These investments represent scenarios in which 71% to 90% of the heavy-duty vehicle fleet are replaced with fuel cell trucks by 2050. The wide range of these findings reflects the large uncertainties in estimates of how hydrogen technologies will develop over the course of the next thirty years. Policy recommendations are drawn from these results and a clear opportunity for future work is outlined. Most notably the results from this study should be compared with research investigating the investments required to decarbonize the heavy-duty vehicle sectors with alternative technologies such as battery-electric trucks biodiesel and catenary systems. Such a comparison would ensure that the most cost effective decarbonization strategy is employed.