Publications

This paper provides a comprehensive review and outlook on power converters devised for supplying polymer electrolyte membrane (PEM) electrolyzers from photovoltaic sources. The produced hydrogen known as green hydrogen is a promising solution to mitigate the dependence on fossil fuels. The main topologies of power conversion systems are discussed and classified; a loss analysis emphasizes the issues concerning the electrolyzer supply. The attention is focused on power converters of rated power up to a tenth of a kW since it is a promising field for a short-term solution implementing green hydrogen production as a decentralized. It is also encouraged by the proliferation of relatively cheap photovoltaic low-power plants. The main converters proposed by the literature in the last few years and realized for practical applications are analyzed highlighting their key characteristics and focusing on the parameters useful for designers. Future perspectives are addressed concerning the availability of new wide-bandgap devices and hard-to-abate sectors with reference to the whole conversion chain.

Energy system optimization models offer insights into energy and emissions futures through least-cost optimization. However real-world energy systems often deviate from deterministic scenarios necessitating rigorous uncertainty exploration in macro-energy system modeling. This study uses modeling techniques to generate diverse near cost-optimal net-zero CO2 pathways for the United States’ energy system. Our findings reveal consistent trends across these pathways including rapid expansion of solar and wind power generation substantial petroleum use reductions near elimination of coal combustion and increased end-use electrification. We also observe varying deployment levels for natural gas hydrogen direct air capture of CO2 and synthetic fuels. Notably carbon-captured coal and synthetic fuels exhibit high adoption rates but only in select decarbonization pathways. By analyzing technology adoption correlations we uncover interconnected technologies. These results demonstrate that diverse pathways for decarbonization exist at comparable system-level costs and provide insights into technology portfolios that enable near cost-optimal net-zero CO2 futures.

Hydrogen has become a prospective energy carrier for a cleaner more sustainable economy offering carbon-free energy to reduce reliance on fossil fuels and address climate change challenges. However hydrogen production faces significant technological and economic hurdles that must be overcome to reveal its highest potential. This study focused on evaluating the economics and technoeconomic resilience of two large-scale hydrogen production routes from African palm empty fruit bunches (EFB) by indirect gasification. Computer-aided process engineering (CAPE) assessed multiple scenarios to identify bottlenecks and optimize economic performance indicators like gross profits including depreciation after-tax profitability payback period and net present value. Resilience for each route was also assessed considering raw material costs and the market price of hydrogen in relation to gross profits and after-tax profitability. Route 1 achieved a gross profit (DGP) of USD 47.12 million and a profit after taxes (PAT) of USD 28.74 million while Route 2 achieved a DGP of USD 46.53 million and a PAT of USD 28.38 million. The results indicated that Route 2 involving hydrogen production through an indirect gasification reactor with a Selexol solvent unit for carbon dioxide removal demonstrated greater resilience in terms of raw material costs and product selling price.

Pressure vessels are used for large commercial and industrial applications such as softening filtration and storage. It is expected that high-pressure hydrogen storage vessels will be widely used in hydrogen-fuelled vehicles. Progressive failure properties the burst pressure and fatigue life should be taken into account in the design of composite pressure vessels. In this work the model and analysis of hydrogen storage vessels along with complete structural and thermal analysis. Liquid hydrogen is seen as an outstanding candidate for the fuel of high altitude long-endurance unmanned aircraft. The design of lightweight and super-insulated storage tanks for cryogenic liquid hydrogen is since long identified as crucial to enable the adoption of the liquid hydrogen. The basic structural design of the airborne cryogenic liquid hydrogen tank was completed in this paper. The problem of excessive heat leakage of the traditional support structure was solved by designing and using a new insulating support structure. The thermal performance of the designed tank was evaluated. The structure of the tank was analyzed by the combination of the film container theory and finite element numerical simulation method. The structure of the adiabatic support was analyzed by using the Hertz contact theory and numerical simulation method. A simple and effective structure analysis method for a similar container structure and point-contact support structure was provided. Bases for further structural optimization design of hydrogen tank will be provided also. The analysis will be carried out with different materials like titanium nickel alloy and some coated powders like alumina Titania and zirconium oxide. The results will be compared with that.

With the gradual maturity of wind power technology China’s wind power generation has grown rapidly over the recent years. However due to the on-site inconsumable electricity the phenomenon of large-scale “wind curtailment” occurs in some areas. In this paper a novel hybrid hydrogen/electricity refueling station is built near a wind farm and a part of the surplus wind power is used to charge electric trucks and the other part of the surplus power is used to produce “green hydrogen”. According to real-time load changes different amounts of liquid hydrogen and gas hydrogen can be properly coordinated to provide timely energy supply for hydrogen trucks. For a 400 MW wind farm in the western Inner Mongolia China the feasibility of the proposed system has been carried out based on the sensitivity and reliability analysis the static and dynamic economic modeling with an entire life cycle analysis. Compared to the conventional technology the initial investment of the proposed scheme (700.07 M$) decreases by 13.97% and the dynamic payback period (10.93 years) decreases by 25.87%. During the life cycle of the proposed system the accumulative NPV reaches 184.63 M$ which increases by 3.14 times compared to the case by conventional wind technology.

Trains have been a crucial part of modern transport and their high energy efficiency and low greenhouse gas emissions make them ideal candidates for the future transport system. Transitioning from diesel trains to hydrogen fuel cell electric trains is a promising way to decarbonize rail transport. That’s because the fuel cell electric trains have several advantages over other electric trains such as lower life-cycle emissions and shorter refueling time than battery ones and less requirements for wayside infrastructure than the ones with overhead electric wires. However hydrogen fuel technology still needs to be advanced in areas including hydrogen production storage refueling and on-board energy management. Currently there are several pilot projects of hydrogen fuel cell electric trains across the globe especially in developed countries including one commercialized and permanent route in Germany. The experiences from the pilot projects will promote the technological and economic feasibility of hydrogen fuel in rail transport.

The use of aluminum-based products is widespread and growing particularly in industries such as automotive food packaging and construction. Obtaining aluminum is expensive and energy-intensive making the recycling of existing products essential for economic and environmental viability. This work explores the potential of using green hydrogen as a replacement for natural gas in the smelting and refining furnaces in aluminum recycling facilities. The adoption of green hydrogen has the potential to curtail approximately 4.54 Ktons/year of CO2 emissions rendering it a sustainable and economically advantageous solution. The work evaluates the economic viability of a case study through assessing the Net Present Value (NPV) and the Internal Rate of Return (IRR). Furthermore it is employed single- and multi-parameter sensitivity analyses to obtain insight on the most relevant conditions to achieve economic viability. Results demonstrate that integrating on-site green hydrogen generation yields a favorable NPV of €57370 an IRR of 9.83% and a 19.63-year payback period. The primary factors influencing NPV are the initial electricity consumption stack and the H2 price.

The transition to low-carbon energy systems requires efficient hydrogen production methods that minimise CO2 emissions. This study presents a techno-economic assessment of hydrogen production via methane pyrolysis utilising a novel liquid metal bubble column reactor (LMBCR) designed for CO2-free hydrogen and solid carbon outputs. Operating at 20 bar and 1100 ◦C the reactor employs a molten nickel-bismuth alloy as both catalyst and heat transfer medium alongside a sodium bromide layer to enhance carbon purity and facilitate separation. Four operational scenarios were modelled comparing various heating and recycling configurations to optimise hydrogen yield and process economics. Results indicate that the levelised cost of hydrogen (LCOH) is highly sensitive to methane and electricity prices CO2 taxation and the value of carbon by-products. Two reactor configurations demonstrate competitive LCOHs of 1.29 $/kgH2 and 1.53 $/kgH2 highlighting methane pyrolysis as a viable low-carbon alternative to steam methane reforming (SMR) with carbon capture and storage (CCS). This analysis underscores the potential of methane pyrolysis for scalable economically viable hydrogen production under specificmarket conditions.

The hydrogen sector is envisaged as one of the key enablers of the energy transition that the European Union is facing to accomplish its decarbonization targets. However regarding the technologies that enable the deployment of a hydrogen economy a growing concern exists about potential burden-shifting across sustainability dimensions. In this sense social life cycle assessment arises as a promising methodology to evaluate the social implications of hydrogen technologies along their supply chains. In the context of the European projects eGHOST and SH2E this study seeks to advance on key methodological aspects of social life cycle assessment when it comes to guiding the ecodesign of two relevant hydrogen-related products: a 5 kW solid oxide electrolysis cell stack for hydrogen production and a 48 kW proton-exchange membrane fuel cell stack for mobility applications. Based on the social life cycle assessment results for both case studies under alternative approaches the definition of a product-specific supply chain making use of appropriate cut-off criteria was found to be the preferable choice when addressing system boundaries definition. Moreover performing calculations according to the activity variable approach was found to provide valuable results in terms of social hotspots identification to support subsequent decision-making processes on ecodesign while the direct calculation approach is foreseen as a complement to ease the interpretation of social scores. It is concluded that advancements in the formalization of such suitable practices could foster the integration of social metrics into the sustainable-by-design framework of hydrogen-related products.

Hydrogen as a zero-emission fuel produces only water when used in fuel cells making it a vital contributor to reducing greenhouse gas emissions across industries like transportation energy and manufacturing. Efficient hydrogen storage requires lightweight high-strength vessels capable of withstanding high pressures to ensure the safe and reliable delivery of clean energy for various applications. Type V composite pressure vessels (CPVs) have emerged as a preferred solution due to their superior properties thus this study aims to predict the performance of a Type V CPV by developing its numerical model and calculating numerical burst pressure (NBP). For the validation of the numerical model a Hydraulic Burst Pressure test is conducted to determine the experimental burst pressure (EBP). The comparative study between NBP and EBP shows that the numerical model provides an accurate prediction of the vessel’s performance under pressure including the identification of failure locations. These findings highlight the potential of the numerical model to streamline the development process reduce costs and accelerate the production of CPVs that are manufactured by prepreg hand layup process (PHLP) using carbon fiber/epoxy resin prepreg material.

Blending hydrogen in existing natural gas pipelines compromises steel integrity because it increases fatigue crack growth promotes subcritical cracking and decreases fracture toughness. In this regard several laboratories reported that the fracture toughness measured in a hydrogen containing gaseous atmosphere KIH can be 50% or less than KIC the fracture toughness measured in air. From a pipeline integrity perspective fracture mechanics predicts that injecting hydrogen in a natural gas pipeline decreases the failure pressure and the size of the critical flaw at a given pressure level. For a pipeline with a given flaw size as shown in this work the effect of hydrogen embrittlement (HE) in the predicted failure pressure is largest when failure occurs by brittle fracture. The HE effect on failure pressure diminishes with a decreasing crack size or increasing fracture toughness. The safety margin after a successful hydrostatic test is reduced and therefore the time between hydrotests should be decreased. In this work all those effects were quantified using a crack assessment methodology (level 2 API 579-ASME FFS) considering literature values for KIH and KIC reported for an API 5L X52 pipeline steel. To characterize different scenarios various crack sizes were assumed including a small crack with a size close to the detection limit of current in-line inspection techniques and a larger crack that represents the largest crack size that could survive a hydrotest to 100% of the steel specified minimum yield stress. The implications of a smaller failure pressure and smaller critical crack size on pipeline integrity are discussed in this paper.

Can Norway be an important hydrogen exporter to the European Union (EU) by 2030? We explore three scenarios in which Norway’s hydrogen export market may develop: A Business-as-usual B Moderate Onshore C Accelerated Offshore. Applying a sector-coupled energy system model we examine the techno-economic viability spatial and socio-economic considerations for blue and green hydrogen export in the form of ammonia by ship. Our results estimate the costs of low-carbon hydrogen to be 3.5–7.3€/kg hydrogen. While Norway may be cost-competitive in blue hydrogen exports to the EU its sustainability is limited by the reliance on natural gas and the nascent infrastructure for carbon transport and storage. For green hydrogen exports Norway may leverage its strong relations with the EU but is less cost-competitive than countries like Chile and Morocco which benefit from cheaper solar power. For all scenarios significant land use is needed to generate enough renewable energy. Developing a green hydrogen-based export market requires policy support and strategic investments in technology infrastructure and stakeholder engagement ensuring a more equitable distribution of renewable installations across Norway and national security in the north. Using carbon capture and storage technologies and offshore wind to decarbonise the offshore platforms is a win-win solution that would leave more electricity for developing new industries and demonstrate the economic viability of these technologies. Finally for Norway to become a key hydrogen exporter to the EU will require a balanced approach that emphasises public acceptance and careful land use management to avoid costly consequences.

This study evaluated the greenhouse gas (GHG) emissions associated with hydrogen production in South Korea (hereafter referred to as Korea) using water electrolysis. Korea aims to advance hydrogen as a clean fuel for transportation and power generation. To support this goal we employed a life cycle assessment (LCA) approach to evaluate the emissions across the hydrogen supply chain in a well-to-pump framework using the Korean clean hydrogen certification tiers. Our assessment covered seven stages from raw material extraction for power plant construction to hydrogen production liquefaction storage and distribution to refueling stations. Our findings revealed that among the sixteen power sources evaluated hydroelectric and onshore wind power exhibited the lowest emissions qualifying as the Tier 2 category of emissions between 0.11 and 1.00 kgCO2e/kgH2 under a well-to-pump framework and Tier 1 category of emissions below 0.10 kgCO2e/kgH2 under a well-to-gate framework. They were followed by photovoltaics nuclear energy and offshore wind all of which are highly dependent on electrolysis efficiency and construction inputs. Additionally the study uncovered a significant impact of electrolyzer type on GHG emissions demonstrating that improvements in electrolyzer efficiency could substantially lower GHG outputs. We further explored the potential of future energy mixes for 2036 2040 and 2050 as projected by Korea’s energy and environmental authorities in supporting clean hydrogen production. The results suggested that with progressive decarbonization of the power sector grid electricity could meet Tier 2 certification for hydrogen production through electrolysis and potentially reach Tier 1 when considering well-to-gate GHG emissions.

The current study comprehensively examines the application of wave tidal and undersea current energy sources of Turkiye for green hydrogen fuel production and cost analysis. The estimated potential capacity of each city is derived from official data and acceptable assumptions and is subject to discussion and evaluation in the context of a viable hydrogen economy. According to the findings the potential for green hydrogen generation in Turkiye is projected to be 7.33 million tons using a proton exchange membrane electrolyser (PEMEL). Cities with the highest hydrogen production capacities from marine applications are Mugla Izmir Antalya and Canakkale with 998.10 kt 840.31 kt 605.46 kt and 550.42 kt respectively. The study calculations obviously show that there is a great potential by using excess power in producing hydrogen which will result in an economic value of 3.01 billion US dollars. This study further helps develop a detailed hydrogen map for every city in Turkiye using the identified potential capacities of renewable energy sources and the utilization of electrolysers to make green hydrogen by green power. The potentials and specific capacities for every city are also highlighted. Furthermore the study results are expected to provide clear guidance for government authorities and industries to utilize such a potential of renewable energy for investment and promote clean energy projects by further addressing concerns caused by the usage of carbon-based (fossil fuels dependent) energy options. Moreover green hydrogen production and utilization in every sector will help achieve the national targets for a net zero economy and cope with international targets to achieve the United Nation's sustainable development goals.

The integration of wind and solar energy with green hydrogen technologies represents an innovative approach toward achieving sustainable energy solutions. This review examines state-ofthe-art strategies for synthesizing renewable energy sources aimed at improving the efficiency of hydrogen (H2 ) generation storage and utilization. The complementary characteristics of solar and wind energy where solar power typically peaks during daylight hours while wind energy becomes more accessible at night or during overcast conditions facilitate more reliable and stable hydrogen production. Quantitatively hybrid systems can realize a reduction in the levelized cost of hydrogen (LCOH) ranging from EUR 3.5 to EUR 8.9 per kilogram thereby maximizing the use of renewable resources but also minimizing the overall H2 production and infrastructure costs. Furthermore advancements such as enhanced electrolysis technologies with overall efficiencies rising from 6% in 2008 to over 20% in the near future illustrate significant progress in this domain. The review also addresses operational challenges including intermittency and scalability and introduces system topologies that enhance both efficiency and performance. However it is essential to consider these challenges carefully because they can significantly impact the overall effectiveness of hydrogen production systems. By providing a comprehensive assessment of these hybrid systems (which are gaining traction) this study highlights their potential to address the increasing global energy demands. However it also aims to support the transition toward a carbon-neutral future. This potential is significant because it aligns with both environmental goals and energy requirements. Although challenges remain the promise of these systems is evident.

The use of hydrogen as a source of fuel for marine applications is relatively nascent. As the maritime industry pivots to the use of alternate low and zero-emission fuels to adapt to a changing regulatory landscape hydrogen energy needs to present and substantiate a technical and commercially viable use case to secure its value proposition in the future fuel mix. This paper leverages the technoeconomic and environmental assessment previously performed on HyForce a hydrogen-fuelled harbour tug which has shown encouraging results for both technical and commercial aspects. This study aims to create a digital twin of HyForce to accurately predict her operability in real-world scenarios. The results from this study identify the strengths and drawbacks of the proposed use case. This is achieved by embedding the detailed design of HyForce in a virtual environment to further evaluate its operational performance through Computational Fluid Dynamics (CFD) simulations of realistic environmental conditions such as wind wave sea currents and friction attributed to the properties of seawater. The results from this study indicate a base case power requirement of 93 kW to 1892 kW to achieve speeds of 5 to 12 knots in the absence of external environmental influences. Consequently the speed of HyForce has a profound impact on total resistance peaking at 97.3 kN at 12 knots. Seawater properties such as low seawater temperature of 0C and a high salinity of 50g/kg increased friction. Additionally wind speeds of 10 m/s acting on HyForce delivered a resistance of 3 kN. However these will be well mitigated through the design of the propulsion system which will be able to deliver a thrust power of 1892 kW and with assistance from the energy storage systems produce 2 MW of power to overcome the resistance experienced. The findings presented in this paper can serve as a foundation for constructing a robust model for the development of a predictive controller for future work. This controller has the potential to optimize the configuration of hydrogen and battery energy storage aligning with desired cost functions.

The decarbonization of industrial process heat is one of the bigger challenges of the global energy transition. Process heating accounts for about 20% of final energy demand in Germany and the situation is similar in other industrialized nations around the globe. Process heating is indispensable in the manufacturing processes of products and materials encountered every day ranging from food beverages paper and textiles to metals ceramics glass and cement. At the same time process heating is also responsible for significant greenhouse gas emissions as it is heavily dependent on fossil fuels such as natural gas and coal. Thus process heating needs to be decarbonized. This review article explores the challenges of decarbonizing industrial process heat and then discusses two of the most promising options the use of electric heating technologies and the substitution of fossil fuels with low-carbon hydrogen in more detail. Both energy carriers have their specific benefits and drawbacks that have to be considered in the context of industrial decarbonization but also in terms of necessary energy infrastructures. The focus is on high-temperature process heat (>400 ◦C) in energy-intensive basic materials industries with examples from the metal and glass industries. Given the heterogeneity of industrial process heating both electricity and hydrogen will likely be the most prominent energy carriers for decarbonized high-temperature process heat each with their respective advantages and disadvantages.

Solid oxide fuel cells (SOFC) have developed to a mature technology able to achieve electrical efficiencies beyond 60%. This makes them particularly suitable for off-grid applications where SOFCs can supply both electricity and heat at high efficiency. Concerns related to lifetime particularly when operated dynamically and the high investment cost are however still the main obstacles toward a widespread adoption of this technology. In this paper we propose a hybrid cogeneration system that attempts to overcome these limitations in which the SOFC mainly provides the baseload of the system. Introducing a purification unit allows the production and storage of pure hydrogen from the SOFC anode off-gas. The hydrogen can be stored and used in a proton exchange membrane fuel cell (PEMFC) during peak demands. The SOFC system is completed with a battery used during periods of high electricity production. We propose the use of a mixed integer-linear optimization framework for the sizing of the different components of the system and particularly for identifying the optimal trade-off between round-trip efficiency and investment cost of the battery-based and hydrogen-based storage systems. The proposed system is applied and optimized to two case studies: an off-grid dwelling and a cruise ship. The results show that if the SOFC is used as the main energy conversion technology of the system the use of hydrogen storage in combination with a PEMFC and a battery is more economically convenient compared to the use of the SOFC in stand-alone mode or of pure battery storage. The results show that the proposed hybrid storage solution makes it possible to reduce the investment cost of the system while maintaining the use of the SOFC as the main energy source of the system.

Energy production and consumption are major contributors to greenhouse gas (GHG) emissions exacerbating one of the greatest challenges faced by modern societies: climate change. Thus societies must switch to more sustainable energy sources. Green hydrogen has emerged as a promising alternative energy carrier facilitating storage and utilization across various industries. However amidst different production processes solely sustainable electrolysis stands out as an environmentally benign production method. Hydrogen producers must prove provenance and sustainable production to regulatory bodies and hydrogen buyers to comply with the regulations for sustainable development. Blockchain provides a viable solution encompassing trustworthy and secure information sharing between untrusted partners. In this article we employ a design science research approach to develop a blockchain-based certification system (BLC-CS) for green hydrogen. Through collaboration with experts to gather requirements and conduct evaluations we design an artifact that streamlines the certification process for producers regulators and consumers. Our proposed solution facilitates information gathering verification and reporting contributing to the advancement of sustainable energy practices. We provide a comprehensive discussion of the BLC-CS’s feasibility for green hydrogen certification including technical extensions recommendations for practitioners and directions for future research.

Because ammonia is easier to store and transport over long distances than hydrogen it is a promising research direction as a potential carrier for hydrogen. However its low ignition and combustion rates pose challenges for running conventional ignition engines solely on ammonia fuel over the entire operational range. In this study we attempted to identify a stable engine combustion zone using a high-pressure direct injection of ammonia fuel into a 2.5 L spark ignition engine and examined the potential for extending the operational range by adding hydrogen. As it is difficult to secure combustion stability in a low-temperature atmosphere the experiment was conducted in a sufficiently-warmed atmosphere (90 ± 2.5 ◦C) and the combustion emission and efficiency results under each operating condition were experimentally compared. At 1500 rpm the addition of 10% hydrogen resulted in a notable 20.26% surge in the maximum torque reaching 263.5 Nm in contrast with the case where only ammonia fuel was used. Furthermore combustion stability was ensured at a torque of 140 Nm by reducing the fuel and air flow rates.

In this study an environmental and economic assessment of hydrogen production from biowaste and biomass is performed from a life cycle perspective with a high degree of primary life cycle inventory data on materials energy and investment flows. Using SimaPro LCA software and CML-IA 2001 impact assessment method ten environmental impact categories are analyzed for environmental analysis. Economic analysis includes capital and operational expenditures and monetization cost of life cycle environmental impacts. The hydrogen pro duction from biowaste has a high climate impact photochemical oxidant and freshwater eutrophication than biomass while it performs far better in ozone depletion terrestrial ecotoxicity abiotic depletion-fossil abiotic depletion human toxicity and freshwater ecotoxicity. The sensitivity analysis of LCA results indicates that feedstock to biogas/pyrolysis-oil yields ratio and the type of energy source for the reforming process can significantly influence the results particularly climate change abiotic depletion and human toxicity. The life cycle cost (LCC) of 1 kg hydrogen production has been accounted as 0.45–2.76 € with biowaste and 0.54–3.31 € with biomass over the plant’s lifetime of 20 years. From the environmental impacts of climate change photo chemical oxidant and freshwater eutrophication hydrogen production from biomass is a better option than biowaste while from other included impact categories and LCC perspectives it’s biowaste. This research con tributes to bioresources to hydrogen literature with some new findings that can be generalized in Europe and even globally as it is in line with and endorse existing theoretical and simulation software-based studies.

This research explores the optimal operation of an offshore wave-powered hydrogen system specifically designed to supply electricity and water to a bay in Humboldt California USA and also sell it with hydrogen. The system incorporates a desalination unit to provide the island with fresh water and feed the electrolyzer to produce hydrogen. The optimization process utilizes a mixture of experts in conjunction with the Quantitative Structure-Activity Relationship (QSAR) algorithm traditionally used in drug design to achieve two main objectives: minimizing operational costs and maximizing revenue from the sale of water hydrogen and electricity. Many case studies are examined representing typical electricity demand and wave conditions during typical summer winter spring and fall days. The simulation optimization and results are carried out using MATLAB 2018 and SAM 2024 software applications. The findings demonstrate that the combination of the QSAR algorithm and quantum-inspired MoE results in higher revenue and lower costs compared to other current techniques with hydrogen sales being the primary contributor to increased income.

Renewable hydrogen production from biomass thermochemical conversion is an emerging technology to reduce fossil fuel consumptions and carbon emissions. Biomass-derived hydrogen can be produced by pyrolysis gasification alkaline thermal treatment etc. However the removal of impurities from biomass thermochemical conversion products to improve hydrogen purity is currently technical bottleneck. It is important to assess and investigate the types and properties of impurities the difficulty of separation and the impact on downstream utilization of hydrogen in the biomass-derived hydrogen production process. The key objectives of this comprehensive review are: (1) to reveal the current status and necessity of developing biomass-derived hydrogen production; (2) to evaluate the types devices and impurities distribution of biomass thermochemical conversion; (3) to explore the formation pathways and removal technologies of typical impurities of tar CO2 sulfides and nitrides in hydrogen production process; and (4) to propose future insights on the separation technologies of typical impurities to promote the gradual substitution of biomass-derived hydrogen for fossil-derived energy.

The underground hydrogen storage (UHS) capacities of shut down oil and gas (O&G) fields along the Norwegian continental shelf (NCS) are evaluated based on the publicly available geological and hydrocarbon production data. Thermodynamic equilibrium and geochemical models are used to describe contamination of hydrogen loss of hydrogen and changes in the mineralogy. The contamination spectrum of black oil fields and retrograde gas fields are remarkably similar. Geochemical models suggest limited reactive mineral phases and meter-scale hydrogen diffusion into the caprock. However geochemical reactions between residual oil reservoir brine host rock and hydrogen are not yet studied in detail. For 23 shut down O&G fields a theoretical maximum UHS capacity of ca. 642 TWh is estimated. We conclude with Frigg Nordost Frigg and Odin as the best-suited shut down fields for UHS having a maximum UHS capacity of ca. 414 TWh. The estimates require verification by site-specific dynamic reservoir models.

The Mediterranean basin has been characterized by a net flow of fossil commodities from the North African shore to Southern Europe and the Middle East for decades; however decarbonizing the energy system implies to substantially modify this situation turning the current “black dialogue” into a “green dialogue” (i.e. based on the exchange of renewable electricity and green hydrogen). This paper presents a feasibility study conducted to estimate the potential green hydrogen production by electrolysis in three Tunisian sites. It shows and compares several plant layouts varying the size and typology of renewable electricity generators and electrolyzers. The work adopts local weather data and technical features of the technologies in the computations and accounts for site specific topographical and infrastructural constraints such as land available for construction and local power grid connection capacities. It shows that configurations able to produce large quantities of green hydrogen may not be compliant with such constraints basically nullifying their contribution in any hydrogen strategy. Finally results show that the LCOH lies in the range 1.34 $/kgH2 and 4.06 $/kgH2 depending on both the location and the combination of renewable electricity generators and electrolyzers.