Publications

As the global economy moves toward net-zero carbon emissions large-scale energy storage becomes essential to tackle the seasonal nature of renewable sources. Underground hydrogen storage (UHS) offers a feasible solution by allowing surplus renewable energy to be transformed into hydrogen and stored in deep geological formations such as aquifers salt caverns or depleted reservoirs making it available for use on demand. This study thoroughly evaluates UHS concepts procedures and challenges. This paper analyzes the most recent breakthroughs in UHS technology and identifies special conditions needed for its successful application including site selection guidelines technical and geological factors and the significance of storage characteristics. The integrity of wells and caprock which is important for safe and efficient storage can be affected by the operating dynamics of the hydrogen cycle notably the fluctuations in pressure and stress within storage formations. To evaluate its potential for broader adoption we also examined economic elements such as cost-effectiveness and the technical practicality of large-scale storage. We also reviewed current UHS efforts and identified key knowledge gaps primarily in the areas of hydrogen–rock interactions geochemistry gas migration control microbial activities and geomechanical stability. Resolving these technological challenges regulatory frameworks and environmental sustainability are essential to UHS’s long-term and extensive integration into the energy industry. This article provides a roadmap for UHS research and development emphasizing the need for further research to fully realize the technology’s promise as a pillar of the hydrogen economy

In 2021 the global electricity and heat sector recorded the highest increase in carbon dioxide (CO2) emissions in comparison with the previous year highlighting the ongoing challenges in reducing emissions within the sector. Therefore combined heat and power (CHP) plants running on renewable fuels can play an important role in the energy transition by decarbonising a process increasing the efficiency and capacity factor. Since 2003 Luxembourgish CHP plants have been transitioning from natural gas to biomass mainly wood pellets. However even though wood pellets are a renewable alternative the market volatility in 2022 highlighted the vulnerability of a system reliant solely on one type of fuel. This study assesses the feasibility of using hydrogen to decarbonise a cogeneration plant powered by a natural gas-fuelled internal combustion engine. Although the technology to use hydrogen as a fuel for such systems already exists a technical and economic analysis of implementing a hydrogen-ready plant is still lacking. Our results show that from a technical perspective retrofitting an existing power plant to operate with hydrogen is feasible either by adapting or replacing the engine to accommodate hydrogen blends from 0 up to 100%. The costs of making the CHP plant hydrogen-ready vary depending on the scenario ranging from a 20% increase for retrofitting to a 60% increase for engine replacement in the best-case scenarios. However these values remain highly variable due to uncertainties associated with the ongoing technology development. From an economic standpoint as of 2024 running the plant on hydrogen remains more expensive due to significant initial investments and higher fuel costs. Nevertheless projections indicate that rising climate concerns CO2 taxes geopolitical factors and the development of the hydrogen framework in the region—through projects such as MosaHYc and HY4Link— could accelerate the competitiveness of hydrogen making it a more viable alternative to fossil-based solutions in the near future.

The industrial sector’s movement toward decarbonization is regarded as essential for governments. This paper assesses a system that uses only solar energy to synthesize liquid hydrogen and ammonia as energy carriers. Photovoltaic modules deliver electrical power while parabolic dish collectors are responsible for directing thermal energy to the solid oxide electrolyzer for hydrogen production which then mixes with nitrogen to produce ammonia after a number of compression stages. To investigate the proposed system comprehensive thermodynamic and exergo-economic studies are performed using an engineering equation solver and ASPEN PLUS software.

Biogas (primarily biomethane) as a carbon-neutral renewable energy source holds great potential to replace fossil fuels for sustainable hydrogen production. Conventional biogas reforming systems adopt strategies similar to industrial natural gas reforming posing challenges such as high temperatures high energy consumption and high system complexity. In this study we propose a novel multi-product sequential separation-enhanced reforming method for biogas-derived hydrogen production which achieves high H2 yield and CO2 capture under mid-temperature conditions. The effects of reaction temperature steam-to-methane ratio and CO2/CH4 molar ratio on key performance metrics including biomethane conversion and hydrogen production are investigated. At a moderate reforming temperature of 425 ◦C and pressure of 0.1 MPa the conversion rate of CH4 in biogas reaches 97.1% the high-purity hydrogen production attains 2.15 mol-H2/mol-feed and the hydrogen yield is 90.1%. Additionally the first-law energy conversion efficiency from biogas to hydrogen reaches 65.6% which is 11 percentage points higher than that of conventional biogas reforming methods. The yield of captured CO2 reaches 1.88 kg-CO2/m3 -feed effectively achieving near-complete recovery of green CO2 from biogas. The mild reaction conditions allow for a flexible integration with industrial waste heat or a wide selection of other renewable energy sources (e.g. solar heat) facilitating distributed and carbonnegative hydrogen production.

Hydrogen–methane gas mixtures are increasingly recognized as a viable path toward achieving carbon neutrality leveraging existing natural gas infrastructure while reducing greenhouse gas emissions. This study investigates a novel static mixing device designed for blending hydrogen and methane employing both experimental tests and threedimensional computational fluid dynamics (CFD) simulations. Hydrogen was introduced into a methane flow via direct injection with experimental mixtures ranging from 5% to 18% hydrogen. The mixture quality was assessed using a specialized gas chromatograph and the results were compared against simulated data to evaluate the mixer’s performance and the model’s accuracy. The system demonstrated effective blending maintaining uniform hydrogen concentrations across the outlet with minimal variations. Experimental and simulated results showed strong agreement with an average accuracy error below 2% validating the reliability of the CFD model. Smaller nozzles (0.4 mm) achieved greater mixing uniformity while larger nozzles (0.6 mm) facilitated higher hydrogen throughput indicating trade-offs between mixing precision and flow capacity. The mixing device proved compatible with existing pipeline infrastructure offering a scalable solution for hydrogen integration into natural gas networks. These findings underscore the mixer’s potential as a practical component in advancing the hydrogen economy and achieving sustainable energy transitions.

As the European countries strive to meet their ambitious climate goals renewable hydrogen has emerged to aid in decarbonizing energy-intensive sectors and support the overall energy transition. To ensure that hydrogen production aligns with these goals the European Commission has introduced criteria for additionality temporal correlation and geographical correlation. These criteria are designed to ensure that hydrogen production from renewable sources supports the growth of renewable energy. This study assesses the impact of these criteria on green hydrogen production focusing on production costs and technology impacts. The European energy market is simulated up to 2048 using stochastic programming applying these requirements exclusively to green hydrogen production without the phased-in compliance period outlined in the EU regulations. The findings show that meeting the criteria will increase expected system costs by €82 billion from 2024 to 2048 largely due to the rapid shift from fossil fuels to renewable energy. The additionality requirement which mandates the use of new renewable energy installations for electrolysis proves to be the most expensive but also the most effective in accelerating renewable energy adoption.

The global shift away from fossil fuels necessitates swift and transformative action underscoring the need for timely and accurate insights into emerging low-carbon technologies. This review provides a comprehensive and systematic analysis of innovation trends within the hydrogen technology ecosystem. Drawing on global patent data as a key indicator of industrial innovation the study offers a forward-looking assessment of technological developments spanning the entire hydrogen value chain like production storage distribution transformation and end-use applications across various sectors. By evaluating patent activity over time and across regions the review highlights significant innovation trends identifies leading industrial contributors and maps the evolving global competitive landscape. Particular attention is given to regional dynamics and sector-specific breakthroughs offering a nuanced perspective for policymakers investors and stakeholders engaged in energy transition planning. As hydrogen becomes increasingly central to decarbonization strategies worldwide this study serves as a critical intelligence resource illuminating current trajectories and signalling potential technological inflection points in the ongoing energy transformation.

Green hydrogen plays a vital role in facilitating the transition to sustainable energy systems with stable and high-capacity offshore wind resources serving as an ideal candidate for large-scale green hydrogen production. However as the capacity of offshore wind turbines continues to grow the increasing size and weight of these systems pose significant challenges for installation and deployment. This study investigates the application of high-temperature superconducting (HTS) materials in the generator and the power conducting cables as a promising solution to these challenges. Compared to conventional wind turbines HTS wind turbines result in significant reductions in weight and size while simultaneously enhancing power generation and transmission efficiency. This paper conducts a comprehensive review of mainstream electrolysis-based hydrogen production technologies and advanced hydrogen storage methods. The main contribution of this research is the development of an innovative conceptual framework for a superconducting offshore windto-hydrogen energy system where a small amount of liquid hydrogen is used to provide a deep-cooling environment for the HTS wind turbine and the remaining liquid hydrogen is used for the synthesis of ammonia as a final product. Through functional analysis this study demonstrates its potential for enabling large-scale offshore hydrogen production and storage. Additionally this paper discusses key challenges associated with real-world implementation including optimizing the stability of superconducting equipment and ensuring component coordination. The findings offer crucial insights for advancing the offshore green hydrogen sector showing that HTS technology can significantly enhance the energy efficiency of offshore wind-to-hydrogen systems. This research provides strong technical support for achieving carbon neutrality and fostering sustainable development in the offshore renewable energy sector.

An on-site hydrogen refueling station (HRS) directly supplies hydrogen to vehicles using an on-site hydrogen production method such as electrolysis. For the efficient operation of an on-site HRS it is essential to optimize the entire process from hydrogen production to supply. However most existing approaches focus on the efficiency of hydrogen production. This study proposes an optimal operation model for a renewable-energy-integrated on-site HRS which considers the degradation of electrolyzers and operation of compressors. The proposed model maximizes profit by considering the hydrogen revenue electricity costs and energy storage system degradation. It estimates hydrogen production using a voltage equation models compressor power using a shaft power equation and considers electrolyzer degradation using an empirical voltage model. The effectiveness of the proposed model is evaluated through simulation. Comparison with a conventional control strategy shows an increase of over 56% in the operating revenue.

Hydrogen has emerged as a pivotal energy carrier in the global transition toward sustainable energy systems. This study analyses current trends sectoral dynamics and future demand projections for hydrogen employing a multi-methodological framework that integrates Compound Annual Growth Rate (CAGR) extrapolation scenario-based modeling and regional comparative analysis. By leveraging historical growth patterns of geothermal bioenergy and wind energy sectors in the European Union (EU) three hydrogen demand scenarios—Conservative (3.25 % CAGR) Moderate (8.33 % CAGR) and Optimistic (15.42 % CAGR)—are projected to 2050. Results indicate that global hydrogen demand could range from 18.8 to 381.3 million tonnes per year by 2050 depending on technological advancements policy frameworks and infrastructure investments. The transportation and industrial sectors are identified as critical drivers while regional disparities highlight leadership from the EU the U.S. and Asia-Pacific nations. The study underscores the necessity of coordinated policy cost reduction in green hydrogen production and infrastructure scalability to realize hydrogen’s potential in decarbonizing energy systems.