Publications

To address the global climate crisis maritime logistics are undergoing a transition away from fossil-based energy sources. The transition is envisaged to be both green (involving renewables) and digital (involving various kinds of digitalization). Much of the hope rests on the new hydrogen economy involving the build-up of infrastructure for hydrogen-derived alternative fuels such as methanol and ammonia. Indeed the new hydrogen economy is often portrayed as set to revolutionize maritime transport. The hope behind the hype reflects a belief in the performativity of hypes: some technological phenomenon will eventually materialise in innovation and business practices. In this paper we critically analyse the current hydrogen hype in the field of Finnish maritime logistics as a paradigmatic case of performative techno-optimism. Based on causal network analysis and thematic analysis of expert interviews and workshop data we argue that the phenomenon of performative techno-optimism is more nuanced than hitherto presented in the related literature. We showcase a variety of stances along a spectrum ranging from radical optimism to radical pessimism. Furthermore our causal network analysis indicates that the current green and digital transition of maritime transport is caught in a systemic catch-22: transitioning to alternative fuels in maritime logistics faces a lock-in of between overly cautious demand for alternative fuels leading to overly cautious investment in supply which only secures the modest demand. Finally our thematic analysis of techno-optimist stances suggests the following two major ways out of the systemic dilemma: large-scale technological innovations and global regulatory solutions.

The integration of renewable resources with advanced storage technologies is critical for sustainable energy systems. In this paper a planning framework for an energy hub incorporating hydrogen and renewable energy systems is developed with the objective of minimizing operational costs while participating in flexible ramping product (FRP) markets. The energy hub is designed to utilize a hybrid storage system comprising multi-type battery energy storage (BESS) accounting for diverse chemistries and degradation behaviors and hydrogen storage (HS) to meet concurrent electric and hydrogen demands. To address uncertainties in renewable generation and market prices a stochastic optimization model is developed to determine the optimal investment capacities while optimizing operational decisions under uncertainty using scenario-based stochastic programming. Financial risks associated with price and renewable variability are mitigated through the Conditional Value-at-Risk (CVaR) metric. Case studies demonstrate that hybrid storage systems including both BESS and HS can reduce total costs by 23.62% compared to single-storage configurations that rely solely on BESS. Based on the results BESS participates more in providing flexible ramp-up services while HS plays a major role in providing flexible ramp-down services. The results emphasize the critical role of co-optimized hydrogen and multi-type BESS in enhancing grid flexibility and economic viability.

Within energy system analysis there is discourse regarding the role and economic benefits of nuclear energy in terms of overall system costs. The reported findings range from considerable drawbacks to substantial benefits depending on the chosen models scenarios and underlying assumptions. This article addresses existing gaps by demonstrating how subtle variations in model assumptions significantly impact analysis outcomes. Historically uncertainties associated with nuclear energy costs have been well documented whereas renewable energy costs have steadily declined and have been relatively predictable. However as land availability increasingly constrains future renewable expansion development is shifting from onshore to offshore locations where cost uncertainties are greater and anticipated cost reductions are less reliable. This study emphasizes this fundamental shift highlighting how uncertainties in future renewable energy costs could strengthen the economic case of nuclear energy within fully integrated sector-coupled energy systems especially when the costs of all technologies and weather conditions are set in the moderate range. Focusing specifically on Denmark this article presents a thorough sensitivity analysis of renewable energy costs and weather conditions within anticipated future ranges providing a nuanced perspective on the role of nuclear energy. Ultimately the findings underscore that when examining total annual system costs the differences between scenarios with low and high nuclear energy shares are minimal and are within ±5 % for the baseline assumptions while updated adjustments reduce this variation to ±1 %.

Underground hydrogen storage in aquifers is a promising solution to address the imbalance between energy supply and demand yet its practical implementation requires optimized strategies to ensure high efficiency and economic viability. To improve the storage and production efficiency of hydrogen it is essential to select the appropriate cushion gas and to study the influence of reservoir and process parameters. Based on the conceptual model of aquifer with single-well injection and production three potential cushion gas (carbon dioxide nitrogen and methane) were studied and the changes in hydrogen recovery for each cushion gas were compared. The effects of temperature initial pressure porosity horizontal permeability vertical to horizontal permeability ratio permeability gradient hydrogen injection rate and hydrogen production rate on the purity of recovered hydrogen were investigated. Additionally the impact of different well pattern on the purity of recovered hydrogen was studied. The results indicate that methane is the most effective cushion gas for improving hydrogen recovery in UHS. Different well patterns have significant impacts on the purity of recovered hydrogen. The mole fractions of methane in the produced gas for the single-well line-drive pattern and five-spot pattern were 16.8% 5% and 3.05% respectively. Considering the economic constraints the five-spot well pattern is most suitable for hydrogen storage in aquifers. Reverse rhythm reservoirs with smaller permeability differences should be chosen to achieve relatively high hydrogen recovery and purity of recovered hydrogen. An increase in hydrogen production rate leads to a significant decrease in the purity of the recovered hydrogen. In contrast hydrogen injection rate has only a minor effect. These findings provide actionable guidance for the selection of cushion gas site selection and operational design of aquifer-based hydrogen storage systems contributing to the large-scale seasonal storage of hydrogen and the balance of energy supply and demand.

Fuel-cell flying vehicles suffer from limited endurance while ammonia decomposed onboard to supply hydrogen offers a carbon-free high-density solution to extend flight missions. However the system’s performance is governed by a multi-scale coupling between propulsion and control systems. To this end this paper introduces a novel optimization paradigm termed physics-informed gradient-enhanced multi-objective optimization (PIGEMO) to simultaneously optimize the ammonia decomposition unit (ADU) catalyst composition powertrain sizing and flight control parameters. The PI-GEMO framework leverages a physics-informed neural network (PINN) as a differentiable surrogate model which is trained not only on sparse simulation data but also on the governing differential equations of the system. This enables the use of analytical gradient information extracted from the trained PINN via automatic differentiation to intelligently guide the evolutionary search process. A comprehensive case study on a flying vehicle demonstrates that the PIGEMO framework not only discovers a superior set of Pareto-optimal solutions compared to traditional methods but also critically ensures the physical plausibility of the results.

Hydrogen blending offers significant potential for decarbonizing natural gas-based thermal processes particularly in the steel and cement sectors. Due to its distinct combustion properties compared to natural gas – such as lower minimum air requirements and altered flame speeds – the hydrogen fraction of the fuel must be monitored for combustion control. In this study we present an ultrasonic time-of-flight measurement system for hydrogen concentrations of 0–40% in natural gas. The system is verified with test gas mixtures at laboratory scale and validated in a technical-scale setup using a real blower burner (< 60 kW). We evaluate uncertainty of the hydrogen fraction measurement and analyze the influence of varying natural gas compositions. We show that standard uncertainties below 4% can be achieved without knowledge of the specific natural gas composition. Our results provide insights for measurement system design and support the safe application of hydrogen in thermal systems for industrial processes.

Developing new injection systems and combustion chambers for hydrogen is a central topic for the new generation of engines. In this effort simulations take a central role but methods developed for conventional hydrocarbons (methane kerosene) must be revisited for hydrogen. Validation then becomes an essential part and clean well documented experiments are needed to guaranty that computational fluid dynamics solvers are as predictive and accurate as expected. In this framework the HYLON case is a swirled hydrogen/air burner used by multiple groups worldwide to validate simulation methods for hydrogen combustion in configurations close to gas turbine burners with experimental data available through the TNF web site. The present study compares recent Raman spectroscopy and Particle Image Velocimetry measurements and Large Eddy Simulations (LES). The LES results are evaluated against a dataset comprising mean and RMS measurements of H2 N2 O2 H2O molar fractions temperature and velocity fields offering new insights into flame stabilization mechanisms. The simulations incorporate conjugate heat transfer to predict the combustor wall temperatures and are conducted for two atmospheric-pressure operating conditions each representing distinct combustion regimes diffusion and partially premixed. Novelty and significance statement Data on confined hydrogen flames in burner similar as industrial ones are limited. This work aims to fill this gap by performing multiple and simultaneous diagnostics on the swirled hydrogen-air flame called HYLON. For the first time in such a swirled configuration mean and RMS fields of temperature main species and velocities are compared to LES allowing new insight into the potential and limits of the models as well as the physics of these flames. These experimental results will be made available on TNF as over 30 research groups worldwide have expressed interest in using them.

Towards low-carbon buildings with resilient energy performance renewable energy resources and flexible energy assets play key roles in managing the electrical and heat demands. Hydrogen-based systems represent a promising solution through renewable hydrogen production and long-term storage. This paper systematically reviews 35 peer-reviewed studies (1990–2024) on hydrogen integration in buildings focusing on demand-side management (DSM) optimization methods and system performance. The review covers the environmental impacts feasibility and economic viability of integrating different hydrogen systems for supplying energy. Across critical reviews case studies hydrogen supplementary systems achieved CO2 reductions between 12 % and 87 % operational cost decreases of up to 40 % and efficiency gains exceeding 80 %. Payback periods varied widely between 9 and 20 years demonstrating high investment costs. Key gaps include limited field validation economic feasibility and public acceptance of hydrogen homes. One key area for future investigation is optimizing energy flows across production storage and demand particularly in Vehicle-to-Building (V2B) applications. This review paper highlights opportunities especially the potential of hydrogen system in decarbonization of buildings by long-term energy storage barriers and policy needs for implementing hydrogen technologies in grid-connected and remote areas to enhance sustainable and resilient buildings.

Metal oxides (e.g. SnO2 ZnO TiO2) have been widely investigated materials for gas sensing applications including hydrogen detection. However the potential for hydrogen sensing of metal oxides such as CuO In2O3 NiO exhibiting p-type conduction has been largely overlooked. Over the last 15 years structures based on TiO2 and CuO have gained increasing interest as a promising system for hydrogen detection. Therefore this article aims to: 1) provide an overview of the performance of TiO2 as a reference material and discuss methods to enhance its sensing performance 2) summarize and highlight the role of copper oxides in hydrogen gas detection as the materials that have predominantly been studied for H2S detection 3) review efforts made to improve the sensing performance of heterostructures of CuTiOx from structures with charge compensation effect to those successfully sensing hydrogen 4) present the potential of CuTiOx for H2 detection.

Hydrogen embrittlement (HE) can degrade the mechanical integrity of steel pipes increasing failure risks in naval fuel systems. This study assesses HE effects on ASTM A131 and A36 steels through tensile testing and numerical modeling. Tests conducted with varying exposure times to hydrogen revealed that A131 outperformed A36 in terms of mechanical strength. However both materials experienced property degradation after six hours. After nine hours a transient increase in strength occurred due to temporary microstructural hardening though the overall trend remained a decline. The maximum reductions in ultimate tensile strength and toughness were 19% and 47% for A131 and 39% and 61% for A36 respectively. Additionally microstructural analysis revealed the presence of inclusions intergranular decohesion and micro-crack in specimens exposed for longer periods. Finally a combined GTN-PLNIH numerical model was implemented demonstrating its effectiveness in predicting the mechanical behavior of structures exposed to hydrogen.