United Kingdom
A CFD Comparison of Interfacial Phase Change Models for Boil-off, Self-pressurisation and Thermal Stratification in Liquid Hydrogen Storage Tanks
Nov 2025
Publication
Liquid hydrogen (LH2 ) is a promising energy carrier for future clean fuel technologies. However its cryogenic storage and handling pose significant challenges particularly due to self-pressurisation and boil-off from ambient heat ingress. Accurate modelling of these phenomena is essential for the safe and efficient design of LH2 storage systems. A key aspect of such modelling is the selection and implementation of an appropriate interfacial phase change model. This study presents a comparative assessment of three widely used phase change models; the Schrage model the Modified Energy Jump (MeJ) model and the Lee model. A parametric study was conducted across three coefficients for each model with validation performed against five experimental benchmark cases from NASA’s K-Site and MHTB cryogenic tanks focusing on planar interface problems with thermally induced phase change under normal gravity. A CFD approach using STAR-CCM+ was employed to evaluate each model’s ability to predict tank pressure temperature and boil-off behaviour. The Schrage model demonstrated the most robust and accurate results exhibiting minimal sensitivity to coefficient variation and offering both numerical stability and physical fidelity. It demonstrated a maximum mean absolute percentage error (MAPE) of just 3.0% in its pressurisation predictions. The MeJ model showed comparable accuracy when its heat transfer coefficient was appropriately selected highlighting its reliance on an empirically derived coefficient. In contrast the Lee model performed the poorest exhibiting numerical divergence at high coefficient values and substantial deviation in its prediction of self-pressurisation with errors of up to 11% MAPE. These findings provide practical guidance for the selection and implementation of phase change models in CFD simulations and highlight key considerations for modelling LH2 storage tanks in industrial applications.
Techno-economic Analysis of Technologies for Decarbonizing Low- and Medium-Temperature Industrial Heat
Dec 2025
Publication
Decarbonizing industrial heat is critical for achieving climate targets. This study evaluates the economic viability of technologies for decarbonizing industrial heat in Europe through a techno-economic analysis. High-temperature heat pumps (HTHPs) and electric hydrogen and biomass boilers are compared in terms of levelized cost of heat (LCOH) under various scenarios including the impact of thermal storage leveraging dynamic electricity prices. In scenarios for the year 2030 we show that HTHPs leveraging free excess heat achieve LCOH values at least 30% to 60% lower than hydrogen boilers and up to 37% lower than biomass boilers. Integrating daily thermal storage reduces LCOH by up to 15% for heat pumps and 27% for electric boilers. By 2050 anticipated cost and efficiency improvements further enhance the competitiveness of heat pumps. These results highlight the economic advantage of HTHPs particularly when integrating excess heat and thermal storage.
Sustainable Power System Transition Pathways: Regional Decarbonisation and Resource Conservation Aided by Small Modular Reactors
Oct 2025
Publication
Clean energy technologies offer promising pathways for low-carbon transitions yet their feasibility remains uncertain particularly in rapidly developing regions. This study develops a Factorial Multi-Stochastic Optimization-driven Equilibrium (FMOE) model to assess the economic and environmental impacts of clean power deployment. Using Small Modular Reactors (SMRs) in Guangdong China as a case study the model reveals that SMRs can reduce system costs and alleviate GDP losses supporting provincial-level Nationally Determined Contributions (NDCs). If offshore wind capital costs fall to 40 % of SMRs’ SMR deployment may no longer be necessary after 2030. Otherwise SMRs could supply 22 % of capacity by 2040. The FMOE model provides a robust adaptable framework for evaluating emerging technologies under uncertainty and supports sustainable power planning across diverse regional contexts. This study offers valuable insights into the resource and economic implications of clean energy strategies contributing to global carbon neutrality and efficient energy system design.
Rooftop Agrivoltaic Powered Onsite Hydrogen Production for Insulated Gasochromic Smart Glazing and Hydrogen Vehicles: A Holistic Approach to Sustainable Residential Building
Nov 2025
Publication
The study focused on designing a sustainable building involving rooftop agrivoltaics advanced glazing technologies and onsite hydrogen production for a residential property in Birmingham UK where green hydrogen produced by harnessing electricity generated by agrivoltaics system on rooftop of the building is employed to change the transparency of vacuum gasochromic glazing and refuel hydrogen-powered fuel cell vehicle using storage hydrogen for a sustainable building approach. The change in the transparency of the glazing reduces the energy requirement of the building according to the occupant’s requirement and weather conditions. This research investigates the performance of various rooftop agrivoltaic systems including vertical optimal 30◦ tilt and dome setups for both monofacial and bifacial agrivoltaic consisting of tomato farming. Promising results were observed for agrivoltaic systems with consistent tomato production of 0.31 kg/m2 with varying shading experienced due to the different photovoltaic setups. Maximum electricity is produced by bifacial 30◦ with 7919 kWh though the lowest LCOE can be observed by monofacial 30◦ with £0.061/kWh. It also compares the efficiency of vacuum gasochromic windows against double glazing vacuum double glazing electrochromic and gasochromic options which can play an essential role in energy saving and reduced carbon emission. Vacuum gasochromic demonstrated the lowest U-value of 1.32 Wm2 K though it has the highest thickness with 24.6 mm. Additionally the study examines the feasibility of small-scale green hydrogen production from the electricity generated by agrivoltaics to fuel hydrogen vehicles and glazing considering the economic viability. The results suggested that the hydrogen required by the glazing accounts for 52.56 g annually and the maximum distance that can be covered theoretically is by bifacial 30◦ which is approximately 64.23 km per day. The interdisciplinary approach aims to optimise land use enhance energy efficiency and promote sustainable urban agriculture to contribute to the UK’s goal of increasing solar energy capacity and achieving net-zero emissions while addressing food security concerns. The findings of this study have potential implications for urban planning renewable energy integration especially solar and sustainable residential design.
A Comprehensive Review on the Compatability of Polymeric Materials for Hydrogen Transportation and Storage
Nov 2025
Publication
This review evaluates the current state of the art on polymeric materials for hydrogen transportation and storage highlighting the importance of developing a sustainable hydrogen infrastructure worldwide. It analyses different polymeric materials used for hydrogen transportation and storage applications including high-density polyethylene (HDPE) polytetrafluoroethylene (PTFE) polyimides (PI) polyether ether ketone (PEEK) polyamide ethylene propylene diene monomer (EPDM) polyvinylidene fluoride (PVDF) and fluorinated ethylene propylene (FEP). These materials are assessed using key characteristics such as hydrogen permeability mechanical strength chemical resistance and thermal stability. The review finds that while PEEK and polyimides exhibit the highest thermal stability (up to 400 °C) and pressure resistance (300–400 bar) HDPE remains the most cost-effective option for low-pressure applications. PTFE and FEP offer the lowest hydrogen permeability (<0.01 cm3 mm/m2·day·bar) making them ideal for sealing and lining in hydrogen storage systems. Furthermore key research gaps are identified and suggestions for future research and development directions are outlined. This comprehensive review is a valuable resource for researchers and engineers working towards sustainable hydrogen infrastructure development.
Quantifying Conservatism in ASME B31.12 Option A for Hydrogen Pipeline Repurposing
Nov 2025
Publication
Hydrogen is a key enabler of the energy transition and repurposing existing natural gas pipelines offers a costeffective pathway for large-scale hydrogen transport. However hydrogen embrittlement raises integrity concerns and current design standards such as ASME B31.12 Option A adopt highly conservative safety margins without a quantified reliability basis. This study evaluates whether the conservative safety margins in ASME B31.12 Option A for hydrogen pipelines can be safely relaxed. A semi-elliptical flaw (depth 0.25t length 1.5t) is assessed using the Failure Assessment Diagram (FAD) method and Monte Carlo simulations with up to 2.5 × 107 iterations. Fracture toughness is fixed at 69.3 MPa√m while wall thickness and yield strength vary statistically. Three design scenarios explore safety factor products from 0.388 to 0.720 at 0 ◦C and 20 ◦C. Results show that flaw acceptability is maintained in all deterministic cases and the probability of failure remains below 10− 6 . No failures occur when the safety factor product drops below 0.637. The analysis uses only codified flaw assumptions and public material data. These findings confirm that Option A provides a highly conservative envelope and demonstrate the value of a reliability-based approach for assessing hydrogen pipeline repurposing while addressing the gap between prescriptive standards and quantified reliability. This integrated FAD–probabilistic framework demonstrates that Option A includes significant conservatism and supports a reliability-based approach to evaluate hydrogen pipeline repurposing without experimental inputs.
State and Disturbance Estimation with Supertwisting Sliding Mode Control for Frequency Regulation in Hydrogen Based Microgrids
Nov 2025
Publication
This study considers the use of an enhanced super-twisting sliding mode control (STSMC) scheme via the incorporation of a hybrid extended state observer (ESO) and a higher order sliding mode observer (HOSMO) state estimation and disturbance observer (DO) based on exponential decay embedded via a tracking element in order to hasten the estimation of disturbance thus improving performance significantly. This scheme is employed to generate single and multiple control signals per agent based on the microgrid’s presented components such as energy storage devices and renewable energy sources (RESs) alongside the harness of a puma optimizer (PO) metaheuristics scheme to optimize each area regulator’s performance. The sliding surface incorporated is chosen based on desired control objectives. Adjusting the constricted area frequency and reducing tie-line power transfer fluctuations are considered the primary goals for frequency regulation in a multi-area power system. Also based on the presented simulations adequate performance in terms of minimum chattering low complexity fast convergence and adequate robustness has been achieved. Using various microgrid peripheral components such as a multi-terminal soft open point (SOP) with a dedicated terminal for hydrogen energy storage alongside the proposed enhanced STSMC the frequency change and power transfer rate of change are maintained within the range of ×10−6 values substantially preserving proper performance compared to other simulated scenarios. In regard to the final simulated case involving SOP the following has been achieved: steady state errors of 2.538×10−6 Hz for ΔF1 3.125×10−6 Hz for ΔF2 and 1.920×10−6 p.u for ΔPtie alongside peak disturbance overshoot reduction in comparison to stochastic case of 99.580% 99.605% and 99.771% for same mentioned elements respectively. Also a reduction in peak disturbance undershoot of 95.589% 99.547% and 99.573% respectively has been achieved. Thus the enhanced STSMC can effectively mitigate frequency fluctuations and tie-line power transfer abnormalities.
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