Heriot-Watt University

Direct wind-to-hydrogen systems, in which a wind farm supplies power to an electrolyser without a firm grid connection, must accommodate the full variability of the wind resource, yet many existing techno-economic and design studies rely on input data with temporal resolutions of several minutes to one hour. This coarse averaging can mask short-term power fluctuations that drive electrolyser performance, cycling and degradation. This paper presents a novel wind-to-electrolyser model that synthesises effective wind speed suitable for a power curve wind model at 1 Hz, combining low-frequency trend variation, mesoscale wind speed changes and Kaimal turbulence, validated against aeroelastic simulations. The resulting power output is supplied to a PEM electrolyser model incorporating bank-level thermal dynamics and steady-state, cyclic and on/off degradation, enabling the effect of wind-power variability on long-term electrolyser performance to be quantified. Using 10-year simulations of a wind farm at a site in Orkney, Scotland, two scenarios are investigated: the effect of wind farm size (1–10 turbines) and input temporal resolution (1 s, 1 min, 10 min) on power variability, degradation and hydrogen production; and the effect of turbine configuration for a fixed installed capacity (three 5 MW turbines versus one 15 MW turbine). Results show that coarser temporal resolution substantially overestimates hydrogen production, particularly for small wind farms, where 10-minute-averaged data increase predicted output by up to 428% relative to 1 s data, primarily due to underestimated on/off and cyclic degradation. Aggregating turbines and, to a lesser extent, using larger rotors both smooth the power input and reduce this sensitivity, though the effect remains significant even for 10-turbine farms. These findings demonstrate that high-frequency wind power variability must be explicitly considered in the design and performance assessment of wind-to-hydrogen systems.

Environmental, Social, and Governance (ESG) has become a critical measure of multinational enterprises’ global competitiveness, yet emerging market multinational enterprises (EMNEs) face distinct legitimacy challenges due to weak home-country ESG regulations, known as the liability of home origin. Although prior studies have examined the relationship between internationalization and ESG, they have largely treated the two directions separately, leaving unclear whether they operate as competing explanations or as mutually reinforcing processes. Drawing on legitimacy theory, this study conceptualizes internationalization and ESG performance as exhibiting mutually reinforcing associations over time. Using longitudinal data from 2460 Chinese listed firms between 2009 and 2020, we examine the reciprocal relationship between internationalization and ESG performance, and the moderating role of digitalization. Findings indicate that internationalization is consistently associated with stronger ESG performance, suggesting EMNEs use ESG to mitigate liabilities of origin and build legitimacy abroad. The reverse association is weaker but most robust for foreign-country scope, indicating that ESG performance may support international expansion by signaling alignment with international sustainability expectations. The moderating associations of digitalization are uneven and are concentrated in visible foreign organizational and geographic presence, such as overseas subsidiaries and foreign-country scope, rather than overseas revenues.

This paper presents a comprehensive investigation into the fire performance of axially restrained stainless-clad bimetallic steel (SCBS) columns. Based on the fire tests of five SCBS columns, finite element models were developed using ABAQUS. Thermo–mechanical analysis was conducted to obtain the variations of surface temperature, structural displacement and axial load with time, as well as key parameters such as buckling and failure temperatures. The numerical results were validated against experimental results. Based on the validated models, a comprehensive parametric study was performed to evaluate the effects of cross-sectional dimensions, initial global imperfections, load ratio, axial restraint stiffness ratio, slenderness ratio and cladding ratio on the fire resistance of the SCBS columns. Four key influencing parameters (axial restraint stiffness ratio, slenderness ratio, load ratio and cladding ratio) were identified, and their coupled interactions were analysed. Furthermore, based on the stress state of restrained SCBS columns at elevated temperatures and the design framework of EN 1993–1-2, theoretical formulae for predicting the buckling temperature, incorporating the effects of load ratio, axial restraint stiffness ratio, slenderness ratio and cladding ratio, were proposed and validated against 291 numerical cases. The developed model provides an accurate and practical approach for the fire resistance design of axially restrained SCBS columns.

Replaceable corrugated steel web (CSW) links offer a practical energy-dissipating solution for bridge piers, combining straightforward detailing with stable hysteretic properties. To assess their effectiveness in enhancing seismic performance, this study evaluates the seismic fragility and resilience of bridges equipped with such links in double-column piers (DCPs). A simplified spatial-grid modeling approach is introduced for CSW links, and a corresponding restoration model for the DCP system across multiple damage states is established and validated via finite element analysis. These methods are applied to a case study bridge, where dynamic response and seismic fragility are analyzed. Key resilience metrics, namely post-earthquake immediate functionality and equivalent downtime, are quantified. The proposed modeling strategy significantly improves computational efficiency without compromising accuracy. The results confirm that CSW links contribute substantial energy dissipation, effectively limiting residual pier drifts and protecting the primary structural members. Compared to a conventional DCP system without links, the CSW-equipped system demonstrated average reductions in the ultimate ductility ratio of 76%, 43%, and 28% at PGA levels of 0.3 g, 0.6 g, and 1.2 g, respectively. The overall computational framework, which integrates engineering demand parameters (pier ductility ratio and link shear drift ratio) with the developed restoration model, is shown to be both applicable and reliable. At seismic fortification levels corresponding to 50-year probabilities of exceedance of 10% and 2%, the bridge with CSW links exhibits approximately 8% and 22% higher post-earthquake immediate functionality, respectively, indicating a clear improvement in seismic resilience. The performance evaluation system developed herein provides a valuable reference for the design and assessment of conventional-span bridges utilizing replaceable CSW links.

Municipal solid waste (MSW) recovery is critical to global decarbonization agendas. Existing studies have provided important insights into the environmental performance of alternative waste-treatment pathways through life-cycle and scenario-based assessments. However, less is known about whether recovery expansion translates into measurable reductions in observed carbon emissions. This study employs an instrumental-variable framework to estimate the economy-wide carbon-emission effects of MSW recovery using a 32-country panel from 1998 to 2023, addressing reverse-causality concerns in the recovery-emission relationship. The results show that, across the 32-country sample, a 10% increase in aggregate MSW recovery is associated with an average 0.95–1.15% reduction in per capita carbon emissions. This estimate reflects the net system-level effect of recovery expansion under the observed mix of recovery pathways and national conditions, rather than a common effect of individual recovery technologies. The effect varies substantially across recovery systems: energy-recovery-dominated systems show stronger mitigation effects than recycling-dominated systems, with further differences across recovery scale, energy structure, and socioeconomic conditions. Finally, selected non-sample countries are compared with the 32-country sample across key structural moderators to identify where recovery expansion is most likely to deliver large mitigation gains. Overall, the study provides cross-country causal evidence on how MSW recovery translates into economy-wide emission outcomes under different national conditions, offering a system-level basis for aligning recovery strategies with broader decarbonization goals.