Hydrogen is a clean, non-polluting fuel and a key player in decarbonizing the energy sector. Interest in hydrogen production has grown due to climate change concerns and the need for sustainable alternatives. Despite advancements in waste-to-hydrogen technologies, the efficient conversion of mixed plastic waste via an integrated thermochemical process remains insufficiently explored. This study introduces a novel multi-stage pyrolysis-reforming framework to maximize hydrogen yield from mixed plastic waste, including polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). Hydrogen yield optimization is achieved through the integration of two water–gas shift reactors and a pressure swing adsorption unit, enabling hydrogen production rates of up to 31.85 kmol/h (64.21 kg/h) from 300 kg/h of mixed plastic wastes, consisting of 100 kg/h each of HDPE, PP, and PS. Key process parameters were evaluated, revealing that increasing reforming temperature from 500 °C to 1000 °C boosts hydrogen yield by 83.53%, although gains beyond 700 °C are minimal. Higher reforming pressures reduce hydrogen and carbon monoxide yields, while a steam-to-plastic ratio of two enhances production efficiency. This work highlights a novel, scalable, and thermochemically efficient strategy for valorizing mixed plastic waste into hydrogen, contributing to circular economy goals and sustainable energy transition.

Plastics have become integral to modern life, playing crucial roles in diverse industries such as agriculture, electronics, automotive, packaging, and construction. However, their excessive use and inadequate management have had adverse environmental impacts, posing threats to terrestrial and marine ecosystems. Consequently, researchers are increasingly searching for more sustainable ways of managing plastic wastes. Pyrolysis, a chemical recycling method, holds promise for producing valuable fuel sustainably. This study explores the process of the pyrolysis of plastic and incorporates recent advancements. Additionally, the study investigates the integration of reforming into the pyrolysis process to improve hydrogen production. Hydrogen, a clean and eco-friendly fuel, holds significance in transport engines, power generation, fuel cells, and as a major commodity chemical. Key process parameters influencing the final products for pyrolysis and in-line reforming are evaluated. In light of fossil fuel depletion and climate change, the pyrolysis and in-line reforming strategy for hydrogen production is anticipated to gain prominence in the future. Amongst the various strategies studied, the pyrolysis and in-line steam reforming process is identified as the most effective method for optimising hydrogen production from plastic wastes.

Direct air capture (DAC), as a complementary strategy to carbon capture and storage (CCS), offers a scalable and sustainable pathway to remove CO₂ directly from the ambient air. This study presents a detailed evaluation of the amine-functionalised metal-organic framework (MOF) sorbent, mmen-Mg₂(dobpdc), for DAC using a temperature–vacuum swing adsorption (TVSA) process. While this sorbent has demonstrated promising performance in point-source CO₂ capture, this is the first dynamic simulation-based study to rigorously assess its effectiveness for low-concentration atmospheric CO₂ removal. A transient one-dimensional TVSA model was developed in Aspen Adsorption and validated against experimental breakthrough data to ensure accuracy in capturing both the sharp and gradual adsorption kinetics. To enhance process efficiency and sustainability, this work provides a comprehensive parametric analysis of key operational factors, including air flow rate, temperature, adsorption/desorption durations, vacuum pressure, and heat exchanger temperature, on process performance, including CO₂ purity, recovery, productivity, and specific energy consumption. Under optimal conditions for this sorbent (vacuum pressure lower than 0.15 bar and feed temperature below 15 °C), the TVSA process achieved ~98% CO₂ purity, recovery over 70%, and specific energy consumption of about 3.5 MJ/KgCO₂. These findings demonstrate that mmen-Mg₂(dobpdc) can achieve performance comparable to benchmark DAC sorbents in terms of CO₂ purity and recovery, underscoring its potential for scalable DAC applications. This work advances the development of energy-efficient carbon removal technologies and highlights the value of step-shape isotherm adsorbents in supporting global carbon-neutrality goals.

This study examines the feasibility of utilising outside air for ‘free cooling’ in modular data centres through the implementation of an air-side economiser, as an alternative to traditional mechanical cooling systems. The objective is to offset the energy consumption associated with cooling by leveraging the natural cooling capacity of the ambient air. To investigate this potential, a 90-kW modular data centre is employed as the base case for model validation and analysis of energy reduction possibilities. The research employs dynamic thermal modelling techniques to assess the efficacy of the air-side economiser in four distinct climatic zones: Stockholm, Dubai, San Francisco, and Singapore, representing diverse worldwide climates. The model is meticulously calibrated and validated using power usage effectiveness (PUE) values obtained from the Open Compute Project. Simulation runs are conducted to evaluate the energy-reduction potential achievable with the air-side economiser compared to conventional mechanical air-conditioning systems. The results indicate significant energy reductions of up to 86% in moderate climates, while minimal reductions are observed in dry and hot climates. This comprehensive analysis offers valuable insights into the intricate relationship between modular data centres, their operational characteristics, and the viability of employing air-side economisers for free cooling and energy efficiency across different climatic conditions. The contribution of this publication to this field of science lies in its exploration of the practicality and energy-saving potential of air-side economisers in modular data centres. By utilising dynamic thermal modelling and empirical validation, this study provides evidence-based insights into the effectiveness of this cooling strategy, shedding light on its applicability in various climates. The findings contribute to the understanding of energy-efficient cooling solutions in data-centre design and operation, paving the way for more sustainable practices in the field.

Geobag (sand-filled geotextile bags) revetments have recently emerged as long-term riverbank protection measures in developing countries; however, their performance is still not well understood. The hydraulic stability of geobag revetments used for riverbank protection has been studied within an extensive laboratory programme to improve our understanding of the complete failure processes of geobag revetments. A 1:10 scale distorted physical model was tested in a laboratory flume, comparing a range of different construction methods and revetment side slopes, subjected to different flow loading. The results indicate that whilst failure mechanisms are highly dependent on water depth and revetment slope, the construction method had no noticeable impact. It was thus concluded that the dominating factor is the friction between individual geobags, which itself is dependent on bag longitudinal overlap rather than a specific construction method.