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Modeling and control of heating and heat circulation in direct air capture system
No full textDirect air capture (DAC) is a critical technology for mitigating climate change. However, the high heat consumption of temperature vacuum swing adsorption (TVSA)-based DAC processes hinders its widespread deployment. This study focuses on developing a control strategy to optimize the energy efficiency of the TVSA heating phase. A novel adsorbent temperature estimation method, validated through experimental data, was integrated into a cascaded PI controller with a fuzzy gain scheduler (FGS). Experimental results demonstrate that the proposed control strategy effectively regulates the heating process, achieving a potential energy saving of up to 14%. This work contributes to enhancing the feasibility and sustainability of DAC technologies.</p
Sustainable service ecosystems in Positive Energy Districts:A conceptual framework to steer longterm impacts
No full textPositive energy districts (PEDs) are central in the global transition towards sustainable, decentralized, and self-sufficient energy systems. Energy transformation taking place locally in cities may trigger broader sustainability transitions (STs) towards PED ecosystems at macro-level. The work adopts a service ecosystems perspective to tackle the complexity of STs in the energy sector. The work builds a conceptual framework intended to support the transition and renewal of PED service ecosystems at a micro- and meso-levels and uses illustrative case examples from a PED located in Espoo, Finland. The framework is intended to map the interdependencies between different actors in commercializing PED service ecosystems, and acts as a transformational tool for the public and private organizations to address change in PEDs. The framework concretizes the value propositions, actor roles, resource integration and monetization mechanisms, as well as the transformation enablers, challenges, and long-term impacts. Additionally, the goal of the framework is to help municipalities to understand their roles in strengthening the institutional and social enablers for the local energy transformation with clear regulatory frameworks, incentive mechanisms, long-term political commitment, and vision. Overall, the study supports our understanding on the underlying mechanisms in the paradigm change towards sustainable energy systems
Global progress towards the Coal: Tracking coal Reserves, coal Prices, electricity from Coal, carbon emissions and coal Phase-Out
No full textCoal remains a significant energy source globally, with the United States holding a substantial portion of the world’s coal reserves but it creates the dangerous effects of global warming. Despite its abundance, questions arise regarding the accessibility and environmental impact of coal reserves. Therefore, this research forecasted the future of coal reserves, coal prices, electricity from coal, carbon emissions and coal phase-out targets globally using the SARIMAX Python® model for the study period 2023 to 2050 by using the economic data from the year 1980 to 2022. It is found that, the global coal reserve capacity is 1.07 trillion tons with an average coal prices vary with region to region, ranging from US 206 per tone until 2050. The global production of electricity from coal will also increase from 10415.49 TWh in 2023 to 13316.57 TWh until 2040 and 15243.36 TWh until 2050 which ultimately enhances the production of carbon emissions, increases from 157,768 billion metric tons in 2023 to 188,535 billion metric tons until 2040 and 215,077 billion metric tons until 2050. Furthermore, this study undertakes and presented the country wise examination of coal phase out and it is found that in many countries 75% of coal will phase out by 2030 and 100% by 2040 for meeting the Intergovernmental Panel on Climate Change (IPCC) 1.5 0C targets. Therefore there is a dire need to shift towards cleaner energy sources, leading to a decline in coal-fired power generation and a trend towards coal phase-out
Printed cellular structure enhancing re-passivation of stress corrosion cracking in high-temperature water
Get PDFCellular structure with high-density dislocations and elemental segregation is a unique characteristic for laser powder bed-fusion (L-PBF) 316 L stainless steels (SSs), but the role of such structure to stress corrosion cracking (SCC) remains pending. Herein we adopt multiple verification methods, including transmission electron microscope, atomic force microscopy and density-functional theory calculations to unveil its advantageous contribution to SCC resistance in high-temperature oxygenated water. Convincing evidence verify that the intrinsic Cr/Mo segregation across cellular boundaries (CBs) initiates a diffusion-induced stress and a nano-scale galvanic cell to provide a robust and stable Cr/Mo source towards near-surface grain boundaries (GBs). Consequently, there exists a Cr/Mo-rich enrichment zone at the crack tip, improving the re-passivation capacity of the SCC tip
A Calibrator Fuzzy Ensemble for Highly-Accurate Robot Arm Calibration
No full textThe absolute positioning accuracy of an industrial robot arm is vital for advancing manufacturing-related applications like automatic assembly, which can be improved via the data-driven approaches to robot arm calibration. Existing data-driven calibrators have illustrated their efficiency in addressing the issue of robot arm calibration. However, they mostly are single learning models that can be easily affected by the insufficient representation of the solution space, therefore, suffering from the calibration accuracy loss. To address this issue, this study proposes a calibrator fuzzy ensemble (CFE) with twofold ideas: 1) implementing eight data-driven calibrators relying on different sophisticated machine learning algorithms for an industrial robot arm, which guarantees the accuracy of individual base models and 2) innovatively developing a fuzzy ensemble of the obtained eight diversified calibrators to obtain impressively high calibration accuracy for an industrial robot arm. Extensive experiments on an ABB IRB120 industrial robot implemented with MATLAB demonstrate that compared with state-of-the-art calibrators, CFE decreases the maximum error at 8.59%. Hence, it has great potential for real applications.</p
<i>Capsicum chinense </i>cell cultures: a biotechnological platform for the sustainable production of bioactive metabolites for the cosmetics market
Get PDFEngineered biocatalytic architecture for enhanced light utilisation in algal H<sub>2</sub> production
No full textThin-layer photosynthetic biocatalysts (PBCs) offer an innovative and promising approach to the solar-powered generation of renewable chemicals and fuels. Thin-layer PBCs incorporate photosynthetic microbes, engineered for the production of targeted chemicals, into specifically tailored bio-based polymeric matrices. This unique integration forms a biocatalytic architecture that allows controlled distribution of light, nutrients, and substrates to the entrapped cells, optimising their performance. The research outlined in this study offers a systematic engineering approach to developing a biocatalytic architecture with improved light utilisation and enhanced photosynthetic conversion of captured light energy to molecular hydrogen (H2), an important energy carrier and fuel. This was achieved by entrapping wild-type green alga Chlamydomonas reinhardtii and its mutants with truncated light-harvesting chlorophyll antenna (Tla) complexes within thin-layer (up to 330 μm-thick) polymeric matrices under sulphur-deprived conditions. Our step-by-step engineering strategy involved: (i) synchronising culture growth to select cells with the highest photosynthetic capacity for entrapment, (ii) implementing a photosynthetic antenna gradient in the matrix by placing Tla cells atop the wild-type algae for better light distribution, (iii) replacing the conventional alginate formulation with TEMPO-oxidised cellulose nanofibers for improved matrix stability and porosity, and (iv) employing a semi-wet production approach to simplify the removal of produced H2 from the matrix with entrapped cells, thus preventing H2 recycling. The engineered PBCs achieved a fourfold increase in H2 photoproduction yield compared to conventional alginate films under the same irradiance (0.65 vs. 0.16 mol m−2 under 25 μmol photons m−2 s−1, respectively) and maintained H2 photoproduction activity for over 16 days. This resulted in a remarkable 4% light energy to hydrogen energy conversion efficiency at peak production activity and over 2% throughout the entire production period. These significant advancements highlight the potential of engineered thin-layer PBCs for efficient H2 production. The technology could be adapted for biomanufacturing various renewable chemicals and fuels.</p
Does the difference make a difference? Evaluating Contracts for Difference design in a fully decarbonised European electricity market
No full textDue to their ability to mitigate price risks, Contracts for Difference (CfDs) gained popularity amidst high electricity prices during the energy crisis in 2022. Depending on their specific design, CfDs are known to affect investment and dispatch decisions in electricity markets. We evaluate these effects in a fully decarbonised, sector-coupled European electricity market in terms of their impact on the power system and from an investor's and consumer perspective. We consider four different types of governmental CfDs awarded to wind onshore power plants in a competitive auction for the contracts’ underlying strike price. On the one hand, the CfD types differ in terms of the allowed direction and unit (energy vs. capacity) of payments with consequences for dispatch decisions. On the other hand, they apply different reference prices with implications for investment decisions as reflected by optimally derived strike prices. Implementing the CfDs in an energy system optimisation model, we find that these differences affect curtailment, electrolyser load and market prices in fully decarbonised electricity markets. From a consumer's perspective, our results show that system costs are lowest for types of CfDs that foster investments in more system-friendly power plants. For investors, in turn, these types of CfDs incur the highest discrepancy of ex ante expected and ex post realised CfD payments, such that they do not necessarily suffice to recover their costs. We conclude that this could be addressed by an adequate risk premium on the strike price, which should be subject to future research.</p
Corrigendum to “Integrating ‘nature’ in the water-energy-food nexus: Current perspectives and future directions” [Science of The Total Environment, Volume 966, 2025, 178600]
No full textThe authors regret that there were two formatting mistakes: 1. Definitions of key “Nexus” and “ecosystems” terms appear as a paragraph on page 4 rather than within Box 1. The revised Box 1 is [Table presented] Box 1. Glossary of key terms. 2. The caption for Fig. 7 is separated from the figure and appears as a paragraph on page 15. The revised caption of Fig. 7 is [Figure presented] Fig. 7. Proposed hybrid WEFE Nexus paradigm – elements and interlinkages. Examples for some of the interlinkages are provided. Connection 4: the provisioning ecosystem service of wild foods, but also the expected trends due to planning and strategic conservation efforts that can lead to an increase in their availability and use (Sajeev et al., 2023). Connection 5: the provisioning ecosystem service of wood and biomass, as well as the influence of the energy sector on the use and management of land resources. Connection 6: provisioning of fresh water and water purification as ecosystem services, on one hand, and policy and governance measures for protection and preservation of aquatic habitats and biodiversity, prevention of overexploitation of freshwater, sustaining environmental flows from reservoirs, on the other. Connection 7: the social and governance processes involved in setting aside land and resources for new sectoral developments (e.g., a new reservoir), as well as constraints to such new developments arising from policy (e.g., the EU biodiversity strategy for 2030) and social dynamics; sectoral activities providing livelihoods; global and national agreements setting targets on emissions reductions, as well the socio-economic implications of decarbonization plans (Plazas-Niño et al., 2022), just transition plans (Wang and Lo, 2021), and the economic transformation towards net-zero economies, job creation in emerging sectors, innovation and investment, and social adjustments (Krishnan et al., 2022). Connection 8: the impact of infrastructure development in the water sector (e.g., a new reservoir) on freshwater ecosystems; the impact of agricultural expansion on terrestrial ecosystems; the influence of biotic and abiotic components of ecosystems on the WEF Nexus sectors: pests and diseases, invasive species, pollination, river flow regimes, including floods and low flows. The authors would like to apologise for any inconvenience caused.</p
Effects of elevated temperature on Wyoming bentonite and its implications for sorption of radioactive strontium
No full textBentonite is a key barrier material in deep geological facilities for spent nuclear fuel, where it may be exposed to temperatures >100 °C because of radiogenic heating. Understanding how prolonged heating affects its physicochemical properties and radionuclide retention capacity is critical for ensuring long-term repository safety. This study investigated the impacts of dry heating (unconfined, evaporation allowed) at 150 °C for 36 months on the mineralogical and geochemical stability of a Wyoming bentonite, chosen for the Finnish geological disposal facility, and its subsequent sorption behavior with 90Sr. Although the bentonite mineralogy remained mostly stable, combined X-ray diffraction, cation exchange capacity, titrations, demonstrated partial Na to Ca exchange within montmorillonite's interlayer following heating, and specific surface area analyses revealed a > 50 % reduction in specific surface area (30 to 14 m2/g). Colloid stability tests revealed that bentonite colloids did not form under repository-relevant saline conditions (I = 0.2 M), and heat treatment did not significantly impact colloid formation in reduced ionic-strength systems. Sorption isotherms demonstrated that Sr sorption was strongly pH-dependent, increasing from ∼40 % at pH 8 to ∼90 % at pH 13, and heating slightly enhanced Sr retention at pH 8. Two-site protolysis non-electrostatic surface complexation and cation exchange modelling suggested that in unheated bentonite, Sr was bound via a combination of surface complexation (∼30 %) and cation exchange (∼70 %) at pH 8, while at pH 13, sorption shifted towards surface complexation. However, after heating, cation exchange dominated at both pH values. Extended X-ray absorption fine structure analysis confirmed outer-sphere Sr sorption at pH 8 and increasing inner-sphere complexation at pH 13. Together, these findings highlight that despite minor physicochemical alterations, bentonite retained its Sr sorption potential, supporting its continued suitability as a buffer material in the ONKALO® repository.</p