Reduction Of CO2 Footprint Research Articles

Enhancing fluidity and mechanical properties in Limestone Calcined Clay cements with one-third Portland clinker content

Limestone Calcined Clay Cements (LC3) are attracting considerable attention due to their low CO2 footprints and relatively fast hydration kinetics. LC3-50 formulations (approximately 50 % Portland clinker, 30 % kaolinitic calcined clay, 15 % limestone and 5 % gypsum) are being extensively investigated and the hydration chemistry, rheology, mechanical strength developments and durability performances are starting to be well established. LC3 binders with lower clinker factors are possible, offering an opportunity for further CO2 footprint reduction. However, these blends have been much less studied. This work contributes to fill this gap. Here, a LC3-35 binder (i.e. 35 % Portland clinker content) is investigated and its performances are compared to those of the original Portland cement (PC) and a standard LC3-50 binder. The effects of two superplasticizers and a strength-enhancing admixture are thoroughly investigated in mortars and pastes. Larger calcined clay contents result in an exacerbation of the slump retention problem, but this issue is solved by the use of a new superplasticizer. Moreover, the low mechanical strengths at early ages can be partly mitigated with a C-S-H nucleation seeding admixture. Employing the right admixtures, LC3-35 binders can develop strength values similar to those of neat PC and LC3-50 at 7 and 28 days. The laboratory X-ray powder diffraction results for LC3-35 pastes, when using the strength-enhancing admixture, show that C4AF exhibits an accelerated reaction rate, leading to the formation of larger amounts of AFt and AFm phases. Approximate mass balance calculations are carried out to estimate the metakaolin reaction degree. Finally, an environmental performance indicator is used to place the footprints of the reported binders within the LC3 landscape.

A Case Study of a 42-m High GRS Retaining Structure and CO2 Footprint Reduction due to the use of Marginal Backfill Available on site

A Case Study of a 42-m High GRS Retaining Structure and CO2 Footprint Reduction due to the use of Marginal Backfill Available on site

Development of a new standard for evaluation of sustainable refurbishment

PurposeIncreasing focus on sustainability, in general, climate change impact, circular economy and a substantial need for CO2 footprint reduction within the construction industry, requires new knowledge and processes regarding the existing buildings. To satisfy new laws and regulations for new buildings is an easier challenge in comparison with possibilities in existing building stock which has the biggest contribution to sustainability within the construction industry. The purpose of the study is to develop and present a standardized process for sustainable refurbishment which, in addition to technical aspects, has a goal to create “well-being” for stakeholders, people organizations in private and public businesses and society itself.Design/methodology/approachThe latest state of the art in the mentioned field has been assessed, and the developments along with potential future research focus have been identified. The process is presented in this paper, from the starting point of establishing the Norwegian standards in 1995 (NS 3454) until now, the development of the new CEN standard (prEN 17860:2022). The basic methodology designed for NS 3454 was improved through Nordic tools for indicator requirements SURE 1 (2011) and SURE 2 (2015). Further development of the tool was adopted by CEN TC 350 Sustainable Construction in 2017 with the aim to extend the good Nordic practices to the European level. In the paper, the design of the new standard prEN 17860:2022 is presented, from the process and content perspective, following the Nordic approach of standardized methodology and enhancing it with new dimensions and evaluation tools. Throughout the years, the standardized methodology, based on NS 3424, has been implemented in practical use for facility management in the Norwegian public sector. Positive experiences and feedback from this practical implementation have been taken into consideration in prEN 17680:2022.FindingsThe authors present the guidance, developed as a process, leading facility managers and other stakeholders through sustainable refurbishment standards and rules to make a clear decision about their concrete investment. The tool enables decisions about all three sustainability pillars and better decisions for health, well-being and quality of life. All the characteristics of the standardized methodology from the Nordic approach were supplemented (technical aspects; adaptability; usability; social aspects; energy, water and operational impacts and quality of indoor environment including health aspects) and some new were added (economic, feasibility, climate resilience and embodied environmental impacts). The tool also presents a building performance profile for further service life.Social implicationsSustainable cities have been a focus for many years now from various perspectives such as SURE 1 or 2 and CEN TC 350. What these studies neglect is a clear and helpful guideline, supporting the FM, users and investors while deciding the operating and maintaining infrastructure in an urban environment. Better standardized forms give the possibility to make better climate-neutral choices and keep the well-being focus by choosing buildings with a potential for a long lifetime.Originality/valueThe new focus of addressing all stakeholders, including people, promoting sustainable refurbishment by informing, engaging and empowering them to take the decisions.

Education on Metaverse Platforms Effects on Co2 Footprint Reduction: Istanbul School of Metaverse Case

Education on Metaverse Platforms Effects on Co2 Footprint Reduction: Istanbul School of Metaverse Case

An engineering drag losses model for rolling bearings

Rolling bearing friction is an important measure of bearing performance. With increasing industrial trends of energy savings and CO2 footprint reduction, rolling bearing friction has become a very important parameter in the machinery design and selection process. Particular importance have high-speed applications like spindles or electrical vehicle traction drives and gearboxes. Since handling thermal effects has become an important problem to solve in these applications, oil lubrication is gaining interest due to its cooling capacity. Bearing friction is made of rolling, sliding and drag losses components in oil lubricated bearings. In this paper the emphasis is given to the drag losses component, which becomes the most critical in oil bath in medium and high-speed applications. An engineering model is derived for the calculation of this component for medium and potentially high speeds. The results are compared with experimental measurements (in-house and literature). In general, good agreement is found between the engineering model and the experimental results.

Multi-Step Recycling of BF Slag Heat via Biomass for CO2 Mitigation

Iron- and steelmaking processes create slags, valuable by-products. Industrial utilisation of slag as a lower-value secondary mineral source has been established for decades. Slag heat recovery is an ongoing research topic and has the potential to maximise energy efficiency in iron and steel production. Heat recuperation aims to tap the unused thermal recycling potential of molten slags. This short communication expands the concept for the utilisation of recovered heat for producing torrefied biomass and biogas. The torrefaction process is linked with slag heat recovery and via the BASE method with enhanced blast furnace operation. Such a combination reduces CO2 emissions significantly in ironmaking processes. Assuming a coke consumption of 350 kg coke per tonne of hot metal and replacing it with 5% torrefied biomass injected as PC with an additional 100 m3/tHM biogas injection, the BF’s CO2 emission related to the coke can be lowered by 7.9% to 108 kg/tHM. In such a manner, the recovered slag heat can directly contribute to CO2-footprint reduction and improve the circular economy and metallurgical sustainability.

Life cycle CO₂ footprint reduction comparison of hybrid and electric buses for bus transit networks

To control the global warming by ensuring the greenhouse gas emissions reduction of the automotive sector, the standards or norms are getting ever stricter globally, specifically in the past few years. In view of this, great emphasis is currently being given to the shift towards electric vehicles. However, it is very important to critically evaluate the overall life cycle of different powertrain technologies. In this study, such analysis has been carried out for the bus rapid transit networks in the 4 largest cities of Spain: Madrid, Barcelona, Valencia and Seville. Ten different lines were selected from each city and their driving-cycles were designed by extracting real time data from GPS used for simulating 3 different bus powertrains (diesel, hybrid and electric) for real-life results of the vehicles on each route. A life cycle analysis of the different bus configurations was done considering a wide perspective from manufacturing, use, maintenance to end-of-life stages, to compare the CO₂ footprints of the 3 evaluated powertrains using the database of the software GREET. The CO₂ footprints of the electric bus was also estimated for the years 2030 and 2050, using the predictions for cleaner electricity grids for future perspective. Compared to the standard diesel bus results, the overall results for hybrid and electric bus show 40% decrement and 30% increment of CO₂ well-to-tank emissions, respectively, 40% and 60% decrement of CO₂ life cycle emissions; 30% increment and 60% decrement of the buses’ driving range and, 2.5% and 30% addition in the life cycle cost.

Phase and microstructure evolutions in LC3 binders by multi-technique approach including synchrotron microtomography

Limestone Calcined Clay Cements, LC3, are attracting a lot of attention as it is possible to reduce the clinker factor by 50%, which means a cement CO2 footprint reduction of 40%. This is compatible with maintaining the mechanical strength performances after one week, if the kaolinite contents of the raw clays are above ~40 wt%. Durability properties are also maintained or even enhanced. Here, it is used a multi-technique approach to understand the phase and microstructure developments. From the thermal analysis, partial limestone reactivity is proven. Chiefly, high-resolution synchrotron microtomography has been employed, for the first time in these systems, to characterize their microstructures. The measured total porosities, within our 1 μm spatial resolution (voxel size 0.32 μm), were 16.6, 10.0 and 2.4 vol% at 7, 8 and 60 days of hydration, respectively. Pore connectivity strongly decreases with hydration time due to the chemical reactions producing new phases filling the pores. The 6-connected porosity fractions were 92, 78, and 9% at 7, 8 and 60 days. The reactions filling the pores were investigated by Rietveld quantitative phase analysis and 27Al MAS-NMR.

Effects of Window Films in Thermo-Solar Properties of Office Buildings in Hot-Arid Climates

The electricity consumption in residential/office buildings corresponded to 45% of the total annual electricity demand in hot-arid climates. This accounted for 27.2 TWh of electricity consumption with 14.2 MWh/capita/year in Kuwait. In this research, four offices in an educational building were equipped with a meteorological data logging system using temperature, humidity, and illuminance sensors. All four offices had double-glazed windows. Moreover, two offices were equipped with two types of commercially available window films. Two million data were stored in iCloud using Wi-Fi and an Internet of Things (IoT) system for the 3 months of June, July, and August 2019. Here, histograms and the kernel density estimation (KDE) of temperature/humidity were analyzed and compared for the two offices with/without 3M Neutral 20 window films. Two floors of the same building consisting of 31 offices were also modeled and simulated to study energy saving and CO2 footprint reduction using various window films. The results of simulations for the month of July 2019 using SOL 101 and SOL 102 window films, respectively, showed that about 250 kg and 255 kg of production of CO2 could be reduced and energy saving counted for 416 and 422 kWh. Measurements from offices with 3M Neutral 20% and 3M Neutral 70% window films for the month of July 2019 indicated that the carbon footprint could be reduced by about 82 kg and 0.43 kg and energy saving counted for 147.11 and 0.71 kWh, respectively. It was observed that an annual energy saving and CO2 footprint reduction of 2.76% could be achieved using window films in a hot-arid climate.

3D concrete printing for structural applications

Recent years have seen a rapid growth of additive manufacturing methods for concrete construction. Potential advantages include reduced material use and cost, reduced labor, mass customization and CO2 footprint reduction. None of these methods, however, has yet been able to produce additively manufactured concrete with material properties suitable for structural applications, i.e. ductility and (flexural) tensile strength. In order to make additive manufacturing viable as a production method for structural concrete, a quality leap had to be made. In the project ‘3D Concrete Printing for Structural Applications’, 3 concepts have been explored to achieve the required structural performance: applying steel fiber reinforcement to an existing printable concrete mortar, developing a strain-hardening cementitious composite based on PVA fibers, and embedding high strength steel cable as reinforcement in the concrete filament. Whereas the former produced only an increase in flexural tensile strength, but limited post-peak resistance, the latter two provided promising strain hardening behavior, thus opening the road to a wide range of structural applications of 3D printed concrete.

Life Cycle Analysis of AA Alkaline Batteries

From energy and CO2 footprint perspectives, this study focuses on the Life Cycle Analysis (LCA) of AA alkaline batteries considering options other than landfill namely downcycling or, more ambitiously, recycling/remanufacturing. With the exception of lead-acid batteries that are recycled intensively in an energy-efficient manner, many types of batteries are not recycled and are disposed of via traditional disposal routes. Currently, there is lack of economical incentive given that available processes used in recycling batteries to reclaim metals require 6-10 times more energy than extracting/refining those metals from ores. Some processes (e.g., pyrometallurgical) require large capital investment and use large amounts of energy. For AA batteries, current recycling techniques involve 1) burning off the plastic wrapper, 2) batteries are shredded, and 3) melted where metals segregate into layers according to their respective densities, and 4) each molten metal layer is then collected.This study addresses the feasibility of recycling alkaline batteries, as they are the most common dry batteries as well as being more benign as compared with other types such as lithium-ion or Ni-cadmium. From energy and CO2 footprint perspectives, this study makes a case for downcycling or even recycling/remanufacturing (depending on the material of the separated components) for the zinc metal, manganese oxide concentrates, and other components for recycling/reuse in an efficient/environmentally-friendly manner. Life cycle analysis (LCA) findings suggest that, if technology is developed so that the cathode and anode materials are recycled/reused, there will be significant recovered energy and CO2 values. For a world annual production estimate of 4 billion AA alkaline batteries, the EOL potential findings estimate energy savings and CO2 footprint reduction of about 6.2*1015 J and 3.75*108CO2 kg, respectively.

Carbon footprint reduction of acid gas enrichment units in hot climates: A techno-economic simulation study

In natural gas processing plants, acid gas enrichment (AGE) units play a vital role in increasing H2S purity in the acid gas feed of sulfur recovery units (SRUs). Moreover, AGE units also produce a CO2-rich gas stream that is often vented to atmosphere. If CO2 purity is sufficiently high, this stream can be used as an injection gas for enhanced oil recovery (EOR) or for sequestration. In hot climates, AGE units operate at significantly low efficiencies owing to the exothermic nature of their operation. Any enhancement in the efficiency can reap significant benefits. In this work, we study the economic and environmental impact of a process scheme wherein a Ranque–Hilsch vortex tube (RHVT) is used as a cooling system for a lean solvent in an AGE unit located in a hot region of the United Arab Emirates. A simulation model is built using the process simulator ProMax® and is validated using plant design data. It is found that reducing the lean solvent temperature increased the purity of H2S and CO2 product streams. At temperatures lower than 25 °C, the inverse occurs as CO2 absorption becomes favorable thermodynamically. Consequently, a lean solvent temperature of 25 °C is identified to be optimal, thus achieving the lowest energy consumption and carbon footprint, while maintaining high purities of the product gases. At the optimal temperature, the proposed scheme results in steam savings of 13 kg/s (equivalent to 40% reduction in total steam rate). This reduced energy consumption leads to an annual CO2 footprint reduction of 83.7 million kg (equivalent to 40% reduction in total CO2 footprint). The optimal lean solvent temperature increases the purity of the H2S-rich gas stream (acid gas) to 67.3 mol% compared to its base case value of 45.7 mol%. Further, the purity of CO2-rich gas stream increases to 97 mol% compared to its base case value of 89 mol%, thus making it suitable for EOR or sequestration. Economically, the evaluated annual energy savings translate to 11.2 million USD, at a crude oil price of 50 USD. The computed payback period is 1.3 years, thus showing the potential of the proposed process. The process scheme proved to be superior to other commercial alternatives from economic and environmental perspectives.

Stabilized biomass ash as a sustainable substitute for commercial P‐fertilizers

AbstractThe reuse of biomass ash as a fertilizer is generally recognized as good practice with several environmental benefits. However, the possible presence of leachable heavy metals in this ash limits the potential extent of its application and the implementation of an appropriate legal framework. For the first time, a method to stabilize wood ash based on the use of other by‐products (coal fly ash and rice husk ash) is presented. No commercial chemicals are employed in the procedure. The results show that despite the initial presence of leachable heavy metals in the ash, the final obtained material is stable. In addition, the lowering of pH (from 13.5 to approximately 7.5) due to carbonation reactions and the addition of Ca‐rich ash increases the phosphorous availability compared with the starting wood ash and makes the obtained material suitable for use in soil fertilization. The sustainability of the new proposed technology is quantitatively discussed with regard to the differences in embodied energy and CO2 footprint of phosphorous between raw materials and stabilized wood ash. This work shows that the prospects for energy saving and CO2 footprint reduction using stabilized wood ash as a substitute for inorganic commercial P‐fertilizers are significant and offer a new way to reach these objectives. The simplicity of the method and the general availability of the by‐products employed in the stabilization also render the procedure suitable for applications in developing countries.

New Feedstocks and Chemistry for Lower CO2‐Footprint: Today, Tomorrow, and in the Future

AbstractIndustrial research targets the reduction of CO2 footprint by means of renewable feedstocks. Three different topics are addressed: the use of the biomass as feedstock for fuels and chemicals, utilization of carbon dioxide as feedstock in the polymer industry, and finally, a concept to apply renewable energy in combination with carbon dioxide to make intermediates for chemical synthesis. These examples have been selected in order to illustrate that the strategic change of feedstocks has to be addressed on different time scales, necessity for the multidisciplinary approach, and the enabling role of catalysis.

Renewable energy from biogas with reduced carbon dioxide footprint: Implications of applying different plant configurations and operating pressures

Renewable energy from biogas has the potential to decarbonise energy systems. For example, biomethane derived from raw biogas may partially displace fossil fuels in the transportation sector. The implemented renewable energy actually decarbonises energy systems only if its life cycle CO2 footprint is lower than that of displaced conventional technologies, which is sometimes uncertain. Therefore, this study has been undertaken to review and synthesise knowledge available in the academic literature on the CO2 footprint of renewable energy from biogas. The typical life cycle CO2 footprint of biogas reported in literature is between 50 and 450kgCO2/MWhel. The review analyses three phases associated with biogas: (i) biomass production, (ii) biomass-to-biogas conversion, and (iii) biogas end use. It is found that remarkable CO2 footprint reduction can be achieved by innovating the biomass-to-biogas phase through limiting the amount of CO2 liberated to biogas. The mechanism for reducing CO2 footprint is proposed and suitable solutions are discussed and evaluated. The literature review is followed by a case study that improves the practical understanding of CO2 footprint reduction potentials. In the case study anaerobic digestion (AD) and pressurised anaerobic digestion (PAD) are compared in terms of their biomethane, power and heat generations, and CO2 emissions. Six plant configurations involving AD, biogas upgrading and combined heat and power (CHP) generation are modelled and simulated. The results show that due to the methane enrichment in biogas (94% CH4 at the self-sustained digester pressure of 5MPa) CO2 footprint is reduced. It is revealed that PAD based biogas plants may generate high purity biomethane with the extremely low direct CO2 footprint of about 13kgCO2/MWhf which contrasts with conventional CHP systems achieving about direct CO2 footprint of 700kgCO2/MWhel. The study also explores the fundamentals of PAD which is one of emerging biogas technologies.*Corresponding author.

Increasing the sustainability of membrane processes through cascade approach and solvent recovery—pharmaceutical purification case study

Membrane processes suffer limitations such as low product yield and high solvent consumption, hindering their widespread application in the pharmaceutical and fine chemicals industries. In the present work, the authors propose an efficient purification methodology employing a two-stage cascade configuration coupled to an adsorptive solvent recovery unit, which addresses the two limitations. The process has been validated on purification of active pharmaceutical ingredient (API) from genotoxic impurity (GTI) using organic solvent nanofiltration (OSN). The model system selected for study comprises roxithromycin macrolide antibiotic (Roxi) with 4-dimethylaminopyridine (DMAP) and ethyl tosylate (EtTS) as API and GTIs, respectively. By implementing a two-stage cascade configuration for membrane diafiltration, the process yield was increased from 58% to 95% while maintaining less than 5 ppm GTI in the final solution. Through this yield enhancement, the membrane process has been “revamped” from an unfeasible process to a highly competitive unit operation when compared to other traditional processes. The advantage of size exclusion membranes over other separation techniques has been illustrated by the simultaneous removal of two GTIs from different chemical classes. In addition, a solvent recovery step has been assessed using charcoal as a non-selective adsorbent, and it has been shown that pure solvent can be recovered from the permeate. Considering the costs of solvent, charcoal, and waste disposal, it was concluded that 70% solvent recovery is the cost-optimum point. Conventional single-stage diafiltration (SSD) and two-stage diafiltration (TSD) configurations were compared in terms of green metrics such as cost, mass and solvent intensity, and energy consumption. It was calculated that implementation of TSD, depending on the batch scale, can achieve up to 92% cost saving while reducing the mass and solvent intensity up to 73%. In addition, the advantage of adsorptive solvent recovery has been assessed revealing up to 96% energy reduction compared to distillation and a 70% reduction of CO2 footprint.

Numerical Simulation and Optimization of Sleipner Carbon Sequestration Project

The capability of accurate numerical simulation and optimization is greatly desired as the technology of geological carbon sequestration (GCS) advances. It can provide quick information for preliminary design of a GCS project. The simulation and optimization results can provide better understanding of the nature of GCS and the uncertainties associated with it and therefore can provide guidelines and the development of best practices for its deployment. In this paper, first the satisfactory history-matching of the Sleipner GCS project is achieved by using the TOUGH2 simulation package. Next, the reservoir engineering technique known as water-alternating-gas (WAG) is applied to the model of the Utsira formation and optimization studies are conducted to determine the optimal WAG operation using the recently developed simulation/optimization code GA-TOUGH2. Results of WAG optimization suggest that in situ CO2 footprint reduction and dissolution acceleration can be achieved while minimizing the water usage.

The role of Smart Grids to foster energy efficiency

The traditional electricity grid has remained the same for most of last century, without major architectural improvements. However, its requirements, guidelines and goals do have changed, especially during the last few years, driven by the sustainability in energy generation and energy efficiency principles. Thus, taking greenhouse gases emissions and CO2 footprint reduction as key objectives and information and communications technologies as key enabler technologies, a novel and revolutionary electric grid paradigm, the so-called Smart Grid, is emerging, in which energy efficiency and renewable generation play a central role. This paper presents an overview on the main requirements and features of Smart Grids to integrate energy efficiency, on the work done and to be done, on the enabler technologies, as well as on the expected impacts and the main benefits Smart Grids will bring.

KR08 Achieving Sustainable Development in Southern California: Collaborative Learning through System Dynamics Modeling

AbstractSouthern California's gateway to international commerce is through major ports in the San Pedro Bay. The University of Southern California is working with local business and other port stakeholders to enable collaborative learning about sustainable business practices. We are using system dynamics‐based models for participants to locate leverage points that yield the highest CO2 footprint reduction for the lowest cost for the shipping of goods from China through one of the ports. As goods movement is a process in which numerous business entities connect, it also offers an opportunity for a collaborative learning approach. We model key leverage points in the supply chain to explore the affects of potential business decisions on the CO2 footprint of shipping containers. These include options for global route choices and clean technologies for ships, rails and trucks. We are expanding the models for refined route options, adding cost functions, and composite clean technology choices across the transport modalities.