High CO2 Emissions Research Articles

A forest-based circular bioeconomy for sustainable development: a case study of Konya Province, Turkey

The concept of the circular bioeconomy is becoming increasingly important for the implementation of the 2030 Agenda for Sustainable Development worldwide. The aim of this study is to develop a set of indicators suitable to monitor the implementation of the circular bioeconomy principles in the forest-based sector. The indicators were defined considering the 4R framework and tested in a case study in Konya Province, Turkey. The data to calculate the indicators were collected through the administration of a questionnaire to wood processing enterprises in the study area. The results show that the majority of roundwood processed by enterprises and the workforce are locally sourced. Two strengths of the forest-based sector are the high average productive yield and the economically efficient allocation of wood residues for panels and bioenergy production. Conversely, the main weaknesses are the low amount of certified roundwood processed and the high CO2 emissions due to the transport of wood materials. Considering the results of this study, the current situation in Konya Province could be improved through an enhancement of the Chain of Custody (CoC) certification for both local roundwood and wood residues.

Adaptive Computational Solutions to Energy Efficiency in Cloud Computing Environment Using VM Consolidation.

Cloud Computing has emerged as a computing paradigm where services are provided through the internet in recent years. Offering on-demand services has transformed the IT companies' working environment, leading to a linearly increasing trend of its usage. The provisioning of the Computing infrastructure is achieved with the help of virtual machines. A great figure of physical devices is required to satisfy the users' resource requirements. To meet the requirements of the submitted workloads that are usually dynamic, the cloud data centers cause the over-provisioning of cloud resources. The result of this over-provisioning is the resource wastage with an increase in the levels of energy consumption, causing a raised operational cost. High CO2 emissions result from this huge energy consumption by data centers, posing a threat to environmental stability. The environmental concern demands for the controlled energy consumption, which can be attained by optimal usage of resources to achieve in the server load, by minimizing the number of active nodes, and by minimizing the frequency of switching between active and de-active server mode in the data center. Motivated by these actualities, we discuss numerous statistical, deterministic, probabilistic, machine learning and optimization based computational solutions for the cloud computing environment. A comparative analysis of the computational methods, on the basis of architecture, consolidation step involved, objectives achieved, simulators involved and resources utilized, has also been presented. A taxonomy for virtual machine (VM) consolidation has also been derived in this research article followed by emerging challenges and research gaps in the field of VM consolidation in cloud computing environment.

Selecting nitrogen carriers used for chemical looping ammonia generation of biomass and H2O by thermodynamic method

The demand for NH3 as a new energy carrier will lead to a gradual increase in its production. The Haber-Bosch process, commonly used today, has high energy consumption, high operating pressure and high CO2 emissions due to hydrogen extraction from fossil fuels. For efficient and environmentally friendly preparation of NH3, chemical looping ammonia generation (CLAG) of biomass and H2O is proposed. The selection of suitable nitrogen carriers is the key in CLAG. Since the variety of available substances is large, a systematic method is needed to perform screening efficiently. In this paper, 28 different oxide/nitride pairs were investigated. We mainly investigated the Gibbs free energy change and the equilibrium compositions in the N-absorption and N-desorption reactions. Suitable nitrogen carriers were selected by the minimum N-absorption temperature, nitrogen transport capacity, sintering resistance, price and by-product. When Al2O3/AlN was used as the nitrogen carrier, the minimum N-absorption temperature was 1371 °C, and the nitrogen transfer capacity was high. When TiO2/TiN was used as a nitrogen carrier, the minimum N-absorption temperature was 966 °C, the nitrogen transfer capacity was lower than Al2O3/AlN, and NH3 and H2 were generated simultaneously in the N-desorption step. Compared with SiO2/Si3N4, Cr2O3/Cr2N, Cr2O3/CrN, MnO/Mn5N2, Fe2O3/Fe4N, ZrO2/ZrN, and MoO2/Mo2N, Al2O3/AlN and TiO2/TiN produced less carbide in N-absorption step and had less mass decay in the cycle, making them more suitable as nitrogen carriers. Appropriately increasing the molar ratio of nitrogen carrier to carbon can improve feedstock utilization and the efficiency of CLAG.

Investigation of using waste marble powder, brick powder, ceramic powder, glass powder, and rice husk ash as eco-friendly aggregate in sustainable red mud-metakaolin based geopolymer composites

Geopolymers are an important composite material alternative to cement with high CO2 emission, which allows the use of waste materials in its structure. However, which waste material contributes to the geopolymer composite structure to what extent is still an ongoing research area. This study has been prepared to contribute to closing the gap in this field. In this study, industrial waste materials (waste marble powder (MP), waste brick powder (BP), ceramic waste powder (CW), waste glass powder (GP), and rice husk ash (RHA)) were used 25%, 50%, and %75 percentage as aggregate instead of recycled concrete (RC) on red mud-metakaolin based geopolymer mortars. Mechanical properties (ultrasonic pulse velocity (UPV), splitting tensile, compressive, and flexural strengths), physical properties (void ratio, water absorption, unit weight, and workability properties), abrasion test, and microstructure analyzes (SEM-EDS and XRD) were performed. The highest compressive strength results were in seen the 25% brick powder substitution, with an increase of 74.01% compared to the control sample. Also, the compressive strength results increased in the case of increasing the use of ceramic waste. High silica and alumina contents in both materials were effective in these cases. In terms of the abrasion test, the highest performance was seen as a 49.2% decrease in the mass loss in 75% marble powder replacement. As a result, substitute materials have shown a successful performance, creating significant potential in the production of a sustainable geopolymer.

Embedding Double Transition Metal Atoms in B-Modified Two-Dimensional Carbon-Rich Conjugated Frameworks for Efficient Ammonia Synthesis.

It is important to develop an efficient green catalyst for electrochemical nitrogen reduction under environmental conditions to replace the Haber-Bosch process with high energy consumption, limited economic scale of production, and high CO2 emissions, but there are still some difficulties in its development and design. In this work, based on 2D CCFs, a B-modified rectangular-shaped expanded phthalocyanine bimetallic atomic catalyst is proposed. Because both the TM-d orbital and the B-sp3 hybrid orbital can accept the lone pair and feedback electrons of N2, and there are significantly different valence electron distributions between the two different metals and boron, this catalyst not only keep the advantages of metal catalysts but also play the role of the B atom to further increase the polarity of nitrogen and activate N2. In order to evaluate the catalytic performance of this catalyst, its stability, activity, selectivity, reactivity, and other aspects are screened and analyzed by density functional theory calculation. Among them, the FeNb-BPc CCF catalyst has better N2 adsorption capacity under ambient conditions, exhibits excellent catalytic activity through a continuous mechanism, and has a lower limiting potential of -0.24 V. We believe that this work opens a new path for the rational design of efficient N2 reduction reaction catalysts and also provides a theoretical basis for experimental development.

Performance and mechanism of modified biological nutrient removal process in treating low carbon-to-nitrogen ratio wastewater

For solving the challenge of difficult nutrient removal, high running cost and CO2 emission at low carbon-to-nitrogen (C:N) ratio, Bi-Bio-Selector for nitrogen and phosphorus removal (BBSNP) process was developed. Under parallel operation conditions, full-scale BBSNP was less influence by low C:N ratio (3.5–2) than Anaerobic-anoxic-aerobic (AAO) and achieved better nitrogen removal performance. The mechanism of performance advantage in BBSNP was analyzed by mass balance and high throughout sequencing. It demonstrated BBSNP developed unique microbial community at C:N ratio of 2. Higher abundance of Saccharibacteria, Ferruginibacter, Ottowia, Dokdonella, Candidatus_Nitrotoga and Nitrospira in BBSNP was responsible for better chemical oxygen demand (COD) utilization efficiency, denitrification, denitrifying phosphorus removal and nitrification. Meanwhile, under low C:N ratio, BBSNP could save 10% organic carbon and 15% oxygen requirement, reduce 53% running cost and 21% CO2 emission, which had practical value in relieving energy crisis and carbon emission of wastewater treatment plants (WWTPs).

Interface between energy consumption, CO2 emissions, economic growth, and macroeconomic openness in financial action task force countries through the lens of a causality approach.

There is strong scientific evidence to suggest that carbon dioxide (CO2) emissions are one of the key drivers of global warming. Rising CO2 emissions across the globe have been traced back to increasing global trade and rapid industrial development powered by fossil fuels. High CO2 emissions have had an adverse effect on the quality of life and economic growth of communities across the globe. In this study, the Granger causality approach is used to examine scientifically some causal relationships between energy consumption, CO2 emissions, economic growth, and key macroeconomic variables (trade openness and foreign direct investment) in the panel of Financial Action Task Force (FATF) countries. FATF countries are signatories to agreements to adhere to good financial practices to ensure sustainable development of their economies. The empirical analysis was conducted for the period 1980 to 2020. Results indicate a strong endogenous relationship between the variables in the short and long run. The analysis suggests that careful co-curation of economic, trade, energy, foreign direct investment, and environmental management policies is needed to ensure sustainable economic development in the FATF countries. Global trade and foreign direct investment policies must foster new environmental-friendly industries and greater use of clean renewable energy among these countries. Note: Arrows indicate direction of possible causal links between the variables.

Taking benefits of using PCMs in buildings to meet energy efficiency criteria in net zero by 2050

Considering the share of 40% and 35% of buildings in energy consumption as well as CO2 emissions, adding phase change materials (PCMs) is an effective technique to tackle high energy demand and considerable CO2 emissions. When PCMs are injected into the building envelopes, they improved the sensible/latent storage features of the envelopes. In this study, using numerical methods, defining first (no PCM), second (PCM without phase transition), and third building (with phase transition), the importance of sensible storage feature was compared to latent one. It was found that the sensible/latent importance is dependent on the thermal resistance of the envelopes and setpoint. At setpoint 22 °C, it was found that the PCM-enhanced building consumed less power by 32.4 kWhm2. Under this condition, the share of sensible storage as well as latent storage was 54% and 46%, respectively. The reason for the lower share of latent storage was that PCM never participated in phase change about 40% of the year. To boost PCM effectiveness, it was found that the PCM installation near the uppermost layer enhanced energy-saving by 3.72 kWhm2. The presence of phase change in PCM is not always considered a positive point. In one situation, it was observed that if PCM did not undergo phase transition, it reduces energy consumption by 9.4 kWhm2, while for PCM with phase transition this value was 7.1 kWhm2. PCM was also beneficial on CO2 reduction either with phase change or without phase change. In the former, CO2 emissions declined by 34.9 kgm2, and under the latter circumstances it was 23.9 kgm2.

Fire-extinguishing performance and gas-phase pollution characteristics of different foam agents in extinguishing transformer oil pool fire

In this study, aqueous film-forming foam, fluoroprotein foam, and synthetic foam were applied to extinguish the transformer oil pool fires. The fire-extinguishing performance and burn-back resistance were investigated using a laboratory fire-extinguishing system. Moreover, the emission products were analyzed to evaluate the gas-phase pollution characteristics. Results show that aqueous film-forming foam presents the highest fire-extinguishing efficiency, while fluoroprotein foam has the best burn-back performance. Flue gas and gas chromatography–mass spectrometer analyses demonstrate that the use of fluoroprotein foam results in much higher CO emissions than other foams, and the pollutants are mainly from various hydrocarbons produced by incomplete combustion of transformer oil. Synthetic foam and aqueous film-forming foam lead to higher SO2 and NO emissions, and pollutants are mainly dominated by alcohols and ethers. Noteworthily, when using aqueous film-forming foam to extinguish oil pool fire, a persistent organic pollutant, perfluorooctanoic acid, is detected in the gas phase.

Biodegradable microplastic increases CO2 emission and alters microbial biomass and bacterial community composition in different soil types

Plastic input to the terrestrial environment is of global concern and the still increasing production and release worldwide reinforces this problem. It has been shown that microplastics (MPs) can affect soil structure and soil organisms, possibly leading to an increase in soil carbon turnover, microbial activity and resulting CO2 emissions. Yet, the response of soil CO2 emissions to various types, quantities, and sizes of microplastic is not well understood. The aim of this work was to investigate the effect of conventional and biodegradable microplastics on soil microbial biomass, bacterial community composition and CO2 development. Two types of plastics, LDPE (low-density polyethylene) and PBAT (polybutylene adipate-co-terephthalate), at low (0.1 %) and high (1 %) concentrations and in three different size ranges (50–200 μm, 200–500 μm, and 0.63–1.2 mm) were amended to a sandy loam and a loamy soil and CO2 emissions were measured over four weeks. Afterwards, microbial biomass and growth were estimated, and prokaryotic community shifts were inferred by amplicon sequencing. No effect of LDPE on soil CO2 emissions could be detected, but higher CO2 emissions (13–57 %), microbial biomass (1–7 %), and a shift in community composition was induced by addition of the biodegradable PBAT when added at high concentration. Soil CO2 emissions were 10–13 % greater when small PBAT particles were added compared to large ones. PBAT addition at low concentration had no significant effect independent of its size. Overall, the effect of PBAT addition on soil CO2 emissions was larger in sandy loam than in loam. Several bacterial lineages known to degrade polyesters and other biodegradable MPs, such as members of the Caulobacteraceae and Comamonadaceae were found enriched after PBAT amendment, but effects were soil specific. We conclude that direct impacts of plastic on soil properties are not the main reason for increased soil CO2 emissions, but rather relate to the different recalcitrance of polymer types. Soils contaminated with biodegradable plastic may emit larger amounts of CO2, which needs to be considered in predictions of global impacts of plastic pollution and its mitigation.

Physically mixed black liquor as a catalytic additive for pressurised steam gasification of different rank bituminous coals

Increasing prices and limited availability of oil and natural gas resulted in the popularity of gasification-based coal chemical production. However, the problems with low fuel conversion and high CO2 emission are hindering its competitiveness with other fossil fuels. Blending black liquor from the pulp and paper industry with coal could potentially mitigate the problem due to its carbon neutrality and high catalyst content, but their performance needs extensive analysis. Therefore, three bituminous coals with variable petrographic composition and ash content were physically mixed with various loadings of black liquor (5–20%wt) and gasified under pressurised steam at 800–1000 °C. The parameters such as syngas production and carbon conversion were measured and kinetic parameters were calculated with Random Pore Model, Grain Model and Isoconversional Model. The results have shown that the presence of black liquor has equally increased the gasification performance of each coal despite their different reactivity. For most reactive samples with an addition of 10%wt. Black liquor, the syngas yield had grown by up to 61%, carbon conversion increased by up to 23% and energies of activation reached as low as 39 kJ⋅mol-1, which makes the approach highly competitive against other catalytic impregnation methods.

Study on Preparation and Properties of Sintered Brick from Multi-Source Solid Waste

The recycling of construction waste and the use of a new sintering process in the field of sintered bricks can greatly solve the problems of clay resource depletion, soil structure destruction, and high CO2 emissions that always limit the development of the sintered brick field. The study was carried out using an orthogonal experiment to derive the optimal mix ratio for the preparation of sintered bricks, and subsequently, the sintered bricks were prepared using the optimal mix ratio. The experimental results show that the maximum compressive strength of construction waste sintered brick (MRB sintered brick) prepared using high-temperature sintering is 8.1 MPa, and the water absorption is 11. When the waste glass slag is mixed with 10%, it can show a better fluxing effect in the preparation of sintered bricks by mixing construction waste with waste glass slag (MGB sintered bricks), so that the MGB sintered bricks have a higher densification. The compressive strength is 32.9% higher and the water absorption is 3.5% lower than that of MRB sintered brick. MGS sintered bricks were prepared by mixing Yellow River sedimentary sand into MGB sintered bricks. The strength of MGS sintered bricks increased with the replacement rate of Yellow River sedimentary sand, and when the replacement rate of Yellow River sedimentary sand reached 16%, the strength of the MGS sintered bricks increased by 88.9%, and the water absorption rate was reduced by 4.6% compared with the MGB sintered bricks. The sintering mechanism had significant effects on the compressive strength, weathering resistance, and frost resistance of the sintered brick. The microwave sintering process has the characteristics of high efficiency, uniform heating, selective heating, and low thermal inertia, which can increase the compressive strength of MGS sintered brick by 4.6%, reduce the water absorption by 12.9%, shorten the sintering time by 43.6%, and improve the frost resistance.

A comparative study on the combustion process and emissions formation of a CI engine fueled with isomers n-octanol and di-n-butylether

Two C8 biofuels, n-octanol (OCT) and di-n-butylether (DnBE), have attracted much attention due to their potential to replace diesel. In this work, compression ignition (CI) engines fueled by OCT and DnBE were numerically compared in terms of combustion characteristics and emissions formation. The KIVA4-CHEMKIN code package was used to model the combustion process in the cylinder. To realize detailed chemistry calculation, a multi-component reaction mechanism including OCT and DnBE was implemented in the code. Also, a mono-variate spherical soot model based on the moment projection method was integrated to handle the soot particle dynamics calculation. The engines fueled with OCT and DnBE were operated under the same condition. The comparison results suggest that the DnBE fueled engine exhibits a shorter ignition delay than the OCT fueled engine due to the rapid evaporation process and high cetane number of DnBE. As a result of earlier ignition, the DnBE fueled engine shows a mixing-controlled combustion regime and a longer combustion duration. The DnBE fueled engine generates more NO emissions because of its higher peak in-cylinder temperature and longer combustion duration. In the bowl region of the combustion chamber, a leaner mixture could be observed for the OCT fueled engine. Consequently, the OCT fueled engine produces less particle number and mass, but higher CO emissions.

Thermal Effect and Metallurgical Characteristics of Hydrogen Bottom Blowing in Top–Bottom Combined Blowing Converter

A new technology of hydrogen bottom blowing instead of traditional argon blowing in the current converter steelmaking process is proposed herein, in the aim of overcoming problems such as energy shortages caused by increased scrap charging, the low stirring intensity of bottom blowing, high CO2 emissions, and endpoint carbon content control. The thermal effect and metallurgical characteristics of hydrogen bottom blowing were investigated based on the production data of a steelmaking converter in Pangang Group Xichang Steel & Vanadium Co., Ltd. This study shows that hydrogen bottom blowing at an intensity of 0.1–0.5 m3·min−1·t−1—rather than argon blowing at an intensity of 0.1 m3·min−1·t−1—can increase the smelting temperature by 16–73 K, increase the scrap charging ratio by 0.89–5.19%, and reduce CO2 emissions by 19.79–115.96 kg per ton of steel. Intensive hydrogen blowing could significantly reduce the oxygen content of molten steel in the late stage of steelmaking and be beneficial to controlling oxygen at the endpoint. Hydrogen can also reduce the (FeO) content in slag, and the equilibrium partial pressure ratios of H2O/H2 for the reaction H2 + (FeO) = H2O + Fe in the middle and late periods are 0.41 and 0.11, respectively. Hydrogen can also slightly suppress the decarbonization reaction in the late period of steelmaking, and the equilibrium partial pressure ratio of H2O/H2 for the reaction H2 + (CO) = [C] + H2O in the late period is 9.65 × 10−2, which means that hydrogen is beneficial in preventing the rapid decrease in [C] and, in turn, helps control the endpoint carbon content. By comparing the degree of the reaction (P2O5) + 5H2 = P2(g) + 5H2O and the reaction (P2O5) + 5H2 = 2[P] + 5H2O, it can be seen that intensive bottom-blown hydrogen may have a slight positive effect on slag gasification dephosphorization. The FactSage simulation results further verify the conclusions of the above analysis.

Metal-Free N-Doped Carbons for Solvent-Less CO2 Fixation Reactions: A Shrimp Shell Valorization Opportunity.

High anthropogenic CO2 emissions are among the main causes of climate change. Herein, we investigate the use of CO2 for the synthesis of organic cyclic carbonates on metal-free nitrogen-doped carbon catalysts obtained from chitosan, chitin, and shrimp shell wastes, both in batch and in continuous flow (CF). The catalysts were characterized by N2 physisorption, CO2-temperature-programmed desorption, X-ray photoelectron spectroscopy, scanning electron microscopy, and CNHS elemental analysis, and all reactivity tests were run in the absence of solvents. Under batch conditions, the catalyst obtained by calcination of chitin exhibited excellent performance in the conversion of epichlorohydrin (selected as a model epoxide), resulting in the corresponding cyclic carbonate with 96% selectivity at complete conversion, at 150 °C and 30 bar CO2, for 4 h. On the other hand, in a CF regime, a quantitative conversion and a carbonate selectivity >99% were achieved at 150 °C, by using the catalyst obtained from shrimp waste. Remarkably, the material displayed an outstanding stability over a reaction run time of 180 min. The robustness of the synthetized catalysts was confirmed by their good operational stability and reusability: ca. (75 ± 3)% of the initial conversion was achieved/retained by all systems, after six recycles. Also, additional batch experiments proved that the catalysts were successful on different terminal and internal epoxides.

Techno-economic assessment of CO2 capture possibilities for oil shale power plants

Oil shale is a calcium-rich fossil fuel, and its combustion in power plants generates high CO2 emissions, which must be reduced drastically. Thus, this study conducts a comparative techno-economic analysis of adding CO2 capture technologies, namely, post- and oxy-fuel combustion technologies, to existing oil shale power plants in Estonia. Estonia's energy sector is unique due to its heavy reliance on oil shale. The study's technical analysis indicates that oxy-fuel combustion capture would outperform post-combustion capture in oil shale power generation. However, integration of CO2 capture technology would result in reductions in power units' heat rate performances by more than 10% points due its energy requirements. From a financial perspective, the feasibility of Estonian oil shale power plant CO2 capture depends upon the long-term trends in the electricity market and CO2 emissions trading system. Full-capacity operation over an assumed 24-year lifetime would cost at least 89 euros per ton of CO2 captured and stored in 2021 values. The actual cost might exceed paying CO2 emission allowance fees and environmental charges or result in a competitive disadvantage. Thus, only in the event that the negative externalities resulting from CO2 emissions and national energy security concerns cannot be feasibly mitigated with alternative, stable, and controllable energy sources should state aid be used for CO2 capture technologies for oil shale power plants. The need to impose higher taxes, ceteris paribus, to cover the state aid or transfer the CO2 capture costs to the private sector might reduce the Estonian economy's overall competitiveness.

Carbon Emissions, Ecological Efficiency, and the Economic Development Stage: Evidence from the Yellow River Basin

This paper has explored the relationship between CO2 emissions, eco-efficiency, and economic growth, which has important theoretical and practical significance for realizing high-quality development of the Yellow River Basin (YRB). Based on the data of 99 prefecture-level cities in the YRB from 2003 to 2017, this paper analyses the temporal and spatial variation and agglomeration characteristics of CO2 emissions and eco-efficiency in the YRB. The spatial Durbin model (SDM) with fixed effects is used to test the relationship between CO2 emissions, eco-efficiency, and economic growth in the YRB by using new structural economics theory and the EKC hypothesis. The results show that (1) the YRB is in a stage of extensive economic development with the coexistence of high CO2 emissions and low eco-efficiency and shows a trend of transformation and upgrading to a stage of high-quality economic development; (2) CO2 emissions and eco-efficiency are spatially heterogeneous; CO2 emissions and eco-efficiency in the upper reaches are low, and the middle maintains relatively high eco-efficiency and high CO2 emissions while the lower reaches have both high CO2 emissions and low eco-efficiency; (3) the relationship between CO2 emissions and economic growth is N-shaped, and there is an inflection point of accelerated increase (per capita GDP is 45,558 yuan). The YRB has crossed this inflection point, and CO2 emissions are accelerating with economic development at this stage. The relationship between eco-efficiency and economic growth is U-shaped, with the inflection point of per capita GDP at 46,483 yuan. The YRB has just crossed the point, and eco-efficiency will subsequently steadily rise with economic development.

Secondary processes on coal deposits change the emission of greenhouse gases

The opencast Bilina coal mine (Czech Republic) produces eight million tons of subbituminous coal per year. To evaluate greenhouse gas emissions from the mine, we measured the chemical and isotopic composition of gases released from fresh coals using the canister method and after coal crushing and milling. The δ13C values of the released methane (CH4) and carbon dioxide (CO2) corresponded to their biogenic origin (δ13C (CH4) −70 ‰ to −55 ‰ vs. VPDB, δ2H − 275 ‰ to −260 ‰ vs. VSMOW, δ13C (CO2) -10 ‰ to −16 ‰ vs. VPDB). The findings revealed that secondary biogenic gas production replaced original coal bed gases and the excavated coal is rich in CO2 (0.615 m3 ton−1), but very low in CH4 (0.09 m3 ton−1). Additionally, most of the secondary CH4 was released before excavation. The loss of CH4 (0.235 m3 ton−1) was calculated back from the isotope fractionation of residual CO2. High CO2 emission increased its atmospheric concentration in the mine (570–2000 ppm).

Cutting Cement Industry CO2 Emissions through Metakaolin Use in Construction

Cement production is one of the most important industries on the planet, and humans have relied on is use dating back to the dawn of civilization. Cement manufacturing has increased at an exponential rate, reaching 3 billion metric tons in 2015, representing a 6.3% annual growth rate and accounting for around 5–8% of global carbon dioxide (CO2) emissions. Geopolymer materials, which are inorganic polymers made from a wide range of aluminosilicate powders, such as metakaolin, fly ash, and blast furnace or steel slags, have also been elicited for use due to concerns about the high energy consumption and CO2 emissions connected with cement and concrete manufacturing. This study focused on the mechanical and durability properties of metakaolin in concrete production. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) analyses were used to confirm the characteristics of kaolin and metakaolin. The results showed that 15 wt.% metakaolin can be used to partially replace cement, and that metakaolin, when synthesized with alkaline activators, can also be utilized as a geopolymer to totally replace cement in concrete production. For predicting the compressive strength of different concrete mixtures, few practical models have been presented. This research has shed light on the possibility of utilizing ecologically friendly materials in the building, construction, and transportation sectors to decrease carbon dioxide emissions.

A research on the easy-to-use energy efficiency performance indicators for energy audit and energy monitoring of industrial compressed air systems

Compressed air systems have a high energy transfer capacity. They are widely used in the manufacturing industry due to being clean, dependable, and simple-to-use. On the other hand, these systems are among the most significant energy consumers in the manufacturing sector because they are inefficient with high electricity usage and high CO2 emissions. As a result, all kinds of the energy efficiency enhancements in these systems promote cleaner production by lowering total energy consumption and CO2 emissions in factories. In this paper, the energy-saving potential and carbon emissions of Compressed Air Systems are investigated using data from in-situ energy audits. A simple set of equations is proposed to calculate the mass flow rate of air leakage. The sound intensity (dB) obtained from ultrasonic flow measurements were used as the input of the equation set. Furthermore, two new Energy Performance Indicators have been proposed to guide energy audit evaluation and continuous monitoring of the energy efficiency of Compressed Air Systems in industrial facilities. The new evaluation criteria “Specific Compressed Air Savings” and “Specific Leakage Savings” provide a comparison tool to help decision-makers with their compressed air system investment decisions. Using the “Specific Compressed Air Savings” and “Specific Leak Savings” parameters, the analysis method is demonstrated for an example industrial plant. The facility's specific compressed air and leakage savings are calculated as 0.0067 TOE/ton and 0.0035 TOE/ton, respectively.