Search Results (166)

Most industrial processes depend on heat, electricity, demineralized water, and chemical inputs, which themselves are produced through energy- and resource-intensive industrial activities. In this work, acetic acid (AA) production from syngas (CO, CO₂, and H₂) fermentation is explored and compared against a thermochemical fossil benchmark and other thermochemical/biological processes across four main Key Performance Indicators (KPI)—electricity use, heat use, water consumption, and carbon footprint (CF)—for the years 2023 and 2050 in Portugal and France. CF was evaluated through transparent and public inventories for all the processes involved in chemical production and utilities. Spreadsheet-traceable matrices for hotspot identification were also developed. The fossil benchmark, with all the necessary cascade processes, was 0.64 kg CO_2-eq/kg AA, 1.53 kWh/kg AA, 22.02 MJ/kg AA, and 1.62 L water/kg AA for the Portuguese 2023 energy mix, with a reduction of 162% of the CO₂-eq in the 2050 energy transition context. The results demonstrated that industrial practices would benefit greatly from the transition from fossil to renewable energy and from more sustainable chemical sources. For carbon-intensive sectors like steel or cement, the acetogenic syngas fermentation appears as a scalable bridge technology, converting the flue gas waste stream into marketable products and accelerating the transition towards a circular economy. Full article

EU accession countries, including the Republic of Serbia, are under growing pressure to align their plastic waste management systems with EU environmental directives. Despite this, significant challenges remain, including inadequate infrastructure, a limited recycling capacity, and weak enforcement mechanisms. This study employs life cycle assessment (LCA) to evaluate the environmental impacts of polyethylene terephthalate (PET) packaging waste in Serbia, focusing on three end-of-life scenarios (EoL): landfilling, recycling, and incineration. Using GaBi Professional v6.0 software and the ReCiPe 2016 methodology, the results indicate that mismanaged PET waste contributes notably to terrestrial ecotoxicity (3.69 kg 1.4-DB eq.) and human toxicity (non-cancer) (2.36 kg 1.4-DB eq.). In 2023, 14,967.8 tons of PET were collected by authorized operators; however, unreported quantities likely end up in landfills or the natural environment. Beyond the quantified LCA results, this study highlights microplastic pollution as an emerging environmental concern. It advocates for the development of Serbia-specific characterization factors (CFs) for PET microplastics, incorporating localized fate, exposure, and effect data. Tailored CFs would enhance the precision of impact assessments for Serbian terrestrial ecosystems, contributing to more effective, evidence-based environmental policies. These insights are crucial for supporting Serbia’s transition to sustainable waste management and for meeting EU environmental standards. Full article

Environmental sustainability constitutes a strategic priority for Germany, with the circular economy serving a crucial function in its realization. Circular practices foster sustainable development by decreasing reliance on finite resources, minimizing waste, and reducing greenhouse gas (GHG) emissions. The circular economy provides ecological advantages and strengthens economic resilience through the promotion of innovation, enhancement of supply chain efficiency, and creation of green jobs. Complementary measures, including the preservation of natural capital, the enactment of structural economic reforms, and the implementation of environmental taxes, enhance sustainability objectives. Ecosystem conservation enhances carbon absorption, structural changes facilitate low-emission industries, and environmental taxes incorporate environmental costs. In contrast, industrial activity continues to be a significant contributor to GHG emissions, necessitating policy examination. This study analyzes the relationships between the circular economy, natural capital, structural change, environmental taxation, and industrial activities on GHG emissions in Germany from the first quarter of 2010 to the fourth quarter of 2022. The study employs wavelet coherence analysis (WCA), fully modified ordinary least squares (FMOLS), and dynamic ordinary least squares (DOLS), demonstrating that circular economy practices, natural capital, structural changes, and environmental taxes significantly reduce GHG emissions. Conversely, industrial activities continually elevate GHG emissions in Germany. Moreover, WCA further reveals the time–frequency dynamics and co-movement patterns between key variables and GHG emissions, enabling the detection of both short-term and long-term dependencies. The results indicate that enhancing environmental sustainability in Germany could be effectively achieved by mandating the integration of recycled materials within key industrial sectors to improve environmental sustainability, which would help lower resource extraction and related GHG emissions. Full article

The transformative trajectory of urban development in the contemporary era has engendered a substantial escalation in construction waste generation, particularly in China, where it constitutes approximately 40% of the total solid waste stream. Traditional landfill disposal methodologies pose formidable ecological challenges, encompassing soil contamination, groundwater pollution, and significant greenhouse gas emissions. Furthermore, the unsustainable exploitation of natural sandstone resources undermines energy security and disrupts ecological balance. In response to these pressing issues, an array of scholars and researchers have embarked on an exploratory endeavor to devise innovative strategies for the valorization of construction waste. Among these strategies, the conversion of waste into recycled aggregates has emerged as a particularly promising pathway. However, the practical deployment of recycled aggregates within the construction industry is impeded by their inherent physico-mechanical properties, such as heightened water absorption capacity and diminished compressive strength. To surmount these obstacles, a multitude of enhancement techniques, spanning physical, chemical, and thermal treatments, have been devised and refined. This paper undertakes a comprehensive examination of the historical evolution, recycling methodologies, and enhancement strategies pertinent to recycled aggregates. It critically evaluates the efficacy, cost–benefit analyses, and environmental ramifications of these techniques, while elucidating the microstructural and physicochemical disparities between recycled and natural aggregates. Furthermore, it identifies pivotal research gaps and prospective avenues for future inquiry, underscoring the imperative for collaborative endeavors aimed at developing cost-effective and environmentally benign enhancement techniques that adhere to the stringent standards of contemporary construction practices, thereby addressing the intertwined challenges of waste management and resource scarcity. Full article

The sustainability of the chemical industry requires replacing oil and natural gas with alternative raw materials and reducing CO₂ emissions from processes and utilities. In the particular case of petrochemicals, decarbonization is not easy, since carbon is an integral part of the products. Fossil carbon can be replaced with recycled carbon and renewable carbon, but it is the use of CO₂ as a raw material that will finally make it possible to close the carbon cycle in the chemical industry. The options available are discussed herein, highlighting recent breakthroughs in catalysis and identifying areas where further research is needed. Full article

Natural gas with a high carbon dioxide (CO₂) content presents significant operational and environmental challenges when used as a fuel. A high CO₂ content lowers the calorific value of natural gas, reducing its fuel efficiency and increasing the risk of corrosion in pipelines and processing equipment. Consequently, such natural gas must be purified to reduce the CO₂ content to acceptable levels before it can be effectively used as a fuel. Various technologies for natural gas purification are currently employed, primarily focusing on CO₂ removal. This research explores an innovative approach where highly contaminated natural gas is utilized to synthesize hydrogen for subsequent methanol production. Methanol synthesis necessitates both hydrogen and CO₂, integrating the use of by-products effectively in the production chain. Following the production of methanol, it is then converted into dimethyl ether (DME), a compound with considerable value as a clean fuel alternative due to its lower emissions when burnt. The open-source COCO simulator was used to model and simulate these processes, allowing for the creation of a detailed process flowsheet. The simulation covered four main stages: (1) purification of the natural gas to remove excess CO₂, (2) production of hydrogen, (3) synthesis of methanol using the hydrogen and captured CO₂, and (4) conversion of methanol to DME. This integrated approach mitigates the issues associated with high CO₂ content in natural gas and leverages this component as a valuable feedstock, demonstrating a comprehensive use of all extracted compounds. The proposed process illustrates a promising route for utilizing highly contaminated natural gas, potentially transforming an environmental liability into valuable chemical commodities. Full article

The chemical industry faces major challenges worldwide. Since 1950, production has increased 50-fold and is projected to continue growing, particularly in Asia. It is one of the most energy- and resource-intensive industries, contributing significantly to greenhouse gas emissions and the depletion of finite resources. This development exceeds planetary boundaries and calls for a sustainable transformation of the industry. The key transformation areas are as follows: (1) Non-Fossil Energy Supply: The industry must transition away from fossil fuels. Renewable electricity can replace natural gas, while green hydrogen can be used for high-temperature processes. (2) Circularity: Chemical production remains largely linear, with most products ending up as waste. Sustainable product design and improved recycling processes are crucial. (3) Non-Fossil Feedstock: To achieve greenhouse gas neutrality, oil, gas, and coal must be replaced by recycling plastics, renewable biomaterials, or CO₂-based processes. (4) Sustainable Chemical Production: Energy and resource savings can be achieved through advancements like catalysis, biotechnology, microreactors, and new separation techniques. (5) Sustainable Chemical Products: Chemicals should be designed to be “Safe and Sustainable by Design” (SSbD), meaning they should not have hazardous properties unless essential to their function. (6) Sufficiency: Beyond efficiency and circularity, reducing overall material flows is essential to stay within planetary boundaries. This shift requires political, economic, and societal efforts. Achieving greenhouse gas neutrality in Europe by 2050 demands swift and decisive action from industry, governments, and society. The speed of transformation is currently too slow to reach this goal. Science can drive innovation, but international agreements are necessary to establish a binding framework for action. Full article

The global emphasis on clean energy has increased interest in producing hydrogen from petroleum reservoirs through in situ combustion-based processes. While field practices have demonstrated the feasibility of co-producing hydrogen and oil, the question of which offers greater economic potential, oil, or hydrogen, remains central to ongoing discussions, especially as researchers explore ways to produce hydrogen exclusively from petroleum reservoirs. This study presents the first integrated techno-economic model comparing oil and hydrogen production under varying injection strategies, using CMG STARS for reservoir simulations and GoldSim for economic modeling. Key technical factors, including injection compositions, well configurations, reservoir heterogeneity, and formation damage (issues not addressed in previous studies), were analyzed for their impact on hydrogen yield and profitability. The results indicate that CO₂-enriched injection strategies enhance hydrogen production but are economically constrained by the high costs of CO₂ procurement and recycling. In contrast, air injection, although less efficient in hydrogen yield, provides a more cost-effective alternative. Despite the technological promise of hydrogen, oil revenue remains the dominant economic driver, with hydrogen co-production facing significant economic challenges unless supported by policy incentives or advancements in gas lifting, separation, and storage technologies. This study highlights the economic trade-offs and strategic considerations crucial for integrating hydrogen production into conventional petroleum extraction, offering valuable insights for optimizing hydrogen co-production in the context of a sustainable energy transition. Additionally, while the present work focuses on oil reservoirs, future research should extend the approach to natural gas and gas condensate reservoirs, which may offer more favorable conditions for hydrogen generation. Full article

Polyvinyl chloride (PVC) is one of the most widely used polymers due to its physical properties and versatility. Water consumption of the suspension method is a critical issue that hinders competitiveness. In that case, this study implements water integration through direct recycling, with the aim of minimizing both freshwater consumption and wastewater generation. The source–sink diagram was used to generate the recycled water network, and the integrated process was simulated using software. From simulation data, the water–energy–product (WEP) analysis method was used to assess the process performance, and sustainability indicators for water, energy, and product were evaluated. Fractional water consumption and wastewater production ratio indicators increased to 51.1% and 55.0%, compared to 41% and 54% in the non-integrated process, showing improved water efficiency and cost reduction. The unreacted material reuse index reached 100%, while the production yield was 99.8%, due to effective recycling of unreacted VCM. The use of natural gas and energy integration led to optimal performance in TCE, NGCI, and EECI indicators. However, the ESI indicator was high (3.59 MJ/t) due to energy demands from thermal control equipment for water recirculation. Full article

The construction industry significantly impacts the environment, consuming 50% of natural resources and generating 20% of global greenhouse gas (GHG) emissions. In developing countries, managing construction and demolition (C&D) waste is a growing challenge due to rapid urbanization and inadequate waste management practices. This study employs life cycle assessment and life cycle costing to compare landfill and recycling scenarios for C&D waste using ISO 14040 (Environmental Management—Life Cycle Assessment—Principles and Framework) and ISO 14044 (Environmental Management—Life Cycle Assessment—Requirements and Guidelines). The study’s system boundary encompasses the entire life cycle of C&D waste management, with one ton of C&D waste as the functional unit. The results demonstrated that landfilling C&D waste is harmful due to negative impacts from transportation and landfill emissions. Recycling shows promising potential by significantly reducing environmental impacts and lowering the demand for new raw materials. The recycling scenario substantially decreased GHG emissions, saving 37 kg of CO₂ equivalents per ton of waste. Economically, recycling C&D waste proved more viable, with favorable indicators. Implementing a recycling plant in Lahore could save USD 2.53 per ton in resource costs and mitigate significant environmental impacts. This study recommends that policymakers in developing countries prioritize C&D waste recycling to enhance sustainability and support the transition to a circular economy. The findings provide valuable insights for developing effective waste management strategies, contributing to environmental conservation and economic efficiency. These recommendations guide future initiatives for sustainable C&D waste management, promoting a greener and more resilient urban environment. Furthermore, this study underlines the potential of C&D waste recycling to contribute significantly to achieving Sustainable Development Goals (SDGs), particularly sustainable cities (SDG 11), responsible consumption and production (SDG 12), and climate action (SDG 13). Full article

Aluminum recycling is a key pillar of sustainable metallurgy, protecting natural resources, reducing energy consumption by up to 15 times compared with primary aluminum production and significantly lowering the demand for raw materials. This article presents a comprehensive study on the impact of barbotage refining time and recycled scrap content on EN AC-46000 (AlSi9Cu3) alloy, covering the entire process from the initial ingot to the final casting, contributing to a circular economy. The input material consisted of varying proportions of pure ingots and scrap, with scrap content set at 80%, 70%, and 60%, respectively. Each material batch underwent different refining times: 0, 7, 9, and 15 min. Microstructural studies were conducted using light and scanning electron microscopy techniques. Additionally, pore distribution and their proportions within the material volume were analyzed using X-ray computed tomography. This study also examined hardness and gas content relative to the refining time. It was demonstrated that the refining process promoted microstructural homogenization and reduced porosity throughout the production process. Furthermore, extending the refining time positively impacted the reduction of porosity in thin-walled castings and lowered the gas emission level from the alloy, resulting in improved final product quality. Full article

This paper presents the results of naturally aspirated compression ignition (CI) internal combustion engine (ICE) bench tests of fuels in the form of a blend of diesel oil with recycled oil (RF) in the form of tire pyrolysis oil (TPO) as an admixture with the content of pyrolytic oil with the blend being 10% m/m (D90+RF10). The results relate to reference conditions in which the engine is fed with pure diesel oil (D100). The experiment included the evaluation of engine performance and the determination of the content of selected substances in the exhaust gas for brake-set engine loads equal to 5 Nm, 10 Nm, 15 Nm, and 20 Nm. For each load, engine operating parameters and emissions of selected exhaust components were recorded at preset speeds in the range of 1400–2400 rpm for each engine load. The hourly fuel consumption and exhaust gas temperature were determined. The contents of CO₂, CO, and HC in the exhaust gas were measured. The consumption of D90+RF10 increased by 56%, and CO₂ emissions were 21.7% higher at low loads. The addition of sulfur-containing pyrolytic oil as an admixture to diesel oil resulted in SO_x emissions. The results show the suitability of pyrolytic oil and the possibility of using it as an admixture to fossil fuels. In order to meet SO_x emission levels in land-based installations and for vehicle propulsion, it is necessary to desulfurize fuel or desulfurize deSO_x exhaust gas systems. The CO and HC emission levels in the exhaust gases from the engine powered by the D90+RF10 fuel meet current requirements for motor vehicle exhaust composition. Full article

The growing demand for renewable energy positions it as a cornerstone for climate change mitigation and greenhouse gas emissions reduction. Although renewable energy sources generate around 30% of global electricity, their production and deployment involve significant environmental challenges. This review analyzes renewable energy projects from a life cycle perspective, focusing on environmental impacts throughout the supply chain. Particular emphasis is placed on the energy-intensive nature of manufacturing phases, which account for 60% to 80% of total emissions. The extraction of critical raw materials such as neodymium, dysprosium, indium, tellurium, and silicon is associated with emission levels ranging from 0.02 to 0.09 kg of carbon dioxide equivalent per kilowatt-hour for rare earth elements, along with an estimated average land degradation of 0.2 hectares per megawatt installed. Furthermore, the production of solar-grade silicon for photovoltaic panels consumes approximately 293 kilowatt-hours of electricity per kilogram, significantly contributing to the overall environmental footprint. Through a comprehensive review of the existing literature, this study integrates life cycle assessment and sustainable supply chain management approaches to identify environmental hotspots, quantify emissions, and propose strategic improvements. The analysis provides a structured, systematized, and data-driven evaluation, highlighting the relevance of circular economy principles, advanced recycling technologies, and digital innovations to enhance sustainability, traceability, and resilience in renewable energy supply chains. This work offers actionable insights for decision-makers and policymakers to guide the low-carbon transition. Full article

This research presents a sensitivity analysis of various parameters that affect the carbonation of recycled aggregates (RAs), namely CO₂ concentration, temperature, and relative humidity. The range of parameter values is close to that found in cement plant chimneys with regard to the forced carbonation of RAs. With this purpose, the main characteristics of flue gas streams (CO₂ concentration, temperature, and relative humidity) from two Portuguese cement plants were identified and used in this research. The results indicated that temperatures around 60 °C and CO₂ concentrations around 25% accelerate the carbonation reaction and increase CO₂ absorption in mixed recycled aggregates (MRAs). CO₂ absorption consistently decreased as the relative humidity was reduced from 60% to 40%. The highest amount of CO₂ captured was by a recycled concrete aggregate (RCA) in the conditions of 23 °C, 60% RH, and 25% CO₂. Overall, the RAs were able to capture a significant amount of CO₂, ranging from 52 to 348 kg of CO₂ per tonne of cement paste, depending on the nature of the RA. These findings drawn from a parametric campaign provide valuable insights into the potential enforcement of carbonation for recycled aggregates under conditions that closely reflect those found in cement plants. Full article

The study investigates the impact of water use in energy production in industrial plants, considering the interdependence between water and energy, or the water–energy nexus, to promote sustainable water and energy management. More specifically, it focuses on the industrial sector, particularly on electricity production in thermoelectric power plants, which require large amounts of water for cooling in its production cycle. The field of analysis is set in Italy, referring to the applications of the European Industrial Emissions Directive and Italian regulations that govern water and energy usage. The focus is on large combustion plants, which need to be monitored by national authorities. The Italian situation is outlined, exposing consumption data from major thermoelectric power plants in 2021 through 2023, highlighting the water usage trend and electricity production. In 2023, total water use for these installations was 9,892,719,965 m³—mainly from seawater—with an overall production of electric energy of 117,239,954 MWh, with a relevant fuel consumption from natural gas (18,544,742,774 Sm³). It also analyzed the application of best available techniques to reduce water consumption, recycle water flows, and minimize the environmental impact of power plants. Finally, the main fuels used in these plants, such as natural gas, coal, and biomass, are presented, along with the environmental performance of the power plants based on water use per unit of energy produced. Full article