Photochemical Ozone Formation Research Articles

Innovative valorization of biomass waste-derived sodium silicate for geopolymer concrete synthesis: Sustainability assessment and circular economy potential

Exorbitant greenhouse gas emissions associated with commercial sodium silicates (SS) have curtailed the large-scale practical implementation of geopolymers and have also led to discrepancies related to their sustainability. As a result, the extraction of SS from silica-rich biomass/agricultural waste ashes (AGWA) have gained the attention of researchers. This process involves heat treatment of AGWA with sodium hydroxide in addition to the calcination to produce the ash itself, thus requiring a systematic study to justify its sustainability. Therefore, this study presents an integrated techno-economic analysis (TEA) and life cycle assessment (LCA) to determine the economic and environmental feasibility of AGWA-derived activators for geopolymer concrete synthesis. The LCA results showed a 60–62% reduction in the greenhouse gas emissions of commercial SS-based geopolymer. A significant improvement was also observed in photochemical ozone formation, wherein the emissions were lesser from binders using AGWA based SS as compared to binders produced with commercially available SS. The TEA indicated that although the AGWA-derived SS reduced the cost of the activator by 50–70%, the overall cost of geopolymer concrete with these activators was still higher than OPC based concrete. The hydrothermal process was found to have a lower CO2 emissions and production cost as compared to the thermochemical method to prepare AGWA-derived SS. All in all, the innovative valorization of biomass-waste-derived sodium silicate in geopolymer concrete has a lot of potential to foster a circular bioeconomy by closing the loop of agricultural waste and also promote circular construction by repurposing of waste materials in concrete.

Influence of updated isoprene oxidation mechanisms on the formation of intermediate and secondary products in MCM v3.3.1

In this study, we developed an observation based photochemical box model with the measurement data collected at a suburban site (i.e., the Xianghe, XH site) of the Beijing-Tianjin-Hebei (BTH) region and the latest version of the Master Chemical Mechanism (MCM v3.3.1), which newly incorporated 498 reaction for the additional 155 species with the oxidation of isoprene by the OH radical. The influence of updated isoprene degradation on the radical budgets, formation of intermediate and secondary products by comparing the simulation results in the original version (MCM v3.2) was firstly analyzed to estimate whether the updates of precursors could influence the model performance on its evolution pathways and related products. The results demonstrated that though the input of isoprene could significantly decrease or increase the concentrations of OH and HO2 radicals in the model simulation, respectively, the difference in the simulated concentrations of these radicals with isoprene oxidation before and after the updates was not statistically significant. For intermediate products, the simulated concentrations of formaldehyde and methacrolein (MACR) did not significantly alter before and after the updates, while the abundance of methyl vinyl ketone (MVK) reduced obviously (the maximum reduction of 31%) due to lower reaction coefficient between ISOPBO2 and NO and the lower branching ratios caused by the newly added pathways involving CISOPA and TISOPA in the updated scheme. On the other hand, the simulation concentrations of acrolein (ACR), glyoxal (Gly) and methylglyoxal (Mgly) increased significantly after the model updates. The dominant pathway for the increment of ACR was the decomposition of CH2CHCH2O produced by PE4E2CO, while those of Gly and Mgly were associated with radicals of C537O and PACLOOA that were both from the new intermediate radical of CISOPC. In addition, 39 isoprene oxidation products among the 155 new added species were identified to partition in the formation of secondary organic aerosol (SOA), which were coupled in the gas-particle partitioning module to optimize the formation of SOA, contributing 1.15 μg m−3 to the increase of SOA mean concentration. The updates of isoprene degradation further resulted in the significant change for its sensitivity in SOA formation, making it as the secondary important SOA precursor at the XH site. Last but not the least, the influence on photochemical ozone formation related to updates of isoprene degradation was ignorable. Overall, the above results confirmed the insufficient description of the degradation of precursors indeed limited the simulation of the intermediate and secondary products, highlighting the needs of exploring and parameterizing the precursor degradation processes for better understanding of their behaviors and SOA formation in the atmosphere.

O3 sensitivity and vertical distribution of summertime HCHO, NO2, and SO2 in Shihezi, China

Shihezi City has experienced severe ozone pollution. The vertical observation of ozone precursors (NO2 and HCHO) and SO2 in this area was conducted by multi-axis differential optical absorption spectroscopy in summer, 2023. During this experiment, ozone was measured at an average concentration of 94.89 ± 37.46 μg/m3, and it mainly increased when the northerly wind dominated, accompanied by the increasing of its precursors. In addition, SO2 had a relatively high concentration and elevated with the rising ozone concentration, remarkably different from other cities in China. The average vertical distribution of HCHO in the ozone pollution period was a Gaussian type, with the peak value at about 0.2 km. In contrast, the vertical distribution of NO2 and SO2 decreased exponentially with the rise of vertical height, and their concentrations dropped rapidly within 0–1 km. The RFN range of the transitional regime in Shihezi City was [1.26, 2.80]. Given that ozone pollution mostly occurred when RFN was 1–2, the chemical production of near-surface ozone in Shihezi City was controlled by a transition regime. The RFN vertical pattern was Gaussian type and reached a maximal value at 400–600 m. RFN increased at the middle altitude (0.4–1.2 km), and the ozone formation was controlled by the transitional regime. RFN decreased above 1.2 km, and the photochemical ozone formation was mainly controlled by a VOCs-limited regime. This study provides an improved understanding of O3 precursors vertical distribution and O3 formation sensitivity in Shihezi City.

Environmental assessment of construction waste prevention: A case study in a social housing project in Southeast Brazil

This study analyzed construction waste prevention measures applied to a social housing project, with life cycle assessment (LCA), by three scenarios: base case scenario (BCS) – a single family house built with masonry blocks; prevention scenario 1 (PS1) – BCS assuming a theoretical optimization in materials consumption; prevention scenario 2 (PS2) – a house built with cast-in-situ concrete walls. The prevention scenarios showed waste reductions of 4% (PS1) and 36% (PS2). The environmental impacts have been evaluated by using CML baseline v.3.05; the impact categories were selected according to the EN 15.978:2011: global warming potential (GWP), acidification (AP), eutrophication (EP), ozone layer depletion (ODP), photochemical ozone formation (POF), abiotic depletion (AD), and abiotic depletion – fossil fuels (ADF). The PS1 reduced environmental impacts by 5% whereas PS2 increased by 15%, compared with BCS. The most critical construction steps for BCS and PS1 were coating and superstructure, whereas for PS2 were superstructure and painting. The materials extraction and production stage represent about 90% of the total impacts. The most critical materials for BCS and PS1 were concrete, cement, and steel, whereas for PS2 those were concrete, steel, and paint. The most relevant categories for the three scenarios analyzed were GWP, ADF, and AP. The waste management stage was irrelevant in generating impacts, contributing for less than 1% of the total impacts. These results highlight that despite reducing waste generation, prevention does not necessarily reduce the overall impacts of the edification, and therefore, the materials and construction methods used are especially relevant.

Vertical Evolution of Ozone Formation Sensitivity Based on Synchronous Vertical Observations of Ozone and Proxies for Its Precursors: Implications for Ozone Pollution Prevention Strategies.

Photochemical ozone (O3) formation in the atmospheric boundary layer occurs at both the surface and elevated altitudes. Therefore, the O3 formation sensitivity is needed to be evaluated at different altitudes before formulating an effective O3 pollution prevention and control strategy. Herein, we explore the vertical evolution of O3 formation sensitivity via synchronous observations of the vertical profiles of O3 and proxies for its precursors, formaldehyde (HCHO) and nitrogen dioxide (NO2), using multi-axis differential optical absorption spectroscopy (MAX-DOAS) in urban areas of the Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) regions in China. The sensitivity thresholds indicated by the HCHO/NO2 ratio (FNR) varied with altitude. The VOC-limited regime dominated at the ground level, whereas the contribution of the NOx-limited regime increased with altitude, particularly on heavily polluted days. The NOx-limited and transition regimes played more important roles throughout the entire boundary layer than at the surface. The feasibility of extreme NOx reduction to mitigate the extent of the O3 pollution was evaluated using the FNR-O3 curve. Based on the surface sensitivity, the critical NOx reduction percentage for the transition from a VOC-limited to a NOx-limited regime is 45-72%, which will decrease to 27-61% when vertical evolution is considered. With the combined effects of clean air action and carbon neutrality, O3 pollution in the YRD and PRD regions will transition to the NOx-limited regime before 2030 and be mitigated with further NOx reduction.

The importance of photochemical loss to source analysis and ozone formation potential: Implications from in-situ observations of volatile organic compounds (VOCs) in Guangzhou, China

The chemical loss of volatile organic compounds (VOCs) is influenced by atmospheric and is closely related to the photochemical formation of ozone (O3). Therefore, research on the atmospheric chemical transformation of VOCs is essential to understand their contribution to O3 formation. This study collected data on photochemical-related atmospheric components and meteorological factors in spring at a typical comprehensive observation platform in Guangzhou, China. The photochemical age method was used to evaluate the loss of VOCs due to atmospheric photochemical transformation and to analyze the contribution of such transformation to the source apportionment of VOCs and to the ozone formation potential (OFP). The results show that the mean photochemical loss of total volatile organic compounds (TVOCs) during the observation period was 4.1 ppbv, accounting for approximately 15% of the initial TVOC content. Alkenes had the highest consumed concentration/initial concentration (C/I ratio) of 37.3%. A comparison of the source apportionment results obtained using observational positive matrix factorization (Ob-PMF) and in situ positive matrix factorization (In-PMF) revealed that photochemical losses significantly affected VOCs emitted from industrial and biological sources. Furthermore, neglecting the photochemical loss of VOCs in PMF source apportionment could lead to an underestimation of the contribution of VOCs from industrial and biological sources. The calculated values of OFP under VOC loss (OFPC–VOCs) showed that OFPC-VOCs constituted approximately 30% of the OFP of the initial VOCs. 93.2% of the OFP was attributed to the photochemical loss of alkenes and aromatic hydrocarbons, indicating their significant influence on O3 formation. This study emphasizes the importance of fully considering the photochemical loss of VOCs for accurately assessing their sources and contributions to ozone pollution. It also provides theoretical support for formulating VOC emission reduction strategies in the Pearl River Delta region.

Environmental impacts of carbon fiber production and decarbonization performance in wind turbine blades

The application of carbon fiber in the wind power industry is of great interest in declining CO2 emissions but the carbon fiber manufacturing process is still a long way heading cleaner production. Since little to no information clarifies the dual effects from carbon fiber production to application, this study carried out a life cycle assessment (LCA) to recognize the environmental performances of polyacrylonitrile (PAN)-based carbon fiber production and explore the decarbonization effects of carbon fiber application in wind turbine blades. Based on on-site data from a leading carbon fiber production chain in China, potential environmental impacts of carbon fiber production predominantly originated from the precursor spinning stage (accounted for 13–91%). Fossil depletion (20.24 kg oil eq.), climate change (67.79 kg CO2 eq.), terrestrial ecotoxicity (165.63 kg 1,4-DCB eq.) and photochemical ozone formation (0.14 kg NOx eq.) were the four noteworthy areas to improve the sustainable development. Different scenarios in energy and advanced technology were set to explore the potential improvement of the environmental performance of carbon fiber products. Energy structure (wind power) can improve an average of 22.58% environmental benefit compared with the background scenarios. Regarding the decarbonization effects, the energy payback time and the carbon payback time were estimated to be 0.73 and 0.37 months respectively. Therefore, carbon fiber is a trustworthy material in the strategy to achieve sustainable development from a life cycle perspective.

Assessing the environmental impacts of beef production chains integrating grazing and landless systems

Livestock production systems contribute significantly to environmental impacts at the global level, and meat consumption is projected to increase with the population. There is a need to reduce the impact of food production, including that from beef systems. Different production systems, ranging from traditional grazing to landless systems, coexist within the beef sector. Among these, mixed systems have emerged as a promising alternative. These mixed systems typically involve adult cattle in grazing systems alongside fattening calves in landless systems, potentially achieving higher productivity while reducing the overall environmental impacts. The first step towards proposing mitigation strategies involves identifying the impacts of the sector. This study aimed to estimate the main environmental impacts of four types of mixed beef systems based on the origin of the calves that are raised, fattened, and slaughtered. Using life cycle assessment, the study evaluated the environmental impacts from the cradle to the slaughterhouse gate, expressed per kilogram of carcass weight. The four systems assessed include suckler cow farms that fatten their own offspring (beef single farm, BSF), a system in which calves raised on a suckler farm are fattened on a different farm (beef fattening unit, BFU), and systems in which dairy calves are fattened on growing units, with calves either from Spain (dairy national, DN) or from farms located abroad (dairy abroad, DA). Primary data were obtained from representative surveys of farmers and slaughterhouses, and allocation between co-products was performed according to the updated guidelines of Environmental Product Declarations and the Product Category Rules for meat. Seven environmental impact categories were assessed: climate change, marine eutrophication, freshwater eutrophication, stratospheric ozone depletion, terrestrial acidification, photochemical ozone formation on ecosystems, and photochemical ozone formation on human health. The results indicate that meat production from BSF and BFU has greater environmental impacts than that from DN and DA systems, primarily due to the lower environmental burden allocated to dairy calves, whereas the contribution of slaughterhouse activities to the environmental impacts was minimal. This study highlights the importance of mitigating the environmental impacts associated with feed production, enteric fermentation, and manure management in beef systems. Future studies should consider potential environmental benefits of grazing animals such as carbon sequestration and biodiversity promotion.

Advancing Biodiesel Production System from Mixed Vegetable Oil Waste: A Life Cycle Assessment of Environmental and Economic Outcomes

This study aims to evaluate the environmental and economic performance of biodiesel production from mixed vegetable oil waste using the life cycle assessment (LCA) model. Due to its huge potential, Pakistan is taken as a case study. It produces 468,842 tons of vegetable oil waste annually. As no biodiesel production plant exists to process it, the environmental performance of biodiesel prototypes has not been investigated. Therefore, the current study is conducted to support the design of a plant to produce biodiesel from mixed oil waste. An attributional LCA was conducted using ReCiPe (H) and found that 400 kg of biodiesel can be produced from 1 t of mixed oil waste. The results, based on a functional unit of 1 ton, showed that biodiesel production from mixed vegetable oil waste is more eco-friendly than the existing landfilling practices with a global warming potential of 1.36 × 10−4 kg CO2 eq, human toxicity of 5.31 kg 1.4 DB eq, ozone depletion potential of 0.00271 kg CFC-11 eq, eutrophication potential of 0.0118 kg P eq, acidification potential of 123 kg SO2 eq, and photochemical ozone formation of 51.4 kg NOx eq. Scenario modelling was conducted using electricity from photovoltaic solar cells, which decrease fine particulate matter formation from 44.5 to 0.725 kg PM2.5 eq, instead of using electricity from a grid to the plant. Hotspot identification was carried out to highlight the effects of individual impact categories. An economic analysis showed that 638,839 USD/year revenue would be generated. Generating energy from discarded vegetable oils through biodiesel production presents a sustainable and economically viable approach. This process benefits the environment and contributes to cost savings by reducing waste disposal in landfills. Furthermore, it aligns with the principles of a circular economy, in which resources are reused and recycled. It also supports the pursuit of the United Nations’ Sustainable Development Goals (SDGs), particularly SDG-7, which focuses on affordable and clean energy, and SDG-12, which emphasizes responsible consumption and production.

Environmental and material criticality assessment of hydrogen production via anion exchange membrane electrolysis

The need to drastically reduce greenhouse gas emissions is driving the development of existing and new technologies to produce and use hydrogen. Anion exchange membrane electrolysis is one of these rapidly developing technologies and presents promising characteristics for efficient hydrogen production. However, the environmental performance and the material criticality of anion exchange membrane electrolysis must be assessed. In this work, prospective life cycle assessment and criticality assessment are applied, first, to identify environmental and material criticality hotspots within the production of anion exchange membrane electrolysis units and, second, to benchmark hydrogen production against proton exchange membrane electrolysis. From an environmental point of view, the catalyst spraying process heavily dominates the ozone depletion impact category, while the production of the membrane represents a hotspot in terms of the photochemical ozone formation potential. For the other categories, the environmental impacts are distributed across different components. The comparison of hydrogen production via anion exchange membrane electrolysis and proton exchange membrane electrolysis shows that both technologies involve a similar life-cycle environmental profile due to similar efficiencies and the leading role of electricity generation for the operation of electrolysis. Despite the fact that for proton exchange membrane electrolysis much less material is required due to a higher lifetime, anion exchange membrane electrolysis shows significantly lower raw material criticality since it does not rely on platinum-group metals. Overall, a promising environmental and material criticality performance of anion exchange membrane electrolysis for hydrogen production is concluded, subject to the expected technical progress for this technology.

Technology transition strategies for textile-dyeing sludge management in China from the environmental and economic perspectives

Textile-dyeing sludge reutilization is considered as an effective management scheme in the transition to low-carbon and sustainable development from the conventional incineration or landfilling. However, few studies have focused on its assessment from environmental and economic perspectives. In this study, a bin-to-grave life cycle thinking is applied to compare the environmental and economic performances of four promising and newly industrialized sludge reutilization technologies (i.e., pyrolysis-gasification-incineration, co-combustion in coal-fired power plants, sludge-to-brick, and sludge-to-biochar) with the traditional landfill option. Results indicate that technology transition to sludge-to-biochar option outperforms other transition strategies. The sludge-to-biochar option could gain environmental benefits in 7 categories i.e., primary energy demand (−6.1 × 103 MJ/t sludge), abiotic depletion potential (−4.9 × 10−4 kg antimony eq./t sludge), eutrophication (−0.15 kg PO43− eq./t sludge), ozone depletion(−1.67 × 10−5 kg CFC-11 eq./t sludge), photochemical ozone formation (−2.25 kg NMVOC eq./t sludge), ionizing radiation-human health effects (−3.1 kg U235 eq./t sludge), and ecological toxicity (14.4 CTUe/t sludge). Direct emissions of GHG in sludge reutilization technologies contribute to >70 % of the global warming potential category. Adopting the preferred sludge-to-biochar option at the provincial scale could mitigate approximately 0.81 million t of CO2 eq./year, which is equivalent to the amount of CO2 annually absorbed by 44.1 million trees in China. Feedstock (i.e., chemicals) contributes to about 77.9 %–97.9 % of toxicity-related environmental loads (i.e., human toxicity-cancer effects and ecological toxicity) for sludge-to-biochar, whereas in other utilization technologies, the key factor is heavy metal emission. The sludge reutilization technologies could break even within 3 years except pyrolysis-gasification-incineration (7 years). Meanwhile, contribution, sensitivity, and scenario analyses indicate that reducing primary energy consumption and improving the product quality and yield could effectively alleviate environmental burdens. A reasonable sludge disposal fee could help with the circular regeneration of textile-dyeing sludge. Despite that sludge-to-biochar stands as the foremost advantageous option for the technology transition in managing textile-dyeing sludge, certain aspects (for example, product quality and feedstock consumption) still necessitate further enhancements before its large-scale application in China.

Comparative Life Cycle Assessment of Alternative Marine Fuels

With the stricter rules introduced by the policymakers in maritime transportation, harmful emissions are aimed to be mitigated. Consequently, studies on alternative fuels have emerged, and different methods had adopted to evaluate fuel choices. Within this context, a well-to-wake life cycle assessment method is used to determine the environmental impacts of the fuel options. Included fuels in the study are ammonia, biodiesel, Dimethyl ether, electro Fischer Tropsch diesel fuel, electro methanol, Fischer Tropsch diesel fuel, hydrogen, liquefied natural gas, liquefied petroleum gas, marine diesel oil, marine gas oil, marine bio-oil, methanol, pyrolysis oil, renewable diesel, straight vegetable oil, and ultra-low sulfur heavy fuel oil. The paper aims to evaluate the fuels according to the 2050 strategy of the International Maritime Organization. Hence, black carbon, carbon monoxide, carbon dioxide, nitrous oxide, nitrogen oxide, sulfur oxide, particulate matter, methane, and volatile organic compounds are considered emissions. During the study, an ocean tanker model available in the GREET Model 2022 was used for life cycle inventory analysis, and life cycle assessment was conducted by Environmental Footprint Method 3.0, which is included in the OpenLCA. The assessment was carried out according to climate change, acidification, freshwater ecotoxicity, marine eutrophication, terrestrial eutrophication, non-cancer human toxicity, particulate matter, and photochemical ozone formation criteria. The results show that out of eight criteria, marine bio-oil became the most dominant choice due to the consumption of CO2 and methane while producing and low emission generation during combustion.

Towards environmentally sustainable battery anode materials: Life cycle assessment of mixed niobium oxide (XNO™) and lithium‑titanium-oxide (LTO)

Electric mobility has proven to be essential for the carbon neutrality of the transport sector. However, several studies have demonstrated the environmental costs linked to the supply of rechargeable batteries, which should not be overlooked. The supply of some elements has raised concerns, either because they are associated with environmental and social risks, or because they are considered critical raw materials due to their concentrated geographical supply. It is therefore important to look for innovative technologies capable of reducing the demand for traditional battery raw materials and technologies, but that also have lower environmental impacts linked to their supply. Niobium has been reported to improve the performance of battery components and could (partially) replace some traditional battery materials, but little is known about the environmental impacts of niobium-based battery materials. This study compares two commercial lithium-ion battery anode materials, namely lithium-titanate (LTO) and an innovative mixed niobium oxide anode material (ECA-302, a formulation of XNOTM). Life cycle assessment is employed to quantify the environmental impacts of both technologies, taking into account impacts on global warming potential (GWP), acidification, ozone depletion, photochemical ozone formation (POF) and the use of fossil resources. The impacts were quantified by mass (1 kg anode material) and functionality (1 kWh delivered/cycle life), using primary industrial data for ECA-302 and literature-adapted data for the LTO. Results show that ECA-302 performs better than LTO considering both the material mass and energy delivery per cycle levels. The GWP for the supply of the ECA-302 was 51% lower than the LTO, but the most remarkable differences were observed for POF, for which ECA-302 had an impact about 72% lower than LTO at the production stage and 77% lower at the energy delivery. The results also indicate that 20% less ECA-302 material is needed to deliver 1 kWh over the cycle life of the battery compared to LTO.

Summertime carbonyl compounds in an urban area in the North China Plain: Identification of sources, key precursors and their contribution to O3 formation

Carbonyl compounds are critical components of volatile organic compounds, which significantly participate in the photochemical formation of atmospheric ozone and thus threaten human health. Here we measured 15 C1–C8 carbonyl compounds at an urban site in Linyi, a typically industrialised city in the North China Plain (NCP). Formaldehyde (3.89 ppbv), acetaldehyde (1.66 ppbv) and acetone (2.03 ppbv) were found to be the top three carbonyl compounds, accounting for 76.11% of the total concentration of carbonyl compounds. Anthropogenic secondary formation was recognised as the main source of the top five carbonyl compounds, which included formaldehyde, acetaldehyde, acetone, butyraldehyde and benzaldehyde, and accounted for 46–54% of all sources. Alkenes were the most important precursors of formaldehyde and acetaldehyde, suggesting that reducing the emission of alkenes from anthropogenic sources is an effective way to control carbonyl compound pollution in Linyi. Furthermore, the photolysis of carbonyl compounds played a significant role (68–75%) as sources of HO2• and RO2• and thus made a significant contribution (14.6%) to the photochemical formation of O3. This study highlights the importance of anthropogenic secondary formation as a source of carbonyl compounds and provides a scientific basis for O3 pollution control in carbonyl compound-enriched cities in the NCP.

Life cycle assessment of food waste management options: a case study at campus level to foster sustainable campus

ABSTRACT This study aims to evaluate the environmental impact savings by different food waste management options of a university campus to support decision-making in the scope of sustainable campus. For this purpose, food waste generated inside the campus was characterized, and a hypothetical anaerobic digestion plant with a biogas recovery system was modeled. Two scenarios, representing the modeled plant, and current practices (landfilling and energy production methods) were formed, and life cycle assessment was conducted. For the modeled plant, the biogas and methane yields were calculated as 0.66 and 0.36 l/g VS, respectively, and generated electricity and heat were found as 92.6 and 188.9 kWh/day, respectively. Impact assessment results showed that global warming and acidification potential are the main impacts resulting from the current practices. More than 88% of impact savings can be achieved in all assessed impact categories by shifting to anaerobic digestion. In the scope of campus sustainability, 23% and 16% of the electricity and heat demand of the selected building on the campus can be supplied which results in 7%, 5%, 5%, and 4% impact reduction on campus level for global warming, photochemical ozone formation – impact on vegetation, terrestrial eutrophication, and acidification, respectively. Our results suggest that micro-scale changes may also provide a considerable amount of environmental impact savings.

LCA Analysis Decarbonisation Potential of Aluminium Primary Production by Applying Hydrogen and CCUS Technologies

The energy intensity and high emissions of extractive industries bring a major need for decarbonisation actions. In 2021, extraction and primary processing of metals and minerals were responsible for 4.5 Gt of equivalent CO2. The aluminium industry specifically accounted for total emissions of 1.1 Gt CO2 eq. per year. Reaching the European milestone of zero emissions by 2050, requires a 3% annual reduction. To achieve this, the industry has searched for innovative solutions, considering the treatment of emitted CO2 with techniques such as Carbon Capture Utilisation and Storage (CCUS), or the prevention of CO2 formation on the first place by utilising alternative fuels such as hydrogen (H2). This study aims to comprehensively compare the overall environmental performance of different strategies for addressing not only greenhouse gas (GHG) emission reduction potential, but also emissions to air in general, as well as freshwater and terrestrial ecotoxicity, which are commonly overlooked. Specifically, a Life Cycle Assessment (LCA) is conducted, analysing four scenarios for primary Al production, utilising (1) a combination of fossil fuels, specifically Natural Gas (NG), Light Fuel Oil (LFO) and Heavy Fuel Oil (HFO) (conventional approach); (2) carbon capture and geological storage; (3) Carbon Capture and Utilisation (CCU) for methanol (MeOH) production and (4) green H2, replacing NG. The results show that green H2 replacing NG is the most environmentally beneficial option, accounting for a 10.76% reduction in Global Warming Potential (GWP) and 1.26% in Photochemical Ozone Formation (POF), while all other impact categories were lower compared to CCUS. The results offer a comprehensive overview to support decision-makers in comparing the overall environmental impact and the emission reduction potential of the different solutions.

Characteristics, Ozone Formation Potential and Sources of VOCs in Shandong Province, Eastern China

Between 9 July and 19 August 2016, the air concentrations of 57 volatile organic compounds (VOCs) were measured in Shandong Province, eastern China. Seven sampling sites representing urban, coastal and background sites were selected for sampling. The measured data were employed to investigate the VOCs’ characteristics, ozone formation potential, and main sources. During the sampling period, the concentrations of the VOCs ranged between 15.3 and 883 ppbv, with a mean of 139 ppbv. The most severely polluted city was Zibo (833 ppbv), followed by Jinan (33.5 ppbv) and Qingdao (32.8 ppbv). Propane was the most abundant species in all of the sampling sites, with a concentration range of 1.05–9.86 ppbv. Ethene, i-butane, 1-butene, cis-2-butene, n-butane, i-pentane, n-pentane, benzene and toluene were the predominant species in both the urban and coastal sites. Propylene equivalent concentrations (Pro-Equiv) and maximum incremental reactivity (MIR) were employed to assess the reactivity and contribution of each species to the photochemical ozone formation. The results showed that alkenes and aromatics were the most active species performing a key function in the ozone formation, accounting for 43.9–90.7% of the Pro-Equiv and 41.0–93% of the ozone formation potential (OFP). The ratios of ethylbenzene and m/p-xylene were calculated, and the results showed that local emissions were the main sources. Gasoline exhaust/fuel evaporation, industry process/solvent usage, diesel exhaust/petrochemical emission and coal burning were the dominant sources of VOCs in Shandong Province.

Environmental and economic sustainability of fresh-cut and pre-cooked vegetables

Due to the growing awareness about the environmental and economic sustainability of food products, the present research aims to evaluate the sustainability of fresh-cut and pre-cooked vegetables, a niche market with growing demand. An analysis was carried out using a detailed material, energy, and economic inventory based on a commercial food processing plant located in northeast Spain. The environmental sustainability was determined using process-based environmental life cycle assessment (E-LCA), applying a cradle-to-market approach, and using the EF3.0 impact assessment methodology to quantify impacts on five midpoint categories (climate change, photochemical ozone formation, acidification, freshwater eutrophication, and fossil resource use) and an aggregated single score. Additionally, an environmental life cycle costing (E-LCC) was performed. The pre-cooked vegetable products showed a higher environmental footprint than the fresh-cut products in all the impact categories (between 14.0 % and 39.9 %) and involved higher life cycle costs (15.2 %), due to the increased demand for ingredients, packaging materials, and electricity consumption per FU (kg of product). The carbon footprint (CF) and the cost for the fresh-cut products were 0.72 kg CO2 eq/kg and 2.62 €/kg, respectively, compared to 0.86 kg CO2/kg and 3.02 €/kg for the pre-cooked vegetables. The environmental profiles of both products were rather similar, with a dominance of the Upstream stage (production of ingredients and packaging materials), followed by the Core stage (mainly due to electricity consumed during vegetable processing). The relevance of the Core stage is amplified in the economic analysis due to the incorporation of certain processes which were not included in the process-based E-LCA (e.g., labour, capital, insurance, maintenance costs, etc.). To integrate the economic and environmental analyses, an eco-efficiency index was calculated that describes the carbon emissions per unit of monetary cost, resulting in 0.27 kg CO2eq/€ for the fresh-cut and 0.28 kg CO2 eq/€ for the pre-cooked vegetables.

How does sharing economy advance cleaner production? Evidence from the product life cycle design perspective

The sharing economy is a recent worldwide development; however, its impact on sustainability remains unclear, particularly in regards to the advancement of cleaner production. In order to explore the potential and contribution of specific sharing economy business practices in the transition to cleaner production, this study empirically analyzed how China's free-floating bike-sharing (FFBS) improved environmental sustainability through optimization of product life cycle design. Specifically, the impact on climate change and human health of three generations of shared bike products was quantitatively analyzed by using product environmental footprint (PEF) approach. The results show that sustainable product lifecycle design can effectively improve the sustainability of FFBS. Through optimized design and product upgrades, the environmental impact intensity of FFBS has decreased by approximately 25.09% –34.34%. This causes FFBS to gradually evolve from exerting negative impacts on climate change to achieving considerable climate benefits (22.18 CO2-eq/pkm). The environmental benefits on ozone depletion and photochemical ozone formation also increased by about 2.46 μg CFC11eq/pkm and 85.77 mg NMVOC eq/pkm with the upgrade of shared bikes from the first generation to the third generation. In addition, although the negative effects of FFBS on respiratory inorganics, non-cancer human health effects and cancer human health effects have been significantly reduced, the corresponding positive environmental benefits still need to be achieved by significantly increasing the utilization rate of shared bikes. Furthermore, this suggests that the sustainable production life cycle design of FFBS can follow the principles of safety, ease of maintenance, durability, ease of use, universality, resource conservation, and recyclability. This empirical study can not only help authorities, managers and the public better understand the contribution of the sharing economy to cleaner production, but also provides new insights and valuable references for improving the sustainability of the sharing economy.

Comparison of science-based and policy-based distance-to-target weighting in life cycle assessment - Using the example of Europe

Weighting of impacts is frequently applied to enable the prioritization of life cycle assessment (LCA) results for the support of decision making. Most Distance-to-Target (DtT) weighting approaches consider policy targets, whereas potential is seen in the weighting of environmental impacts on a more scientific basis. This study aims at the comparison of science-based (SB) to policy-based (PoB) DtT weighting approaches as well as the application in a comparative case study for the domestic footprint of the European Union. The developed approaches integrated SB targets from ten environmental impact categories into the DtT weighting method of the Ecological Scarcity Method in an effort to derive SB eco-factors. In addition to SB eco-factors based on existing weighting factors for Europe from the literature, weighting factors for the European Union were developed. The application of the eco-factors in the case study showed that the SB approach led to three times higher absolute weighting results in contrast to PoB results. SB weighting was dominated by the impact category climate change with the strictest weighting factors in all approaches considered and a share of 87–92%. For the remaining impact categories, common PoB weighting factors were generally stricter. PoB results showed a more balanced distribution, with shares of 64% for climate change, 10% for photochemical ozone formation, 7% for acidification, and 7% for terrestrial eutrophication. Science-based targets can not replace conventional PoB weighting approaches but should be integrated into the weighting step to provide a more comprehensive view of the environmental performance of product systems. SB weighting results are an additional source of information on environmental sustainability regarding environmental carrying capacity that can broaden the basis for decision making.