Lower Greenhouse Gas Research Articles

Deep Learning Techniques for Enhanced Flame Monitoring in Cement Rotary Kilns Using Petcoke and Refuse-Derived Fuel (RDF)

The use of refuse-derived fuel (RDF) in cement kilns offers a multifaceted approach to sustainability, addressing environmental, economic, and social aspects. By converting waste into a valuable energy source, RDF reduces landfill use, conserves natural resources, lowers greenhouse gas emissions, and promotes a circular economy. This sustainable practice not only supports the cement industry in meeting regulatory requirements but also advances global efforts toward more sustainable waste management and energy production systems. This research promotes the integration of RDF as fuel in cement kilns to reduce the use of fossil fuels by improving the control of the combustion. Addressing the variable composition of RDF requires continuous monitoring to ensure operational stability and product quality, traditionally managed by operators through visual inspections. This study introduces a real-time, computer vision- and deep learning-based monitoring system to aid in decision-making, utilizing existing kiln imaging devices for a non-intrusive, cost-effective solution applicable across various facilities. The system generates two detailed datasets from the kiln environment, undergoing extensive preprocessing to enhance image quality. The YOLOv8 algorithm was chosen for its real-time accuracy, with the final model demonstrating strong performance and domain adaptation. In an industrial setting, the system identifies critical elements like flame and clinker with high precision, achieving 25 frames per second (FPS) and a mean average precision (mAP50) of 98.8%. The study also develops strategies to improve the adaptability of the model to changing operational conditions. This advancement marks a significant step towards more energy-efficient and quality-focused cement production practices. By leveraging technological innovations, this research contributes to the move of the industry towards sustainability and operational efficiency.

Scaling-up a Photo-Electrocatalytic Reactor for CO2 Capture and Conversion to Syngas

The most challenging deal we face today is the need to lower greenhouse gas (GHG) emissions and tackle climate change. Though calls to reduce them are growing louder yearly, emissions remain unsustainably high. CO2 is the key contributor to global climate change in the atmosphere. Electrochemical CO2 reduction (EC CO2R) into chemicals or fuels holds great research interest as a promising approach to mitigate CO2 emissions and reach a carbon-neutral future.1 In this regard, an extraordinary effort has been made to discover new efficient and sustainable catalysts at the laboratory level over recent years. High-performance electrocatalysts in aqueous electrolytes often rely on noble metals, which may hinder their industrial applications. Herein, we successfully synthesized core-shell Cu2O/SnO2 nanoparticles2–4 functionalized with a silane group, using a simple and versatile methodology based on a three-step scalable synthesis method involving wet precipitation followed by salinization and, finally, a rhenium-based complex has been assembled by electro-polymerization.5 The carbon paper-supported Cu2O/SnO2-Re electrocatalyst was characterized at 10 cm2 scale achieving a CO:H2 ratio from 3 to 9, and demonstrating an stable syngas production up to 24 hours at -20 mA·cm-2. To translate those developments from the laboratory level to a higher TRL towards the practical application of CO2 capture and utilization6, an additional chamber was added to the system for the continuous CO2 capture and electrochemical conversion, increasing the electrode area from 10 cm2 to 100 cm2. Captured CO2 co-electrolysis to syngas (H2:CO ratio of 5) in one step was demonstrated with a high CO2 conversion at a current up to -2 A, indicating the scale-up potential of this intensified system. The technology is currently under validation in a TRL4 reactor composed of an array of 5 modules (i.e., 4 x 5 cells x 100 cm2) with a total active area of or 0.2m2 for direct CO2 conversion from simulated anthropogenic sources. The design integrates low-cost photovoltaic (PV) cells to provide any required additional bias to drive the reaction, thus, Perovskite PV panels with a cost of up to 5 times lower (10 €/m2) than Si PV cells were used. The TRL5 demonstration of the developed technology will be done with real flue gas emissions the first semester of 2024. Acknowledgements The financial support of the SUNCOCHEM project (Grant Agreement No 862192) of the European Union’s Horizon 2020 Research and Innovation Action programme is acknowledged. References Guzmán, H., Russo, N. & Hernández, S. CO2 valorisation towards alcohols by Cu-based electrocatalysts: challenges and perspectives. Green Chemistry vol. 23 1896–1920 Preprint at https://doi.org/10.1039/d0gc03334k (2021).Cuatto, G. et al. Standardization of Cu2O nanocubes synthesis: Role of precipitation process parameters on physico-chemical and photo-electrocatalytic properties. Chemical Engineering Research and Design 199, 384–398 (2023).Zoli, M., Guzmán, H., Sacco, A., Russo, N. & Hernández, S. Cu2O/SnO2 Heterostructures: Role of the Synthesis Procedure on PEC CO2 Conversion. Materials 16, (2023).Zoli, M. et al. Facile and scalable synthesis of Cu2O-SnO2 catalyst for the photoelectrochemical CO2 conversion. Catal Today 413–415, 113985 (2023).Miró, R. et al. Solar-driven CO2 reduction catalysed by hybrid supramolecular photocathodes and enhanced by ionic liquids. Catal Sci Technol 13, 1708–1717 (2023).Sullivan, I. et al. Coupling electrochemical CO2 conversion with CO2 capture. Nat Catal 4, 952–958 (2021). Figure 1

Fundamental Studies of Discharge Mechanism and Capacity Limits of Lead Acid Battery Electrodes

Long-duration energy storage provides key benefits such as consistent power supply during periods of high demand for grid reliability and flexibility. For environmental benefits, it allows for more renewable energy integration and helps reduce reliance on fossil fuels to lower greenhouse gas emission. Lead batteries have the economic potential to continue serving as an important energy storage technology for a decarbonized sustainable energy future given they are earth-abundant, inexpensive, and 99% recyclable. Advancing the design of lead batteries with higher material utilization, fast recharge rates, and long-cycle life requires a fundamental understanding of the electrochemical and chemical processes taking place at the atomic and molecular scales. In this work, we will discuss how the use of well-defined electrode interfaces allows us to gain insights into the fundamental limits of discharge capacity and recharge rates. We were able to unveil the relationships between discharge rates and PbSO4 particle size/layer thickness that ultimately governs the maximum discharge capacity accessible as a function of discharge rate on both the negative and positive lead electrodes. This data helped us develop a mathematical model that captures the key processes concerning lead ion and (bi)sulfate ion gradients coupled to nucleation and growth that explain, from first principles, the origin of the well-known empirical Peukert law. In this context, exploring how variables such as acid concentration, temperature, and the presence of lignosulfonate additives in the electrolyte further influence discharge capacity allows us to understand how thermodynamic, kinetic, and even mass transport play a huge role in governing the accessible capacity from the electrodes. This study paves the way for a deeper understanding of the variables that are most important in improving the discharge capacity of lead-acid batteries, and thus batteries that can be utilized at their full potential.

Readiness of Malaysian PV System to Utilize Energy Storage System with Second-Life Electric Vehicle Batteries

The potential of renewable energy sources to lower greenhouse gas emissions and lessen our reliance on fossil fuels has accelerated their integration globally, and especially that of solar photovoltaic (PV) systems. Malaysia has shown great progress in the adoption of photovoltaic systems thanks to its plentiful solar resources. On the other hand, energy storage systems (ESSs) are becoming more and more necessary in order to guarantee grid stability and fully realize the benefits of PV systems. This study attempts to assess the current condition of PV installations in Malaysia with an emphasis on their economic feasibility, regulatory compliance, technological capabilities, and compatibility with various energy storage technologies. Malaysian photovoltaic (PV) systems’ readiness to integrate energy storage systems (ESSs) using second-life electric vehicle batteries (SLEVBs) is examined in this article. Integrating PV systems with SLEVBs in residential ESSs shows economic viability, with a 15-year payback and 25% return on investment (ROI). Therefore, for every 1 MW of installed PV capacity, with ESS integration it is estimated to reduce approximately 3504 metric tons of CO2 emissions annually in Malaysia. The homeowner benefits from large electricity bill savings, net metering revenue, and various incentives or financing alternatives that make the project financially attractive despite the extended payback time. Energy storage solutions are needed to improve grid stability, energy usage, and solar power generation in Malaysia as renewable energy adoption increases. Reusing retired EV batteries for stationary storage could solve environmental and economic issues. This study examines the feasibility, regulatory frameworks, and economic viability of combining second-life EV batteries with PV installations in Malaysia.

Intergranular Shielding of Ultrafine-Grained Ni-Rich Layered Cathode for Advanced Lithium-Ion Batteries

To achieve carbon neutrality on a global scale, fuel-powered vehicles are being steadily phased out over environmentally recommended electrified vehicles (EVs) with low greenhouse gas emissions. In a battery, the cathode is among the foremost components, as it predominantly determines the LIB’s performance and price. However, since current fleet of layered oxide NCM and NCA cathodes have a relatively lower Ni content, they can extract only a limited amount of reversible capacity (210 mAh∙g-1), restricting the driving range of EVs. To achieve higher energy densities, many studies have focused on increasing the average fraction of Ni in NCM or NCA cathodes to more than 90%. However, the extraction of large amounts of lithium ions is seriously compromised by the rapid deterioration of both cycle life and thermal safety. Recent studies on X-doped cathodes (X = B, Nb, Ta, Sb, W, and Mo) have offered promising results by engineering their geometric microstructural configurations to suppress intergranular cracking.1,2 This approach has proven its potential to improve the electrochemical cycling performance of Ni-rich NCA, NCM(A), and NM cathodes. However, prolonged exposure of the Ni-enriched (Ni ≥ 95%) cathode to the electrolyte generally results in continuous oxidative decomposition of electrolytes and subsequent cathode structural transformation, rendering the cathode unsuitable for applications requiring long battery life.3 Herein, we propose a highly stabilized Ni-enriched (Ni ≥ 95%) layered cathode by adopting a multi-stage engineering strategy, i.e., the construction of an ultrafine-scaled microstructure and subsequent intergranular shielding of the refined grains. The formation of an F induced protective layer at the intergranular boundaries of the ultrafine grains in Li[Ni0.95Co0.04Mo0.01]O2 (denoted as Mo1-NC96) noticeably improved both the structural and chemical stability of the cathode, with a limited degree of structural degradation and gas evolution. Reference s : [1] U.-H. Kim, G.-T. Park, B.-K. Son, G.W. Nam, J. Liu, L.-Y. Kuo, P. Kaghazchi, C.S. Yoon, Y.-K. Sun, Nat. Energy, 5 (2020) 860-869.[2] G.-T. Park, B. Namkoong, S.-B. Kim, J. Liu, C.S. Yoon, Y.-K. Sun, Nat. Energy, 7 (2022) 946-954.[3] F. Kong, C. Liang, L. Wang, Y. Zheng, S. Perananthan, R.C. Longo, J.P. Ferraris, M. Kim, K. Cho, Adv. Energy Mater., 9 (2019) 1802586.

Methane slip and other emissions from newbuild LNG engine under real-world operation of a state-of-the art cruise ship

Liquefied natural gas (LNG) use as shipping fuel has increased in recent years. While LNG results in lower carbon dioxide (CO2) emissions as well as benefits in terms of air pollutants, the slip of unburned methane, the main component of LNG, has remained a concern. In this study, methane together with other climate warming agents, CO2 and black carbon (BC), as well as other emission compounds were characterized from 4-stroke low-pressure dual fuel engine on-board a newly build cruise ship utilizing LNG as well as marine gas oil (MGO). The brake specific methane slip was found to vary according to engine load, being 2.3–3.0 g/kWh at 54–80% loads, but increasing to 10 g/kWh at 25% load and 21 g/kWh at 12% load. The LNG combustion also resulted in higher formaldehyde emissions compared to MGO, but reduction in formaldehyde levels was observed over the SCR catalyst present in the exhaust line of the dual-fuel engine, without urea injection, suggesting it may provide a pathway for formaldehyde mitigation. In terms of particle emissions, LNG use reduced particle mass (PM) by 87–93% and BC by 94–99% compared to MGO combustion. Non-volatile particle number above 23 nm (PNnv,>23nm) and 10 nm (PNnv,>10nm) were reduced by 88–97% and 97–99%, except at lowest engine load where PNnv,>10nm increased by 26% compared to MGO utilization. When total greenhouse gas (GHG) emissions including CO2 and BC were considered, LNG use resulted in 13–15% lower GHG at high loads, but the benefit was undermined by the escaping methane at low load conditions. Following the engine activity profile during 8-months of vessel operation on the Mediterranean suggested, however, that in a diesel-electric cruise ship, low load conditions are used mainly during arrivals and departures from harbors, as the engine was operated at loads above 40% for 90% of the operation time. Weighted emission factor, representing the actual engine operation, resulted in methane slip of 2.8 g/kWh or 1.7% of the fuel use, which is below the value considered in the FuelEU Maritime. The results suggest that load specific methane slip, together with engine load profile should be considered when evaluating methane slip on vessel or fleet level.

Rethinking environmental sustainability in rainfed cropping systems

Activity data from a 30-year on-farm experiment with six soil-management treatments were used to develop inventory data for environmental partial life-cycle assessment (LCA). The purpose was to compare the treatments based on environmental outcomes and evaluate conservation agriculture (CA) in Australia's dryland cropping zone. Multiple trade-offs were revealed that highlight the need for a nuanced approach to sustainable intensification and show that rules-based CA is not sufficient to guarantee low greenhouse gas (GHG) emissions, nor low overall environmental impact. Nutrient mining in dryland cropping even under CA can lead to losses in soil carbon that can double GHG intensity. In these systems, additional nutrient inputs can reduce the loss of soil carbon as well as net GHG emissions, demonstrating the critical need to include the effects of soil carbon change in LCA to prevent perverse outcomes.The treatment involving strategic tillage and nutrient balancing, along with stubble retention, had the lowest GHG intensity, but there was a trade-off with the higher embedded impacts across several other environmental categories. Higher fertiliser input could lead to toxicity impacts, due to heavy-metal content, that contribute significantly to the Human health endpoint. However, limitations in modelling such local, site-specific impacts were considerable and more research is needed to address this.In general, trade-offs were found to exist between impacts from on-farm activities versus upstream manufacture of inputs; between GHG emissions and land use (yield) versus other environmental categories; and between different on-farm GHG emission sources. Despite these trade-offs, the treatments all had similar overall scores in the Human health and Ecosystems damage categories. There was no single treatment with low, or high, impact scores across all environmental indicators, indicating that trade-offs need to be carefully considered when making farm-management decisions in the context of net-zero or carbon-neutral farming.

Co-incorporating green manure and crop straw increases crop productivity and improves soil quality with low greenhouse-gas emissions in a crop rotation

In a nine-year field experiment in a wheat–maize–sunflower cropping system in Hetao Irrigation Area, Inner Mongolia, China, organic amendments applied as straw, manure, green manure, and the combination of green manure and straw increased wheat and maize yield, soil aggregate stability, and soil microbial activity in comparison with chemical fertilizer, without changing greenhouse gas emission intensity.

How green is my reusable bronchoscope?

IntroductionSingle-use bronchoscopes have replaced reusable ones in many institutions. This study aimed to evaluate the environmental and financial impacts of both strategies: reusable and single-use bronchoscopes. Material and methodsWe conducted a pragmatic study in a 21-bed polyvalent ICU, in Saint-Brieuc, Bretagne, France. The eco-audit consisted of estimating greenhouse gas (GHG) emissions, considering the life cycle of each strategy. Greenhouse gas (GHG) emissions related to construction, packaging, transport and waste elimination were compared between 2 devices: the reusable bronchoscope, a Pentax® FI-16RBS that was disinfected twice daily; and the single-use bronchoscope, the bronchoflex agile® from TSC. ResultsFor the reusable bronchoscope, GHG emissions were marginally impacted by the number of bronchoscopies performed (from 185 kg eq.CO2 per year to 192 kg eq.CO2 for 10 or 110 bronchoscopies per year). For the reusable device, GHG emissions directly depended on the number of bronchoscopies performed with 3.82 kg eq.CO2 emitted per bronchoscopy. The breakeven point for the reusable bronchoscope was estimated at 50 bronchoscopies in terms of GHG emissions and 96 bronchoscopies for financial considerations. ConclusionConsidering current practice in our ICU, reusable bronchoscopes have lower GHG emissions when used more than 50 times a year and a lower cost when used more than 96 times a year as compared with single-use bronchoscopes.

Sustainable jet fuel from municipal solid waste–Investigation of carbon negativity and affordability claims

Addressing the challenges posed by municipal solid waste (MSW) and alternative aviation fuel is crucial for promoting circular economy and achieving carbon neutrality aligned with UN Sustainable Development Goals. While most studies in this field have focused on catalyst development for MSW-to-jet fuel conversion, this study investigates the environmental and economic performance of sustainable aviation fuels derived from MSW. Life cycle emissions for six conversion pathways were estimated to be 1187–9694 kg CO2 eq/t jet fuel. Fischer-Tropsch (FT) and Plasma FT synthesis emerged as promising options due to their lower greenhouse gas emissions (∼2000 kg CO2eq/t jet fuel) and high net present value (∼$859 million). Furthermore, Monte Carlo simulations and sensitivity analysis quantified the potential outcomes for net present value and carbon footprints. This study also discussed social acceptance, policy implications and real-world limitations for strategic decision-making and advancing the transition to alternative aviation fuels.

Role of Sustainable Alternatives to Petrochemical Based Plastics in Achieving the SDGS

A significant transition from fossil fuel-based economy to one based on biomass is occurring as a result of global warming, socioeconomic challenges, and new policies, which are propelling decarbonisation process across industries. The usage of bioplastics is the most effective way to address the issue of plastic trash. Bioplastics are a safe and sustainable substitute for petrochemical or traditional plastics that lessen our reliance on fossil fuels. The strategic substitution of sustainable products for those derived from petrochemicals not only promotes environmental conservation but also advances the achievement of several sustainable development goals (SDGs). Post-treatment methods, such as photolysis, thermochemical treatment, and biodegradation were used in this study. These alternatives support in lowering greenhouse gas emissions and increasing resource efficiency, which greatly supports SDGs 12 and 15, Responsible Consumption and Production and Life on Land, respectively. This study explores how the (SDGs) could be implemented effectively and makes it clear that sustainable consumption and production (SCP) should be given significant consideration in their production.

Methods of wind energy harnessing: A state-of-the-art and bibliometric analysis

Wind energy is one of the most promising alternatives for obtaining a sustainable electricity generation model with low greenhouse gas emissions. The maturity of this technology, coupled with its low investment costs and good performance, makes it highly interesting for countries to develop projects within this field. However, its high operation intermittency caused by the natural behavior of wind requires preliminary research on the technical conditions (Installation, Capacity, Environmental, Legal, Administrative, Logistics) of the geographical area wherein the wind energy project is planned. This paper provides an overview of the state-of-the-art research studies on the potential of wind energy within a territory. This review describes current methodological alternatives for assessing wind energy generation projects and potential energy studies in different geographical areas globally. Therefore, a bibliometric analysis is included, examining the scientific research trends in the field of wind energy in addition to the different technologies and innovations that have contributed to the viability of a greater wind energy generation project. Finally, the study discusses the technical restriction criteria faced by any such project. This paper also seeks to become a point of reference for future reviews and decision-making in wind projects.

Identifying a sustainable rice-based cropping system via on-farm evaluation of grain yield, carbon sequestration capacity and carbon footprints in Central China

ContextRice-based cropping system is a major anthropogenic source of direct greenhouse gases (GHG) emissions, agricultural inputs also produces numerous indirect GHG emissions and environmental problems. Identification of rice cropping systems with lower GHG emissions and higher grain yields is of great significance to ensure food security while minimizing agricultural carbon footprint (CF). ObjectiveThis study aimed to identify the optimal rice-based cropping system with lower greenhouse effects and comparable annual yield in central China. MethodsUsed life cycle assessment, a two-year field experiment was performed to evaluate the direct and indirect GHG emissions, CF, and carbon sequestration capacity in the six rice-based cropping systems widely used in central China, which consisted of fallow-early rice-late rice, rapeseed-early rice-late rice, fallow-ratoon rice, rapeseed-ratoon rice (RRaR), fallow-middle rice, and rapeseed-middle rice. ResultsThe results showed that compared with the three systems with fallow season, the three systems with rapeseed had lower annual CH4 emissions. The two systems with ratoon rice had lower annual indirect and direct GHG emissions than the two systems with double rice. The three systems with rapeseed had higher annual biomass, grain yields, and fixed carbon in biomass and significantly lower CF than the three systems with fallow season, and RRaR had the highest value of fixed carbon in biomass. The systems with ratoon rice had lower average CF than those systems with double rice. CH4 emissions from paddy fields were the primary source of total annual GHG and the main component of CF. Compared with the three systems with fallow season, the three systems with rapeseed had significantly higher annual carbon sequestration capacity based on net ecosystem production (NEP). Ratoon rice systems had higher average NEP than double- and middle-rice systems. RRaR had the lowest CF per unit yield and highest NEP among all the six systems. ConclusionsThe results indicated that appropriate rice-based cropping systems may alleviate the greenhouse effect via reducing GHG emissions and enhancing paddy NEP, RRaR could achieve relatively higher annual grain yield and carbon sequestration capacity as well as lower CF. SignificanceThis study highlight conversion of double rice and middle rice systems to RRaR may help improve grain yield and mitigate greenhouse effect. The findings may provide a theoretical basis for selection of sustainable development of rice based cropping systems in central China.

New insights for simultaneous nitrogen removal and greenhouse gas reduction by biological-electrolysis constructed wetland in the treatment of aquaculture wastewater under varied C/N

Aiming to address the challenges of poor nitrogen (N) removal and greenhouse gas (GHG) emissions in aquaculture wastewater treatment, biological-electrolysis constructed wetland (BECW) and constructed wetland (CW) were established to comparatively evaluate the N removal efficiency, the greenhouse gas (GHG) emissions, and specific microbial gene abundances under various influent C/N ratios. Increasing influent C/N ratio markedly enhanced the removal rates of COD, NH4+-N, NO3−-N, and TN, while markedly reduced N2O fluxes in CW and BECW. The integration of an electric field with CW (BECW) significantly compensated for the shortcomings of the poor NO3−-N removal efficiency and high N2O emissions when C/N < 6. However, this compensating effect gradually weakened with the continue increase of C/N. BECW simultaneously achieved the high COD (89.26 ± 6.08 %), NO3−N (97.03 ± 1.22 %), and TN (83.17 ± 3.19 %) removal rates, and low GHG emissions (486.00 ± 36.61 mg/m2/h) at C/N = 6. The BECW significantly decreased the abundance of mcrA and pmoA genes while increased the abundance of nirK, nirS, and nosZ genes, and the ratios of pmoA/mcrA and nosZ/(nirS + nirK) across all C/N condition. The emission flux of CH4 in BECW was positively correlated with C/N and the mcrA abundance but significantly negatively correlated with pmoA abundance and pmoA/mcrA. The emission flux of N2O was positively correlated with nirS and nirK abundance but significantly negatively correlated with C/N, NO3−-N removal rates, nosZ abundance, and the index of nosZ/(nirS + nirK). This research offers an innovative approach to get both low GHG emissions and high NO3−-N removal rate in aquaculture wastewater treatment.

Techno-economic Assessment of Solar-driven Polygeneration System for Agri-food Industries

This paper examines the technical, economic and environmental assessment of a solar-driven polygeneration system (SDPS) of a dairy industry located in Tauste, Zaragoza, Spain. The results showed that the proposed SDPS has a solar fraction of 64.3% with a lower cost and lower greenhouse gas (GHG) emissions than conventional system.

Circular battery production in the EU: Insights from integrating life cycle assessment into system dynamics modeling on recycled content and environmental impacts

AbstractThe European Union (EU) Battery Regulation aims to establish a circular battery production and sets minimum battery material recycled targets for new batteries from post‐production and post‐consumer waste batteries. However, it is uncertain whether these targets can be met due to dynamic market developments and if their compliance results in environmental benefits. Therefore, this study examines the circular battery production in the EU and its impact on material flows and the environment from a market perspective. We combined a system dynamic market model with process models for battery production and recycling, using prospective life cycle assessment. According to our analysis, the projected amount of post‐consumer waste alone may not meet the specified levels of recycled materials due to long battery lifetimes. Thereby, the targets for cobalt are particularly ambitious, with a gap of between 9.8 and 14.6 percentage points for most scenarios. In the case of reduced battery lifetimes, the achievable recycled content across all materials increases by more than 75% in 2032 and by more than 85% in 2037. The avoidance of post‐production waste leads to 9% lower greenhouse gas (GHG) emissions compared to recycling with 100% recycling efficiency. Thus, attributable amounts of post‐production waste and unfavorable prolonged use of batteries create misguided incentives to meet legal targets. Additionally, the delay between production and recycling limits the potential for circular production as this depends significantly on market conditions. Our study highlights, that besides recycling, the industry should especially advance production processes including upstream material extraction and refinement to reduce environmental impacts.

Understanding the Dairy Sector in Slovenia: A Modeling Approach for Policy Evaluation and Decision Support

This study investigates the dairy sector in Slovenia, focusing on farm heterogeneity, efficiency in resource utilization, and policy implementations. Through a modeling approach, we explore the differences among dairy farms, considering factors such as herd size, farm management, natural conditions, and production potential. Based on 32 typical dairy farms, representing the entire dairy sector, composed of 6400 dairy farms, the analysis was performed using the farm model (SiTFarm). We emphasize the importance of accurate assessments, given the variability of policy impacts across farm types. While medium-to-large, specialized farms dominate milk production, smaller farms, particularly in less favored areas, hold social and environmental importance despite facing competitive challenges. Addressing environmental sustainability could involve promoting practices that improve milk yield and include grazing, as this tends to lower greenhouse gas emissions per kilogram of milk (−5%). Dairy farms contribute about one-third of the generated revenue in Slovene agriculture, of which a good half goes to farms located in less favored areas. They manage a good quarter of permanent grassland in Slovenia, and it is certainly the sector that can achieve the highest return on these areas. In 75% of the farms, the gross margin is higher than 1756 EUR/ha and using best practices they exceed 3400 EUR/ha. The model results indicate that the average hourly rate on dairy farms during the observed period falls within the range of EUR 7.3 to 17.4 of gross margin for most farms, with the top-performing ones exceeding 24 EUR/h. However, due to the significant reliance on budgetary payments (on average, 58% of the gross margin), the implementation of the common agricultural policy strategic plan generally leads to a deterioration in the economic indicators of dairy farms. This impact is particularly pronounced on medium-sized and larger farms, increasing the effect on income due to the substantial fixed costs involved. Our findings underscore the interplay between policy interventions, farm characteristics, and sectoral outcomes, offering valuable insights for policy-makers and stakeholders.

Effect of agricultural management system (“cash crop”, “livestock” and “climate optimized”) on nitrous oxide and ammonia emissions

AbstractThe study aimed to measure soil-atmosphere N2O fluxes and their controlling factors, as well as NH3 emissions and yields for two soils (silt loam and clay loam) in three management systems over two years under subsequent wheat and maize cultivation. The management systems were characterized as follows: (1) cash crop (C) with mineral fertilizer and conventional tillage; (2) livestock (L) with biogas residue fertilization and its incorporation prior to sowing in maize and reduced tillage; and (3) climate optimized (O) with minimum tillage, 8-year crop rotation, with biogas residue fertilization, in maize without incorporation in clay loam soil or incorporation by strip-tillage prior to seeding in silt loam soil. Stable isotope ratios of N2O and mineral N were determined to identify N2O processes. Within the organically fertilized maize treatments, cumulative N2O fluxes were highest in the O-system treatments of both sites (4.0 to 9.4 kg N ha− 1 a− 1), i.e. more than twice as high as in the L-system (1.5 to 3.1 kg N ha− 1 a− 1). Below root-strip till fertilizer application did not enhance N2O fluxes. Fluxes with mineral fertilization of wheat (1.1 to 3.1 kg N ha− 1 a− 1) were not different from those with organic fertilization. Isotopic values of emitted N2O revealed that bacterial denitrification dominated most of the peak flux events, while the N2O/(N2 + N2O) ratio of denitrification was mostly between 0.1 and 0.5. It can be concluded that, contrary to the intention to lower greenhouse gas fluxes by the O-system management, the highest N2O fluxes occurred in the O-system without biogas digestate incorporation in maize. With respect to NH3 fluxes, we could confirm that the application of digestate application in growing crops without incorporation or late incorporation in fertilization before sowing induces high fluxes. The beneficial aspects of the O-system including more stable soil structure and resource conservation, are thus potentially counteracted by increased N2O and NH3 emissions.

Evaluating the economic and environmental benefits of deploying a national-scale, thermo-chemical plastic waste upcycling infrastructure in the United States

Emerging chemical technologies can upcycle plastic waste by producing high-value polymers and other products. In this work, we study the economic and environmental benefits of deploying an upcycling infrastructure in the continental United States for producing low-density polyethylene (LDPE) and polypropylene (PP) from post-consumer plastic waste. Our analysis is based on a computational framework that integrates techno-economic analysis, life-cycle assessment, and value chain optimization. Our results demonstrate that the infrastructure could generate a market of nearly 20 billion USD per year and that this market is robust to various externalities. Our analysis also indicates that the infrastructure can achieve a plastic-to-plastic degree of circularity of 34% relative to residential plastic waste production, and leads to significant environmental benefits over alternative waste disposal methods, including 69%–75% lower greenhouse gas emissions than waste-to-energy systems and 38 million tonnes of avoided landfill waste per year.

Guidelines for efficient nitrogen preservation in sewage sludge-based fertilizers

This study explores sustainable methods to mitigate nitrogen (N) loss in agriculture amid rising food demands and limited arable land. It examines sewage sludge (SS) as an alternative to synthetic N fertilizers. SS is rich in nitrogen (4.21 ± 0.42 %) and phosphorus (3.60 ± 0.72 %), making it suitable for nutrient recovery and soil enhancement. Unfavorable sludge management methods result in the loss of 950,000 tons of nitrogen, meeting almost 10 % of the EU's nitrogen fertilization demand. This research evaluates SS treatment methods, including chemical conversion, thermal treatment, and biological composting, focusing on nitrogen conservation efficiency. Results show nitrogen loss during hydrolysis is minimized at pH 4 to 8 but increases significantly as ammonia (NH3) at pH 9 to 11, ranging from 4.2 % to 9 %. Neutralizing the hydrolysate is crucial; using solid KOH resulted in 13.5 % nitrogen loss, 11 times more than using slightly alkaline ash (1.22 %). Adding ash during drying reduced nitrogen emissions by 30 % compared to traditional drying at 105 °C. Improving the C/N ratio with food residues reduced nitrogen losses by 46.3 % during composting. These findings highlight the importance of pH control in chemical processes and temperature regulation in thermal treatments. Adding residues from other processes, such as biomass combustion waste, enhances SS processing conditions. Understanding nitrogen retention mechanisms is crucial for the environmental sustainability of SS usage. Efficient nitrogen retention strategies improve the fertilization value of SS and reduce its environmental footprint by lowering greenhouse gas emissions, particularly ammonia. Reducing nitrogen loss during SS treatment significantly lowers ammonia emissions, a major contributor to greenhouse gas emissions. These results help determine optimal methods for managing and processing SS to minimize emissions and increase agricultural usability.