Search Results (227)

As declared in the European Green Deal, the decarbonization of the EU energy system is essential for achieving Europe’s climate neutrality targets, demanding a substantial expansion of renewable energy sources and the rapid phase-out of coal and gas. It is therefore essential that newly installed PV products within the EU are designed to avoid creating additional environmental burdens due to environmental impacts during production and at the end of life (EOL) of photovoltaic (PV) modules. This study presents a life cycle assessment (LCA) of sustainable/green PV module designs in terms of recyclability using advanced high-quality recycling technologies. It compares two product systems both based on mono c-Si PV technology and the glass–glass (G–G) module design: 1. Passivated Emitter and Rear Contact (PERC) and 2. Tunnel Oxide Passivated Contact (TOPCon) cell technologies, which are assessed under production scenarios in China and Germany, and two recycling scenarios (hypothetical high-recovery recycling and partial recycling) using inventory data from eco-invent and literature sources. The results across most impact categories show that the PERC and TOPCon module designs produced in Germany with high-recovery recycling as the end-of-life strategy exhibit lower impacts than those produced in China with partial recycling as the end-of-life strategy under the adopted assumptions such as electricity mix and end-of-life modelling choices for module-only impacts (excluding BOS components). The climate change results show that TOPCon cell design under high-recovery recycling yields 10.4% lower emissions than the PERC cell design under partial recycling in Germany and 9.7% lower in China. However, both module designs emit 26.6% and 27.2% less GHG emissions when produced in Germany compared to production in China, respectively, which is line with earlier studies. With the exception of human toxicity, both PERC and TOPCon cell technologies perform better in this study than previously reported in reviewed LCA studies, reflecting the use of more recent state-of-the-art industry data concerning manufacturing requirements. The sensitivity analysis carried out on the design changes and electricity grid mix available shows that any improvements in the design process and increases in renewable energy penetration into the grid corresponds to a proportional reduction in environmental impacts across all impact categories. Full article

This study investigates whether the optimal utilization of the biomass potential contained in municipal solid waste (MSW) can support the implementation of circular economy (CE) principles and contribute to climate policy objectives, particularly the reduction in greenhouse gas (GHG) emissions in the waste management sector. The analysis evaluates whether waste-to-energy recovery can support the objectives of the European Green Deal, including a 55% reduction in GHG emissions by 2035 and the achievement of climate neutrality by 2050. The assessment was conducted for two MSW streams generated in a Polish municipality: separately collected biowaste and residual MSW remaining after meeting European reuse and recycling targets. The study summarizes the results of detailed experimental investigations of the physicochemical and fuel properties of these waste streams. Proven and commercially available energy recovery technologies, including anaerobic digestion (AD) of biowaste and incineration of residual waste, were analyzed. GHG emissions were assessed using a life cycle assessment (LCA) approach, taking into account both direct emissions and avoided emissions resulting from the substitution of conventional energy and fertilizer production. The experimental results revealed significant variability in the biodegradability and energy potential of individual biowaste fractions, with the highest biogas yields observed for kitchen waste. Residual waste exhibited a considerable calorific value and a significant share of renewable energy due to its biomass content. The results indicate that the share of renewable energy in electricity generated from waste is expected to increase from 46.1% in 2025 to 49.9% in 2040. In relation to the total electricity demand of the analyzed city, energy recovered from waste accounts for 1.8 ± 0.3% in 2025 and 1.3 ± 0.2% in 2040. Scenario-based modeling demonstrated that the target system, maximizing energy recovery from both biowaste and residual waste, achieves a consistently negative GHG emission balance throughout the analyzed period (2025–2040), ranging from −72 ± 15 kg CO₂-eq/ton in 2025, through the most favorable value of −81 ± 17 kg CO₂-eq/ton in 2035, to −57 ± 12 kg CO₂-eq/ton in 2040, expressed per ton of total managed biowaste and residual waste. Full article

One of the most critical challenges in maritime transport decarbonization, as part of the EU greenhouse gas (GHG) neutrality strategy, is the reduction in GHG and harmful emissions from the energy systems of existing vessels. Furthermore, the potential for implementing decarbonization technologies in operating vessels remains significantly more limited compared to newly constructed ships. Selecting appropriate decarbonization measures requires a comprehensive evaluation of technological feasibility, economic viability, and environmental performance, in accordance with the regulatory frameworks established by the IMO and the EU. A major limitation in such decision-making processes is ensuring the representativeness and reliability of expert judgments. In order to improve the reliability of results by expanding and structuring the information base, this study proposes and implements a method based on the integration of SWOT analysis with multi-criteria decision-making (MCDM) methods. The objective of this study was to examine the methodological aspects of testing the integrated application of comprehensive analysis and ranking methods for decarbonization technologies as applied to a prototype oil tanker. Based on the SWOT analysis method, technological solutions that are available for practical application were identified for the medium-term decarbonization period considered in the study, up to 2030–2035. Subsequent rating based on several applied multi-criteria (MCDM) analysis methods (TOPSIS, COPRAS, SAW) allowed us to examine the range, stability and sensitivity of the obtained solutions in relation to the methods themselves and scenarios with variations in the weighting factors of the evaluation criteria. The complete match of the ratings obtained using the TOPSIS and COPRAS methods confirms the stability of the multi-criteria decision-making process (priority-compromise order): CCS, kite, air lubrication, Flettner rotor. The performed sensitivity analysis showed that the technology rankings remain relatively stable when the weighting factor for the CO₂ reduction criterion varies within a range of approximately ±10%, while larger deviations result in an increasing difference between all three MCDM methods. For the TOPSIS method, the change limits for the critical values of the threshold indicators were ±20%, the COPRAS method showed intermediate results, and changing the weighting coefficients within a ±20% range did not alter the selection of the best technology. The results obtained allow for a positive assessment of the effectiveness of the proposed integrated methodology when applied as an alternative in the initial stage of ranking decarbonization methods for in-service ships. Full article

Wastewater treatment plants (WWTPs) are significant contributors to anthropogenic greenhouse gas (GHG) emissions through both direct biological processes generating methane (CH₄), nitrous oxide (N₂O), and biogenic carbon dioxide (CO₂) and indirect energy consumption. This comprehensive research paper synthesizes findings from 30 peer-reviewed studies to present a holistic analysis of carbon footprints in wastewater treatment, with a specific quantitative assessment of a sequencing batch reactor (SBR) facility processing 5000 m³/day. The SBR operates with anoxic–aerobic cycles (fill–anoxic react–aerobic react–settle–decant–idle). The analysis reveals that N₂O emissions can constitute up to 75% of a plant’s carbon footprint, while aeration accounts for 40–75% of total energy consumption. For the SBR facility, the baseline carbon footprint is 1648 tCO₂e/year [95% CI: 1420–1910] (0.90 kg CO₂e/m³) under conservative assumptions, with CH₄ yield of 0.03 kg CH₄/kg COD removed and N₂O yield of 0.008 kg N₂O-N/kg TN removed. A realistic baseline using median literature values gives 0.52 kg CO₂e/m³. The carbon footprint of WWTPs varies by treatment technology, scale, and operational conditions, ranging from 61 to 161 kg CO₂e per population equivalent (PE) annually. Through anaerobic digestion with biogas recovery and anoxic phase optimization, emissions can be reduced by 38% to 1018 tCO₂e/year [95% CI: 860–1190]. The findings underscore that achieving carbon neutrality requires extending accounting beyond plant boundaries to include effluent exports, sludge management, and urban infrastructure integration. This paper provides a transparent, practitioner-ready framework for understanding, quantifying, and mitigating carbon emissions from wastewater treatment, with particular emphasis on SBR technology. Full article

The steel sector is one of the main contributors to carbon dioxide emissions among the industrial activities. It is mostly the use of carbon-rich blast furnaces and natural gas direct reduction processes that cause this. Hydrogen-based direct iron reduction (H-DRI) is a demonstrated method of lowering steel production carbon emissions by using hydrogen rather than carbon monoxide as the reducing agent; therefore, water vapor is released instead of carbon dioxide. This work offers a detailed analysis of the trends, operating concepts, industrial-scale trials, difficulties, and advantages of H-DRI. It is well supported by both energetic and reaction rate considerations that hydrogen is an efficient agent for the reduction of iron oxides to iron metal, giving metallization rates up to those of the traditional processes and at the same time significantly reducing GHG emissions. Moreover, industrial trials confirm that the method is technically feasible on a large scale, which is not yet realized because green hydrogen is very expensive, infrastructure needs are high, and there are still hurdles to be overcome in process optimization, such as water vapor management, pellet quality, and reactor design. According to the studies of product life cycles, if the hydrogen is extracted from renewable sources of energy, then the reduction in CO can be as high as 90%. The article also discusses different aspects of the economy, environment, and law that are already there and the ones that need to be developed so that research, technological breakthroughs, and industrial harmonization can be directed to the right spots. Practical deployment requires control of hydrogen supply, optimizing reduction processes, integrating renewable energy, and regulatory support. The results offer operational insights to the steel industry, policymakers, and academia on the path to sustainable, energy-efficient, and carbon-neutral steel production while retaining the metallurgical quality and industrial scale of the steelmaking processes. Full article

The global imperative for climate action and the accelerating energy transition have positioned higher-education institutions (HEIs) as vital laboratories for achieving carbon neutrality. In full alignment with Türkiye’s national commitment to reach net-zero emissions by 2053, this study develops and optimizes a phased roadmap for Erciyes University, a major public institution, to transition its energy system toward full sustainability. The research focuses on the techno-economic and environmental optimization of a hybrid renewable energy system (HRES) integrating solar photovoltaic (PV), wind, and locally sourced biomass resources to meet the campus’s annual electricity demand of 30.4 GWh. Using the HOMER Pro simulation tool, three strategic scenarios were evaluated: short-term (2030), medium-term (2040), and long-term (2053). System performance was assessed based on sizing, net present cost (NPC), levelized cost of energy (LCOE), and greenhouse gas (GHG) emission reduction. Results reveal that renewable energy penetration levels of 30–70% can reduce GHG emissions by over 60% and lower NPC by up to 31% compared with a fully grid-dependent baseline. In the final stage, configurations with 80–90% renewable fractions achieved the optimal balance between deep decarbonization and economic viability, whereas the fully off-grid system achieved zero emissions at a higher cost due to extensive storage requirements. Overall, this research presents a scalable, data-driven framework for sustainable campus energy transitions, providing a replicable model for HEIs and policymakers advancing national net-zero agendas. Full article

The revised EU Urban Wastewater Treatment Directive (UWWTD, EU 2024/3019) expands the scope of the previous directive (Council Directive 91/271/EEC, 1991) by explicitly including combined sewer systems, stormwater discharges, and overflow events while promoting energy neutrality and reducing greenhouse gas (GHG) emissions across urban wastewater systems. Although the Directive establishes energy accountability at the system level, it does not define how energy performance in wastewater collection networks should be structured, assessed, or benchmarked, resulting in a significant implementation gap. This paper presents a novel, regulatory-aligned, data-driven framework to organise, analyse, and interpret energy-relevant information in support of UWWTD requirements, with specific focus on wastewater collection networks. Using Portuguese regulator datasets, supplemented with published sources, existing metrics are reorganised into energy-significant dimensions that differentiate structural, excess-driven, operational, and renewable-related components of energy use. The preliminary findings show that available datasets already support a screening-level diagnosis of specific energy intensity, pumping-related energy shares, inflow-driven excess volumes, and associated GHG emissions. However, important gaps remain regarding subsystem disaggregation, hydraulic normalisation, and measurement granularity. The study restructures existing information into a novel audit-compatible framework, proposes additional metrics and measurement requirements, and identifies measures to facilitate UWWTD implementation. Although developed for the Portuguese context, the framework offers a scalable pathway for integrating wastewater collection networks into energy neutrality governance across European Member States. Full article

Globally, greenhouse gas (GHG) emissions have risen dramatically due to accelerated industrialization, excessive fossil fuel extraction, and agricultural activities, leading to global warming and ecosystem collapse. Achieving net-zero carbon emissions has therefore become a crucial global priority. Despite substantial international efforts, only a small number of countries have achieved carbon neutrality so far, with the majority aiming to do so by 2050 or 2060. Progress remains hindered by fragmented international coordination and inadequate integration of mitigation and adaptation co-benefits. However, agriculture is a major carbon emitter with significant mitigation potential. Attaining local carbon neutrality in agricultural landscapes is highly costly and strongly impacted by the spatial heterogeneity of GHG emissions and the diversity of available mitigation possibilities. This sector remains a major contributor to methane (CH₄) and nitrous oxide (N₂O) emissions, mainly through enteric fermentation and fertilizer use, and thus must be prioritized in global carbon neutrality strategies. Tactics such as improved livestock management, reduced use of synthetic fertilizers, conservation agriculture, afforestation, and renewable energy adoption can reduce emissions. These technical approaches should be supported by effective policy instruments, like carbon taxes, cap-and-trade schemes, low-carbon practice subsidies, and regulatory frameworks. Together, these measures can enable a transition toward long-term sustainability in agriculture by balancing emissions with removals through enhanced carbon sinks and credible offset mechanisms. Full article

The development of bioenergy crops on saline–alkaline land has been recognized as a potential pathway for both land restoration and combating global warming. However, the role of soil organic carbon (SOC) dynamics under such conditions remains insufficiently quantified in long-term assessments. In this study, an exploratory assessment was conducted to evaluate the long-term soil carbon sequestration (SCS) potential and life-cycle greenhouse gas (GHG) emissions of sustainable aviation fuel (SAF) produced from Arundo donax in the Bohai Rim region of China. The CENTURY model was integrated with Long Short-Term Memory (LSTM) time series forecasting to simulate SOC dynamics under future climate scenarios (2024–2035). Compared with the original CENTURY simulation, the LSTM model yielded a substantially more conservative estimate of SOC accumulation, with an Ensemble Mean SCS rate of 0.032 t C/ha/a and a 95% confidence interval ranging from −0.079 to 0.143 t C/ha/a. This result indicates a positive regional average tendency toward soil carbon sequestration, while also suggesting that some locations may behave as carbon sources under less favorable climatic conditions. The total SCS potential across the study area was estimated at 0.615 Tg C. When these soil carbon benefits were incorporated into the life-cycle assessment of Fischer–Tropsch (F-T) SAF, the pathway could become potentially net-negative under the adopted assumptions, reaching −32.1 g CO₂e/MJ, which corresponds to a potential reduction of 136.1% relative to fossil aviation fuel. These results should be interpreted as exploratory and scenario-based, given that large-scale cultivation of Arundo donax has not yet been established in the Bohai Rim region and the assessment therefore relies on assumptions. Beyond GHG mitigation, the cultivation of Arundo donax on degraded saline–alkaline soils may also have potential relevance to broader sustainability objectives, including SDG 13 (Climate Action) and SDG 15 (Life on Land). These findings highlight the possible synergies among energy crop cultivation, soil restoration, and climate neutrality goals, and provide preliminary insights for integrating marginal land utilization into sustainable land management and low-carbon aviation strategies. Full article

The decarbonization of hard-to-abate sectors remains a significant challenge in achieving net-zero emissions targets. These industries depend on energy-dense fuels, making direct electrification and the direct use of hydrogen technically and economically challenging. Electrofuels present a promising pathway to reducing emissions while leveraging surplus renewable energy. This review evaluates the feasibility of electrofuels for deep decarbonization, focusing on production processes, energy demands, and economic viability. Environmental performance is discussed in terms of lifecycle greenhouse gas (GHG) emissions, carbon circularity considerations, and energy conversion efficiencies, while techno-economic feasibility is evaluated using metrics such as levelized cost of hydrogen (LCOH), CO₂ capture costs, and projected fuel production costs. The review indicates that while electrofuels can achieve substantial lifecycle emission reductions up to 40–90%, depending on pathway and electricity source, their deployment remains constrained by high energy demand, conversion losses, and capital costs. Projected reductions in LCOH to below $2.1/kg by 2030 and declining renewable electricity costs could significantly improve competitiveness, particularly in regions with abundant solar and wind resources. However, substantial trade-offs exist between efficiency, infrastructure compatibility, scalability, and carbon neutrality across different electrofuel routes. The review identifies key technological bottlenecks, cost drivers, and research priorities necessary to position electrofuels as a strategic solution for deep decarbonization in sectors where direct electrification is not feasible. Full article

Despite a growing interest in biochar for olive orchard fertility management, little is known about its effects on nitrogen (N) dynamics and greenhouse gas (GHG) emissions in Mediterranean soils, particularly when comparing neutral (pH 6.7) and alkaline (pH 8.2) soils using farmer-accessible flame-curtain pyrolysis biochar. In this 60-day soil mesocosm study, we hypothesized that biochar amendments in fertilized soils would enhance soil N availability and potentially reduce N₂O emissions, with effects modulated by soil pH. Treatments included: control, urea fertilizer, and urea plus biochar (5% w/w). Urea fertilization significantly increased soil ammonium (NH₄⁺) and total oxidized nitrogen (NO₃⁻ + NO₂⁻) in both soils, and co-application of biochar further increased these pools, particularly in the neutral soil (NH₄⁺: + 91% and + 62% in neutral and alkaline soil, respectively). Biochar addition consistently reduced cumulative carbon dioxide (CO₂) emissions in both soils, supporting its role in stabilizing soil organic carbon. However, impacts on nitrous oxide (N₂O) emissions were soil-pH-dependent: biochar slightly reduced N₂O emissions in neutral soil, though nearly doubled N₂O emissions in alkaline soil, highlighting that biochar’s efficacy for GHG mitigation is context-specific. These findings underscore biochar’s potential to improve soil N availability and reduce carbon losses but reveal clear limitations for N₂O mitigation in alkaline soils, necessitating site-specific application strategies that explicitly consider soil pH when targeting climate benefits in Mediterranean olive production. Full article

Robust quantification of greenhouse gas (GHG) balances in tea plantations is critical for evaluating their contribution to agricultural carbon neutrality. This study aimed to develop data-driven models to quantify soil organic carbon (SOC) sequestration and N₂O emissions in Chinese tea plantations, evaluate their net GHG balance at the national scale, and assess the mitigation potential under alternative nitrogen management scenarios. Using a comprehensive national dataset, we compared multiple machine learning (ML) approaches with a conventional multiple linear regression (MLR) model to simulate N₂O emissions and SOC changes in Chinese tea plantations. All ML models substantially outperformed the MLR model, with the Random Forest (RF) algorithm achieving the highest predictive accuracy. The RF models yielded R² values of 0.68 for N₂O emissions and 0.67 for SOC changes, with no significant prediction bias. Variable importance and marginal effect analyses revealed strong non-linear controls. Mineral N fertilizer input was the dominant driver of N₂O emissions, followed by organic N input, soil clay content, and SOC. In contrast, SOC dynamics were primarily regulated by organic carbon inputs, tea plantation age, climate variables, and soil pH. National-scale simulations indicated an average N₂O emission intensity of 9.03 kg N₂O ha⁻¹ yr⁻¹ and a mean SOC sequestration rate of 0.88 t C ha⁻¹ yr⁻¹. Overall, SOC sequestration offset N₂O emissions, rendering Chinese tea plantations a net GHG sink (−2525 Gg CO₂-eq yr⁻¹). Scenario analyses showed that mineral N reduction increased net GHG uptake by 1804 Gg CO₂-eq, while organic fertilizer substitution achieved a substantially larger mitigation potential of 5961 Gg CO₂-eq. By integrating SOC sequestration and N₂O emissions within a unified modeling framework and applying machine-learning-based national-scale simulations, this study provides a more comprehensive and data-driven quantification of GHG balances in tea ecosystems, offering a scientific basis for evaluating their role in agricultural carbon neutrality strategies. Full article

Coastal wetlands represent significant sources of greenhouse gases (GHGs) and serve as crucial ecological interfaces between terrestrial and marine environments, substantially contributing to global biogeochemical cycles. However, GHG emission fluxes are strongly influenced by complex anthropogenic activities, yet their underlying microbial mechanisms remain poorly understood. This study investigated seven representative human-impacted sites within the Yellow River Delta. Employing a combined approach of in vitro microcosm cultivation, molecular biology, and multivariate statistical analysis, we investigated the integrated mechanisms controlling nitrous oxide (N₂O) and methane (CH₄) fluxes, with consideration of soil depth, environmental factors, microbial communities, and functional microbes. The results indicated that significant differences in GHG fluxes among different anthropogenic activities and soil depths (p < 0.05). Surface soil N₂O fluxes were positive within sewage irrigation areas (20.98–35.08 mg N₂O-N m⁻² h⁻¹) and tourism development areas (12.52–23.87 mg N₂O-N m⁻² h⁻¹), while mariculture areas displayed negative fluxes. CH₄ fluxes were positive exclusively in natural areas (surface soil: 25.02–55.54 mg CH₄-C m⁻² h⁻¹; deep soil: 8.38–356.68 mg CH₄-C m⁻² h⁻¹), while other areas predominantly showed negative values (surface soil: −130.98–44.32 mg CH₄-C m⁻² h⁻¹; deep soil: −106.16–65.24 mg CH₄-C m⁻² h⁻¹). Furthermore, a structural equations model highlighted the pivotal role of key functional microbes in soil carbon–nitrogen cycling (e.g., nirK, nosZII, and SRB) involved in soil carbon–nitrogen cycling in negatively regulating N₂O and CH₄ fluxes. The study also revealed distinct microbial responses across diverse habitats, underscoring the significant role of Proteobacteria in wetland soil. This research enhances our understanding of GHG dynamics in coastal wetlands and provides scientific evidence and potential regulatory pathways for enhancing soil biological mitigation functions and achieving carbon neutrality and sustainability within wetland ecosystems. Full article

Reducing biogas produced by solid waste landfills is a key solution in achieving climate neutrality goals, contributing to GHG emission reduction. This study aimed to investigate the opportunity to invest in a landfill biogas energy production plant when the quality of the biogas (methane concentration) is low. The research was conducted on three municipal solid waste landfills located in Bacău, Ilfov, and Brașov in Romania. Due to improper selective collection and recycling, the average methane content in these landfills is between 7 and 30%. The methodology used to conduct the research combined scientific and digital bibliographic sources, data processing and economic calculations using MS Excel, and the estimation of landfill gas emissions using LandGEM software. The analysis showed sales prices ranging between 155 and 450 [EUR/MWh]. However, the environmental analysis highlights that only the third landfill, with a methane concentration of over 30%, truly contributes to reducing emissions. Also, the use of high quantities of natural gas for energy production is incompatible with the European Union’s climate neutrality objectives. These results demonstrate the need for more efficient technologies or methods for producing and using biogas from waste before it reaches the landfill. Full article

To mitigate the emission of greenhouse gases (GHG) from fossil fuel combustion, biomass-to-power development via biochemical or thermochemical pathways has been recognized as a sustainable route for advancing towards a society based on a circular bioeconomy. The key differences between these pathways lie in operating temperature, process design capacity, feedstock characteristics and primary products. The biochemical route focuses on specific biofuels (e.g., biogas), and the thermochemical route often offers broader energy forms like heat and electricity. This perspective paper updates Taiwan’s achievements of its installed capacity and power (electricity) generation over a period of five years (2020–2024) under regulatory promotion that echoes official policies for sustainable development goals (SDGs) and 2050 carbon neutrality. Furthermore, the challenges of the biomass-to-power development in Taiwan (especially biogas-to-power systems) are addressed in the present study. These key issues include biomass resource, promotion incentives, stationary air pollution, site land use requirements and units for meeting performance durability requirements. Based on installed capacity, the main findings showed that biomass-to-power systems using biochemical routes (i.e., anaerobic digestion) in Taiwan showed an increasing trend, as well as increasing results for those using thermochemical routes (direct combustion, gasification). Furthermore, the data on total power generation indicated an upward trend from 201.7 Gigawatt-hour (GWh) in 2021 to 237.7 GWh in 2024, regardless of the kind of route used, whether biochemical or thermochemical. In conclusion, biomass-to-power systems have provided sustainable waste management and a circular bioeconomy model in Taiwan, which can be linked to the targets of sustainable development goals (SDGs) like SDG-7 (i.e., affordable and clean energy) and SDG-12 (i.e., responsible consumption and production). Full article