Indirect Greenhouse Gas Emissions Research Articles

Investigating Microbial Triggers of Nitrous Oxide Emissions in Agriculturally Influenced Aquatic Ecosystems

The agricultural sector in Canada is responsible for approximately 9% of greenhouse gas (GHG) emissions in Canada, accounting for 54 MT of carbon dioxide (CO2), as well as 31% of methane (CH4) and 75% of national nitrous oxide (N2O) emissions in 2021 (Environment and Climate Change Canada 2021). However, these estimates do not include the indirect GHG emissions that occur in agriculturally impacted waterways. Ontario is home to over 45 000 kilometers of agricultural drainage ditches, with tile drains directly connecting terrestrial and aquatic environments. Microbial biogeochemical cycles in the causeways experience fluxes of nutrients leading to hotspots for GHG at the sediment-water interfaces. Along with fluxes of nutrients, the causeways are regularly disturbed by anthropogenic effects (e.g., dredging, removal of vegetative buffers) and increasing frequency of storm events. Previous studies have used static chambers to evaluate GHG emissions from aquatic systems (Mu et al. 2022, Xiao et al. 2016). However, this approach can be time consuming and labour intensive and is impractical in aquatic systems due potential extensive underestimation of fluxes from diffusion. To resolve driving factors contributing to GHG in these systems a detailed study investigating the activity of the microbial community is warranted. In this study we hypothesize microbial activity within the sediment will correlate with N2O emissions. To test the response of the microbial community a combination of molecular approaches (i.e., qPCR and Ion torrent) targeting archaeal and bacterial nitrifiers and denitrifies was used. These functional responses were evaluated with respect to N2O emissions, which were measured in the field at the time of sampling using Unisense N2O probes. In this study, N2O sensor response was calibrated to a functional gene index for rapid risk assessment of GHG hotspots.

Long-term energy transition planning: Integrating battery system degradation and replacement for sustainable power systems

The transition towards sustainable energy systems has gained significant importance globally due to high levels of environmental pollution caused by the use of fossil fuels. This study addresses a critical aspect of the global transition towards sustainable energy systems. We emphasize the impact of considering energy storage system degradation and replacement in long-term energy transition planning. The importance of this lies in mitigating the challenges posed by the intermittency and variability of renewable energy sources, such as wind and solar, without failing to consider the negative effect that excessive use of batteries as a storage energy system would have. We propose an optimization model that integrates power systems generation and transmission infrastructure with strategic energy storage system implementation to optimize their size, operation, and location for maximum efficiency and benefits. This paper offers a comprehensive approach to take into account the environmental effect of the depth of the discharge and replacement of battery systems over a long-term planning horizon considering hourly operation of representative time periods. The electricity system of Baja California, Mexico, a region heavily reliant on fossil fuels, is presented as a case study to show the applicability of the model. Results demonstrate that continuous replacement of dispatchable generators (natural gas power plants) for non-dispatchable generators (variable renewable power plants) may cause an unexpected increase of indirect greenhouse gas emissions from the continuous replacement of batteries when degradation is not considered. The results of the case study show an average emissions factor of 0.325 Ton CO2eq/MWh, approximately 24 % lower than government expectations, using the proposed MILP model.

서울시 전기차 온실가스 간접배출량 산정과 인벤토리 반영 방안

서울시 전기차 온실가스 간접배출량 산정과 인벤토리 반영 방안

Insights into greenhouse gas emissions from a wastewater treatment plant in vulnerable water areas of China

Wastewater treatment plants (WWTPs) are a significant anthropogenic source of greenhouse gas (GHG), but the quantitative assessment of GHG emissions from WWTPs in vulnerable water areas under stricter discharge limits remains unclear. Herein, depending on a case WWTP in southern China, we investigated the impacts of discharge standard improvement and key drivers of GHG emissions using daily operating data. We demonstrated that the stricter discharge limits increased the total GHG emission intensity by 18.2 %, with direct emissions increasing more than indirect GHG emissions. The GHG emissions were negatively correlated with water quantity, showing the scale effect, which became more pronounced after the discharge standard improvement. Increasing influent chemical oxygen demand and total nitrogen concentrations significantly drove the variations in GHG emissions, which were accelerated under stricter discharge limits. This study provides insights into the evaluation of GHG emission from WWTPs in vulnerable water areas and carbon-neutral wastewater management policies.

Trifluoroiodomethane as a Precursor to High Global Warming Potential Climate Pollutants: Could the Transformation of Climatically Benign CF3I into Potent Greenhouse Gases Significantly Increase Refrigerant-Related Greenhouse Gas Emissions?

The transition away from the production and consumption of high global warming potential (GWP) hydrofluorocarbons (HFCs) under the 2016 Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) has prompted air conditioning, refrigeration, and heat pump equipment manufacturers to seek alternative refrigerants with lower direct climate impacts. Additional factors affecting alternative refrigerant choice include safety (i.e., flammability and toxicity), environmental, and thermodynamic constraints. At the same time, manufacturers are incentivized to seek refrigerants with higher energy efficiency, which saves on electricity costs and reduces indirect greenhouse gas emissions from electricity generation. The life cycle climate performance (LCCP) metric is commonly used to assess the combined direct and indirect climate impacts of refrigerant-use equipment. Here, we consider an additional impact on climate performance: the degradation of refrigerant in equipment, i.e., the direct climate impacts of high-GWP byproducts that can form as the result of adding trifluoroiodomethane (CF3I) to refrigerant blends to reduce flammability. Such a production of high-GWP gases could change the acceptability of CF3I-containing refrigerants. Further, it highlights the need to understand refrigerant degradation within equipment in calculations of the environmental acceptability of new cooling technology.

Environmental footprinting of hospitals: Organizational life cycle assessment of a Canadian hospital

AbstractHealthcare is a critical and complex service sector with direct and indirect greenhouse gas (GHG) emissions amounting to 5%–10% of the national total in developed economies like Canada and the United States. Along with a growing, albeit sporadic, set of life cycle assessment (LCA) (and “carbon footprinting”) studies of specific medical products and procedures, there is growing interest in “environmental footprinting” of hospitals. In this article, we advance this rapidly evolving area through a comprehensive organizational LCA of a 40‐bed hospital in British Columbia, Canada, in its 2019 fiscal year. Our results indicate that the total environmental footprint of the hospital includes, among other things, global warming potential of 3500–5000 t CO2 eq. (with 95% confidence). “Hotspots” in this footprint are attributable to energy and water use (and wastewater released), releases of anesthetic gases (which are potent GHGs), and the upstream production of the thousands of materials, chemicals, pharmaceuticals, and other products used in the hospital. The generalizability and comparability of these results are limited by inconsistencies across the few environmental footprinting studies of hospitals conducted to date. Nonetheless, our novel methodological approach, in which we compiled new LCA data for 200 goods and services used in healthcare—strategically selected to statistically represent the 2927 unique products in the hospital's “supply‐chains”—has broad applicability in healthcare and beyond.

The carbon footprint of ambulatory gastrointestinal endoscopy.

Endoscopy is considered the third highest generator of waste within healthcare. This is of public importance as approximately 18 million endoscopy procedures are performed yearly in the USA and 2 million in France. However, a precise measure of the carbon footprint of gastrointestinal endoscopy (GIE) is lacking. This retrospective study for 2021 was conducted in an ambulatory GIE center in France where 8524 procedures were performed on 6070 patients. The annual carbon footprint of GIE was calculated using "Bilan Carbone" of the French Environment and Energy Management Agency. This multi-criteria method accounts for direct and indirect greenhouse gas (GHG) emissions from energy consumption (gas and electricity), medical gases, medical and non-medical equipment, consumables, freight, travel, and waste. GHG emissions in 2021 were estimated to be 241.4 tonnes CO2 equivalent (CO2e) at the center, giving a carbon footprint for one GIE procedure of 28.4 kg CO2e. The main GHG emission, 45 % of total emissions, was from travel by patients and center staff to and from the center. Other emission sources, in rank order, were medical and non-medical equipment (32 %), energy consumption (12 %), consumables (7 %), waste (3 %), freight (0.4 %), and medical gases (0.005 %). This is the first multi-criteria analysis assessing the carbon footprint of GIE. It highlights that travel, medical equipment, and energy are major sources of impact, with waste being a minor contributor. This study provides an opportunity to raise awareness among gastroenterologists of the carbon footprint of GIE procedures.

Measurement and Management of Value Chain Greenhouse Gas Emissions from Supermarket Retailing

Abstract This study quantified greenhouse gas emissions from indirect activities along the whole value chain of supermarket retailing to derive mitigation measures. Both direct and indirect greenhouse gas emission sources of a supermarket retailing value chain were identified and calculated using the national guidelines for estimating the carbon footprint for organizations, based on a total area of 13 248 m2 and operating 12 h per day. A scoring matrix was applied that considered the magnitude of emissions, the level of influence, and the risks or opportunities associated with business operations. The scoring results indicated a major contribution from value chain activities that should be included in any greenhouse gas analysis. The calculation revealed that the greenhouse gas emissions from the value chain activities were 33 784 t CO2 emitted yr−1 or 94% of total emissions. The key contributors were linked to the production of purchased goods and the management of food waste. Thus, value chain activities should not be overlooked in developing efficient greenhouse gas management strategies. Furthermore, purchased products and services carrying a carbon-reduction label should be given priority, and the application of artificial intelligence and innovation could be considered to reduce the amount of food waste from expired goods.

Are SRI funds financing carbon emissions? An input-output life cycle assessment of investment funds

Indirect greenhouse gas (GHG) emissions (scope 3) generally represent more than half of the total life cycle impact attributable to a company or an investment. However, widely used sustainability assessment tools for investment funds fail to take these into account. Building on best practices from the industrial ecology field, we develop an input-output life cycle assessment (IOLCA) methodology to estimate life cycle GHG emissions of companies and investment funds. We apply our method to a sample of 1340 sustainable (SRI) and conventional equity funds domiciled in Europe and their 11,275 unique holdings. We extend our application to a case study of funds self-classified as Article 8 and Article 9 funds under the recent European Sustainable Finance Disclosure Regulation (SFDR, 2019). Our model estimates life cycle emissions for 94% of the companies held – compared to 17% coverage in the Carbon Disclosure Project (CDP). When including scope 3, the exposure to GHG emissions of both SRI and conventional funds is two to three times larger than when considering only direct impacts from holdings' operations. Finally, 24% of the sampled Europe-domiciled SRI funds are more exposed to life cycle carbon emissions than the ETF tracking the conventional market index MSCI Europe.

The CO2NSTRUCT European project: Modelling the role of Circular Economy in construction value chains for a carbon-neutral Europe

Linear climate mitigation models look into aggregated economic sectors and model greenhouse gas (GHG) emissions disregarding downstream value chains, making particular sectors accountable for downstream (or upstream) GHG emissions. Hence, the present climate mitigation models inconsistently account for indirect GHG emissions; underrepresent upstream and downstream value chains; do not address Circular Economy (CE) practices; do not cover resource consumption, thus not considering materials’ circularity. To provide curated policy support for decision-making for carbon neutrality and other Sustainable Development Goals (SDGs), models need to shift from linear to circular. To achieve this, a link between energy-climate mitigation modelling and cradle-to-cradle assessment CE analytical tools must be established. This is the core issue covered in the CO2NSTRUCT Horizon project (2022-2026). CO2NSTRUCT proposes a framework to supplement the well-established JRC-EU-TIMES model, using a highly comprehensive technological representation with CE measures. The framework will apply CE measures to the value chain of six carbon-intensive construction materials (i.e., cement, steel, brick, glass, wood, and insulation materials) and will provide new components to the JRC-EU-TIMES model, including citizen behaviour; societal impacts; rebound effects; supply and value chains. The results will be used for policy approaches integrating CE into climate change mitigation actions.

Complex supply chain structures and multi-scope GHG emissions: the moderation effect of reducing equivocality

PurposeClimate change requires the reduction of direct and indirect greenhouse gas (GHG) emissions, a task that seems to clash with increasing supply chain complexity. This study aims to analyse the upstream supply chain complexity dimensions suggesting the importance of understanding the information processing that these may entail. Reducing equivocality can be an issue in some dimensions, requiring the introduction of written guidelines to moderate the effects of supply chain complexity dimensions on GHG emissions at the firm and supply chain level.Design/methodology/approachA three-year panel data was built with information obtained from Bloomberg, Trucost and Compustat. Hypotheses were tested using random effect regressions with robust standard errors on a sample of 394 SP500 companies, addressing endogeneity through the control function approach.FindingsHorizontal complexity reduces GHG emissions at the firm level, whereas vertical and spatial complexity dimensions increase GHG emissions at the firm and supply chain level. Although the introduction of written guidelines neutralises the negative effects of vertical complexity on firm and supply chain GHG emissions, it is not sufficient in the presence of spatial complexity.Originality/valueThis paper offers novel insights by suggesting that managers need to reconcile the potential trade-off effects on GHG emissions that horizontally complex supply chain structures can present. Their priority in vertically and spatially complex supply chain structures should be to reduce equivocality.

Understanding the greenhouse gas emissions from China’s wastewater treatment plants: Based on life cycle assessment coupled with statistical data

Wastewater treatment plants (WWTPs) are significant contributors to energy consumption and anthropogenic greenhouse gas (GHG) emissions. For achieving carbon reduction in the wastewater treatment industry, the direct and indirect GHG emissions generated by WWTPs need to be understood from a holistic perspective. This study estimated GHG emissions from WWTPs at the country scale by integrating process-based life cycle assessment and statistical data. On-site data were collected from 17 WWTPs of various regions in China. Uncertainty analysis based on Monte Carlo was also performed, so as to provide more reliable results. The results show that life cycle GHG emissions generated from the wastewater treatment process vary from 0.29 kg CO2 eq/m3 to 1.18 kg CO2 eq/m3 based on 17 sample WWTPs. The key factors contributing to overall GHG emissions are also identified as carbon dioxide (fossil) and methane (fossil) to air mainly generated from electricity generation, and methane (biogenic) and nitrous oxide (biogenic) to air mainly generated from wastewater treatment. National average GHG emissions was evaluated with the value of 0.88 kg CO2 eq/m3, with on-site GHG emissions and off-site electricity-based GHG emissions accounting for 32% and 34%, respectively. The total GHG emissions generated from wastewater treatment are 56.46 billion kg CO2 eq in 2020, with Guangdong province having the dominant contribution. Policy suggestions (e.g., further adjusting the electricity grid toward a low carbon structure, improving technology to promote treatment efficiency and energy recovery) were highly recommended so that national GHG emissions of WWTPs can be reduced. In order to achieve the synergy of pollutant removal and GHG emission reduction, policy-making on wastewater treatment should be tailored to specific local conditions.

Model-based assessment of biomass incorporation to mitigate nitrogen losses from arable fields in Central Europe

Nitrogen (N) loss by leaching is a major concern in common crop rotations in Central Europe due to high post-harvest soil mineral N, low N uptake in autumn/winter, and percolation. This can lead to eutrophication of water bodies and indirect greenhouse gas emissions. One potential solution is to control microbial immobilization through the incorporation of organic matter. To examine the effectiveness of this approach, we compared the incorporation of crop residues from winter oilseed rape, faba beans, and winter wheat with the application of sawdust in a field-scale experiment. Field observations of the impact on autumn/winter N-dynamics were supplemented with model-derived parameters. Our results showed that the incorporation of crop residues significantly reduced autumn net mineralization in topsoil, with the largest reduction seen with cereal straw. However, the temporal dynamics of the effect did not meet the desired time frame, and the impact on N leaching was low. Field data, modeling processes, and a theoretical amendment assessment suggested that resistant organic matter accumulated under the given environmental conditions, probably resulting in a long-term effect on nutrient dynamics. In conclusion, incorporating crop residues from the preceding crop is the best option to date for mitigating post-harvest N losses and improving soil health with minimal crop management effort. However, controlling microbial immobilization through organic matter incorporation can be a useful measure whose effectiveness depends on the amendment used and field conditions.

Co-opted directors and greenhouse gas emissions: Does ESG compensation matter?

Greenhouse gas (GHG) emissions pose a serious threat to human habitats because they are the cause of the increasing number of ecological problems and adverse weather events blighting our planet. Considering the rising trend in environmental concerns and the critical role of the board of directors in strategic corporate decisions, this paper examines the impact of co-opted boards on GHG emissions and the moderating effect of environmental, social, and governance (ESG) performance-based compensation on the relationship. Using a sample of US firms from 2002 to 2018, the results show a significant negative relationship between co-opted directors and total GHG emissions, i.e., an increase of one standard deviation in the proportion of co-opted directors reduces GHG emissions by 0.27. Additional analysis reports that an increase of one standard deviation in co-opted boards reduces direct and indirect GHG emissions by 0.37 and 1.3, respectively. This implies that firms with co-opted boards ensure the sustainability of their own operations while also making their partner firms environmentally sustainable. Further analysis documents that the influence of co-opted directors on GHG emissions is more pronounced for firms that tie executives’ compensation with ESG performance. Our study provides policy implications for regulators against a background of public outcry and stakeholder pressure on firms to mitigate environmental damage and implement environmentally sustainable business practices.

Low-carbon hydrogen production via molten salt methane pyrolysis with chemical looping combustion: Emission reduction potential and techno-economic assessment

Methane pyrolysis, as a bridge for the transition from fossil fuel to renewable energy, is regarded as a potential low-carbon hydrogen production method. However, there are still critical issues such as the deactivation of catalyst carbon deposits and indirect greenhouse gas emissions caused by combustion for heating. Accordingly, this study put forward a methane pyrolysis system by melting method coupled with chemical looping combustion (MPM-CLC) for heating, aiming to solve the above-mentioned concerns and further demonstrate the thermodynamic and economic feasibility of the system. Thermodynamically, more than 27% of fuel energy input and more than 98% of CO2 emissions can be avoided in the novel system compared with that in conventional standalone production system. The overall system exergy efficiency was calculated to be 85.06%, with CO2 emissions of about 0.51 kg/MWh. Economically, due to lower total equipment costs and lower additional fuel requirements, as well as profit from by-product solid carbon and electricity sales, the levelized cost of hydrogen (LCOH) is only 1.12 $/kg, which is 33% lower than that of steam methane reforming (SMR) and 52% lower than that of SMR with carbon capture. Moreover, although increasing the conversion rate will increase the fuel and total investment costs, the benefits brought by the increased by-product output could offset this part of the cost and help further reduce the LCOH. Importantly, the price of solid carbon played a decisive role in the LCOH. This new system brings a new insight into the low-carbon hydrogen production from methane.

Trade-off between soil carbon emission and sequestration for winter wheat under reduced irrigation: The role of soil amendments

Underground water source in North China Plain (NCP) is limited and extensively explored for wheat irrigation, which has caused high carbon emission. Reduced irrigation strategies and soil amendments have been advocated for sustainable agricultural production. However, the interactive effects of irrigation schedule and soil amendment on direct and indirect greenhouse gas (GHG) emissions, soil organic carbon (SOC) sequestration and carbon footprint (CF) have rarely been systematically quantified. A two-year field study was conducted in wheat season under three irrigation schedules (W0: pre-sowing irrigation only, W1: pre-sowing + jointing irrigation, and W2: pre-sowing + jointing + anthesis irrigation) and three fertilization types (Fc: chemical fertilizer only, Fm: chemical fertilizer + manure, and Fb: chemical fertilizer + biochar). In the Fc treatments, direct emissions from soil N2O and CH4 significantly decreased from W2 or W1 to W0, but SOC also decreased from W2 to W1 or W0. Net GHG emissions (GHGnet) was 14.6% higher in W1 +Fc but 6.0% lower in W0 +Fc compared with W2 +Fc because of the difference in electricity use for irrigation. Notably, the CF in W1 +Fc and W0 +Fc was 40.9% and 63.8% higher than in W2 +Fc mainly due to yield loss. Compared with Fc, direct emissions averaged 63.1% higher under Fm coupled with increased soil nitrate content, microbial biomass carbon (MBC) and nitrogen (MBN). The SOC significantly decreased from W0, W1 to W2 under Fm. Under the identical irrigation level, SOC stocks were 40.0% and 53.9% higher in Fm than in Fc under W1 and W0, while no significant difference under W2. Relative to Fc treatments, under Fm, CF was 28.5% lower in W0 but 6.2% and 45.7% higher in W1 and W2. Compared with Fc, direct emissions averaged 7.7% lower under Fb due to smaller MBN and higher soil porosity under Fb. The CF was lower in Fb than in Fc resulting from SOC increase. Thus, manure and biochar amendment could decrease CF following reduced irrigation, although manure application increased the risk of C loss.

Addressing dairy industry's scope 3 greenhouse gas emissions by efficiently managing farm carbon footprints

Corporate climate action is increasingly considered important in driving the transition towards a low-carbon economy. Especially in the food processing industry indirect greenhouse gas (GHG) emissions upstream in a producer's value chain (scope 3 emissions) often represent the largest portion of the GHG inventory. In order to manage those GHG emissions efficiently there is a need for simple GHG calculation models ready for large scale application on supplying farms. The aim of this study is to describe a procedure for the development of a simplified GHG calculation model specific for dairy farms based on detailed GHG emission calculations. The results presented are obtained from a case study of supplying farms of a Bavarian organic dairy. The simplified model shall reduce the number of input parameters significantly while representing the variations in GHG emissions across farms and allowing the quantification of GHG mitigation measures. The median farm carbon footprint (CCF) of the case study farms calculated with the detailed calculation model is 441.7 t CO2e/a (mean number of dairy cows per farm is 57). The total GHG mitigation potential per farm ranges from 6.51 t CO2e/a to 112.29 t CO2e/a. The simplification of the calculation model results in a less complex and time consuming questionnaire covering 57 parameters instead of up to 467 in the detailed model. The total CCF results of the simplified model give highly comparable results to the detailed calculation model (R2 = 99.7% , standard error = 2.3% of the mean CCF). The correlation between the total mitigation potential calculated per farm by the simplified and detailed calculation model is also high (R2 = 98.92%, standard error = 7.0% of the mean total mitigation potential per case study farm). For the quantification of some mitigation measures with the simplified model, attention must be paid to the question whether calculated GHG emission reductions are significantly higher than the standard error of GHG emissions calculated for the relevant life cycle stage. Summarizing the procedure for the development of a simplified GHG calculation model proposed in this paper, leads to a model that meets the defined requirements.

Carbon source recovery from waste sludge reduces greenhouse gas emissions in a pilot-scale industrial wastewater treatment plant.

Carbon cycle regulation and greenhouse gas (GHG) emission abatement within wastewater treatment plants (WWTPs) can theoretically improve sustainability. Currently, however, large amounts of external carbon sources used for deep nitrogen removal and waste sludge disposal aggravate the carbon footprint of most WWTPs. In this pilot-scale study, considerable carbon was preliminarily recovered from primary sludge (PS) through short-term (five days) acidogenic fermentation and subsequently utilized on-site for denitrification in a wool processing industrial WWTP. The recovered sludge-derived carbon sources were excellent electron donors that could be used as additional carbon supplements for commercial glucose to enhance denitrification. Additionally, improvements in carbon and nitrogen flow further contributed to GHG emission abatement. Overall, a 9.1% reduction in sludge volatile solids was achieved from carbon recovery, which offset 57.4% of external carbon sources, and the indirect GHG emissions of the target industrial WWTP were reduced by 8.05%. This study demonstrates that optimizing the allocation of carbon mass flow within a WWTP has numerous benefits.

Characteristics of greenhouse gases emission from wastewater treatment plants operation in China (2009–2016): A case study using operational data integrated method (ODIM)

The reduction of greenhouse gas (GHG) and achieving carbon neutrality in wastewater treatment plants (WWTPs) has gained significant research attention due to China's dual carbon goals. However, the temporal and spatial characteristics of GHG emissions and the reduction potential regarding GHG emissions from WWTPs in China remain significant uncertainties. This study aims to evaluate GHG emissions characteristics over the years using a set of computational methods, and assess the reduction potential from WWTPs based on operational parameters and economic considerations. This study evaluated GHG emissions of more than 1000 WWTPs in China from 2009 to 2016 using operational data integrated methods (ODIM) and emission factors method to estimate direct N2O, direct CH4 emissions and indirect electricity-induced GHG emissions. GHG emissions were analyzed from temporal, spatial and operational parameters aspects. Besides, data envelopment analysis (DEA) was used to analyze WWTPs' efficiency in 2017. The results show that GHG emissions increased from 8163 Gg in 2009 to 14,008 Gg in 2016, with emission intensity maintained in the range of 0.266 kgCO2-eq/m3 to 0.298 kgCO2-eq/m3. Indirect GHG emissions from electricity consumption were the main source, which accounted for 72%–80% of the total emissions. Remarkable differences in GHG emissions were observed among six different regions and 31 provinces. WWTPs with AAO process, large treatment capacity, high loading, low influent COD concentration and high effluent NH3–N concentration contributed to lower GHG emission intensity. Furthermore, the treatment process was correlated significantly with GHG emission intensity, whereas influent COD concentration had the least influence from regression analysis results. DEA evaluation indicated that the average efficiency score in 2016 was only up to 0.240 with 27 WWTPs reaching a full efficiency score (efficiency score above 1.000). Electricity consumption and ammonia nitrogen reduction were the most prioritized indicators which could be changed by −53.55% and 592.60%, respectively, to achieve a full efficiency score. The study provides a valuable reference for policymakers and stakeholders to reduce GHG emissions and achieve carbon neutrality in WWTPs, thus contributing to the larger goal of reducing GHG and mitigating climate change.

La huella de carbono de la cirugía de catarata en España

Background and purposeClimate change is one of the most important threats to human health nowadays. The healthcare industry produces a significant part of greenhouse gases (GHG) emissions. The aim of this study is to assess direct and indirect GHG emissions due to cataract surgery in Spain to identify opportunities for improving. Material and methodsThis observational case series study estimates and analyses the carbon footprint of a single cataract surgery using phacoemulsification in Ávila Hospital. ISO standard 14064 was applied. ResultsThe carbon footprint of a single cataract surgery in Ávila Hospital was 86.62kg CO2eq. Medical and pharmaceutical equipment were responsible for 85% of GHG emissions. ConclusionsCollaboration between pharmaceuticals and ophthalmologists is important to improve the environmental impact of cataract surgery. Future research is needed to introduce changes that do not compromise patient and surgeon safety. Green surgery models could play an encouraging role in the new global health scene.