Direct Greenhouse Gas Emissions Research Articles

Synergistic cell-free enzyme cocktails for enhanced fiber matrix development: improving dewatering, strength, and decarbonization in the paper industry

BackgroundThe pulp and paper industry is under increasing pressure to adopt sustainable solutions that address its substantial energy consumption and environmental impact. One of the most energy-intensive operations is the thermal drying, which presents significant opportunities for efficiency improvements. This study evaluates a cell-free mild enzyme pretreatment, utilizing a cocktail of cellulases and xylanases, combined with cationic starch, to enhance dewatering efficiency and improve paper strength utilizing bleached hardwood pulp fibers. Life cycle and economic analysis were also conducted to quantify the environmental impact and economic benefits, with a particular focus on direct greenhouse gas emissions. Enhanced water removal during pressing can significantly reduce energy consumption during thermal drying, facilitating the decarbonization of the paper industry.ResultsThe cell-free enzyme pretreatment, applied with mild refining and cationic starch, achieved significant improvements in dewatering efficiency and paper strength. The treatment led to an 11% point increase in solids and a 25% improvement in tensile strength. Morphological analyses revealed no changes in fiber length and width; however, reductions in kink and curl indexes indicated enhanced fiber flexibility and bonding potential. Furthermore, the enzyme–starch combination decreased water retention value by 27%, including substantial reductions in bound and hard-to-remove water content. Environmental assessments estimated a 12% reduction in global warming potential (GWP), with the technology yielding net savings of $11.29 per air-dried ton of paper through reduced natural gas consumption.ConclusionsThis study demonstrates the technical feasibility and economic viability of incorporating enzyme and cationic starch treatments into papermaking. The treatment improves paper quality while reducing energy consumption, costs, and carbon emissions. These findings support the broader adoption of enzyme-based innovations for sustainable manufacturing, aligning with decarbonization goals and industry demands for greater efficiency. The results highlight a promising avenue for achieving significant environmental and economic benefits in the pulp and paper sector.Graphical

Carbon footprint of private dental laboratories in Egypt: A cross-sectional study

BackgroundClimate change poses a serious threat to the planet, mainly driven by greenhouse gas (GHG) emissions. Dental laboratories contribute to GHG emissions through staff travel, waste, energy and water consumption, and procurement. Carbon footprinting is the process of quantifying the direct and indirect GHG emissions associated with a service. This study aimed to assess the Carbon Footprint (CFP) of private dental laboratories in Egypt.Materials and methodsData were collected from private dental laboratories in Cairo, Alexandria, and Elbeheira, Egypt in August 2024 through interview questionnaires. A CFP calculator was used to estimate carbon emissions from staff travel, waste, energy and water consumption, and procurement. The data of all laboratories was summed and divided to determine the average CFP per laboratory and per prothesis/appliance, both with and without the depreciation of dental equipment.ResultsData from 21 dental laboratories were collected. An average private dental laboratory in Egypt worked 309 days with a staff of around 7 persons and makes around 7119 prostheses/appliance per year. The CFP of dental laboratories was around 20,820 kg CO2e, equal to 2.9 kg CO2e per prosthesis/appliance. The largest contributor to the CFP was staff travel (43.6%), followed by procurement (27.8%), energy consumption (25%), waste (3.3%), and water consumption (0.1%). After including the depreciation of dental equipment, the CFP increased by 7.7%.ConclusionPrivate dental laboratories in Egypt produce a significant amount of carbon emissions. Staff travel was the major contributor to the carbon emission because each laboratory hired several couriers to deliver the prostheses/appliances and impressions. The CFP of electricity consumption was significant, likely because the air conditioning ran throughout the year to cool the machines down. Future studies are needed to develop customized country-specific CFP calculators to accurately measure the carbon emissions of dental laboratories in various settings. Preventing oral diseases, educating technicians on sustainable dental practices, optimizing public transportation, using bulk delivery services, shifting to renewable energy, and adopting circular economy are essential to mitigate the carbon emissions of dental laboratories.

Green finance, green technology innovation, and carbon emission reduction

Abstract Green finance, as a financial innovation tool that integrates finance and environmental protection, has become a crucial means of achieving carbon emission reduction. Based on panel data from 334 prefecture-level cities in China from 2000 to 2021, a two-way fixed effects model was constructed to empirically analyze the impact and mechanism of green finance on carbon emission reduction. The main findings are as follows: First, green finance significantly reduces carbon emission intensity; second, green technology innovation plays a mediating role in the impact of green finance on carbon emission intensity; third, green finance has the strongest effect in reducing direct greenhouse gas emissions; fourth, green investment and green bonds have the most substantial effect on reducing carbon emissions, while the direct effect of green equity on reducing carbon emission intensity is not significant. Therefore, to enhance the level of green finance, it is necessary to accelerate the development of green finance and actively build a synergistic development system between green finance and related technological innovations.

Measuring Greenhouse Gas Emissions: What Are the Costs and Benefits?

ABSTRACTWe adopt a financial‐materiality approach in studying the costs and benefits of measuring greenhouse gas (GHG) emissions on social welfare. Production by firms internally generates direct GHG emissions (Scope 1 emissions) whereas outsourcing to suppliers generates indirect emissions (Scope 3 emissions). Our analysis incorporates two frictions: (1) long‐term negative environmental externalities caused by emissions and (2) fragmentation in regulating emissions disclosures across jurisdictions. We show firms' failure to internalize the environmental externalities provides a rationale for mandating Scopes 1 and 3 emissions disclosures. However, such disclosures induce emissions leakage. Disciplining emissions leakage calls for setting complementary—rather than independent—disclosure requirements for Scopes 1 and 3 emissions. Our analysis underscores the importance of improving the reliability of Scope 3 emissions measurements given that measurements of Scope 1 emissions are highly reliable for public firms in Europe and the United States. Regulators can further enhance the disciplinary effects of Scope 3 emission measurements by requiring the allocations of Scope 3 emissions in supply chains to individual firms, especially when allocating Scope 3 emissions is more reliable, and for firms/industries that are more prone to transition climate risk relative to physical climate risk.

Balancing Energy Recovery and Direct Greenhouse Gas Emissions in Wastewater Treatment

Balancing Energy Recovery and Direct Greenhouse Gas Emissions in Wastewater Treatment

Board Size as Moderator: Understanding Environmental Practices in Indonesia

Global warming, driven primarily by carbon emissions, poses a critical challenge worldwide, including in Indonesia. In response, the Indonesian government issued Law No. 71 of 2021 to mitigate risks and promote carbon emission reduction. This study examines the influence of media exposure, managerial ownership, and industry type on carbon emission disclosure (CED), employing a quantitative design with purposive sampling of 66 companies from 2020-2022, resulting in 198 data points. CED is assessed through direct greenhouse gas (GHG) emissions, indirect emissions from electricity, and other GHG emissions. Findings reveal an adjusted R-square of 53.9%, with media exposure and industry type significantly impacting CED positively. The study underscores the importance of organizations adopting carbon-friendly initiatives to reduce emissions in business operations. It highlights the need for stronger governmental regulations to enhance corporate awareness and compliance with carbon disclosure practices.

Mapping Agricultural Greenhouse Gas Emissions via Multi-National Supply Chains: Evidence from Asia and the Pacific Countries

The rapid increase in global agricultural trade has drawn increasing attention to greenhouse gas (GHG) emissions stemming from agricultural activities. Through the application of multi-regional input–output modeling and complex network analysis, this study links embodied GHG emissions with the agricultural trade network especially focusing on Asia and the Pacific countries. The results showed a consistent upward trend in the total amount of direct agricultural GHG emissions associated with both production and consumption activities. However, the embodied agricultural GHG emissions exhibited a larger scale and higher growth rate. Among them, the pathways from Brazil to China and the United States to China are the largest net emission flows within this area. Regional clusters were observed in North America, Western Europe, and Southeast Asia, and their agricultural GHG patterns showed evolutionary characteristics. By depicting embodied agricultural GHG emissions and identifying GHG emission transfer patterns, this study aimed to promote agricultural GHG emission reduction strategies, which attempt to promote sustainable development by encouraging the low-carbon agricultural industry.

Is soil contamination a missing driver of soil heterotrophic respiration in land surface models? A study case with copper –

Land Surface Models (LSMs) are crucial elements of Earth System Models used to estimate the effects of anthropogenic greenhouse gas (GHG) emissions on Earth's climate. Nevertheless, as well as land use change and direct GHG emissions, anthropogenic activities are also associated with contaminant emissions and depositions. Although contamination has a recognized impact on soil processes such as GHG emissions, soil contamination is currently not considered as an important process to consider into LSMs.In this study we hypothesized that soil contamination has significant impact on soil CO2 emissions such as heterotrophic respiration (Rh). To this end, we analyzed how soil contamination may account for residuals of modeled Rh from 11 LSMs as compared to Rh products derived from observations over Europe. We used generalized least squared mixed models to evaluate the primary factors driving of the model residuals. Among contaminants, we focused on copper (Cu), which is widely used in industry or agriculture, causing significant diffuse contamination. Additionally, research demonstrated a strong correlation between soil Rh and Cu availability to soil fauna and various soil pedological and climatic parameters. Hence, we completed our analysis by including pedo-environmental parameters and by analyzing Rh against a proxy of bioavailable Cu.Our findings indicate that Cu is a non-negligible variable in explaining the Rh models inaccuracy considering either total or free Cu forms. Therefore, it can be concluded that Cu should not be disregarded as a key factor in predicting Rh.

Variable emission factors of CH4 and N2O from WWTPs: A model-based analysis on available data

Variable emission factors of CH4 and N2O from WWTPs: A model-based analysis on available data

High-fidelity model development of CO2 booster refrigeration systems in supermarkets using field measurements

High-fidelity model development of CO2 booster refrigeration systems in supermarkets using field measurements

Comparative Life Cycle Assessment and Carbon Footprint of Typical Hydrogen Energy Products

To compare the environmental impact and carbon footprint of gray hydrogen, blue hydrogen, and green hydrogen, inventories were obtained through literature research. Some inventories that were not available in China were obtained through foreign inventories combined with localized power conversion. The localized end-point destructive life cycle impact assessment method was used to calculate the environmental impact potential of the raw material acquisition, transportation, and hydrogen production stages of five hydrogen products. The carbon footprint was calculated, and the sensitivity analysis and uncertainty analysis were carried out and compared with the ReCiPe method. The results showed that： ① The environmental impact from large to small was： gray hydrogen （coal） （1 203 mPt·kg-1） > blue hydrogen （coal） （876 mPt·kg-1） > gray hydrogen （gas） （492 mPt·kg-1） > green hydrogen （323 mPt·kg-1） > blue hydrogen （gas） （252 mPt·kg-1）. The environmental impacts of gray hydrogen and blue hydrogen were mainly concentrated in climate change, fine particulate matter formation, and fossil fuels. The environmental impacts of green hydrogen were mainly concentrated in climate change, fine particulate matter formation, fossil fuels, and mineral resources. ② The carbon footprint from large to small was： gray hydrogen （coal） （23.79 kg·kg-1, measured by CO2eq, the same below） > blue hydrogen （coal） （11.07 kg·kg-1） > gray hydrogen （gas） （10.97 kg·kg-1） > blue hydrogen （gas） （3.47 kg·kg-1） > green hydrogen （1.97 kg·kg-1）. Direct carbon emissions in the production process of gray hydrogen and blue hydrogen accounted for the largest proportion, whereas that of green hydrogen accounted for a large proportion of power input. ③ Measures to reduce environmental impact and carbon emissions include reducing direct emissions of pollutants and greenhouse gases, reducing power consumption, and strengthening raw material substitution and reduction.

US urban land-use reform: a strategy for energy sufficiency

Policy approaches to the global energy transition often focus on technology-based solutions while ignoring challenges of overall energy demand. A sufficiency-first approach aims to limit superfluous consumption while achieving wellbeing for all. This study focuses on US built environment mechanisms of sufficiency under urban land-use policy. The historical context of US exclusionary and car-oriented planning is reviewed with an order-of-magnitude assessment of the effects on greenhouse gas emissions (GHGE). Using national vehicle-miles traveled (VMT) data derived from mobile device locations (Replica) and validated here with federal data, a hypothetical scenario explores the potential for state urban land-use reforms to enable energy sufficiency. Tenth percentile-VMT (per capita) neighborhoods are defined by state: in 47 states, the typical such neighborhood has less than 33% of its housing units in structures larger than four units. Assuming each state redresses its housing shortage while matching this VMT, 31 Mt CO2e (direct GHGE) and about 38 Mt CO2e (indirect and life-cycle GHGE) would be avoided in 2033. Texas, California, and Florida have the largest absolute emissions reduction opportunity. Urban land-use reforms comprise a logical starting point for a US sufficiency agenda. Key priorities for research, data collection, and technology and policy innovation are proposed. Policy relevance International climate policy is increasingly focused on enabling people to consume less energy: not just technological ‘efficiency’ but ‘sufficiency’ is needed. However, sufficiency has seen little uptake in the US. It may be more relevant to US policymakers if related to the growing momentum for reforming land-use planning and housing policy to address the housing shortage and affordability crisis. This crisis stems in part from the US prevalence of single-family zoning and car-centric planning, rooted in a history of racial segregation; these same laws effectively mandate people to maintain more polluting lifestyles. This study estimates how much climate pollution could be avoided with state-led land-use reform. If states committed to solving the housing shortage while building new housing in neighborhoods where people can drive less, the savings could be comparable with expanding electric vehicle policies. Policymakers and practitioners can enable these reforms while supporting complementary policy goals.

Towards environmentally sustainable healthcare: using quality improvement to deliver a net zero NHS

The healthcare industry is a major contributor to climate change globally. There is growing interest in using quality improvement methods to improve the sustainability of healthcare. East London NHS Foundation Trust uses quality improvement as its approach to solving complex problems. This article uses a case study methodology to describe how the trust's programme of sustainability used quality improvement at both systemic and local levels to support the organisation to reduce direct greenhouse gas emissions by 40% by 2025 and indirect emissions by 40% by 2036. Using quality improvement in a structured way enabled staff and service users to consider their contribution to sustainability and develop, test and measure ideas that were within their control. This led to an organisational reduction in gas emissions of 37% and CO2 emissions by 14% in winter months. At a local level, three case studies showcase the accomplishments of teams who successfully reduced medication waste by 66.2kg CO2e per year, reduced spending on single-use plastics by 54% and lowered CO2 emissions by 10798kg per year through the return of walking aids. Supporting structures for the programme included active and visible participation from senior stakeholders, with service users and carers involved at both strategic and operational levels, and tracking data over time. Future work should focus on creating a change package of ideas to serve as a blueprint to scale up these initiatives across the organisation.

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

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

Economic feasibility and direct greenhouse gas emissions from different phosphorus recovery methods in Swedish wastewater treatment plants

Phosphorus (P) is a finite, non-renewable resource that is a critical component of fertilizers; therefore, recovering P from municipal wastewater can provide an alternative sustainable source of this nutrient. This work analyses economic impacts and greenhouse gas emissions of P recovery in Swedish municipal wastewater treatment plants. The study examines different scenarios, including P recovery technologies in individual plants and hubs, and considers various P-rich streams (supernatant, sludge, and ash) in plants, different plant sizes, and multiple sludge management strategies such as land application, incineration, and hydrochar production, under current market conditions. The goal is to identify and offer solutions tailored to local conditions, addressing both technical opportunities and strategies to reduce costs.The results show varying recovery rates: 5 % from supernatant, 36–65 % from sludge, and 17 % from sludge ash relative to total P in wastewater. Despite technical feasibility, P recovery costs are not covered at current market prices of P, indicating a lack of financial incentive, especially for smaller treatment plants. The least expensive recovery method costs about 7 k€/t P for ash, compared to 30–187 k€/t P for supernatant, however with the latter coming with the co-benefit of mitigated greenhouse gas emissions. The emissions from studied plants range from 84 to 123 kt CO2 eq (CO2 equivalent) for supernatant, 94–141 kt CO2 eq for sludge, and 75–102 kt CO2 eq for ash among different P recovery methods. Comparatively, P recovery methods from supernatant showed the lowest emissions, while the lower emissions range for ash is due to the consideration of fewer plants. Developing hub networks and converting sludge into products like hydrochar are crucial for attracting investments, enhancing P recovery, and leveraging economies of scale. Results highlight the urgency for localized strategies and proactive policy interventions to reconcile economic and environmental objectives in P recycling. Furthermore, P recovery from wastewater treatment plants, although more resource-intensive than mineral fertilizer, promotes circularity in the food chain and mitigates the risk of eutrophication.

Impact of an eHighway on the directly emitted greenhouse gases by road freight transport

Impact of an eHighway on the directly emitted greenhouse gases by road freight transport

A comprehensive comparison between two strategies to produce polyhydroxyalkanoates from domestic sewage sludge

Biopolimer materials, such as polyhydroxyalkanoates (PHA), are essential to restrain the use of petroleum-based plastic material fostered by European Union regulation. Despite the recent development regarding the production of PHA, the scale-up of sewage sludge-based technology is still in its infancy since the literature lacks studies on the environmental impact of the process. This work aims to stand as a pioneer study reporting the direct greenhouse gas (GHG) emissions and carbon footprint (CF) of two sewage sludge-based PHA production strategies. The two strategies, aerobic dynamic feeding (ADF) and aerobic/anoxic enrichment (AE/AN), were monitored and compared based on the system's efficiency in removing carbon and nutrients, PHA's production and productivity, nitrous oxide direct emissions and the CF. The produced PHA accounted for 38.21 g PHA g−1 volatile suspended solids (VSS) % and 14.54 g PHA g−1 VSS %, for ADF and AE/AN, respectively. The N2O emissions were lower for ADF than the AE/AN enrichment, 0.39 N2O–N L−1 and 0.98 N2O–N L−1, respectively, as was the CF, which accounted for 3.56 kg CO2 day−1 and 6.91 kg CO2 day−1 for ADF and AE/AN respectively. This innovative study provides valuable insights into comparing the two above-mentioned strategies and a pilot for structuring and designing future studies comprehensively considering the environmental consequences of the process in future life cycle assessments.

Novel extended hybrid tool for real time control and practically support decisions to reduce GHG emissions in full scale wastewater treatment plants

Novel extended hybrid tool for real time control and practically support decisions to reduce GHG emissions in full scale wastewater treatment plants

Decreasing Greenhouse Gas Emissions from the Municipal Solid Waste Sector in Chinese Cites.

Municipal solid waste (MSW) management systems play a crucial role in greenhouse gas (GHG) emissions in China. Although the government has implemented many policies to improve the MSW management system, the impact of these improvements on city-level GHG emission reduction remains largely unexplored. This study conducted a comprehensive analysis of both direct and downstream GHG emissions from the MSW sector, encompassing sanitary landfill, dump, incineration, and biological treatment, across 352 Chinese cities from 2001 to 2021 by adopting inventory methods recommended by the Intergovernmental Panel on Climate Change (IPCC). The results reveal that (1) GHG emissions from the MSW sector in China peaked at 70.6 Tg of CO2 equiv in 2018, followed by a significant decline to 47.6 Tg of CO2 equiv in 2021, (2) cities with the highest GHG emission reduction benefits in the MSW sector were historical emission hotspots over the past 2 decades, and (3) with the potential achievement of zero-landfilling policy by 2030, an additional reduction of 203.7 Tg of CO2 equiv is projected, with the emission reduction focus toward cities in South China (21.9%), Northeast China (17.8%), and Southwest China (17.3%). This study highlights that, even without explicit emission reduction targets for the MSW sector, the improvements of this sector have significantly reduced GHG emissions in China.

A Comparative Study of Carbon Emissions from Industrial and Domestic Wastewater Treatment Plants under the Background of Carbon Neutralization

This paper studied the characteristics of the carbon emission of an industrial wastewater treatment plant (IWWTP) and a domestic WWTP (DWWTP) located in a high-tech industrial park of Shaanxi Province, China. The results showed that the total carbon emissions of the IWWTP and DWWTP were 10.13 kg/t and 1.84 kg/t in 2020, respectively. Indirect carbon emissions play a dominant role in the total carbon emission of the IWWTP, which accounts for about 97.6% of the total amount. The direct carbon emissions of greenhouse gases (e.g., CH4, N2O) account for about 62% of the total carbon emissions in the DWWTP, followed by the indirect carbon emissions generated by electricity consumption (31.06%) and chemical consumption (6.94%). Additionally, the centralized recycling and re-utilization of the wastewater could achieve 1.06 kg/t and 1.16 kg/t of carbon emission reduction in the IWWTP and DWWTP, respectively, while the carbon emissions of the DWWTP are inversely proportional to the treatment capacity. Therefore, it is of great value to collect and utilize intensively the recycled water to achieve the goal of regional carbon emission reduction and carbon neutralization of WWTPs in industrial parks.