Direct Emissions Research Articles

Monitoring high-carbon industry enterprise emission in carbon market: A multi-trusted approach using externally available big data

Carbon markets are widely recognized as effective strategies for regulating carbon emissions from the enterprises of the high-carbon industry. Accurate monitoring of emissions in these enterprises is crucial for ensuring fair and trusted carbon trading. However, traditional monitoring methods have encountered various challenges including poor accuracy, low frequency, significant hysteresis and weak credibility. Addressing these concerns, this paper introduces a novel, multi-trusted, high-frequency monitoring approach for the measurement of both direct and indirect carbon emissions of enterprises, utilizing externally available multi-source big data, vertical federated long short-term memory network with a self-attention mechanism (VF-LSTMSA) and additive homomorphic encryption. The efficacy of this model is thoroughly assessed via case studies on six hourly datasets from the power and steel sectors. Our principal findings include: (1) In the current scenario, the proposed VF-LSTMSA model demonstrates superior federated efficiency, improving with the inclusion of more federated participants. (2) The VF-LSTMSA model surpasses other prevalent AI models, achieving a Mean Absolute Percentage Error (MAPE) of less than 9% across power and steel datasets. (3) The advanced high-frequency carbon emission monitoring method exhibits errors of +0.28%, +1.29%, and −0.41% in the current scenario monitoring task, suggesting that the model effectively leverages multi-source externally available big data to precisely monitor the target enterprise's carbon emissions while safeguarding multi-party data security. These findings suggest that the proposed monitoring method can accurately track corporate hourly carbon emissions, significantly improving the carbon trading and verification processes for enterprises

Life Cycle Assessment Framework for Diagnostic Imaging

The increasing focus on environmental sustainability is becoming essential in the diagnostic imaging sector, which is accredited for about 10% of the healthcare industry’s carbon footprint. A multitude of research initiatives investigated the environmental impacts of diagnostic imaging, encompassing factors like electricity consumption, carbon emissions, and waste generation from these procedures. Life Cycle Assessment (LCA) stands as a prominent method for structural assessment of environmental impacts, offering a detailed framework for examining the environmental consequences of specific processes. The aim of this study includes analyzing existing LCA approaches in literature to identify their limitations and to suggest an elaborate framework for LCA application in diagnostic imaging.Out of 17 original articles on environmental sustainability in radiology published since 2014, but only a part, 29.4% (5/17), described an LCA approach. The different characteristics of these studies provide valuable insights, enabling the proposal of a more comprehensive LCA research methodology.The reviewed articles did not present a uniform research outcome. According to the GreenHouse Gas (GHG) Protocol Corporate Standard, the optimal outcome for assessing environmental impact is the calculation of greenhouse gas emissions. For a thorough methodological approach in LCA, it is essential to cover all direct and indirect emissions associated with diagnostic imaging. All studies (100%, 5/5) considered the electricity consumption of imaging equipment. Usage of consumables was included in 80% (4/5) of the studies. Only 40% (2/5) of articles considered auxiliary equipment like computers and contrast-medium injectors, as well as heating, ventilation and air conditioning (HVAC) systems. Factors like equipment manufacture, staff travel, and waste generation, though crucial to overall greenhouse gas emissions, were each covered in only 20% (1/5) of the studies. The articles also varied in their LCA versions, with two employing the detailed Cradle-to-Grave approach, while others used partial Cradle-to-Gate and Input-Output LCA methods.The insights from this analysis could lead to a valuable framework for a new LCA methodological approach in diagnostic imaging. This novel approach is designed to overcome the limitations observed in existing research, offering a more comprehensive analysis. By enhancing the LCA framework, it will be possible identify the phases in diagnostic imaging that have the most substantial environmental impact, allowing for the development of more targeted strategies to reduce GHG emissions associated with diagnostic procedures.

Surgical Procedures for a Greener Future: An Approach to Assess the Environmental Impact

The healthcare sector is responsible for around 4.4% of worldwide greenhouse gas emissions, according to estimates. These emissions comprise both direct and indirect sources, with direct emissions encompassing aspects like patient transport, fuel consumption, and anaesthetic gases. Indirect emissions are associated with energy usage, including electricity purchases, as well as the products employed in healthcare, such as drugs and medical supplies. Operating rooms (OR) are responsible for the greatest rate of resource consumption and overall hospital waste, varying from 20% to 33%. Hence, it is essential to comprehend the environmental impact of surgical procedures to obtain insight into the total emissions associated with the healthcare sector. Moreover, the lack of uniformity in data collection and the discrepancy of the data used by researchers makes it challenging, if not ineffective, to conduct a rigorous scientific comparison among the currently available studies on the environmental impacts of surgical procedures. This study aims to provide a practical and standardised framework that can be utilised to evaluate, simply and consistently, the environmental impacts of surgical procedures. The adoption of a uniform methodology guarantees the inclusion of important variables and factors, preventing any oversights in the evaluation of the entire process. This allows for emphasis on the most sustainable techniques and permits the identification of controllable factors that can be modified within a short timeframe and are under the direct control of healthcare professionals. These factors include the selection of disposable or reusable instruments, the use of different anaesthetic gases, and the installation of different equipment.

Measurement-based carbon intensity of US offshore oil and gas production

The United States (US) produces oil and gas from six offshore regions: the North Slope of Alaska, Cook Inlet in Alaska, offshore California, and three Gulf of Mexico (GOM) sub-regions: state shallow, federal shallow, and deep waters. Measurement-based assessment of direct greenhouse gas emissions from this production can provide real-world information on carbon emissions to inform decisions on current and future production. In evaluating the climate impact of production, the carbon intensity (CI, the ratio of greenhouse gases emitted compared to the energy of fuels produced) is often used, though it is rarely quantified with measurements. Here, we complete an observational evaluation of the US offshore sector and present the largest current set of measurement-based CIs. We collected airborne measurements of methane, carbon dioxide, and nitrogen oxides from the North Slope, Cook Inlet, and California and combined with prior GOM results. For Alaska and California, we found emissions agree with facility-level inventories, however, the inventories miss some facilities. The US offshore CI, on a 100 year GWP basis, is 5.7 g CO2e/MJ[4.5, 6.8, 95% confidence interval]. This is greater than double the CI based on the national US inventory, with the discrepancy attributed primarily to methane emissions from GOM shallow waters, with a methane dominated CI of 16[12, 22] for GOM federal shallow waters and 43[25–65] for state shallow waters. Regional intensities vary, with carbon dioxide emissions largely responsible for CI on the North Slope 11[7.5, 15], in Cook Inlet 22[13, 34], offshore California 7.2[3.2, 13], and in GOM deep waters 1.1[1.0, 1.1]. These observations indicate offshore operations outside of the GOM in the US have modest methane emissions, but the CI can still be elevated due to direct carbon dioxide emissions. Accurate assessment of different offshore basins, with differing characteristics and practices, is important for the climate considerations of expanded production.

Indicator-based environmental and social sustainability assessment of hospitals: A literature review

The healthcare sector's direct and indirect GHG emissions account for 4%–5% of global net emissions. Hospitals face the challenge of sustainable transformations and need to measure, monitor, and report on their sustainability performance. While indicator-based assessments of hospital sustainability have received increased attention over the last years, they are heterogenous in their terminologies, categories, and included indicators. This study reviews taxonomies and included indicators in hospital sustainability assessments, laying the foundation for future developments of consistent indicator-based assessments. The objective is to (1) critically review existing assessments of hospitals; (2) identify relevant sustainability topics in a hospital context and derive a best-practice categorization; (3) highlight thematical gaps. Based on the PRISMA method, we identify 88 relevant articles. First, 47 articles (comprehensive hospital sustainability assessments with extensive indicator sets) are reviewed, forming the basis for deriving a best-practice categorization. Second, considering an additional 41 articles (proposing indicators for specific hospital aspects), we collect all indicators and compile a consolidated indicator pool. We find substantial variations in the taxonomies and terminologies of the reviewed articles; most notably, there is a disagreement about what constitutes an indicator. 73% of all consolidated indicators are qualitative, and 78% are site-specific. Thematical gaps relate to sustainability along upstream and downstream value chains (esp. food and pharmaceuticals) and quantitative social indicators in general. The developed best-practice taxonomy and the compiled indicator pool serve as a comprehensive basis for future sustainability assessments of hospitals.

Decarbonizing polyamide textile production in China: Footprints and mitigation pathways from life cycle perspective

Escalating demand for textiles has led to the entire supply chain contributing 8 % of global GHGs emissions. However, the carbon footprint (CF) and low carbon pathways of polyamide textile production remain ambiguous. Herein the CF of polyamide textile in China is evaluated using a "cradle to gate" life cycle system boundary allowing for comparison with other textile categories. To explore low carbon pathways of polyamide textile production, we introduce four groups of measures resulting in 12 scenarios. The CF of 1 kg polyamide textile is 35.37 kg CO2-eq, 1.38 and 3.91 times that of polyester and cotton textiles, respectively. Direct emissions from energy combustion, and indirect emissions from raw materials and energy production contribute 43.87 % and 56.13 % of the total CF. Emission reduction potentials vary from 51.37 % to 88.52 % across scenarios. These explored low carbon pathways should serve as references for achieving low and net zero emissions in the textile sector.

Harness the Co-Benefit and Avoid the Trade-off: The Complex Relationship between Income Inequality and Carbon Dioxide Emissions

Abstract Given the dual crises of climate change and rising economic inequality, it is imperative to improve the synergy between climate mitigation and income inequality reduction. Domestic income inequality is linked to nations’ carbon dioxide (CO2) emissions through multiple theorized pathways. Using a multidimensional framework, multiregional input–output analysis, panel regression analysis, and a sample of 34 high-income nations from 2004 to 2015, I investigate the relationships between nations’ income inequality and four components of CO2 emissions with distinct implications for climate change mitigation: (1) emissions generated by domestic-oriented supply chain activities; (2) emissions embodied in exports; (3) direct emissions from end-user activities; and (4) emissions embodied in imports. I theorize that income inequality is heterogeneously related to the four emission components via different pathways. Results show that the relationships vary across emission components, change over time, and differ between inequality measures. The Gini coefficient is generally less influential on CO2 emissions than the income share of the top 10%. Notably, the income share of the top 10% is negatively related to direct end-user emissions from 2009 to 2011 and positively related to emissions in exports from 2011 to 2015, indicating variations in pathways both across emission components and over time—especially during and after the Great Recession. The findings underscore the multidimensionality in the income inequality-CO2 emissions relationship. Whether reducing income inequality can generate the co-benefit of emission abatement while avoiding a potential trade-off is a context-specific question that requires careful policy design and implementation.

Let there be Skyglow—light pollution from a large outdoor music festival (Lollapalooza Berlin 2016)

Live music is often linked to elaborate light shows, particularly at large outdoor music festivals. However, artificial light at night is one form of environmental pollution, light pollution, and because outdoor festivals emit a substantial amount of artificial light into the environment, they are a potential source of light pollution. So far, no studies that quantified the impact of such festivals on urban light pollution and skyglow exist. Here, the light pollution produced by a major rock festival (Lollapalooza Berlin 2016 with 70,000 visitors per day in an urban park) was investigated with ground-based radiometry and night-time light data. A small night-sky radiometer installed near the main stages and a calibrated digital camera from a nearby observation spot inside of the park were used to quantify changes in night sky brightness and direct light emissions within the park. The impact of the music festival on the urban skyglow was indeed measurable. Zenith luminance increased locally by up to a factor of 8 and illuminance increased by about 50% at the observation spot within the park. The radiance detected by night-time satellite was also increased during the festival. This is the first time, that light pollution from such a major rock music event was quantified.

The Dynamic Economic Analysis on Foreign Direct Investment and Carbon Emissions Nonlinear System in Zhejiang Province, China

The Dynamic Economic Analysis on Foreign Direct Investment and Carbon Emissions Nonlinear System in Zhejiang Province, China

Examining Energy Efficiency Practices in Office Buildings through the Lens of LEED, BREEAM, and DGNB Certifications

Energy accounts for a significant share of carbon emissions, and buildings play a substantial role in this by contributing to both direct and indirect emissions throughout their lifecycle. Enhancing energy efficiency in buildings is a strategy to mitigate these impacts. The main goal of this review is to uncover solutions, trends, and examples of good practices in the field of office buildings. It presents effective cases and a SWOT analysis of LEED, BREEAM, and DGNB certifications, highlighting their contributions to energy efficiency in buildings on an international scale. The paper identifies and outlines similarities and differences between each methodology used to achieve energy efficiency in different buildings and contexts. The findings may allow new ways to improve access and obtain results regarding energy efficiency, thereby supporting building owners and companies in finding more effective solutions. The research highlights the necessity for continual enhancements in these systems, which should involve addressing economic factors, conducting post-occupancy evaluations, and considering lifecycle perspectives. The recommendations encompass standardizing practices, considering costs, conducting regular revisions, managing materials and resources, and incorporating occupancy measures.

Life cycle assessment of ammonia co-firing power plants: A comprehensive review and analysis from a whole industrial chain perspective

Ammonia, a reliable low-carbon alternative fuel with energy storage capabilities, has garnered increasing attention for its application of co-firing in coal-fired power plants as a strategy to mitigate direct carbon emissions. However, various types of ammonia production technologies result in diverse economic feasibility and emission intensities. Simultaneously, each stage, spanning from upstream processes such as raw material extraction to downstream applications, contributes to carbon emissions, which cannot be ignored. It is crucial to select the appropriate assessment method to determine the transformation pathways for co-firing systems. To this end, this review presents a comprehensive life cycle assessment of ammonia co-firing systems from a whole industrial chain perspective, encompassing the entire gamut of processes from fuel production and transportation to co-firing. Studies of the industrial chain perspective and of life cycle assessment methodology that are uniquely tailored for co-firing systems are presented. A nuanced exploration of distinct technologies across the spectrum of system processes ensues, including the advantages, limitations, and trends in advancement, based on carbon emissions and economic criteria. Considering the diverse fuel production, especially ammonia, typologies and intricate processes have undergone comprehensive review. The combustion characteristics, emissions, and economic factors associated with the co-firing process are systematically summarized, drawing upon aspects such as dynamics, experiments, simulations, and demonstration projects. This study illuminates the progression and technology selection of co-firing systems across multiple stages of the whole industry chain, thereby furnishing insights relevant to the low-carbon transformation of ammonia co-firing with coal in power plants.

Methane emissions from the natural gas industry in China – A systematically accounting based on the bottom-up approach

The comprehensive and meticulous assessment of methane (CH4) emissions stemming from the natural gas industry stands as an imperative endeavor in steering the natural gas industry toward a trajectory of low-carbon sustainability. This study has meticulously constructed detailed facility-level inventories for CH4 emissions within China's natural gas industry and used a bottom-up approach to fully account for both direct and indirect CH4 emissions. The findings reveal a notable increase in CH4 emissions within the natural gas industry in China, rising from 2.04 Mt in 2012 to 3.94 Mt in 2021. Regionally, Shaanxi, Sichuan, and Xinjiang emerged as the primary emission contributors in 2020, signifying a shift from northeastern and northern China to northwestern and southwestern regions during the 2012–2020 period. The fluctuations in emissions, both overall and regionally, closely align with the evolving landscape of China's natural gas sector. Projections for future CH4 emissions indicate a continued upward trajectory in tandem with industry growth. Consequently, the study emphasizes the urgency of implementing emission reduction measures in China's natural gas industry. Timely intervention is crucial to ensuring the orderly progression of the industry while effectively curbing the associated CH4 emissions.

Effect of applying a full oxygen blast furnace on carbon emissions based on a carbon metabolism calculation model

Abstract In this study, the effects of applying a full oxygen blast furnace (FOBF) on carbon emissions were investigated by determining the ultimate minimum carbon consumption and a carbon metabolism calculation model. The results demonstrate that the minimum coke ratio of the top gas circulation-FOBF (TGR-FOBF) is significantly reduced (from 270 to 207 kg·thm−1) compared to that of the traditional ironmaking blast furnace (TBF). Owing to the complete recycling of the furnace top gas of the TGR-FOBF, the degree of direct reduction of TGR-FOBF significantly decreased to 0.14. The replacement of the TGR-FOBF with the three TBFs significantly reduced the CO2 emissions, which were the highest at 1.761 t-CO2/t-CS. Most of the CO2 emissions were generated by the direct combustion emissions (CDE) and direct process emissions (PDE), with a small amount generated by the electricity indirect emissions (EIE). The CO2 emissions generated by CDE, PDE, and EIE were 0.872 t-CO2/t-CS, 0.840 t-CO2/t-CS, and 0.049 t-CO2/t-CS, respectively. As the amount of TGR-FOBF replaced with the three TBFs increased, the CO2 emissions generated by the CDE and PDE significantly decreased. When all three TBFs were replaced with TGR–FOBF, the CO2 emissions generated by the CDE and PDE decreased to extremely low levels of 0.267 t-CO2/t-CS and 0.065 t-CO2/t-CS, respectively.

The carbon premium: Correlation or causality? Evidence from S&P 500 companies

In the context of whether investors are aware of carbon-related risks, it is often hypothesized that there may be a carbon premium in the value of stocks of firms, conferring an abnormal excess value to firms’ shares as a form of compensation to investors for their transition risk exposure through the ownership of carbon intensive stocks. However, there is little consensus in the literature regarding the existence of such a premium. Moreover few studies have examined whether the correlation that is often observed is actually causal. The pertinent question is whether more polluting firms give higher returns or do firms with high returns have less incentive to decarbonize? In this study, we investigate whether firms’ emissions is causally linked to the presence of a carbon premium in a panel of 141 firms listed in the S&P 500 index using fixed-effects analysis, with propensity score weighting to control for selection bias in which firms increase their emissions. We find that there is a statistically significant positive carbon premium associated with Scope 1 emissions, while there is no significant premium associated with Scope 2 emissions, implying that risks associated with direct emissions by the firm are priced, while bought emissions are not.

Characterizing Spatial and Temporal Variations in N2O Emissions from Dairy Manure Management in China Based on IPCC Methodology

The emission factor method (Tier 1) recommended by the Intergovernmental Panel on Climate Change (IPCC) is commonly used to estimate greenhouse gas (GHG) emissions from livestock and poultry farms. However, the estimation accuracy may vary due to practical differences in manure management across China. The objectives of this study were to estimate the direct and indirect nitrous oxide (N2O) emissions from dairy manure management between 1990 and 2021 in China and characterize its spatial and temporal variations following IPCC guideline Tier 2. The N2O emission factor (EF) of dairy cow manure management systems was determined at the national level and regional level as well. The results showed that the national cumulative N2O emission of manure management from 1990 to 2021 was 113.1million tons of CO2 equivalent, ranging from 90.3 to 135.9 million tons with an uncertainty of ±20.2%. The annual EF was 0.021 kg N2O-N (kg N)−1 for total emissions, while it was 0.014 kg N2O-N (kg N)−1 for direct emissions. The proportions of N2O emissions in North China, Northeast China, East China, Central and Southern China, Southwest China and Northwest China were 32.3%, 18.6%, 11.4%, 5.8%, 6.1% and 25.8%, respectively. In addition, N2O emissions varied among farms in different scales. The respective proportions of total N2O emissions from small-scale and large-scale farms were 64.8% and 35.2% in the past three decades. With the improvement in farm management and milk production efficiency, the N2O emissions per unit mass of milk decreased from 0.77 × 10−3 kg to 0.48 × 10−3 kg in 1990–2021. This study may provide important insights into compiling a GHG emission inventory and developing GHG emission reduction strategies for the dairy farming system in China.

Unveiling the Potential of Hydrogen in a Downsized Gasoline Direct Injection Engine Performance and Emissions Experimental Study

<div>The transportation sector’s growing focus on addressing environmental and sustainable energy concerns has led to a pursuit of the decarbonization path. In this context, hydrogen emerges as a promising zero-carbon fuel. The ability of hydrogen fuel to provide reliable performance while reducing environmental impact makes it crucial in the quest for net zero targets. This study compares gasoline and hydrogen combustion in a single-cylinder boosted direct injection (DI) spark ignition engine under various operating conditions. Initially, the engine was run over a wide range of lambda values to determine the optimal operating point for hydrogen and demonstrate lean hydrogen combustion’s benefits over gasoline combustion.</div> <div>Furthermore, a load sweep test was conducted at 2000 rpm, and the performance and emission results were compared between gasoline and optimized hydrogen combustion. An in-depth analysis was conducted by varying fuel injection time and pressure. This enabled us to explore the effects of these variables on the fuel’s performance and emissions, providing valuable insights for further optimization.</div> <div>The key findings of this study are significant. They note that hydrogen fuel allows the engine to operate under lean conditions with stable combustion up to 3.8 lambda. Lean combustion produces higher engine thermal efficiency, low cyclic variability, and near-zero NO<sub>x</sub> emissions. According to the study, hydrogen combustion produces zero emissions of hydrocarbons (HC), carbon monoxide (CO), and carbon dioxide (CO<sub>2</sub>) under a wide range of operating conditions, making it a clean and environmentally friendly fuel source. During low loading, exhaust hydrogen slip is less than 1000 ppm. This slip drops below 500 ppm as the load increases. Finally, the study proved that hydrogen is more stable than gasoline at a stoichiometric level. This suggests that hydrogen could replace gasoline in some applications, which has major implications for alternative energy.</div>

Distinguishing direct N2O emissions from 15N-labeled manure compost, urea, and maize roots in a field study

Nitrous oxide (N2O) emissions from agricultural activities are a significant contributor to global anthropogenic N2O emissions. Sustainable agriculture practices, including using manure compost to replace nitrogen (N) fertilizers, can reduce chemical fertilizer use and minimize negative impacts on soil health and water quality. However, the direct contributions of manure compost to N2O emissions have not been fully studied. We conducted a field study to distinguish the direct contributions of manure compost, urea, and residual maize roots to N2O emissions in an integrated crop-livestock agricultural system in Shandong Province, China. Using the 15N-labeling technique, we found that the majority (93.3%) of cumulative N2O emissions originated from the soil and other unaccounted sources. Notably, manure compost contributed 1.3%, while current-year urea, residual urea with root exudates, and maize root accounted for 3.4%, 1.9%, and 0.03% of cumulative N2O, respectively. Our results also demonstrated that applying manure compost in combination with urea resulted in lower seed yield-scaled N2O emissions (0.046 g N2O-N kg−1 seed) compared to applying urea alone, even when the total N input was identical, suggesting the potential of manure compost in a more sustainable agriculture model. The low emission factor of manure compost (0.005%) compared to urea (0.019%) supports this potential, indicating the slow-release nature of manure may mitigate N2O while maintaining crop yield. Additionally, the overall low emissions may be attributed to the relatively high soil pH (8.17), which influences the denitrification product ratio, favoring the conversion of N2O to N2. Our study provides valuable insights into the factors contributing to N2O emissions in integrated crop-livestock farming systems, and highlights the importance of distinguishing multiple sources of N2O emissions to develop effective strategies for reducing emissions while promoting sustainable agriculture.

Impact of business strategy on carbon emissions: Empirical evidence from U.S. firms

AbstractThis study examines the nexus between business strategy and carbon emissions by utilising a dataset of U.S. firms from 2007 to 2020. It focuses on two broad types of firms, that is, prospectors and defenders. Regarding carbon emissions, we consider total emissions (Scope 1 & 2), direct emissions (Scope 1) and indirect emissions (Scope 2). The results reveal a significant association between business strategy and total carbon emissions as well as direct carbon emissions. Notably, the results suggest that prospectors, compared to defenders, display higher levels of total and direct carbon emissions. Our findings contribute to the debate on whether prospectors in developed countries mismanage sustainability issues. The study offers valuable insights into the interplay between business strategy and carbon emissions and provides empirical evidence that business strategy is an important determinant of total and direct carbon emissions.

9 Use of new technology to measure methane emissions

Abstract Over recent decades, the impact of human-induced climate change and the role of ruminant agriculture has been of growing concern for both the public and the scientific community. This has led to rapid advancements in technology needed to measure methane emissions accurately and precisely. Primarily, these advancements have been focused on measurements of enteric methane, with the proliferation of GreenFeed emission measurement systems (GEM; C-Lock, Inc; Rapid City, SD) being utilized by animal scientists across the world. The GEM relies on spot measurements collected in a portable head-box, either in a freestall or on a trailer. The GEM uses bait feed to entice animals to place their head into the head-box to collect measurements. Use of respiration chambers or head-boxes are still considered the “gold standard”, but the GEM allows for quantification in production environments and with greater number of animals. While enteric emissions are the primary source of methane from ruminant agriculture, manure methane emissions account for 15.8% of direct emissions from cattle in the U.S. This emission source is a significant contributor to confined feeding operations’ greenhouse gas emissions (GHG), where consolidation and changes in manure handling practices have occurred over the last several decades. From 2010 to 2020, manure methane emissions were a larger contributor to climate warming than enteric methane (90.8 MMT CO2-we vs. 89.2 MMT CO2-we, respectively) when calculated using the new GWP* metric. However, few advancements have been made in quantifying emissions from manure, with the cost-effective static chamber methodology still widely used. This technique allows for the determination of temporal gas concentration change in a known volume of air with a PVC cylinder, inserted 5-10 cm in the soil and posteriorly closed with a PVC lid to generate “known volume” headspace. However, this method does have known limitations on spatial and temporal flux calculations. These limitations include: the PVC chamber may alter the soil microenvironment thereby altering soil GHG flux estimates; they have potential for technician bias; and are short term monitoring, limiting interpretations to that snapshot in time and making comparisons across experiments difficult. Differing measuring techniques, such as eddy covariance and dual-comb, that more accurately and precisely monitor the soil-atmosphere interface may help better understand gas fluxes from livestock systems. Key Word: cattle, enteric, manure, methane

EVALUATION OF THE CARBON FOOTPRINT IN THE TREATMENT OF URBAN WASTEWATER IN THE CANARY ISLANDS (SPAIN)

ABSTRACT: Wastewater treatment plants play an important role within the urban water cycle to prevent the natural water environment and human health from being negatively affected by human activities. However, wastewater treatment processes, such as effluent discharge and indirect emissions resulting from energy or chemical production, also negatively affect the environment. Footprints have been used to track human influence on the environment in different areas of interest and have been applied to assess the sustainability of wastewater treatment plants. In this article, a comprehensive review of footprint assessment was investigated to evaluate the wastewater treatment process in wastewater treatment plants. The review showed that carbon footprinting was used to assess the sustainability of WWTPs, and that other footprint assessment applications (such as nitrogen and phosphorus footprinting) were also introduced to assess eutrophication of water bodies. To promote the application of footprint assessment, this article regulates the study objectives, frameworks, system boundaries, data processing methods, and the resulting interpretation process. The pros and cons of the footprint assessments were discussed and investigated in detail, examining the CO2 production on each island of the Canary archipelago, and several suggestions were proposed to improve the footprint assessments. Analysis of footprint assessments at different wastewater treatment plants revealed that wastewater treatment technologies and scales had a significant impact on footprints. Furthermore, research hotspots identified using a keyword network diagram showed that the water-carbon-energy nexus was a promising direction for future studies. The purpose of the study is to improve the reduction of the carbon footprint both at the level of direct and indirect emissions factors using new tools and methodologies. Key Words: Footprint; Waste water; Canary Islands