Evaluation Of Greenhouse Gas Emissions Research Articles

Corn stover collection prior to biogas production – Evaluation of greenhouse gas emissions

Sustainability in terms of greenhouse gas (GHG) emission saving for biogas production and utilisation is defined by Renewable Energy Directive (RED) and amending documents. The method for determination of GHG emissions defines that, when crop residues are evaluated, only those emissions originating from collection should be considered in the balance. As a result of such approach, lower emissions could be assigned to life cycle of crop residues, due to neglected effects of nutrients removal via residues and digestate management practice. Objective of this study was to evaluate GHG emissions of corn stover collection, intended for biogas production. The evaluation was performed strictly following the method defined in RED, but also by additional scenarios, to consider effects of nutrients removal and digestate management. GHG emissions of corn stover collection were in the range of 14,000 gCO2eq/tDM to 150,000 gCO2eq/tDM depending on the scenario. Lowest emissions are associated with scenario completely in line with the method stated in RED and highest when digestate is used on other fields than those from where corn stover was collected and if removed nitrogen, potassium and phosphorus nutrients are compensated by mineral fertilisers. Further investigations should be oriented to give improved data about nitrogen removal via crop residues, its transformation during anaerobic digestion and emission factors for digestate application. These data could considerably improve evaluation of biogas production from crop residues in terms of GHG emissions.

Evaluating greenhouse gas emissions and energy recovery from municipal and industrial solid waste using waste-to-energy technology

In recent years, considerable efforts have been devoted to developing waste-to-energy (WTE) technologies that can reduce the volume of waste and mitigate its negative effects on the environment. Waste is usually classified as municipal solid waste (MSW) or industrial solid waste (ISW). Both types (without hazards) can be treated by WTE technology, and both offer high potential rates of energy recovery. In Taiwan, five categories of general ISW—wood, cooking oil, plastic, lubricants, and rubber—are routinely recycled as auxiliary fuels in WTE plants. This study examined the potential for energy recovery and the extent of greenhouse gas (GHG) emissions from MSW and general ISW to evaluate the environmental performance of WTE technology using data normalization. Totals of 7,394.13×109 kWh/y and 340.15×109 kWh/y were recovered from incinerating MSW and general ISW, respectively, from 2014 to 2015. For MSW, the incineration of plastic waste produced the most GHGs (874.66 Gg CO2-eq/y), followed by paper waste (53.92 Gg CO2-eq/y) and textile waste (12.61 Gg CO2-eq/y). Of the various types of general ISW, rubber waste had the highest potential to emit GHGs (11.42 Gg CO2-eq/y). The incineration of MSW made a far greater contribution to total GHG emissions than did that of general ISW. Plastic MSW had the greatest environmental impact, and it should thus be treated carefully due to its greater potential for GHG emissions. The WTE technology has shown to improve waste management to treat both MSW and general ISW in Taiwan. These findings may be extrapolated for use in other countries.

Evaluation of greenhouse gas emissions from industrial parks using criteria air pollutants: a case study of Taiwan

An innovative greenhouse gas (GHG) inventory using criteria air pollutants (CAPs) was constructed to evaluate GHG emissions from industrial parks. The inventory included both on- (CAPs from air quality monitoring stations) and off-site GHG emissions from waste generation, wastewater treatment, electricity consumption and transportation. According to the inventory, the total GHG emissions from the industrial parks in Taiwan were ranged from 899.41 to 1,329.69 ppmv CO2-eq yr–1 for on-site emissions and 2.19 × 104 to 1.22 × 107 t CO2-eq yr–1 for off-site emissions. Electricity consumption was the most important factor contributing to higher GHG emissions in the industrial parks. Methane was found to contribute the highest GHG emissions in the wastewater treated. GHG emissions from transportation can be expected to undergo a 1.9–15.4% reduction from the industrial parks in this study. The results of this study have great implications for low-carbon development in other industrial parks worldwide.

Evaluation of Greenhouse Gas Emissions from Industrial Parks Using Criteria Air Pollutants: A Case Study of Taiwan

An innovative greenhouse gas (GHG) inventory using criteria air pollutants (CAPs) was constructed to evaluate GHG emissions from industrial parks. The inventory included both on- (CAPs from air quality monitoring stations) and off-site GHG emissions from waste generation, wastewater treatment, electricity consumption and transportation. According to the inventory, the total GHG emissions from the industrial parks in Taiwan were ranged from 899.41 to 1,329.69 ppmv CO2-eq yr–1 for on-site emissions and 2.19 × 104 to 1.22 × 107 t CO2-eq yr–1 for off-site emissions. Electricity consumption was the most important factor contributing to higher GHG emissions in the industrial parks. Methane was found to contribute the highest GHG emissions in the wastewater treated. GHG emissions from transportation can be expected to undergo a 1.9–15.4% reduction from the industrial parks in this study. The results of this study have great implications for low-carbon development in other industrial parks worldwide.

Energy use and carbon footprint for potable water and wastewater treatment

Abstract Wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs) are sources of emissions of greenhouse gases (GHGs), such as carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Carbon dioxide emissions have a big contribution to climate change. In general they come from burning fossil fuels to generate the electricity necessary for operating the treatment processes. The demand of energy depends on the treatment processes, but also on the quality of water source or wastewater influent. Water companies have to continuously supply safe drinking water to population and to treat and discharge wastewater according to regulations at a cost as low as possible. In Romania reporting of GHGs is not mandatory for water companies. Evaluation of GHG emissions from water industry have become a subject of great interest because of concern regarding climate change. Research and regulation have been conducted by different authors based on a regional basis. This paper proposes to estimate and compare the carbon emissions resulting from power consumption of Constanta South WWTP and PALAS Constanta DWTP. The energy supplier is different for these plants. In order to calculate the carbon emissions the amount of specific CO2 emissions is determined. The contribution of each primary source to produce the amount of electricity which is consumed is taken into account. WWTP has high power consumption in biological processes, because there are the aeration tanks, the sewage pumping station and the equipment for sludge. DWTP has high power consumption because of the pumping equipment used for raw water abstraction from deep wells and those for drinking water distribution to consumers. In order to identify, sort and display possible causes of the high power consumption of WWTP, Ishikawa chart is used. Through its configuration, the diagram allows highlighting and prioritizing the causes which generate this effect. Some management options are presented in order to reduce power consumption in WWTP.

Sectoral Greenhouse Gas Emission Mitigation Possibilities. Why Broad Spectrum of Indicators is Applied

Greenhouse gas (GHG) emissions from agriculture account for 10% of total greenhouse gas emissions in the European Union (EU). Mitigation potential of agriculture can be obtained from enhancement of avoidance and reduction of GHG emissions through management of land and livestock. The share of emissions from agriculture in different EU member states (EU MS) varies considerably in accordance with the significance and comparative magnitude of the agricultural sector. On a regular basis, EU MS data are collated regarding progress in development of agriculture and emission mitigation, using different indicators. The aim of this study is to analyse existing indicators used for the evaluation of impacts of agriculture on environment and propose a tool for assessment of GHG emissions mitigation measurements and assist stakeholders in decision making regarding production of agricultural products with a high added value. The research gives insight on how to achieve climate friendly agriculture. The proposed indicators can be used to evaluate GHG emissions mitigation measurements in agriculture.

GHG emission quantification for pavement construction projects using a process-based approach

Climate change and greenhouse gas (GHG) emissions have attracted much attention for their impacts upon the global environment. Initiating of new legislation and regulations for control of GHG emissions from the industrial sectors has been applied to address this problem. The transportation industries, which include operation of road pavement and pavement construction equipment, are the highest GHG-emitting sectors. This study presents a novel quantification model of GHG emissions of pavement construction using process-based analysis. The model is composed of five modules that evaluate GHG emissions. These are: material production and acquisition, (2) material transport to a project site, (3) heavy equipment use, (4) on-site machinery use, and, (5) on-site electricity use. The model was applied to a hypothetical pavement project to compare the environmental impacts of flexible and rigid pavement types during construction. The resulting model can be used for evaluation of environmental impacts, as well as for designing and planning highway pavement construction.

Evaluating greenhouse gas emissions from dairy manure management practices using survey data and lifecycle tools

Manure is the second largest source of greenhouse gas (GHG) emissions from dairy farms. Detailed data for representative manure systems are needed to guide climate change mitigation strategies. This study uses surveys sent to WI dairies to identify current farm and manure management practices, collect inventory data on manure handling and energy consumption, compare practices based on farm size, and relate these practices to GHG emissions. Results show that manure systems and management practices vary significantly with farm size. For example, larger farms handle liquid manure and have long term storage while small farms handle solid manure and land-apply daily. Sand separation, solid-liquid separation (SLS), and anaerobic digestion (AD) are implemented only by the surveyed facilities that are large enough to require permitting. Ammonia, biotic, and fossil GHG emissions from archetypes small, large, and permitted facilities are estimated using modeling tools. For this, the most common manure management practices identified by the survey are analyzed. Results (per cow, kg of milk, and ton of manure) show that storing liquid manure for long periods of time without processing contributes the most to GHG emissions. When implementing manure processing, permitted facilities are able to reduce emissions significantly, mostly through AD. Small farms keep their emissions lower than large farms as they mostly handle solid manure and land-apply manure daily. Depending on the practice and farm size, GHG emissions per ton of manure range from 2200 to 12,000 g CO2-eq for collection, 200 to 2400 g CO2-eq for transportation, 16,000 to 84,000 g CO2-eq for storage, and 16,400 to 33,500 g CO2-eq for land-application.

Development and Application of a Life Cycle-Based Model to Evaluate Greenhouse Gas Emissions of Oil Sands Upgrading Technologies.

A life cycle-based model, OSTUM (Oil Sands Technologies for Upgrading Model), which evaluates the energy intensity and greenhouse gas (GHG) emissions of current oil sands upgrading technologies, is developed. Upgrading converts oil sands bitumen into high quality synthetic crude oil (SCO), a refinery feedstock. OSTUM's novel attributes include the following: the breadth of technologies and upgrading operations options that can be analyzed, energy intensity and GHG emissions being estimated at the process unit level, it not being dependent on a proprietary process simulator, and use of publicly available data. OSTUM is applied to a hypothetical, but realistic, upgrading operation based on delayed coking, the most common upgrading technology, resulting in emissions of 328 kg CO2e/m3 SCO. The primary contributor to upgrading emissions (45%) is the use of natural gas for hydrogen production through steam methane reforming, followed by the use of natural gas as fuel in the rest of the process units' heaters (39%). OSTUM's results are in agreement with those of a process simulation model developed by CanmetENERGY, other literature, and confidential data of a commercial upgrading operation. For the application of the model, emissions are found to be most sensitive to the amount of natural gas utilized as feedstock by the steam methane reformer. OSTUM is capable of evaluating the impact of different technologies, feedstock qualities, operating conditions, and fuel mixes on upgrading emissions, and its life cycle perspective allows easy incorporation of results into well-to-wheel analyses.

Nitrous oxide emissions from one-step partial nitritation/anammox processes.

Measurements of nitrous oxide were made at pilot- and full-scale plants to evaluate greenhouse gas emissions from one-step partial nitritation/anammox processes applied in moving bed biofilm reactors treating reject water. It was found that 0.51-1.29% and 0.35-1.33% of the total nitrogen loads in the pilot- and full-scale reactor, respectively, were emitted as nitrous oxide. Between 80 and 90% of nitrous oxide emissions were in gaseous form and the rest amount was found in the reactor effluent; over 90% of nitrous oxide emissions occurred in the aerated period and less than 8% in the non-aerated period in the full-scale study. Nitrous oxide productions/consumptions were closely related to aeration and the nitrogen loads applied in the system.

Evaluation of GHG emissions from the production of magnesia refractory raw materials in Dashiqiao, China

Greenhouse gas (GHG) emissions from the industrial sector are rapidly increasing in China. As the largest producer of magnesia-refractory raw materials in the world, the production of magnesia-refractory raw materials in Dashiqiao city causes severe environmental problems, such as greenhouse gas emissions, air pollution and high energy consumption. As Dashiqiao's pillar industry, the production of magnesia refractory raw materials has become a serious obstacle to its sustainable development. At present, most studies are mainly focused on the greenhouse gas emissions from magnesium production and the emissions from magnesia refractory raw material production have not been thoroughly investigated. This research addresses this important information gap. This study focuses on the carbon emissions from the production of five kinds of magnesia refractory raw material products. The results demonstrate that the estimated greenhouse gas emissions are 2.7 t CO2eq/t of caustic calcined magnesia, 3.1 t CO2eq/t of general dead-burned magnesia, 4.7 t CO2eq/t of middle grade dead-burned magnesia, 4.7 t CO2eq/t of single-phase process fused magnesia, and 7.8 t CO2eq/t of two-phase process fused magnesia. In 2014, the five production chains of the main magnesia refractory raw materials in Dashiqiao released 13.76 million t GHGs, in which the single-phase process fused magnesia accounted for 24%, while the caustic calcined magnesia and the middle grade dead-burned magnesia for 23% and 23%, respectively. As one of the most important magnesia producer and supplier, the magnesia related industry in Dashiqiao has emitted large amounts of GHGs during the past 90 years, resulting in a significant contribution to global warming potential and negative impacts on urban sustainable development. Therefore, the city needs the magnesia industry to make structural adjustments and technical improvements.

Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.

In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase.

Assessing individual differences in enteric methane emission among beef heifers using the GreenFeed Emission Monitoring system: effect of the length of testing period on precision

The GreenFeed Emission Monitoring system was used to measure individual greenhouse gas (GHG) emissions while recording feed intake of beef heifers. That technique provides spot-measures of methane (CH4) and carbon dioxide (CO2) fluxes at each visit to the GreenFeed feeder. A sampling variance is attached at each spot-measure due to circadian variation in GHG emission. Averaging spot-measures is required for reducing that sampling error when evaluating GHG emissions of individual cattle. The objective of the present study was to evaluate the length of test period and number of spot-measures for precisely assessing differences among beef heifers. The within-individual (σ2r) and across-individual (σ2i) variances of GHG-flux measures were estimated for 124 Charolais beef heifers fed a roughage diet during an 8-week test period, following 3–4 weeks of adaptation. High repeatability coefficients (>0.77) were obtained with 4-week test averages and ~100 spot-measures for CH4 and CO2 fluxes. Equivalent repeatability was obtained for dry matter intake (DMI). Lower repeatability (<0.7) was obtained for combined traits, namely, CH4/CO2, CH4/DMI and CO2/DMI. Higher precision would have been obtained if the first 2 weeks were not used but considered as further adaptation. In that case, about 50 spot-measures recorded during a 2-week test would be sufficient for a precise individual measure of CH4 emissions. For genetic evaluation, test duration of 5 weeks may be recommended for the simultaneous recording of CH4 emission and feed intake.

Carbon footprint of honey produced in Argentina

The urgent need to mitigate the emissions of gases that contribute to climate change is creating a new scenario for the international trade of goods and services. Countries that are making efforts to reduce those emissions are now demanding that imported goods contain low levels of embedded carbon for those goods to fairly compete with locally produced products. For this purpose the implementation of standards such as the “carbon footprint” becomes critical. Carbon footprint is an environmental sustainability indicator that quantifies the emissions of greenhouse gases generated during the lifecycle of a product. Argentina, as an exporter of agricultural products, has conducted initial studies to estimate the carbon footprint of several food products of high impact in its exports such as meat and wine but yet little had been done about honey production even though the country is one of the world's three largest exporters. This study is the first assessment of the carbon footprint of honey produced in Argentina where almost 95% of the production goes to the export markets. This study also adds scientific value by comparing economic value-based allocation and production-based allocation.Official information, interviews and surveys to key stakeholders in the Argentinean beekeeping chain revealed that the cluster is characterized by low technology development and small-scale production based exclusively in the sale of a commodity (bulk product without differentiation) but recognized by its genuine quality valued on flavor and safety issues. Carbon footprint of honey evaluates greenhouse gas emissions throughout the lifecycle; specifically carbon dioxide, nitrous oxide and methane. Activity data collected includes annual honey production, geographical location of beehives and processing plants, technology used, and fuels and energy consumption. Based on the ISO 14040 method that uses lifecycle assessment, the calculated carbon footprint of honey is 2.5 ± 0.17 kg CO2e/kg honey, being the extraction process responsible for the highest contribution to greenhouse gases (GHG) emissions (90.7%) in contrast to hive management and freight emissions. A strong linear, positive correlation (R2 = 0.999) is found between process emissions and honey production pointing out a high dependence of the process with the use of fossil energy. Carbon dioxide is the dominant GHG emitted (98%) compared to methane and nitrous oxide emissions. The subdivision method applied to calculate emissions allows tracing the burden of each phase of the production process; the functional unit used to estimate emissions proved adequate for comparison purposes and the results achieved were close to those reported in the literature in spite of honey carbon footprint is strongly dependent on the production practices and honey beekeeping chain characteristics. From the results obtained, energy efficiency measures during the processing stage could alleviate the carbon impact of honey production in Argentina.

Greenhouse gases reduction potential through consumer’s behavioral changes in terms of food-related product selection

Sustainable consumption plays an important role in the mitigation of global warming and the conservation of energy. Promoting more environmentally responsible consumer behavior, especially through open communication between stakeholders, is one way to achieve low-carbon consumption. This study evaluates the potential for reducing greenhouse gas (GHG) emissions through behavioral transformation of consumers in terms of their daily shopping habits. In this context, the behavioral transformative actions pertain to certain foods and daily necessities, and are analyzed from a life cycle assessment perspective. We developed multiple product-selection scenarios to evaluate GHG emissions related to the daily purchase of commodities. Based on the life cycle assessment, we estimated the GHG emissions that result from the production and distribution of these commodities, pertaining to both the current product selection and to a possibly improved selection. The results of our study show that because of seasonal consumption patterns and energy conversion, there is a substantial potential to reduce GHG emissions resulting from out-of-season produce cultivation. The GHG reduction potential is not high for each individual commodity because diverse commodities are needed on a daily basis. However, various actions in combination could have substantial potential for reducing emissions.

Emergy and Carbon Footprint Analysis of the Construction of Passive and Active Treatment Systems for Net Alkaline Mine Drainage

Multi-criteria sustainability assessments were completed for the construction of a net-alkaline mine drainage passive treatment system (PTS) in northeastern Oklahoma to compare resource use and greenhouse gas emissions with a hypothetical active treatment system (ATS) alternative. Emergy analysis, an environmental accounting method assessing resource use, and carbon footprint analysis, a tool to evaluate greenhouse gas emissions, were completed for the construction of both systems. Assessing sustainability using multiple criteria is important in evaluating systems on the basis of resource use and environmental impact. Construction of the hypothetical ATS required seven times more emergy purchased from the economy and emitted three times more carbon dioxide equivalents than construction of the PTS. Concrete was the largest factor in both the emergy analysis (ATS and PTS) and carbon footprint (ATS only). Diesel fuel was the largest factor in the carbon footprint of PTS construction. This multi-criteria sustainability assessment shows that a hypothetical ATS alternative to the PTS would have used more resources and emitted more greenhouse gases during construction.

Methodology for the quantification of greenhouse gas emissions during land application of sewage sludge

Land application of sewage sludge improves soil physical, chemical and biological properties, minimizes the mineral fertilizer application and reduces maintenance of soil. In this work, various methods to estimate greenhouse gas (GHG) emissions due to land application of sewage sludge described in the literature were summarized and their limitations were presented. Moreover, an improved methodology to evaluate GHG emissions due to the land application of sewage sludge was proposed. Further, based on the proposed methodology, GHG emissions due to land application of sewage sludge at lower, higher and average concentrations of nutrients (carbon, nitrogen and phosphorus) were assessed. The results revealed that GHG emissions substantially decreased when higher nutrients containing sewage sludge were applied to land. For methodologies presented in the literature, GHG emissions or reductions due to land application did not change with nutrients concentrations of sewage sludge. However, based on the proposed me...

Analysis of greenhouse gas emissions of freight transport sector in China

Due to the increasing commercial activities in China, the rapid growth of energy consumption and greenhouse gas (GHG) emissions in the freight transport sector has alarmed the Chinese central government. However, there is a lack of standard measure for evaluating GHG emissions generated from freight transport operations. To improve this situation, Chinese policy makers need to evaluate GHG emissions for energy saving and pollution reduction. This background leads us to examine the GHG emission trajectories and features of Chinese freight transport patterns in the last decade, i.e. between 2000 and 2011. In this study, we examine different regions’ freight turnover and energy consumption by various transport modes (i.e. railway, highway, waterway, aircraft, and oil pipeline) in China. Our results show that the total amount of GHG emissions caused by the Chinese freight transport sector reached 978 million tons in 2011, indicating an average annual growth of 74 million tons CO2e for the last decade. Shandong, Anhui, and Henan are the main provinces producing GHG emissions, representing 11.7%, 10.3%, and 10% of total emissions generated from the freight transport sector in China, respectively. This study also compares the regional GHG emissions from different freight transport modes including railway, highway, waterway, air transport, and oil pipeline. Based on the findings, policy implications are provided on how to mitigate freight transport emissions among different Chinese regions.

Evaluating greenhouse gas emissions inventories for agricultural burning using satellite observations of active fires

Fires in agricultural ecosystems emit greenhouse gases and aerosols that influence climate on multiple spatial and temporal scales. Annex 1 countries of the United Nations Framework Convention on Climate Change (UNFCCC), many of which ratified the Kyoto Protocol, are required to report emissions of CH4 and N2O from these fires annually. In this study, we evaluated several aspects of this reporting system, including the optimality of the crops targeted by the UNFCCC globally and within Annex 1 countries, and the consistency of emissions inventories among different countries. We also evaluated the success of individual countries in capturing interannual variability and long-term trends in agricultural fire activity. In our approach, we combined global high-resolution maps of crop harvest area and production, derived from satellite maps and ground-based census data, with Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) measurements of active fires. At a global scale, we found that adding ground nuts (e.g., peanuts), cocoa, cotton and oil palm, and removing potato, oats, rye, and pulse other from the list of 14 crops targeted by the UNFCCC increased the percentage of active fires covered by the reporting system by 9%. Optimization led to a different recommended list for Annex 1 countries, requiring the addition of sunflower, cotton, rapeseed, and alfalfa and the removal of beans, sugarcane, pulse others, and tuber-root others. Extending emissions reporting to all Annex 1 countries (from the current set of 19 countries) would increase the efficacy of the reporting system from 6% to 15%, and further including several non-Annex 1 countries (Argentina, Brazil, China, India, Indonesia, Thailand, Kazakhstan, Mexico, and Nigeria) would capture over 55% of active fires in croplands worldwide. Analyses of interannual trends from the United States and Australia showed the importance of both intensity of fire use and crop production in controlling year-to-year variations in agricultural fire emissions. Remote sensing provides an effective means for evaluating some aspects of the current UNFCCC emissions reporting system; and, if combined with census data, field experiments and expert opinion, has the potential to improve the robustness of the next generation inventory system.

Comparison of different modeling approaches to better evaluate greenhouse gas emissions from whole wastewater treatment plants

New tools are being developed to estimate greenhouse gas (GHG) emissions from wastewater treatment plants (WWTPs). There is a trend to move from empirical factors to simple comprehensive and more complex process-based models. Thus, the main objective of this study is to demonstrate the importance of using process-based dynamic models to better evaluate GHG emissions. This is tackled by defining a virtual case study based on the whole plant Benchmark Simulation Model Platform No. 2 (BSM2) and estimating GHG emissions using two approaches: (1) a combination of simple comprehensive models based on empirical assumptions and (2) a more sophisticated approach, which describes the mechanistic production of nitrous oxide (N(2) O) in the biological reactor (ASMN) and the generation of carbon dioxide (CO(2) ) and methane (CH(4) ) from the Anaerobic Digestion Model 1 (ADM1). Models already presented in literature are used, but modifications compared to the previously published ASMN model have been made. Also model interfaces between the ASMN and the ADM1 models have been developed. The results show that the use of the different approaches leads to significant differences in the N(2) O emissions (a factor of 3) but not in the CH(4) emissions (about 4%). Estimations of GHG emissions are also compared for steady-state and dynamic simulations. Averaged values for GHG emissions obtained with steady-state and dynamic simulations are rather similar. However, when looking at the dynamics of N(2) O emissions, large variability (3-6 ton CO(2) e day(-1) ) is observed due to changes in the influent wastewater C/N ratio and temperature which would not be captured by a steady-state analysis (4.4 ton CO(2) e day(-1) ). Finally, this study also shows the effect of changing the anaerobic digestion volume on the total GHG emissions. Decreasing the anaerobic digester volume resulted in a slight reduction in CH(4) emissions (about 5%), but significantly decreased N(2) O emissions in the water line (by 14%).