Dissertations / Theses on the topic 'Greenhouse gas emissions'

Irrigation practices change the soil moisture in agricultural fields, and in turn influence the emissions of greenhouse gases. A two year field study was conducted to assess the emissions of CO2, CH4 and N2O from surface drip and subsurface drip irrigated tomato fields in Southwestern Ontario, Canada. Gas fluxes were obtained through the static chamber method, taking samples every 15 minutes over a one hour time period. Soil moisture and soil temperature were measured once per chamber per hour and used to help explain the gas emissions. A peak mean N2O flux at 405 µg N2O-N m-2 h-1 was observed from the five chambers in the surface drip irrigation treatment on July 8th, 2013, shortly following a rainfall event. Most N2O fluxes which occurred during the irrigated portion of the growing season were around 50 µg N2O-N m-2 h-1 in both treatments, water added here was less than some of the large rainfall where peaks occurred. Both the lowest CO2 mean treatment fluxes (12 mg CO2-C m-2 h-1) and highest (12 mg CO2-C m-2 h-1) were observed in the surface drip irrigation plots. Seasonal emissions of CO2 were significantly greater in surface drip plots than subsurface drip plots in 2013, but not in 2012, and this is likely attributed to soil temperature differences. Methane ¬fluxes were mainly negative, indicating that the soil is a sink, as opposed to a source for this gas. Generally, there was no significant difference in soil moisture between the types of drip system. Consequently, there were only a few days which showed significant differences between subsurface drip irrigation and surface drip irrigation treatments for the hourly collected gas fluxes throughout the two growing seasons. Overall, the use of subsurface drip irrigation or surface drip irrigation does not affect the emissions of greenhouse gases from the tomato fields in this study.
Les techniques d'irrigation affectent l'humidité du sol dans les terres agricoles, ce qui affecte les émissions de gaz à effets de serre. Une étude sur le terrain d'une durée de deux ans a été menée dans le sud-ouest de l'Ontario au Canada afin de déterminer les émissions de CO2, CH4 et N2O de champs de tomates irrigués au goutte-à-goutte de surface et au goutte-à-goutte souterrain. Les flux de gaz ont été obtenus en prenant des échantillons à chaque 15 minute pour une durée d'une heure, en utilisant la méthode de chambre statique. L'humidité et la température des sols ont été mesurés et utilisés afin d'expliquer les émissions de gaz. La moyenne de flux de N2O a atteint un sommet de 405µg N2O-N m-2 h-1 dans le cas de l'irrigation au goutte-à-goutte de surface, peu de temps après un épisode de pluie. La majorité des flux de N2O qui se sont produits pendant le moment de la saison utilisant de l'irrigation était d'environ 50 µg N2O-N m-2 h-1 dans les deux traitements. La plus faible (12mg CO2-C m-2 h-1) et la plus haute (123mg CO2-C m-2 h-1) moyenne des flux des traitements ont toutes les deux été observées dans les champs irrigués au goutte-à-goutte de surface. Les flux de CH4 étaient principalement négatifs ce qui indiquent que les sols sont des puits, plutôt qu'une source de ce gaz. Une différence significative entre les flux des traitements a été démontrée seulement pour un nombre limité de jour parce que l'humidité des sols créée par les deux systèmes d'irrigation de goutte-à-goutte était similaire. Les émissions saisonnières de CO2 étaient significativement plus hautes dans le cas des champs irrigués au goutte-à-goutte de surface que les champs irrigués au goutte-à-goutte souterrain en 2013, mais pas en 2012, ce qui est probablement dû aux différences dans les températures des sols. Globalement, l'utilisation de l'irrigation au goutte-à-goutte de surface ou de l'irrigation au goutte-à-goutte souterraine n'a pas d'effet majeur sur les émissions de gaz des sols dans les champs de tomates.

Climate change has been influenced more by human activities now than previously. These influences are largely attributed to industries, whose activities can potentially produce enormous amounts of carbon dioxide and other greenhouse gases, and exacerbate the speed of climate change. This thesis examines how the financial markets evaluate corporations’ greenhouse gas emission performance. We consider various emission criteria, and distinguish between the better and worse performers in different emission policy regimes, including the US, the UK and the rest of the EU. The investigations have been conducted at three stages, presented in chapter 3, 4 and 5. Firstly, in chapter 3 we examine the carbon effects at the portfolio-level, where total return indices are our main concern. By adopting the long-short strategy, we report that investors in the UK and EU markets, can make an arbitrage profit at the lower cut-off levels, when applying various carbon screening policies and forming equally-weighted portfolios. However, no such profit opportunities can be achieved in the US market. We further consider the reason for such arbitrage opportunities, which is the link between corporate governance/management efficiency and different levels of carbon constraint. Secondly, in chapter 4, the carbon effects are investigated at firm-level, where firms’ financial market values act as the dependent variable. Our regression models are based on the Ohlson framework, which considers firms’ financial market value in relation to its accounting performance, and the ‘other information’, which in our case is the carbon emission performance. We find a significant relationship between the US firms’ values and their carbon emission performances; however, this relationship has been weakened for UK companies, and in fact becomes even unreliable for EU companies. Further, in order to explore the reason for this relationship, we have focused on energy efficiency and firms’ reputation that are associated with carbon reduction activities. The scale effects have also been discussed in this chapter, as the various deflators are adopted. Finally, in chapter 5, again at firm-level, cash flow expectation and cost of capital have been considered to possibly be the source that drives firms’ value. Cash flow expectation is measured at the short-, medium- and long- term, by profitability, earnings growth, and residual income growth rate, respectively. Two portfolios for each target parameters are constructed according to different carbon screening criteria at different cut-off levels, the differences between each pair of portfolios are then calculated and tested for significance. A sub-sample regression, which is based on the observations available from analysts’ earnings forecast, has been conducted for each of the three regimes. After matching the portfolio and regression results, we report that the implied cost of equity is only reduced for the less carbon emission firms, in regimes where more stringent carbon constraints are applied; whereas in regimes where less stringent carbon constraints exist, the less carbon emission firms have not gained any advantage through their implied cost of equity. Also, cash flow expectations indicate diverse outcomes for different time horizon and regimes. Furthermore, various market participants, such as governments, investors, distributors and clients etc, who could possibly influence firms’ carbon behaviour, have also been considered in association with their roles in reducing greenhouse gas emissions. Our work contributes to the existing literature through a wide ranging examination of major financial evaluation methods relating to emerging carbon emission issues.

Agriculture has been reported to contribute a significant amount of greenhouse gases to the atmosphere among other anthropogenic activities. With still more than 870 million people in the world suffering from under-nutrition and a growing global food demand, it is relevant to study ways for mitigating the environmental impact of food production. The objective of this work was to identify gaps in the knowledge regarding the main factors affecting greenhouse gas (GHG) emissions from beef farming systems, to reduce the uncertainty on carbon footprint predictions, and to study the relative importance of mitigation options at the system level. A lack of information in the literature was identified regarding the quantification of the relevant animal characteristics of extensive beef systems that can impact on methane (CH4) outputs. In a meta-analysis study, it was observed that the combination of physiological stage and type of diet improved the accuracy of CH4 emission rate predictions. Furthermore, when applied to a system analysis, improved equations to predict CH4 from ruminants under different physiological stages and diet types reduced the uncertainty of whole-farm enteric CH4 predictions by up to 7% over a year. In a modelling study, it was demonstrated that variations in grazing behaviour and grazing choice have a potentially large impact upon CH4 emissions, which are not normally mentioned within carbon budget calculations at either local or national scale. Methane estimations were highly sensitive to changes in quality of the diet, highlighting the importance of considering animal selectivity on carbon budgets of heterogeneous grasslands. Part of the difficulties on collecting reliable information from grazing cattle is due to some limitations of available techniques to perform CH4 emission measurements. Thus, the potential use of a Laser Methane Detector (LMD) for remote sensing of CH4 emissions from ruminants was evaluated. A data analysis method was developed for the LMD outputs. The use of a novel technique to assess CH4 production from ruminants showed very good correlations with independent measurements in respiration chambers. Moreover, the use of this highly sensitive technique demonstrates that there is more variability associated with the pattern of CH4 emissions which cannot be explained by the feed nutritional value. Lastly, previous findings were included in a deterministic model to simulate alternative management options applied to upland beef farming systems. The success of the suggested management technologies to mitigate GHG emissions depends on the characteristics of the farms and management previously adopted. Systems with high proportion of their land unsuitable for cropping but with an efficient use of land had low and more certain GHG emissions, high human-edible returns, and small opportunities to further reduce their carbon footprint per unit of product without affecting food production, potential biodiversity conservation and the livelihood of the region. Altogether, this work helps to reduce the uncertainty of GHG predictions from beef farming systems and highlights the essential role of studies with a holistic approach to issues related to climate change that encompass the analysis of a large range of situations and management alternatives.

Many fuel cycle greenhouse gas (GHG) emissions assessments of varying scope, detail and methodology have been carried out for various biofuels in recent years, and these have largely concluded that biofuels provide GHG reduction benefits as substitutes for fossil fuels. As more attention is focused on biofuels, however, doubts have been raised about the reliability of previous GHG assessments of these fuels. From a scientific perspective, three main observations give reason to doubt these assessments: 1. There are widely varying results for what appear to be identical fuels. 2. The assessment methodologies involve inherently subjective elements. 3. There is still significant scientific uncertainty in characterisations of important processes that need to be accounted for in most GHG assessments of biofuels. For accurate determination of the GHG emissions impacts of biofuels, there is a need for further development of standardised, demonstrably reliable assessment methods. This research investigates methods used for assessing net GHG emissions from biofuels. It identifies remaining methodological deficiencies that prevent the generation of definitive results. A methodological framework is developed for optimising the reliability of biofuel GHG assessments within the limits of currently available knowledge and methods, and the most important developments required for extending those limits are identified. A new calculation tool and database are developed to facilitate the carrying out of biofuel GHG assessments with optimal reliability. It is concluded that uncertainties associated with existing GHG assessments can significantly limit our ability to draw firm conclusions from comparisons of GHG impacts among biofuels and between biofuels and fossil fuels. Reliable GHG assessments of biofuels require very precise specifications of the systems being described, with clear definitions of the limitations of applicability of the assessment results, explanations of the methodological choices adopted and their implications, and acknowledgement of the limits set by all relevant scientific uncertainty.

Thesis (M.A.)--University of Wyoming, 2008.
Title from PDF title page (viewed on August 4, 2009). Interdisciplinary thesis in International Studies and Environment and Natural Resources. Includes bibliographical references (p. 58-63).

This paper is focused on the greenhouse gas emissions in the pharmaceutical sector. The case study reported is that of Chiesi Farmaceutici S.p.A., a pharmaceutical company based in Parma. Sustainability has always been a primary concern in the way Chiesi operates. Fully aware of the climate emergency that the planet Earth is tackling, Chiesi has set itself a challenge and announces its commitment to becoming carbon neutral by the end 2035, reducing its greenhouse gas emissions and offsetting emissions that are no further reducible to achieve a net zero carbon footprint. There are several existing initiatives to achieve the Carbon Neutrality. The most important initiatives are the transition to a new propellant, that has a much smaller GWP than that of the actual propellant, and the installation of an abatement system to lower the emissions during the manufacturing phase of spray products. These initiatives are used to present reduction targets to the Science Based Target initiative. Science-based targets provide a clearly defined pathway for companies to reduce greenhouse gas (GHG) emissions, helping prevent the worst impacts of climate change and future-proof business growth. Targets are considered ‘science-based’ if they are in line with what the latest climate science deems necessary to meet the goals of the Paris Agreement, limiting global warming to well-below 2°C above pre-industrial levels and pursuing efforts to limit warming to 1.5°C. Chiesi is investing a lot of time and money to set its reduction targets in line with the Paris Agreement, but the present study demonstrates that the there are several important benefits. This is a clear evidence that suggests that financial and environmental performances are far from being exclusive and this is the road to follow both for the public and the private sectors.

Thesis (Honors paper)--Florida State University, 2010.
Advisor: Dr. Tarek Abichou, Florida State University, College of Engineering, Dept. of Civil/Environmental Engineering. Includes bibliographical references.

Two beliefs drove this dissertation to be centered on the analysis of the UK corporate disclosure (CD) related to global climate change (GCC). Firstly, GCC is the most significant environmental concern of our current age (IPCC, 2001; Stern, 2006; IPCC, 2007). Secondly, CD could illustrate the values of organizations and possibilities for changing organizations’ responsibility regarding to GCC (Gray et al., 1996; Bebbington and Larrinaga-Gonzalez, 2008; Bebbington et al., 2009). This study utilizes content analysis as its principal method and seeks to achieve its goal by way of a two investigations. The first investigation focuses on disclosures made by direct participants’ (DP) in the UK Emissions Trading Scheme (UK ETS). It captures GCC disclosures from both stand alone (SA) and annual reports (AR) during 2000 - 2004. This part of the study explores if joining the UK ETS changed GCC disclosures. This is tested on both a longitudinal and matched pair (MP) basis. An analysis using institutional theory suggests that instruments of environmental policy may influence GCC disclosures. Results showed that DP increased GCC disclosure, especially in the AR where mainstream business rationale is accepted. MP disclosures, in contrast, focus on the SA media and on different topics than DP disclosures. AR and SA both contain CD, but in this study they showed different patterns of disclosure and therefore may constitute different disclosure media. The second investigation suggests a method to compare GCC disclosure for a sample of DP and MP, using three different media: carbon disclosure project (CDP), AR and SA. Analysis shows that GCC disclosure did not provide sufficient information to compare GCC initiatives and disclosures. Despite the fact that organizations have similar characteristics in terms of sector, size and origin country, they showed different views on GCC issues and this may partially explain differences on GCC initiatives and disclosure.

The aim of this study was to investigate the effects of biochar amendment on soil greenhouse gas (GHG) emissions and to elucidate the mechanisms behind these effects. I investigated the suppression of soil carbon dioxide (CO2) and nitrous oxide (N2O) emissions in a bioenergy and arable crop soil, at a range of temperatures and with or without wetting/drying cycles. More detailed investigation on the underlying mechanisms focused on soil N2O emissions. I tested how biochar altered soil physico-chemical properties and the subsequent effects on soil N2O emissions. In addition, 15N pool dilution techniques were used to investigate the effect of biochar on soil N transformations. Biochar amendment significantly suppressed soil GHG emissions for two years within a bioenergy soil in the field and for several months in an arable soil. I hypothesised that soil CO2 emissions were suppressed under field conditions by a combination of mechanisms: biochar induced immobilisation of soil inorganic-N (BII), increased C-use efficiency, reduced C-mineralising enzyme activity and adsorption of CO2 to the biochar surface. Soil CO2 emissions were increased for two days following wetting soil due to the remobilisation of biochar-derived labile C within the soil. Soil N2O emissions were suppressed in laboratory incubations within several months of biochar addition due to increased soil aeration, BII or increased soil pH that reduced the soil N2O: N2 ratio; effects that varied depending on soil inorganic-N concentration and moisture content. These results are significant as they consistently demonstrate that fresh hardwood biochar has the potential to reduce soil GHG emissions over a period of up to two years in bioenergy crop soil, while simultaneously sequestering C within the soil. They also contribute greatly to understanding of the mechanisms underlying the effect of biochar addition on soil N transformations and N2O emissions within bioenergy and arable soils. This study supports the hypothesis that if scaled up, biochar amendment to soil may contribute to significant reductions in global GHG emissions, contributing to climate change mitigation. Further studies are needed to ensure that these conclusions can be extrapolated over the longer term to other field sites, using other types of biochar.

As a consequence of most building's long lifespan, changing weather conditions driven by climate change, are likely to influence energy demands for heating and cooling, thereby altering lifecycle Greenhouse Gas (GHG) emissions. This research develops a method to allow estimation of these emissions in the early design stage, accounting for potential future weather conditions projected by the UK Climate Impacts Programme (UKCIP). The method covers both the operational performance of buildings across a lifecycle, as well as allowing investigation of GHG emissions due to upstream manufacture, transportation and construction of building materials and components. The research has developed a novel method to allow operational OHO emissions to be estimated directly from the outputs of the UKCIP Weather Generator tool. These operational GHG emissions are estimated from projected future temperatures using a model 'calibrated' to building performance through dynamic thermal simulation of a selection of example weather years. The new method has also been developed to allow lifecycle GHG emissions to be estimated using software tools regularly applied for compliance with energy efficiency legislation. The result is a process that can estimate upstream and future GHG emissions quickly to ensure information is readily available to designers. Investigation of a real 'mixed-use' building showed upstream emissions contributed over 20% to total lifecycle GHGs, indicating wider industry focus in this area may be appropriate. The case study also showed annual GHG emissions due to space cooling could increase by between 26 and 70% from 2020 to 2080. Over the same period, emissions due to heating may decrease by between 12 and 42%, giving an overall net increase in GHG emissions from these systems. This research has highlighted the potential significance of climate change on building life cycle performance and provided a tested design framework to allow Parsons Brinckerhoff to limit life cycle GHG emissions from new building designs.

There is an increasing need to reduce greenhouse gas (GHG) emissions and to identify influencing factors from wastewater treatment plants (WWTPs), particularly process emissions consisting of nitrous oxide (N2O), and methane (CH4) GHG, with global warming potentials about 310 and 21 times higher than carbon dioxide (CO2) respectively (IPCC, 2006). However, the challenges offered by full-scale environments, have to date, restricted a real-time, comprehensive approach of monitoring emissions and influencing factors. This study aimed at addressing this knowledge gap, by reporting the findings of a long-term, online, continuous monitoring of GHG emissions and operational variables. Lanes were monitored in nitrifying activated sludge plants (ASP) controlled under ammonia (NH4 + ) and dissolved oxygen (DO) set-points (DO setpoints monitored: 1.5 and 2.0 mg/L), as well as in a biological nutrient removal plant (BNR) under NH4 + control. The findings showed that CH4, although potentially formed in non-aerated compartments, was emitted in aerobic zones, at an average emission factor (EF) of 0.07 % of influent and removed chemical oxygen demand (COD). Nitrous oxide EFs on the other hand, depended on relative nitrogen fractions, with influent-based EFs showing a best-case scenario, at 0.05–0.72 % of both influent total nitrogen (TN) and NH4 + , compared to the higher EFs based on removed nitrogen at 0.13–3.9 % of TN and NH4 + removed. The processes operated under the same control settings (DO set-point 1.5 mg/L), had similar, or identical, EF, suggesting that settings could help predict the range of EF. Nitrous oxide was always produced in the presence of NH4 + , even at low concentrations (=<0.5 mg/L), therefore linking N2O production with NH4 + oxidation, particularly with nitrifier nitrification. Incomplete denitrification under low carbon to nitrogen (C/N) ratios also triggered N2O production (EFs of 2.4 and 4.1 % of reduced TN at C/N ratios of 2.8 and 2.4 respectively), particularly with intermittent aeration. Therefore, nitrifier denitrification and incomplete denitrification simultaneously occurred and triggered N2O production in the final stages of nitrification. The BNR lane was the most operationally stable process, therefore offering the best balance between efficiency (60–99 % less aeration and energy per kg of treated NH4 + ), low carbon footprint and reduced EFs (0.08–0.1 % of all nitrogen fractions). The second best option was the DO set-point control of 1.5 mg/L, with low EFs (0.05–0.2 %), stable operational conditions and reduction in aeration requirements (up to 340 % less than DO set-point 2.0 mg/L). Operating ASP under NH4 + control however, led to 7–96 % more efficiency than under DO set-points, although it required better control in the back end of the process. Only an online, long-term methodology such as adopted in this study, could provide insights into emission variability and the effect of operational variables on promoting or reducing emissions. Based on this, strategies to mitigate emissions at full-scale were recommended.

Global greenhouse gas (GHG) emissions have increased alarmingly fuelling climate change. Fossil fuel burning and land-use change are the main contributors to global GHG emissions, and their reductions are required to reduce global GHGs. Protection and conservation of coastal wetlands and agriculture management are the two main sectors that can provide the land-use based climate mitigation, with the potential to be reduced by 35-50%. Therefore, projects and policies involving coastal wetland protection and restoration are being encouraged globally important GHG mitigation approaches. However, the success of all mitigation approaches largely depends upon evidence-based knowledge about the types of mitigation actions, their feasibility, and potential co-benefits. This dissertation consists of six chapters that centre on exploring the magnitude of the GHG emissions due to coastal wetland loss and a potential solution through wetlands restoration on unused agricultural lands. Chapter 2 is a literature review to identify knowledge gaps regarding GHG fluxes from wetlands and other land uses. I synthetised 153 articles and found that GHG fluxes were mainly reported from temperate marshes while GHG fluxes from sub/tropical wetlands were underrepresented. Overall, 48% of the studied wetlands were marshes converted for cropping and grazing, while mangroves were mainly converted to aquaculture. I found that sugarcane fields in tropical Australia, had very high N2O emissions, suggesting that their conversion to wetlands may present a GHG mitigation opportunity. Finally, I found GHG fluxes in tropical ponded pastures, which were potentially very high, were not reported yet, calling to fill in this critical knowledge gap in Australia. In Chapter 3, I explored the soil greenhouse gas (GHG) fluxes from tropical coastal wetlands and their converted agricultural lands. I measured gaseous fluxes throughout two years between 2018 and 2020, considering seasonal differences. The GHG emissions were lowest from coastal wetlands and highest from sugarcane. I found that converted sugarcane and ponded pasture had an order of magnitude higher cumulative GHG (CH4, N2O) fluxes than coastal wetlands, including mangroves, saltmarshes, and supratidal forests (Melaleuca spp.). Therefore, I concluded that wetlands restoration in the tropical region would provide significant GHG mitigation benefits. However, long-term studies on GHG emissions from wetlands and alternative agricultural land use types, including poorly studied systems such as ponded pastures, are required to improve accuracy on the mitigation of GHG through wetland restoration. The Department ii of Industry, Science, Energy and Resources, Queensland used these findings to develop the Australian blue carbon method, which was recently approved. In Chapter 4, a case study was investigated in subtropical Australia, where an unused sugarcane land was successfully restored to coastal wetlands through tidal reinstallation. I measured carbon (C) sequestration and GHG fluxes to estimate abatement. I also measured N soil sequestration and removal through denitrification as indicators of water quality improvement. I compared an active sugarcane farm as a reference site with the restored mangroves, saltmarsh, and supratidal forests (Melaleuca spp.) using a Before-After-Control-Impact design. I found that restoration of unused sugarcane land to supratidal forest provided the highest carbon abatement of ~18.5 Mg CO2-eq ha-1 y-1 followed by restoration to mangroves and saltmarsh at ~11 Mg CO2-eq ha-1 y-1 and ~6.2 Mg CO2-eq ha-1 y-1 respectively. Tree growth, soil accumulation and reduced N2O fluxes due to cessation of fertilisation were the main contributors to the carbon abatement. Carbon abatement benefits overrode the enhanced CH4 emissions due to flooding. Additionally, the restored coastal wetlands provided water quality improvement service through N removal of up to 50.4 mg m-2 d-1. These findings provide baseline data for countries that are seeking to meet their GHG mitigation targets and other SDGs through land management. Chapter 5 of this thesis explored the effects of litter composition on GHG fluxes from the supratidal forest (Melaleuca spp.). In a laboratory incubation experiment, I quantified the GHG fluxes through the addition of 1) a litter fall mixture of Melaleuca quinquenervia bark and leaf litter of other dominant plants found on-site, 2) leaf litter of M. quinquenervia, and 3) oil of M. alternifolia, which is a potent natural antimicrobial. I found that cumulative GHG emissions (CH4 + N2O) were increased in leaf litter and oil treatments, indicating some changes in the microbial communities involved in CH4 and N2O regulation. These studies would add to emerging knowledge of C dynamics in supratidal forest restoration. In summary, this thesis has showed that Australia could have carbon mitigation benefits of up to 63 Mg CO2-eq ha-1 y-1 by restoring tropical wet pastures, and up to 7.5 Mg CO2-eq ha-1 y-1 from restoring unused or marginal sugarcane. The present study presented regional baseline data based on a realistic assessment of GHG mitigation and associated ecosystem services. This research will contribute to national policies targeting GHG reduction targets.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

Esta tesis analiza el tema del transporte y la presión medioambiental a través de tres variables relacionadas: las emisiones, la actividad y la intensidad energética del transporte. El Capítulo 2 analiza la importancia de la población, la actividad económica, el volumen de transporte y las características estructurales de la actividad de transporte —intensidad energética del transporte, participación de los diferentes modos de transporte y participación de las diferentes fuentes energéticas— como factores explicativos de las emisiones de GEI de la actividad de transporte en la Unión Europea-28 entre 1990-2014. El análisis se basa en el modelo STIRPAT, que se amplía para investigar el impacto en las emisiones del transporte de los cambios en dicha actividad y en los del conjunto de la economía. Utilizando técnicas econométricas de datos panel, se identifica la importancia de cada factor explicativo y el impacto de su cambio en las emisiones. El Capítulo 3 estudia el impacto del sector del subsistema de transporte y almacenamiento en las emisiones de GEI de la economía mediante el análisis de subsistemas basado en el modelo input-output de Ghosh. Esta nueva metodología tiene en cuenta toda la actividad del subsistema y no solo la actividad vinculada a su demanda final. Asimismo, las emisiones totales del subsistema se descomponen en cuatro componentes explicativos: el componente escala, el componente interno neto, el componente feed-back y el componente spillover, con el objetivo de conocer las interrelaciones en términos de emisiones entre los subsectores del subsistema y entre estos y la actividad del resto de sectores de la economía. La metodología se aplica empíricamente al sector del transporte y almacenamiento en España en 2014. El Capítulo 4 examina los factores que han influido en la tendencia de la intensidad energética del transporte de mercancías por carretera español durante el período 1996-2012. Se adapta la metodología ASIF con el fin de estudiar la intensidad energética y se completa el estudio con un análisis de descomposición LMDI. Además, el cambio en la intensidad energética se analiza cuantificando la contribución de cada mercancía transportada a través de la metodología de la atribución de cambios en los índices Divisia. Los tres capítulos principales de esta tesis ofrecen varias contribuciones. El Capítulo 2 desarrolla metodológicamente el modelo STIRPAT al aplicar al estudio de las emisiones del transporte la participación de los diferentes modos de transporte y la participación de las diferentes fuentes de energía. En segundo lugar, contribuye a analizar empíricamente las emisiones de GEI del sector del transporte en la Unión Europea en el período 1990-2014. En tercer lugar, evalúa la efectividad potencial de las acciones promovidas en el Libro Blanco del Transporte de 2011. El Capítulo 3 desarrolla metodológicamente el modelo de subsistemas input-output desde la perspectiva de la oferta y este se amplía con el fin de estudiar el impacto medioambiental de sustancias contaminantes. En segundo lugar, ofrece una contribución empírica, ya que aplica el modelo al análisis de los efectos de la actividad del sector de transporte y almacenamiento en las emisiones de GEI de la economía en España en 2014. Finalmente, el Capítulo 4 adapta la metodología ASIF a fin de investigar la intensidad energética del transporte de mercancías por carretera y amplía el análisis mediante la descomposición LMDI. En segundo lugar, identifica el grado en que cada mercancía contribuye al cambio en la intensidad energética a través de la metodología de la atribución de cambios en los índices Divisia. En tercer lugar, investiga empíricamente la intensidad energética del transporte español de mercancías por carretera en el período 1996-2012.
This dissertation analyses the topic of transport and environmental pressure through three closely related issues —transport GHG emissions, transport activity, and transport energy intensity. Chapter 2 analyses the importance of population, economic activity, transport volume, and structural characteristics of transport activity —in terms of transport energy intensity, of transport modes' share, and of energy sources’ mix— as driving factors of GHG emissions in transport activity in the European Union over the period 1990–2014. The analysis is based on the STIRPAT model, which is broadened to investigate in depth the impact on transport emissions of changes in the transport activity and in the whole economy. Using panel data econometric techniques, the significance of each factor and the impact of its change on emissions are identified. Chapter 3 studies the impact of the transport and storage subsystem sector on GHG emissions of the whole economy by using input–output subsystems analysis based on the Ghosh model. This new methodology that is developed in the chapter takes into account the whole activity of the subsystem and not only the activity linked to its final demand. Additionally, in the aim of learning the interrelations in terms of emissions between the subsectors of the subsystem and between them and the activity of the rest of the sectors of the economy, total emissions of the subsystem are decomposed into four explanatory components. These are scale component, net own internal component, feed-back component, and spillover component. The methodology is applied to the Spanish transportation and storage sector in 2014. Chapter 4 examines the factors that have influenced the energy intensity trend of the Spanish road freight transport of heavy goods vehicles over the period 1996–2012. The ASIF methodology is adapted to study it, and the chapter uses multiplicative LMDI decomposition analysis. Additionally, the change in energy intensity is analyzed in more depth by quantifying the role of each commodity transported using the methodology of the attribution of changes in Divisia indices. The three main chapters of this dissertation offer various contributions. Chapter 2 develops methodologically the STIRPAT model since it adds as driving factors of transport emissions the modal share and the energy consumption mix. Second, it empirically contributes to analyze the GHG emissions of the transport sector in the European Union in the period 1990–2014. Third, it evaluates the potential effectiveness of the actions promoted in the 2011 Transport White Paper. Chapter 3 develops methodologically an input–output subsystems model from the supply perspective and expands it in order to study the environmental impact of polluting substances. Second, it offers an empirical contribution, as it applies the preceding model with the purpose of studying the effects of the activity of the transportation and storage sector on GHG emissions of the whole economy in Spain in 2014. Finally, Chapter 4 adapts the ASIF methodology to energy intensity in the road freight transport and enhances it by applying decomposition analysis. Second, it identifies the degree to which each transported commodity has contributed to the change in energy intensity through the methodology of attribution of changes in Divisia indices. Four, it provides an empirical contribution through the analysis of energy intensity of Spanish road freight transport of heavy goods vehicles over the period 1996–2012.

This paper seeks to understand the role that the agriculture sector can play in romoting China's climate change mitigation efforts. In order to understand the history of agricultural and climate change policies in China, the beginning sections are devoted to these topics. In the following chapter,the impact of climate change on agricultural production is explored. Using research data that determine the primary sources of emissions within agriculture, and mitigation practices that have proved effective, potential GHG mitigation measures are proposed in the fourth chapter.Based on recommendations made by economists, the final chapter delineates agricultural policies that would incentive farmers to implement the GHG mitigation strategies outlined in the preceding chapter.

Although models to quantify CO₂e emissions in urban areas exist, they are within isolated disciplines, and are targeted at specific scales, emissions processes, and end-users — not a priori compatible with planning needs. Furthermore, the majority of existing models rely on inventory data, which is typically only available at aggregate space and time scales. It is necessary however, that neighborhood-scale CO₂e emissions estimates are provided to determine the key relationships between urban form and emissions — which can than be applied to future planning strategies. This thesis developed a new methodology to integrate LiDAR data, building simulation software and a building typology database to rapidly model energy and emissions for a large number of buildings. To adjust building energy demand to local urban-context, building morphology, and population density a scaling approach is proposed. This methodology was applied to a study area of 7.4 km² in Vancouver, BC, consisting of 7812 buildings ranging in moderate to high density. Modeled building energy use in this transect was sensitive to local conditions (average variation in building energy use due to urban-context 2.8%, building morphology 2.8%, and population density 3.2%) resulting CO₂e emissions of 14.2 kg CO₂e m⁻²yr⁻¹ (1309 kg CO₂e Inh.⁻¹ yr⁻¹) varying dramatically between the central business district (40.1), mixed-use (12.7), and residential (9.0) neighbourhoods. Spatial and temporal patterns of building energy use, CO₂e emissions and anthropogenic heat release by buildings are presented and discussed in relation to urban form.

In this thesis, the greenhouse gas emissions from the extraction of raw material to construction of planned buildings, roads and tramways in Uppsala are studied. The study is part of the work with Roadmap 2050 for a carbon dioxide neutral Uppsala until year 2050 that the Municipality is developing. The goal of the Municipality is to reduce the greenhouse gas emissions to less than 500 kg CO2-eqv per capita and year, compared to in 2011 just over 7 000 kg CO2-eqv per capita and year. The results of this study are compared to this goal. The study is based on two different possible scenarios of population growth in Uppsala until year 2030 and year 2050. The first one, the base scenario, implies that Stockholm remains the only big centre in the region. The second one, the high scenario, is a network region in which Uppsala has become an equally attractive city. This means that four scenarios have been considered; 2030 base, 2050 base, 2030 high and 2050 high. Another decisive parameter is the composition of material in the different constructions. To calculate the emissions certain LCA:s on roads and buildings, which apply to the situation in Uppsala, has been chosen. For tramways, an approximation had to be made since no LCA could be found. The result shows that the emissions from the extraction and production phase is more than ten times as big as the emissions from the construction phase of the process. For all scenarios, the emissions from roads are the highest ones in the extraction and production phase while the emissions from trams are the lowest ones. In the construction phase the emissions are highest from apartment buildings for all scenarios except 2050 high, where roads are highest. In the construction phase tramways have the lowest emissions in all scenarios. In total, the emissions of 2030 base is the lowest with 39 kg CO2 per capita and year and the scenario 2050 high is the highest with 120 kg CO2 per capita and year.

Seagrass meadows are among the most productive ecosystems in marine environments. Like many terrestrial higher plants, marine seagrasses lose their old leaves during annual or inter-annual senescence, and a significant proportion of these residues is transported in surface waters and washed up on shores by surf, tides and winds. These beach-cast seagrass wracks provide important ecosystem services, such as reducing wave impact, protecting beaches from erosion, providing habitat to birds and invertebrate species that colonize shorelines, and being a primary food resource for beach detritivores. However, seagrass residues accumulation on beaches, following meadows degradation, can negatively impact tourism. Therefore, wrack piles are frequently collected and disposed of in landfills or biomass waste facilities, and the adoption of these management practices implies substantial environmental and economic costs. On the other hand, wrack piles might be a significant source of greenhouse emissions (GHGs). Recent studies reported CO2 and CH4 emission rates and suggested possible mitigation options, such as energy conversion and biochar production through pyrolysis. Even though quantitative estimates of both seagrass coastal distribution and residues disposal to seashores are partially available, at least at regional level, the assessment of their contribution to global GHGs emissions is still lacking, due to a knowledge gap about the effects of peculiar beach ecosystems environmental conditions on seagrass decay rates. Moreover, many studies have proposed several reuse options of beached seagrass residues in order to reduce both economic costs of collection from the shoreline and disposal in landfills and to offer a more sustainable beaches management. seagrass biomass use for energy production is under consideration in several countries of the world, as it combines the continuous increase in energy demand, sustainable costs of applied technology and social acceptance. In this research, the seagrass wracks decomposition dynamics were investigated in both controlled conditions and experimental fields in North-East Italy, with focus on CO2 and CH4 emissions, as a function of temperature, salinity, water supply. Moreover, the problems and perspectives concerning the assessment of beach-cast wrack contribution to the global GHGs emissions were highlighted. Using obtained results, the research then focused on energy recovery of beached seagrass litter as biomass source for anaerobic digestion. It was determined the potential methane production, the average biogas yields using different relative concentrations of seagrass biomass and sewage sludge and salinity effect on anaerobic digestion. Moreover, through genetic analysis, salinity and temperature effect on the anaerobic bacterial community composition was highlighted and the most relevant microbial families for biogas production were determined.

This thesis examines whether capital markets value corporate environmental performance (CEP) as measured by greenhouse gas (GHG) emissions intensity. Core to this examination is the role played by large institutional investors. To fulfil their fiduciary duty to safeguard the long-term interests of their stakeholders, it is argued that institutional investors assign higher values to firms with lower GHG emissions intensity. The findings show a positive relation between firm value and environmental performance in low GHG intensive firms, but the reverse for high GHG intensive firms. Thus, the market appears to treat these two groups of firms differently. The research suggests that most market participants consider reducing GHG emissions a shareholder value destroying activity.

With global emissions estimated at 7.1 Gt CO2 eq per annum, livestock represents 14.5% of all human-induced emissions and it is considered to be the largest source of greenhouse gas (GHG) emissions from the agricultural sector. However, livestock can contribute to convert nutrients from plant biomass into animal-sourced foods, which are rich in essential macro and micronutrients in the form of milk and meat, thereby utilizing resources that cannot otherwise be consumed by humans. Livestock also contributes to global food security and poverty reduction, providing regular income to producers. To achieve a sustainable supply of animal origin food, farmers need, therefore, to identify strategies, in terms of livestock management and feeding, forage systems and feed growing practices, that make the best use of available resources and minimize the potential environmental impact. The studies of the PhD thesis were mainly developed inside the Life project “Forage4Climate”, a four years project, aimed at demonstrating that forage systems connected to milk production can promote climate change mitigation. The aim of the PhD thesis was the evaluation of GHG emission, related to dairy cattle milk production. Specific aims were: • to identify and evaluate the most common forage systems adopted in dairy cow farms in the Po plain, selecting the systems that can improve milk production and soil carbon (C) sequestration reducing emissions per kg of milk; • to evaluate commercial diets related to these different forage systems, in order to directly assess their digestibility, milk and methane (CH4) production; • to identify, through a survey analysis, the main ingredients used in the total mixed ration (TMR) of high producing lactating cows, in order to assess the best diet composition that can lead to high feed efficiency (FE) and low global warming potential (GWP) at commercial farms scale; • in a future perspective of circular economy, to study the exploitation of different inedible human by-products as growing substrates for Hermetia Illucens larvae, in order to substitute soybean meal (SBM) in the livestock diets with insect proteins. A total of 46 dairy cattle farms in Lombardy, Piedmont and Emilia-Romagna were visited, in order to map the main forage systems adopted in each area and to characterize them for GHG emission related to milk production (FPCM, fat and protein corrected milk), and soil organic C stock. The evaluation of environmental impact, in terms of GWP, related to the different forage systems was carried out though a Life Cycle Assessment (LCA) method, using the Software SIMAPRO. Six forage systems based on different forages were identified. The main results in terms of GHG per unit milk were: - CONV - Conventional corn silage system: 1.37 kg CO2 eq/kg FPCM (SD 0.26) - HQFS - High quality forage system: 1.18 kg CO2 eq/kg FPCM (SD 0.13) - WICE - Winter cereal silage system: 1.44 kg CO2 eq/kg FPCM (SD 0.43) - MIXED - Mixed less intensive system: 1.36 kg CO2 eq/kg FPCM (SD 0.26) - PR FRESH- Hay and fresh forage system for Parmigiano Reggiano PDO cheese production: 1.51 kg CO2 eq/kg FPCM (SD 0.23) - PR DRY- Hay system for Parmigiano Reggiano PDO cheese production: 1.36 kg CO2 eq/kg FPCM (SD 0.19). The HQFS system registered the lowest value for GWP, mainly due to the higher milk production per cow (daily FPCM/head). More intensive systems, such as HQFS, confirmed that milk production per cow is negatively related to the impact per kilogram of product, as highlighted also by a PROC GLM analysis. The HQFS system also resulted to be more sustainable, in terms of feed self-sufficiency, as it provided a high amount of dry matter (DM) per hectare, consisting of high digestible forages. Despite the lowest value for GWP, the forage system identified as HQFS showed the lowest organic C soil density: 5.6 kg/m2 (SD 1.1). On the contrary, PR FRESH showed the highest value in terms of organic C density in the soil: 9.7 kg/m2 (SD 2.2), compared with an average of 6.7 kg/m2 (SD 0.88) for the other systems. Further investigations are needed to consider environmental sustainability over a wider spectrum. Enteric CH4 was the main contributor to GWP for all forage systems: on average 45.6% (SD 3.89). For this reason, an in vivo evaluation of CH4 and milk production of lactating dairy cows fed four different diets, obtained from the forage systems identified, was performed. Also digestibility of the diets, energy and nitrogen (N) balance were assessed. Four pairs of Italian Friesian lactating cows were used in a repeated Latin Square design, using individual open circuit respiration chambers to determine dry matter intake (DMI), milk production and CH4 emission and to allow total faeces and urine collection for the determination of N and energy balances. Four diets, based on the following main forages, were tested: corn silage (49.3% DM; CS), alfalfa silage (26.8% DM; AS), wheat silage (20.0% DM; WS), hay-based diet (25.3% DM of both alfalfa and Italian ryegrass hays; PR) typical of the area of Parmigiano Reggiano cheese production. Feeding cows with PR diet significantly increased DMI (23.4 kg/d; P=0.006), compared with the others (on average, 20.7 kg/d), while this diet resulted to be the least digestible (e.g. DM digestibility=64.9 vs 71.7% of the other diets, on average). This is probably the reason why, despite higher DMI of cows fed PR diet, the animals did not show higher production, both in terms of milk (kg/d) and energy corrected milk (ECM; kg/d), compared with the other treatments. The urea N concentration was higher in milk of cows fed WS diet (13.8) and lower for cows fed AS diet (9.24). This was also correlated to the highest urinary N excretion (g/d) for cows fed WS diet (189.5 vs 147.0 on average for the other diets). The protein digestibility was higher for cows fed CS and WS diets (on average 68.5%) than for cows fed AS and PR (on average 57.0%); the dietary soybean inclusion was higher for CS and WS than AS and PR. The higher values for aNDFom digestibility were obtained for CS (50.7%) and AS (47.4%) diets. The rumen fermentation pattern was affected by diet; in particular PR diet, characterized by a lower content of NFC and a higher content of aNDFom as compared to CS diet, determined a higher rumen pH and decreased propionate production as compared to CS. Feeding cows with PR diet increased the acetate:propionate ratio in comparison with CS (3.30 vs 2.44 for PR and CS, respectively). Ruminal environment characteristics (i.e higher pH and higher acetate: propionate ratio), together with increased DMI, led cows fed PR DRY diet to have greater (P=0.046) daily production of CH4 (413.4 g/d), compared to those fed CONV diet (378.2 g/d). However, no differences were observed when CH4 was expressed as g/kg DMI or g/kg milk. Hay based diet (PR) was characterized by the lowest digestible and metabolizable energy contents which overall determined a lower NEL content for PR than CS diet (1.36 vs 1.70 Mcal/kg DM respectively for PR and CS diets). In order to meet the high demand of nutrients needed to assure high milk production, in addition to fodder a lot of concentrates are also used in dairy cows’ TMR. A survey analysis conducted in commercial farms was performed to evaluate the GWP of different lactating cow TMR and to identify the best dietary strategies to increase the FE and to reduce the enteric CH4 emission. A total of 171 dairy herds were selected: data about DMI, lactating cows TMR composition, milk production and composition were provided by farmers. Diet GWP (kg CO2 eq) was calculated as sum of GWP of each ingredient considering inputs needed at field level, feed processing and transport. For SBM, land use change was included in the assessment. Enteric CH4 production (g/d) was estimated using the equation of Hristov et al. (2013) in order to calculate CH4 emission for kg of FPCM. The dataset was analysed by GLM and logistic analysis using SAS 9.4. The results of frequency distribution showed that there was a wide variation among farms for the GWP of TMR: approximately 25% of the surveyed farms showed a diet GWP of 15 kg CO2 eq, 20% of 13 kg CO2 eq and 16.7% of 17 kg CO2 eq. The variation among farms is due to the feed used. Among feed, SBM had the highest correlation with the GWP of the TMR with the following equation: TMR GWP (kg CO2 eq) = 2.49*kg SBM + 6.9 (r2=0.547). Moreover, an inclusion of SBM >15% of diet DM did not result in higher milk production with respect to a lower inclusion (≤15%). Average daily milk production of cows was 29.8 (SD 4.83) kg with a fat and protein content (%) of 3.86 (SD 0.22) and 3.40 (SD 0.14), respectively. The average value of DMI (kg/d) of lactating cows was 22.3 (SD 2.23). The logistic analysis demonstrated that a level of corn silage ≤ 30% on diet DM was associated with higher FE. Almost 50% percent of the farms had an average value of 15.0 g CH4/kg FPCM and about 30% a value of 12.5 g CH4/kg FPCM. The results demonstrated that a lower enteric CH4 production was related to inclusion (% on diet DM) of less than 12% of alfalfa hay and more than 30% of corn silage. Diets with more than 34% of NDF determined higher CH4 production (≥14.0 g/kg FPCM) compared with diets with lower NDF content. On the contrary, a lower enteric CH4 production (<14.0 g/kg FPCM) was related to diets characterized by more than 1.61 NEl (Mcal/kg) and more than 4% of ether extract. The variability in the GWP of TMR shows a significant potential to reduce both the GWP of the diet through a correct choice and inclusion level in the ration of the ingredients (mainly SBM) and the possibility to decrease CH4 enteric emission associated to milk production. Looking forward, in order to evaluate the opportunity of alternative protein sources in the cow diet, to reduce SBM, waste production, and competition between animals and human for crops, a study on the effects of different by-products for Hermetia illucens rearing on the chemical composition of larvae and their environmental impact was conducted, even if, according to the European legislation, today the use of insects as feed source is not possible in ruminants. Regarding climate change, okara and brewer’s grains were the most promising substrates: 0.197 and 0.228 kg CO2 eq/kg of larvae fresh weight, respectively. Results from these studies show the importance of adopting a holistic approach for the assessment of GHG emission from milk production. Therefore, any strategy aimed at mitigating CH4 emission of dairy cows must also take into account the possible effect on the other GHGs, as well as the effect on C sequestration. Based on the studies, it could also be worth evaluating novel feed as a new and useful solution for mitigation of GHG emission related to milk production. The thesis highlights essential differences among forage systems and among feed ingredients of cow ration, confirming that there is room for improvement in sustainability of milk production. These issues should be taken into consideration by farmers, technicians and policy makers, considering that sustainability of livestock production will be one of the priorities for humankind in next future.

Global climate change is becoming a central issue in contemporary science as well as politics. There is a long-lasting debate about the cause of the climate change: anthropogenic activity versus the natural cycle. However, a scientific consensus is coming a conclusion that the contemporary climate change is mainly caused by anthropogenic emissions of the greenhouse gases (GHG), including carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). The main objective of the thesis is the monitoring of such GHG emissions from two ecosystem types: a forest and a rice paddy ecosystem. The forest site is a EMEP experimental station, taking part of the activity of GHG-AGOLU of FP7-JRC project, while the agricultural ecosystem was included in the CarboEurope project and represents also a Level 3 site in the frame of NitroEurope project. The gas monitoring was carried out in 2008. The thesis is composed by 4 chapters, corresponding to specific objectives. The first chapter is relative to the study of the spatial variability of the main soil chemical and physical properties on the basis of which the gas monitoring points were selected. The second and the third chapters are relative to a cropland site. In particular, the second chapter includes monitoring data of CH4, N2O and CO2 fluxes from the paddy field, both during the crop growth season and the fallow period, and the validation results of the DeNitrification DeComposition (DNDC) model, a process-oriented biogeochemical model used for simulating soil gas emissions from the paddy field, are reported. The third chapter contains the study of characterization of microbial community composition using phospholipid fatty acid analysis (PLFA), at eight sampling dates representative of different soil conditions and crop stages and consequently characterized by distinct soil greenhouse emission rates. The fourth and last chapter includes the monitoring study of soil respiration in a forest site and its partitioning into autotrophic and heterotrophic components, applying the indirect linear regression method.

The district heating system (DHS) of Stockholm is one of the largest systems in the world with a total yearly production of 10TWh of heat and 2TWh of electricity (through combined heat and power plants). Large amounts of greenhouse gasses (GHG) are emitted to produce this heat and electricity. Given the goal of the City of Stockholm to reduce the amount of GHG emissions to 3 ton per capita in 2015 and to keep reducing emissions at a similar rate after 2015, it is important to identify the potentials for further reductions. Numerous studies have been done on how the DHS can become more sustainable by installing new generation units. However, also the consumers have an influence on the DHS. After all, it are the consumers who decide when and how much heat or electricity they use. Most former studies and environmental guidelines for the DHS in Stockholm focussed on the producer side. This thesis looks at the consumer perspective of the (heat of the) district heating system. A real-time signal giving the greenhouse gas emissions of individual households is developed and its potential and challenges are discussed. With this signal, households that want to minimise their environmental impact have a tool to decrease their environmental impact by changing their consumption. This can be a first step to transform the DHS to a smart district heating system. First, generic models to calculate the dynamic greenhouse gas intensity of the heat production of district heating and to calculate the greenhouse gas emissions related to the heat consumption of households are suggested. Then the feedback signal with those real-time household emissions is calculated for representative households in Stockholm based on data of Stockholm’s DHS and data about hot tap water consumption in Sweden. Results indicate that variations in household level greenhouse gas emissions mostly reflect changes in consumption but can also result from changes by the producer. Intraday variations are mostly caused by changes in hot tap water consumption, while variations on a timescale of a few days are caused by changes in heating consumption (changing weather) and changes made by the producer (to use different fuels). Then several scenarios are calculated, each scenario looking at the actions a consumer can take to shift or reduce his/her consumption (decrease hot tap water usage, lower indoor temperature etc.). The real-time household emissions are calculated again to see if the signal gives the needed incentives (is the household rewarded for its effort? Does it get further incentives?). It was found that a strong time-incentive (to decrease consumption when it saves most emissions) is missing if the average perspective is used to calculate the emission intensity of the heat production. Also, the results confirmed the finding that the feedback signal might not reflect changes in consumption. Finally, challenges for the signal are discussed. One of the major hurdles is the fact that household consumption of heat (heating and hot tap water) can often not be measured on a household level. Thus, it has to be estimated but it seems very difficult to get this estimation accurate enough to give correct feedback to households, especially about the emissions saved by their efforts to reduce/shift their consumption. Secondly, the time resolution should be chosen well to still get accurate results but not make the signal to data-intensive. Finally, the result is heavily dependent on the chosen methodology (average or marginal perspective? Do you account for the electrical side of the DHS? How about the distribution losses? Etc.).

Mathematical modeling in animal agriculture can be applied at various levels including at the tissue, organ, animal, farm, regional and global levels. The purposes of this research were i) to evaluate models used to estimate volatile fatty acid (VFA) and methane (CH4) production and assess their impact on regional enteric CH4 inventory, and ii) to develop a process-based, whole-farm model to estimate net farm GHG emissions. In the first study, four VFA stoichiometric models were evaluated for their prediction accuracy of rumen VFA and enteric CH4 production. Comparison of measured and model predicted values demonstrated that predictive capacity of the VFA models varied with respect to the type of VFA in rumen fluid which impacted estimated enteric CH4 production. Moving to a larger scale assessment, we examined the enteric CH4 inventory from Manitoba beef cattle (from 1990 to 2008) using two mechanistic rumen models that incorporate VFA stoichiometric models: COWPOLL and MOLLY, and two empirical models: Intergovernmental Panel on Climate Change (IPCC) Tier 2 and a nonlinear equation (Ellis). The estimated absolute enteric CH4 production varied among models (7 to 63%) indicating that estimates of GHG inventory depend on model selection. This is an important consideration if the values are to be used for management and/or policy-related decisions. Development of models at the individual farm component level (animal, soil, crop) does not accurately reflect net GHG emissions generated from the whole production system. We developed a process-based, whole-farm model (Integrated Components Model, ICM), using the existing farm component models COWPOLL, manure-DNDC and some aspects of IPCC to integrate farm components and their associated GHG emissions. Estimates of total farm GHG emissions and their relative contribution using the ICM were comparable to estimates using two other whole-farm models (Integrated Farm System Model and Holos model). Variation was observed among models both in estimating whole-farm GHG emissions and the relative contribution of the different sources in the production system. Overall, whole-farm models are required to explore management options that will mitigate GHG emissions and promote best management practices. However, for full assessment of the production system, other benefits of the system (e.g., carbon sequestration, ecosystem services), which are not part of current whole-farm models, must be considered.

The production of food is responsible for large share of the anthropogenic greenhouse gas emissions. There is a wide range of emissions associated with different food-groups. In particular the production of meat from ruminants causes higher emissions compared to plant-based food. This study compared two different types of meat-free diets (ovo-lacto-vegetarian and vegan) in Sweden and the emission of greenhouse gases that are connected to the aliment and beverages that are consumed in these diets. Dietary records were used to obtain real data on what food is consumed on a weekly basis. On average the food consumed by the vegan sample caused lower emissions that the food consumed by the vegetarian sample. The average vegan diet caused 591 kg CO2e per year whereas the average vegetarian diet caused 761 kg CO2e. The annual difference is thus 170 kg. These findings are in line with existing research although recent studies often used hypothetical diets instead of real data.

Includes bibliographical references (p. 131).
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
(cont.) actions can be made to decrease losses and therefore increase plant efficiencies. As production efficiencies are maximized, fuel use and thus emissions are minimized. From fiscal year 1998 to 2003, the gas turbine efficiency, based on the higher heating value, remained approximately constant at 24%. The heat recovery steam generator effectiveness has decreased 11% from 42.1% to 37.4%. It has been shown that the decrease in the heat recovery steam generator's performance can be attributed to fouling effects on the heat transfer surfaces between the hot exhaust gasses and the water stream. An accurate inventory of MIT's greenhouse gas emissions is a necessary first step in reducing these emissions. This assessment identifies areas with the greatest potential for reducing utility related emissions. This inventory will also allow MIT to continue to evaluate its greenhouse gas emission trends and thus contribute to the emission reduction target the city of Cambridge has created.
This MIT campus emission assessment has been done in response to the City of Cambridge Climate Protection Plan, which is calling for a 20% decrease in greenhouse gas emissions from 1990 levels by the year 2010. This greenhouse gas inventory includes all emissions of carbon dioxide, methane, and nitrous oxide due to utility use from fiscal year 1990 to 2003 and estimates of transportation and solid waste emissions. It accounts for utilities purchased and utilities produced from the MIT Cogeneration Power Plant. A methodology has been developed to allocate the MIT utility plant addition, the assessment includes carbon dioxide emissions due to the MIT commuting population from fiscal year 1999 to 2003, and accounts for equivalent carbon dioxide emissions from solid waste incineration from fiscal year 2000 to 2003. The 20% reduction target from 1990 emission levels sets a cap on campus emissions of 163,830 equivalent metric tons of carbon dioxide per year. At current levels, a 22% decrease in emissions would be required to achieve this target. Emissions released from utility use account for 90% of the campus emissions, with 9.5% attributed to commuters, and 0.5% emissions based on produced electricity, steam, and chilled water. This allows facilities to develop programs that will directly impact the source of highest emissions. In due to campus solid waste. Therefore, reducing the amount of emissions caused by utility production and purchasing would have the largest effect on reducing the total campus greenhouse gas emissions. A thermodynamic availability flow analysis has also been conducted on the gas turbine and heat recovery steam generator system of the MIT cogeneration power plan. Availability losses within the system were targeted and appropriate
by Tiffany Amber Groode.
S.M.

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2008.
Includes bibliographical references (p. 137-147).
The key motivation for this work was the potential impact of alternative jet fuel use on emissions that contribute to global climate change. This work focused on one specific aspect in examining the feasibility of using alternative jet fuels - their life-cycle Greenhouse Gas (GHG) emissions relative to conventional jet fuel. This involved the quantification of the overall GHG emissions of potential alternative jet fuels, from feedstock recovery and transportation, to the production, transportation and utilization of the fuels. The fuels examined in this work included jet fuel and ultra-low sulfur jet fuel from conventional crude, jet fuel from oil sands and oil shale, Fischer-Tropsch jet fuel from natural gas, coal and biomass, and biojet from soy oil and palm oil. By identifying and varying important input parameters, a range of life-cycle GHG emissions for each fuel pathway was derived. From the analyses in this work, only alternative jet fuels from biomass offer substantial life-cycle GHG emissions reductions compared to conventional jet fuel, and that is true only if land use change emissions were negligible. Direct or indirect land use changes from the use of biomass feedstocks (particularly food crops) could potentially increase life-cycle GHG emissions to levels several times above that of conventional jet fuel. A scenario analysis was conducted to examine the amount of biofuel needed to displace conventional jet fuel in 2025 to maintain U.S. aviation GHG emissions at baseline 2006 levels. It was found that the large-scale deployment of biofuels to achieve carbon-neutral U.S. aviation growth through 2025 was limited by feedstock and land availability if current generation biofuels (particularly those made from food crops) were used. Hence, it is important to explore the use of next generation non-food, high yield feedstocks (e.g. algae) that use little land and result in little or no land use change emissions for large-scale biofuel production.
by Hsin Min Wong.
S.M.in Technology and Policy

The second generation bioenergy crops Miscanthus x giganteus and short rotation coppice (SRC) willow are the two main bioenergy crops in the UK and have become an integral part of legislation to provide an alternative to fossil fuels and to reduce national greenhouse gas (GHG) emissions. To reach emission targets, it is estimated that approximately 350,000 ha of land could be made available for bioenergy crops by 2020. Despite the promise of these crops, there have been very few field-studies regarding soil GHG (CO2, CH4 and N2O) emissions and many of the published studies are life cycle analyses or modelled fluxes from soils using default values from the IPCC. The first aim of this research was to quantify the in situ soil GHG budget and to establish the drivers of these GHG fluxes for Miscanthus and SRC willow. The second aim of this research was to provide a more in-depth understanding of C cycling under Miscanthus i.e. litter and roots through two field experiments. Overall, the results from this work confirm minimal emissions of CH4 and N2O from soil under Miscanthus and SRC willow. CO2 flux was found to be the major efflux from soils and it was found in Miscanthus, that the majority of this flux was derived from below ground respiration. Litter played an important part in providing nutrients to the soil, which is vital in systems that are not fertilised. Litter also contributed to SOM accumulation on the soil surface and may promote long-term C sequestration. The results from this work combined with other literature would suggest that these second generation crops offer advantages to first generation crops, but more field-based studies are required to say if they can offer the large-scale GHG savings needed to be a viable alternative to fossil fuels.

Buildings from the record year era are now 40 – 55 years old and in many cases in need of extensive renovation measures. This need for renovation could be seen as an opportunity to achieve overarching sustainability target levels and to perform renovation with a holistic approach. This thesis aims at creating support for the formulation and achievement of adequate environmental targets that relate to overarching Swedish Environmental Quality Objectives. The overall aim of the thesis is to contribute to an understanding of the current situation of environmental management in renovation processes. The scope of this thesis is limited to the aspects energy use and greenhouse gas (GHG) emissions from energy use and material production. This thesis contributes to this aim with a stepwise procedure for evaluation of measures together with a proposal for target levels for three environmental aspects. The first paper appended to this thesis investigates how six Swedish property owners performed renovation projects. From this paper it can be concluded that the main barrier (except economic ones) are characterized by lack of knowledge about overarching objectives and what aspects define a sustainable built environment. The second paper assesses embodied GHG emissions due to material production for the totality of measures needed to reduce operational energy demand per unit heated floor area by 50% compared with 1995. On a national level, embodied GHG emissions are estimated to be 12% of the reduction of GHG emissions achieved by operational energy demand reduction. The final paper appended to this thesis uses a case study building to illustrate a working procedure to identify project-specific target levels for three environmental aspects. In addition, it identifies indicative improvements necessary for the achievement of long-term targets for those aspects, which could be focused and further investigated in later project stages with the help of a long-term plan of action.

QC 20160926

Doctor of Philosophy
Department of Biological and Agricultural Engineering
Ronaldo Maghirang
Emission of greenhouse gases (GHGs), including nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), from open beef cattle feedlots is becoming an environmental concern; however, scientific information on emissions and abatement measures for feedlots is limited. This research was conducted to quantify GHG emissions from feedlots and evaluate abatement measures for mitigating emissions. Specific objectives were to: (1) measure N2O emissions from the pens in a commercial cattle feedlot; (2) evaluate the effectiveness of surface amendments in mitigating GHG emissions from feedlot manure; (3) evaluate the effects of water application on GHG emissions from feedlot manure; and (4) compare the photo-acoustic infrared multi-gas analyzer (PIMA) and gas chromatograph (GC) in measuring concentrations of N2O and CO2 emitted from feedlot manure. Field measurements on a commercial beef cattle feedlot using static flux chambers combined with GC indicated that N2O emission fluxes varied significantly with pen surface condition. The moist/muddy surface had the largest median emission flux; the dry and compacted, dry and loose, and flooded surfaces had significantly lower median emission fluxes. Pen surface amendments (i.e., organic residues, biochar, and activated carbon) were applied on feedlot manure samples in glass containers and evaluated for their effectiveness in mitigating GHG emissions. Emission fluxes were measured with the PIMA. For dry manure, all amendments showed significant reduction in N2O and CO2 emission fluxes compared with the control (i.e., no amendment). For moist manure, biochar significantly reduced GHG emissions at days 10 and 15 after application; the other amendments had limited effects on GHG emissions. The effect of water application on GHG emissions from feedlot manure was evaluated. Manure samples (with and without water application) were placed in glass containers and analyzed for GHG emission using a PIMA. For the dry manure, GHG emissions were negligible. Application of water on the manure samples resulted in short-term peaks of GHG emissions a few minutes after water application. Comparison of the GC and PIMA showed that they were significantly correlated but differed in measured concentrations of N2O and CO2. The PIMA showed generally lower N2O concentrations and higher CO2 concentrations than the GC.

This study evaluates the land use changes and forests in Brazil, focusing on deforestation and its greenhouse gas emissions (GHG). More specifically, it analyses: (i) how the specialized literature integrates land-use changes to GHG emissions into a computable general equilibrium (CGE) framework; and (ii) the economic impacts of halting the deforestation. For this purpose, this study was divided into three independent essays. The first essay is theoretical, and evaluates the state of the art of the integration between land-use change and GHG emissions into CGE models. The second essay, is an empirical study about the economic impacts of zero deforestation in the Amazon Biome. The third essay, evaluates the implication of productivity gains in agriculture on land allocation, GHG emissions and the Brazilian economy. The results highlight the difficulties to integrate land use to its GHG emissions, as well as the effectiveness of the deforestation control in the Amazon to reduce national emissions, although it imposes losses to the economy and boosts regional inequalities. Finally, productivity gains in agriculture in turn, also may reduce the domestic emissions, but with no adverse impacts on the economy. However, such effects are limited, as they expire with the productivity gains.
Este trabalho analisa as mudanças do uso da terra e florestas no Brasil, com ênfase no desmatamento e nas emissões de gases de efeito estufa (GEE). Mais especificamente, avaliam-se: (i) como a literatura especializada realiza a integração entre as mudanças do uso da terra e emissões de GEE no arcabouço dos modelos de equilíbrio geral computável (EGC); (ii) os principais impactos em termos econômicos e de emissões, de políticas de redução do desmatamento. Para isso, esta tese foi dividida em três ensaios independentes. O primeiro ensaio, de caráter teórico, avalia as principais contribuições para a integração das mudanças do uso da terra às emissões de gases de efeito estufa em modelos EGC. O segundo ensaio, é um estudo empírico sobre os impactos econômicos do desmatamento zero no Bioma Amazônia. O terceiro ensaio, analisa as implicações de ganhos de produtividade na agropecuária sobre a alocação de terras, emissões de GEE e economia brasileira. Os principais resultados evidenciam as dificuldades para a integração das mudanças do uso da terra às emissões de GEE, bem como a efetividade do controle do desmatamento na Amazônia em reduzir as emissões nacionais, apesar de impor perdas à economia e intensificar as desigualdades regionais. Já os ganhos de produtividade na agropecuária, também reduziram as emissões domésticas, mas, sem impactar negativamente a economia. Porém, tais efeitos são limitados, uma vez que expiram com os ganhos de produtividade.

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia
The primary aim of this study was to quantify garden waste potential for GHG emissions (with focus on CH4 and N2O); and to identify relationships between these GHG emissions and meteorological variables in different climates. The study was carried out in two countries with contrasting climates and soil structures: Portugal with a Mediterranean climate and Scotland with a hyperoceanic climate. A closed static chamber methodology was used for measure N2O and CH4 gaseous flux in three types of treatments installed in containers kept outdoors: S with soil; S+GW with soil and garden waste layered on top; and GW with only garden waste. The range of N2O fluxes varied on a log-normal scale, ranging from slightly negative values to very high values (3 orders of magnitude). With the exception of the “control” S treatments (maximum flux of 0.54 N2O nmolm-2s-1 at both sites). The percentage of the emitted CO2 equivalent (CO2eq) from the original C content applied to the treatments as garden waste indicates the overall impact on emissions of the composting process. Based on CO2eq global warming potential (GWP) multipliers stated by the IPCC (2014) (25 for CH4 and 298 for N2O), Portugal emitted 28.47% from the treatment S+GW and 11.26% from GW, while the majority of the C remained on soils (>70%). Scotland’s treatment S+GW had a lower CO2eq emission of 11.99%, with 58.47% emitted from the GW treatment. These results show that the overall impact on GWP of composting varies dramatically depending on management, and that CO2 is being converted into considerably high quantities of longer lived GHGs like CH4 and N2O. Cumulative CH4 flux measurements showed sequestration in Portugal and emissions in Scotland, the effects were more pronounced in treatment S for both sites (-210.85 and 209.0519 mgCH4m-2d-1, respectively). The garden waste diminished the emissions for Scotland and hindered the sequestration for Portugal. The contribution of weather conditions from each site was significant and very different relatively to the behaviour of each GHG. Portugal had constant moderate/high temperatures with peaks of rain which stimulated the GHG; Scotland on the other hand had constant rain with low temperatures with occasional rises which was the controlling factor stimulating the GHG
N/A

In the 55th meeting of the International Maritime Organisation's (IMO) Marine Environment Protection Committee (MEPC) in October 2006, the Committee noted that the impact of greenhouse gas emissions from the burning of marine fuel oil on climate change is a serious concern and even though shipping is considered an environmentally friendly mode of transport, it too must change with the times and take action to reduce its own greenhouse gas emissions. If it does not, then shipping will fall behind other industries and become one of the largest producers of greenhouse gas emissions in the future.

Methane (CH4) and carbon dioxide (CO2) are two greenhouse gases and main drivers of global climate change. Lakes are known to be a source of CH4 and CO2 to the atmosphere. While the importance of these emissions is clear, their magnitudes and regulation are still uncertain due to the scarcity of flux measurement data from lakes. Most previous flux measurements have been carried out on lakes <10 km2 and the extrapolations are not representative of large lakes directly. Recent research has led to a growing recognition of the great importance of lakes as a source of emissions. Still, the relationship between environmental variables, lake properties and seasonal changes and the variability between and within lakes raises several question marks. Larger scale studies of greenhouse gases are needed to determine the spatial and temporal dynamics that exist. In this study, a floating chamber method and manual sampling was used to investigate the spatiotemporal variability and influencing variables of CH4 flux and concentration, as well as dissolved inorganic carbon (DIC) and pCO2aq (partial pressure of CO2 in the water). The sampling was conducted during five weeks in September and October 2020 in three large Swedish lakes. Our results generally showed varying CH4 values between the three lakes, indicating that nutrients affect the amount and emission of CH4. A pattern was found where the CH4 was higher near the shore and at a shallower depth. There was a correlation between CH4 concentration and the environmental variables wind speed and air- and water temperatures. Our DIC values were high in two of the lakes and low in one, all lakes’ DIC differed significantly from each other. The pCO2 did not have any difference within the lakes, and there was no difference between the lakes except in one case. Both DIC and pCO2 correlated with air- and water temperature. This study displays the large spatiotemporal variability within and between large lakes and that representative values for large lakes require more measurements under different conditions to distinguish how greenhouse gases emit and flux between lakes and atmosphere.
Metan (CH4) och koldioxid (CO2) är två växthusgaser och stora drivkrafter för globala klimatförändringar. Sjöar är kända för att vara en källa för CH4 och CO2 till atmosfären. Trots att betydelsen av dessa utsläpp är tydlig är deras storlek och reglering fortfarande osäker på grund av brist på flödesmätdata från sjöar. De flesta tidigare flödesmätningarna har utförts på sjöar <10 km2 och det har påvisats att extrapoleringar inte är direkt representativa för stora sjöar. Ny forskning har lett till ett mer allmänt erkännande av sjöars stora betydelse som källa till utsläpp. Trots detta väcker förhållandet mellan miljövariabler, sjöegenskaper, säsongsförändringar och variationen mellan och inom sjöar flera frågetecken. Storskaliga studier om växthusgaser behövs för att bestämma den rumsliga och tidsmässiga dynamiken som finns. I denna studie användes en kammarmetod och manuell provtagning för att undersöka spatiotemporal variabilitet och miljövariabler som kan påverka CH4 flöde och koncentration, samt upplöst oorganiskt kol (DIC) och pCO2aq (partial trycket av CO2 i vattnet). Provtagningen genomfördes under fem veckor i september och oktober 2020 i tre stora svenska sjöar. Våra resultat visade generellt varierande CH4 värden mellan de tre sjöarna, vilket indikerade att näringsämnen påverkar mängd och utsläpp av CH4. Ett mönster noterades där CH4 var högre nära stranden och på ett grundare djup. Det fanns ett samband mellan CH4 koncentration och miljövariablerna vindhastighet och luft- och vattentemperatur. DIC-värdena var höga i två av sjöarna och låga i en, alla sjöarnas DIC skiljde sig signifikant från varandra. pCO2 hade ingen skillnad inom sjöarna, och det fanns ingen skillnad mellan sjöarna utom i ett fall. Både DIC och pCO2 korrelerade med luft- och vattentemperatur. Studien visar den stora spatiotemporala variationen inom och mellan stora sjöar och att representativa värden för stora sjöar kräver fler mätningar under olika förhållanden för att urskilja hur växthusgaser emitterar och flödar mellan sjöar och atmosfär.

Anthropogenic activities perturb the global carbon and nitrogen cycle with large implications for the earth’s climate. Land use activities deliver excess carbon and nitrogen to aquatic ecosystems. In the boreal biome, this is mainly due to forestry and atmospheric deposition. Yet, impacts of these anthropogenically mediated inputs of carbon and nitrogen on the processing and emissions of greenhouse gases from recipient streams and lakes are largely unknown. Understanding the ecosystem-scale response of aquatic greenhouse gas cycling to land use activities is critical to better predict anthropogenic effects on the global climate system and design more efficient climate change mitigation measures. This thesis assesses the effects of forest clearcutting and nitrate enrichment on greenhouse gas emissions from boreal inland waters. It also advances methods to quantify sources and sinks of these emissions. Short-term clearcut and nitrate enrichment effects were assessed using two whole-ecosystem experiments, carried out over four years in nine headwater catchments in boreal Sweden. In these experiments, I measured or modeled air-water fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), combining concentration, ebullition and gas-transfer velocity measurements in groundwater, streams and lakes. By using Swedish national monitoring data, I also assessed broad-scale effects of forest clearcutting by relating CO2 concentrations in 439 forest lakes to the areal proportion of catchment forest clearcuts. To improve quantifications of CO2 sources and sinks in lakes, I analyzed time series of oxygen concentrations and water temperature in five lakes on conditions under which whole-lake metabolism estimates can be inferred from oxygen dynamics given the perturbing influence of atmospheric exchange, mixing and internal waves. The experiments revealed that aquatic greenhouse gas emissions did not respond to nitrate addition or forest clearcutting. Importantly, riparian zones likely buffered clearcut-induced increases in groundwater CO2 and CH4 concentrations. Experimental results were confirmed by monitoring data showing no relationship between CO2 patterns across Swedish lakes and clearcut gradients. Yet, conclusions on internal vs. external CO2 controls largely depended on whether spatially or temporally resolved data was used. Partitioning CO2 sources and sinks in lakes using time series of oxygen was greatly challenged by physical transport and mixing processes. Conclusively, ongoing land use activities in the boreal zone are unlikely to have major effect on headwater greenhouse gas emissions. Yet, system- and scale specific effects cannot be excluded. To reveal these effects, there is a large need of improved methods and design of monitoring programs that account for the large spatial and temporal variability in greenhouse gas dynamics and its controls by abiotic and biotic factors.

Greenhouse gas emission magnitudes, trends, and source contributions are highly uncertain, particularly at sub-national scales. As the world becomes increasingly urbanized, one potential strategy for reducing these uncertainties is to focus atmospheric greenhouse gas measurements in urban areas, where a multitude of emission processes occur, imposing a strong and persistent gradient in the local atmosphere, and contributing a significant fraction of global anthropogenic greenhouse gas emissions. This thesis explores the capabilities and requirements for characterizing and quantifying greenhouse gas fluxes in urban environments using atmospheric measurements and models. The first chapter uses an existing dataset of atmospheric carbon dioxide measurements from Salt Lake City, Utah to assess the capacity of an atmospheric measurement and modeling framework to detect changes in emissions from a city in the context of an emissions verification framework. The results of this work are then used to explore an alternative or complementary measurement strategy of atmospheric column measurements for urban emissions detection, which would be less sensitive than point measurements to the large variability present in urban atmospheres, but would also have more stringent accuracy requirements. The second chapter describes the development and maintenance of a network of greenhouse gas measurement stations in the Boston urban region, which has been continuously running since 2012 and has generated high-quality atmospheric carbon dioxide and methane data that can be used to explore their fluxes across the urban region. The third chapter applies the Boston network data to investigate the magnitude of methane emissions from natural gas infrastructure in the urban region. We find that the natural gas loss rate in 2012-13 was 2.7 ± 0.6 %, two to three times larger than that reported by industry and government. Our findings suggest that natural gas consuming regions may be larger sources of methane than previously thought, and have implications for local and national policies that aim to reduce methane emissions and promote energy-use efficiency. The work presented in this thesis explores general methodological strategies for urban atmospheric measurements and models, and offers example applications of such methods to directed and societally-relevant investigations of urban greenhouse gas emissions.
Engineering and Applied Sciences - Engineering Sciences

Despite the large quantity of research undertaken into the sustainability of food production and transportation systems, there is currently little consensus on the total contribution that greenhouse gas (GHG) emissions make to the overall GHG budget of food production systems. To date, most research has focused on the miles that food has travelled and the energy put into the production of pesticides and fertilisers associated with crop production. Understanding whether food imported from distant countries has a higher GHG footprint than locally produced food remains a very topical issue. Our fundamental lack of knowledge of this issue is limiting policy development in this area. Due to difficulties in field measurements mathematical models such as DNDC (DeNitrification DeComposititon) are being used to predict GHG emissions from different ecosystems. In this thesis, a combination of field measurements and model simulations were used to evaluate GHG emissions from different agricultural production systems undertaken in different countries (UK, Spain and Kenya). This thesis also considered the accuracy of the model by undertaking a sensitivity analysis and evaluating the outputs from different model versions. In addition, the accuracy of using a QIO value approach to predict organic matter degradation was also evaluated. Overall, the results suggested that different model versions gave varying outputs, suggesting that predictions of GHG emissions obtained with models such as DNDC should be treated with caution. However, the model did predict similar results to those obtained in the field, although the model outputs tended to be higher. For comparison of GHG emissions from vegetable types grown in different geographical regions, no specific region produced lower GHG results when averaged across all crops. However, when individual crops were considered, Spain had the highest GHG emissions. The models showed different degrees of sensitivity to different inputs, with some not showing any variation at all. In the Q10 evaluation experiments the Q10 values varied greatly, though all gave results above the standard Q10 of 2. Further research is needed into the accuracy of climate and farm management models, and whether or not it is necessary to compare large data sets when considering different vegetable types and areas.

The awareness of and interest in human activities environmental impact, in the framework of the ongoing climate change, has imposed the need to evaluate waste disposal in terms of greenhouse gases emission, in addition to the productive processes. Constructed wetlands (CW) are a low environmental impact technology to treat wastewater with little or no energy input, increasingly used as a natural-like treatment system that is applicable in urban and/or production contexts. CW systems reproduce the physical, chemical and biological self-purification process of the soil-plant-microorganism systems that characterize aquatic habitats and natural wetlands. Depuration processes, largely operated in these systems by rhizosphere microorganisms that contribute to the reduction of organic and nitrogen wastewater load, determine gaseous compounds release into the atmosphere, some of which act as greenhouse gases, in particular carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The evaluation of greenhouse gases (GHG) emission from CWs, influenced by CW and wastewater types and vegetation and species presence in the beds, has been investigated for about 15 years in CWs in central-northern European Countries, while few experiments, and mostly at laboratory scale, have been conducted in the Mediterranean Basin, and none in Italian CWs. With this in mind, the main aim of this PhD thesis was to evaluate the role of the main components used in the construction of CWs on GHGs emission in the more widespread (full scale or pilot plants) Italian CW systems. For this purpose in two different Italian bioclimatic contexts, Sicily and Veneto, two CW sites were selected that treated urban wastewater and digestate fluid fraction respectively. Particular attention was paid in the research to the role of vegetation on CWs GHGs emission studying different species (Arundo donax L., Phragmites australis (Cav.) Trin. Ex Steud., Cyperus papyrus L., Chrysopogon zizanioides (L.) Roberty and Mischantus x giganteus Greef et Deu.). The results obtained in the Sicilian context showed a species specific effect on CO2 and CH4 emissions. Significantly higher CO2 emissions (median value 16.5 g m-2 d-1) were monitored in the beds vegetated with A. donax, M. giganteus and P. australis, than those vegetated with C. papyrus and C. zizanioides and the unvegetated bed (median value 5.2 g m-2 d-1). The M. giganteus presence in the bed and the absence of vegetation both determined significantly higher CH4 emissions than those monitored with C. papyrus. At the end of the two trial years all vegetated beds showed a CO2(eq) positive balance with better values calculated for A. donax (21.4 kg CO2(eq) m-2), whereas the unvegetated bed showed a net emission into the atmosphere of 5.5 kg CO2(eq) m-2. The CW system in Veneto that treated digestate fluid fraction coming from an anaerobic digester for biogas production fed with livestock slurry and energy crops biomass, showed no significant depuration performance differences between P. australis and A. donax vegetation, but the latter did not regrow in the second year, thus determining a significant increase in CH4 emissions. The digestate fluid fraction, characterized by a high organic matter and nitrogen content, can also be considered as an agronomic resource in a region where land availability is not a limiting factor and considering the limit on its spreading imposed by Directive 91/676/EEC of 12 December 1991. In fact, the intensive mineral fertilization and deep soil tillage that were typical of Italian agriculture in the second half of last century, have caused some problems in the agro-ecosystems, including the loss of organic carbon. The addition of soil organic matter and the use of agricultural techniques to directly or indirectly reduce CO2 emissions, may be a response to soil organic carbon loss with a positive effect on the environment. Taking this into account, an additional investigation topic of the PhD research has been to evaluate the effect exerted by the digestate fluid fraction application on agricultural soil CO2 emissions by: 1) soil texture (sandy loam vs. clay loam) and preparatory tillage (plowing vs ripping) after splash-plate spreading; 2) the digestate fluid fraction injection depth into the soil (10, 25 and 35 cm). The results have shown a CO2 emission peak one hour after digestate distribution and emission values reaching those of un-amended soils after 3 days, using both application methods. Considering the splash-plate technique in the two weeks following spreading, significantly higher CO2 emissions were found in sandy loam than clay loam soil, the preparatory soil tillage showed no significant effect. Digestate fluid fraction soil injection determined after one hour of application, an opposite trend with injection depth, with lower emissions at increasing depth.
La consapevolezza e l'interesse verso l'impatto ambientale delle attività antropiche ha imposto la necessità di valutare in termini di emissione di gas ad effetto serra, oltre ai processi di produzione, anche i processi di gestione e smaltimento dei reflui prodotti. Per il trattamento delle acque reflue la fitodepurazione, una tecnologia a ridotto impatto ambientale con scarsi o nulli input energetici, si sta sempre più diffondendo come sistema di trattamento naturale applicabile in vari contesti urbani e/o produttivi. Essa si basa sulla riproduzione dei processi fisici, chimici e biologici di autodepurazione del sistema suolo-piante-microrganismi che caratterizzano gli habitat acquatici e le zone umide naturali. I processi depurativi, in larga parte operati dai microrganismi che si sviluppano nella rizosfera e che in questi sistemi contribuiscono alla riduzione del carico organico e azotato delle acque reflue, determinano il rilasciano in atmosfera di diversi composti gassosi alcuni dei quali ad effetto serra, in particolare anidride carbonica (CO2), metano (CH4) e protossido di azoto (N2O). La valutazione delle emissioni in atmosfera determinate da questi impianti, influenzate dalla tipologia impiantistica, dalla natura/tipologia dell'acqua reflua trattata e dalla presenza e specie vegetale impiegata, è studiata in Europa da circa 15 anni in impianti perlopiù siti nei Paesi del centro-nord, mentre poche sperimentazioni, e per lo più a scala di laboratorio, sono state condotte nell’area del Bacino del Mediterraneo; e con nessuno studio presso impianti di fitodepurazione Italiani. In considerazione di quanto sopra, scopo principale del lavoro di tesi è stato quello di valutare il ruolo delle diverse componenti dei sistemi di fitodepurazione maggiormente diffusi in Italia (in scala reale o pilota) nelle emissioni di gas serra. A tale scopo sono stati scelti due siti situati in due differenti contesti bioclimatici italiani, Sicilia e Veneto, che trattano rispettivamente acque reflue urbane e frazione fluida di digestato. Particolare attenzione è stata rivolta al ruolo della componente vegetale del sistema sulle emissioni studiando differenti specie adatte alla fitodepurazione (Arundo donax L., Phragmites australis (Cav.) Trin. ex Steud., Cyperus papyrus L., Chrysopogon zizanioides (L.) Roberty e Mischantus x giganteus Greef et Deu.). Relativamente alle specie vegetali indagate, i risultati ottenuti nel contesto siciliano, hanno mostrato emissioni di CO2 e CH4 specie-specifiche con flussi di CO2 significativamente maggiori (mediana 16.5 g m-2 d-1) in presenza di A. donax, M. giganteus e P. australis, rispetto a C. papyrus e C. zizanioides e allo stesso letto non vegetato (mediana 5.2 g m-2 d-1). L’impiego di M. giganteus e l’assenza di vegetazione hanno determinato emissioni significativamente maggiori di CH4 rispetto a quelle monitorate con C. papyrus. Alla fine dei due anni di sperimentazione tutti i letti vegetati hanno mostrato un bilancio positivo della CO2(eq) con i valori più positivi calcolati per A. donax (21.4 kg CO2(eq) m-2) mentre il sistema non vegetato ha mostrato una emissione netta in atmosfera di 5.5 kg CO2(eq) m-2. In Veneto, nell’impianto di fitodepurazione per il trattamento della frazione fluida del digestato proveniente da un impianto di digestione anaerobica di reflui zootecnici e colture dedicate, sebbene la P. australis e l’A. donax non hanno mostrato differenze significative nelle prestazioni depurative, quest’ultimo dopo lo sfalcio non ha ricacciato nel secondo anno di attività, determinando un incremento significativo nelle emissioni di CH4 rispetto ai vaori monitorati impiegando P. australis. La frazione fluida di digestato, caratterizzata da un buon contenuto di sostanza organica e di azoto, può essere considerata anche come una risorsa da valorizzare mediante una sua gestione agronomica in un contesto dove la disponibilità di suolo non è un fattore limitante e tenuto conto dei limiti di sversamento imposti dalla Direttiva 91/676/CEE del 12 dicembre 1991. Infatti l’intensiva fertilizzazione minerale e le profonde lavorazione dei suoli agrari, caratteristiche dell’agricoltura italiana della seconda metà del secolo scorso, hanno determinato alcune criticità agli agro-ecosistemi, fra cui la perdita di carbonio organico. L’apporto di sostanza organica al suolo e l’impiego di tecniche agronomiche volte a ridurre le emissioni di CO2, sia direttamente che indirettamente, possono rappresentare una valida risposta alla perdita di carbonio organico con un effetto positivo anche sull’ambiente. Tenuto conto di ciò, un ulteriore settore di indagine delle attività di ricerca del dottorato è stato quello di valutare l’effetto esercitato dall’applicazione della frazione fluida di digestato sulle emissioni di CO2 da suolo agrario in relazione ai seguenti fattori: 1) dalla tessitura del suolo (franco sabbiosa vs franco argillosa) e dalle lavorazioni preparatorie del terreno adottate (aratura vs rippatura) a seguito dello spandimento superficiale; 2) dalla profondità di interramento (10, 25 e 35 cm) a seguito dell’apporto al suolo del digestato tramite iniezione al suolo. I risultati ottenuti hanno mostrato, con entrambe le metodologie di applicazione, un picco di emissione di CO2 dopo un’ora dalla distribuzione ed emissioni che ritornano ai valori del suolo non ammendato dopo 3 giorni. Considerando la distribuzione in superficie, nelle due settimane successive allo spandimento, la tessitura franco sabbiosa ha determinato maggiori emissioni di CO2 rispetto alla tessitura franco argillosa mentre nessun effetto significativo ha mostrato il tipo di lavorazione preparatoria del terreno. L’iniezione al suolo del digestato ha determinato nella prima ora post-distribuzione flussi di CO2 in atmosfera con un andamento inverso alla profondità di interramento con minori emissioni al crescere della profondità.

Many studies have recently reported estimates of greenhouse gas (GHG) emissions and associated potential climate impacts of biofuel and natural gas (NG) use. U.S. corn ethanol production keeps increasing under federal mandates, and NG production soars due to successful tapping of unconventional resources in North America, particularly shale gas. Numerous life cycle assessment (LCA) studies document technology specific corn ethanol and NG GHG estimates. The estimates often include all life cycle stages from fuel supply to combustion, and point out potential for emissions reductions. Several studies suggest that using GHG emissions as an evaluation metric underestimates corn ethanol’s radiative forcing (RF) impact – a precursor and indicator for global temperature change – by 10-90% over the next few decades. This emissions timing effect may overestimate (i) ethanol’s climate benefits over gasoline and (ii) the effectiveness of U.S. policies mandating and subsidizing ethanol. This work revisits the above studies, and builds upon existing models to quantify RF impacts across the corn ethanol life cycle. The emissions timing factor (ETF) is significantly smaller than previous estimates (2-13% depending on the chosen impact time frame), and the effect is dwarfed by uncertainty in the GHG emissions estimates. Nevertheless, ETF reduces ethanol’s probability of meeting the federal target of 20% GHG reduction relative to gasoline from 53% (according to EPA GHG estimates) to 7-29%. However, the small potential climate impacts from U.S. ethanol use may not actually be observable based on estimated initial increases in global average surface temperature of < 0.001 °C. About 25% of global primary energy production comes from NG, whose life cycle GHG emissions and potential future climate impacts from substituting coal are highly uncertain due to fugitive methane (CH4) emissions from the NG industry. Accurately quantifying the NG fugitive emissions (FE) rate – the percentage of produced NG, mainly CH4 and ethane (C2H6) – released to the atmosphere is challenging due to the size and complexity of the NG industry. Recent LCA estimates suggest that the current NG FE rate could be as high as 8% and 6%, from shale and conventional NG, respectively, and other bottom-up studies indicate even higher rates several decades ago. This work analyzes possible ranges of the global average NG FE rate based on atmospheric CH4, C2H6, and carbon isotope (δ13C-CH4) measurements recorded since 1984, and top-down modeling of their sources and sinks. Box-model, δ13C-CH4mass balance, and 3D-modeling results agree on best estimate NG FE rates of 3-5% (of dry NG production and dry NG composition) globally over the past decade, and 5-8% around 1990. Upper bound FE rates are 5% and 7% in 2010 and 2000, respectively. Best estimate and upper bound values may be overestimated because both assume lower bound emissions from oil and coal production as well as complete absence of natural hydrocarbon seepage. While LCA studies are useful for identifying processes with the greatest NG FE reduction potential, the recent high bottom-up estimates do not appear representative of the U.S. national average based on top-down modeling results. Given the steadily declining NG FE rates one may expect that further emissions abatement is possible if industry practices are further improved.

Climate Change is fast becoming a reality that is gripping the developed and developing world, its economies and people. Erratic weather conditions, rising temperatures and monsoon like weather has scientists asking questions and some countries moving swiftly to ensure that their economies remain stable whilst trying to deal with climate change. South Africa has begun to play an influential role, as a developing country, in international negotiations on climate change. South Africa is not under legal obligation to reduce greenhouse gas emissions but as a large contributor of greenhouse gases in Africa and globally, South Africa has a moral obligation to reduce its emissions. Although not obliged to make commitments to reduce emissions, government has seen the importance of considering long term mitigating actions to play its part to reduce emissions. It can be argued that the policies and strategies being considered are not enough to hold large industries in South Africa more accountable for their own historic responsibility. The “culprits”, the large industries should be more accountable. A tax on greenhouse gas emissions (Carbon Emissions Tax) based on the amount of emissions a corporation produces, should be weighed up as this may be the way towards accountability. South Africa is faced with the task of juggling development (which is largely based on fossil fuels), the eradication of poverty and climate change. There should be an economic policy in place to address and balance these three aspects, in a positive way. According to this study an appropriate tax on emissions may help South Africa in its mitigating actions of reducing greenhouse gas emissions, whilst allowing the country to continue on its path of social and economic development. AFRIKAANS : Klimaatsverandering word vinnig ‘n realiteit wat die ontwikkelde en ontwikkelende wêreld, hul ekonomiese welsyn en bevolking in sy greep het. Wisselvallige weersomstandighede, stygende temperature en reënseisoenagtige weer word deur wetenskaplikes bevraagteken en sommige lande neem voorbehoedende stappe om te verseker dat die ekonomie standvastig bly terwyl hul klimaatsverandering hanteer. Suid-Afrika begin ‘n invloedryke rol speel as ontwikkelende land in internasionale verhandelings oor klimaatsverandering. Suid-Afrika verkeer nie onder enige wetlike verpligting om die vrylating van kweekhuisgasse te verminder maar omdat dit grootliks bydra tot die vrylating van kweekhuisgasse in Afrika en wêreldwyd, het Suid-Afrika ‘n morele verpligting om sy vrylating te beheer. Hoewel nie verplig om enige onderneming te maak om vrylatings te beheer, het die regering die belangrikheid van langtermyn behoedende aksie gesien, en te oorweeg sodat die regering ‘n rol speel om vrylatings te verminder. Dit kan gesê word dat beleid en strategieë wat tans oorweeg word nie voldoende is om die groot nywerhede in Suid-Afrika meer aanspreeklik te maak vir hul historiese verantwoordelikheid. Die “skuldiges”, die groot nywerhede behoort meer toerekeningsvatbaar te wees. Belasting op die vrylating van kweekhuisgas (Koolstof Vrylatingsbelasting), gegrond op die hoeveelheid vrylating wat ‘n korporasie vervaardig, moet opgeweeg word aangesien dit dalk die weg is tot aanspreeklikheid. Suid-Afrika het die taak om ontwikkeling op te weeg (grootliks gebasseer op fossielbrandstof), die uitwissing van armoede en klimaatsverandering. Daar behoort ‘n ekonomiese beleid te wees om hierdie drie aspekte op positiewe wyse te balanseer. Volgens dié studie sou ‘n toepaslike belasting op vrylatings dalk bydra daartoe om Suid-Afrika by te staan om behoedende aksie te neem om kweekhuisgas vrylating te verminder, terwyl die land sy sosiale en ekonomiese ontwikkeling voortsit. Copyright 2011, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Karrappan, A 2011 A carbon emissions tax as a mitigating strategy for reducing greenhouse gas emissions in South Africa, MCom dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-03052012-165638 / > F12/4/144/gm
Dissertation (MCom)--University of Pretoria, 2011.
Taxation
unrestricted

The dynamic mutual relationship between the Regional Greenhouse Gas Initiative (RGGI) carbon permit price and energy prices in the U.S. is examined. Results show that the RGGI and electricity markets are not closely linked, although the carbon permit price is usually closely interrelated with energy prices. The loose relationship between the RGGI and electricity markets can be explained by the recent low carbon credit demand which stems from the low greenhouse gas (GHG) emissions existent in the particular area covered by the RGGI. The low GHG emissions result from fuel switching due to recent low natural gas prices. Unlike the European Union Emissions Trading Scheme, natural gas is the key driver of the RGGI system.

This thesis investigates the potential of improved control to reduce greenhouse gas (GHG) emissions resulting from existing wastewater treatment plants (WWTPs), and demonstrates that significant reductions can be achieved without the need for extensive redesign of treatment processes and without increasing operational costs. An emissions model is developed for use in this study, informed by an in-depth analysis of existing state-of-the-art methods and models for estimating GHG emissions, taking into account their suitability for dynamic modelling and WWTP control strategy optimisation. Through the use of local and global sensitivity analysis tools, sources of uncertainty in the modelling of GHG emissions from wastewater treatment are investigated, revealing critical parameters and parameter interactions; these interaction effects have not been considered in previous studies and thus provide a better understanding of WWTP model characterisation. A key finding is that uncertainty in modelled nitrous oxide (N2O) emissions is the primary contributor to uncertainty in total GHG emissions, due largely to the interaction effects of nitrogen conversion modelling parameters. Further local and global sensitivity analysis is used to investigate the effects of adjusting control handle values on GHG emissions, revealing critical control handles and sensitive emission sources for control. This knowledge assists with the following control strategy development and aids an efficient design and optimisation process. Sources with the greatest variance in emissions, and therefore the greatest need to monitor, are also identified. It is found that variance in total emissions is predominantly due to changes in direct N2O emissions and selection of suitable values for wastage flow rate and aeration intensity in the final activated sludge reactor is of key importance. Sets of Pareto optimal operational and control parameter values are derived using a multi-objective genetic algorithm, NSGA-II, with objectives including minimisation of GHG emissions, operational costs and effluent pollutant concentrations, subject to legislative compliance. It is found that multi-objective optimisation can facilitate a significant reduction in GHG emissions without the need for plant redesign or modification of the control strategy layout, but there are trade-offs to consider: most importantly, if operational costs are not to be increased, reduction of GHG emissions is likely to incur an increase in effluent ammonia and total nitrogen concentrations. Alternative control strategies are also investigated and it is concluded that independent control of dissolved oxygen in each aerated activated sludge reactor is beneficial. Optimised solutions are also assessed with respect to their reliability, robustness and resilience, taking into account the effects of influent perturbations and sensor failures on effluent quality and GHG emissions. This reveals that solutions predicted to achieve the most significant reductions in GHG emissions and operational costs under existing design conditions may perform poorly in reality when subject to threats. Dissolved oxygen setpoints which correspond with unacceptable effluent quality reliability and decision variables which should not be considered in future optimisation due to their negative impacts on reliability, robustness and resilience are also identified. Lastly, guidelines for the development of control strategies to reduce GHG emissions are presented. These address GHG emission sources, key control handles and decision variables, choice of control strategy, optimisation and detailed design, and model limitations and uncertainties.