Ante o intenso uso global dos combustíveis fósseis, com suas massivas emissões de gases de efeito estufa (GEE), hoje, a energia é o maior forçamento antropogênico das mudanças climáticas. Como parte desses combustíveis, o petróleo é a fonte de energia mais utilizada e o segundo maior emissor de GEE do mundo, ainda permanecendo de uso predominante no longo prazo. Visando à mitigação dessas mudanças do clima, desenvolvem-se no mundo três estratégias principais: eficiência energética; intensificação do uso das fontes renováveis; e a captura e estocagem geológica de carbono (CO2) carbon capture and storage (CCS). Estudos recentes demonstram que, por meio da recuperação secundária especial de petróleo enhanced oil recovery (EOR) , com injeção miscível de CO2 (EOR-CO2 miscível), pode-se estocar geologicamente até 320 Gt CO2, produzindo-se, em paralelo, um trilhão de barris adicionais de óleo, globalmente. A EOR-CO2, já praticada há cerca de 40 (quarenta) anos unicamente para aumentar a recuperação de petróleo, também passou a ser o método de CCS de maior potencial global de geosequestro de carbono. Este trabalho investiga as emissões antropogênicas da energia, as características do sistema energético do petróleo, abarcando as condições e os mecanismos de miscibilidade e de sequestro geológico de carbono no atual cenário tecnológico da EOR-CO2, estabelecendo a sua conexão com a mitigação das mudanças climáticas através da CCS. O trabalho conclui que a EOR-CO2 é um método eficiente para a estocagem de carbono ao mesmo tempo em que aumenta o fator de recuperação. Hoje, com potencial global para sequestrar 85 Mt CO2/ano, ele já é responsável por 58% de todo o carbono geosequestrado no mundo; nas Américas, alcança 91%. Além de aumentar a eficiência no uso desse recurso disponível na biosfera, por extrair centenas de bilhões de barris adicionais de óleo, a EOR-CO2 transformou o sistema energético do petróleo num sumidouro de carbono com novo e relevante papel na mitigação das mudanças climáticas. / The intense using of fossil fuels on worldwide scale, with their massive greenhouse gas (GHG) emissions, makes energy the greatest anthropogenic cause of climate change. Petroleum is and will remain, in the long term, the most used energy source and the second greatest emitter of GHG of the world. With the goal of mitigating climate changes, three major worldwide strategies are being applied: energy efficiency, increase using of renewable sources and carbon capture and storage (CCS). Recent studies show that, by enhanced oil recovery (EOR), with miscible injection of CO2 (miscible CO2-EOR), it is possible to store geologically up to 320 Gt of CO2, producing, at the same time, a trillion of additional oil barrels, globally. CO2-EOR, already used for 40 years in order to increase oil recovery, has also becomes the CCS method with the greatest global potential of geological carbon storage. This work aims to investigate the contribution of the petroleum energy system to mitigate climate change, with a greater efficiency in its recovery (optimizing the utilization of energy deposits available in the biosphere) at the same time that it allows the capture and geological storage of CO2 in the reservoir. EOR-CO2 is an effective means for carbon storage. With its capability to store 85 Mt of CO2 per year, it is already responsible for 58% of all carbon geosequestration in the world. In the Americas, reaches 91 %. EOR-CO2 increases oil production, in the order of hundreds billions barrels, and transforms the oil energy system in a carbon sink with a new and important role in climate change mitigation.

Higher atmospheric concentration of greenhouse gases (GHG) such as carbon dioxide and methane has contributed to an increase in Earth's mean surface air temperature and caused climate changes. This largely reflects the increase in global energy consumption, which is heavily dependent on oil, natural gas, and coal. If not controlled, the combustion of these fossil fuels can also produce high levels of nitrogen oxides (NOx) and soot emissions, which adversely affect the air quality. New and extremely challenging fuel efficiency and exhaust emissions regulations are driving the development and optimisation of powertrain technologies as well as the use of low carbon fuels to cost-effectively meet stringent requirements and minimise the transport sector's GHG emissions. In this framework, the dual-fuel combustion has been shown as an effective means to maximise the utilisation of renewable liquid fuels such as ethanol in conventional diesel engines while reducing the levels of NOx and soot emissions. This research has developed strategies to optimise the use of ethanol as a substitute for diesel fuel and improve the effectiveness of dual-fuel combustion in terms of emissions, efficiency, and engine operational cost. Experimental investigations were performed on a single cylinder heavy-duty diesel engine equipped with a high pressure common rail injection system, cooled external exhaust gas recirculation, and a variable valve actuation system. A port fuel injection system was designed and installed, enabling dual-fuel operation with ethanol energy fractions up to 0.83. At low engine loads, in-cylinder control strategies such as the use of a higher residual gas fraction via an intake valve re-opening increased the combustion efficiency (from 87.7% to 95.9%) and the exhaust gas temperature (from 468 K to 531 K). A trade-off between operational cost and NOx reduction capability was assessed at medium loads, where the dual-fuel engine performance was less likely to be affected by combustion inefficiencies and in-cylinder pressure limitations. At high load conditions, a Miller cycle strategy via late intake valve closing decreased the in-cylinder gas temperature during the compression stroke, delaying the autoignition of the ethanol fuel and reducing the levels of in-cylinder pressure rise rate. This allowed for the use of high ethanol energy fractions of up to 0.79. Finally, the overall benefits and limitations of optimised ethanol-diesel dual-fuel combustion were compared against those of conventional diesel combustion. Higher net indicated efficiency (by up to 4.4%) combined with reductions in NOx (by up to 90%) and GHG (by up to 57%) emissions can help generate a viable business case of dual-fuel combustion as a technology for future high efficiency and clean heavy-duty engines.

Abstract available in the Lancet.

No description available.

The passage of AB 32 in 2006 initiated the need for city planners in California to consider the quantification of greenhouse gas emissions at the community level in order to develop policies and programs to reduce emissions in the future. Although local jurisdictions are not required to quantify and report emissions at this time, the AB 32 Climate Change Scoping Plan recommended a reduction goal for local governments of 15 percent below today’s levels by 2020 to ensure consistent reduction goals at the state and local levels. ICLEI-Local Governments for Sustainability initiated the Cities for Climate Protection (CCP) campaign in 1993, which provides a framework for local governments to develop a baseline emissions inventory and identify reduction measures as part of a climate action plan. This inventory is developed under the framework of the CCP campaign. A review of the current practice of local greenhouse gas emissions inventories in California identified significant consistencies across jurisdictions in the overall framework of community and municipal emissions inventories– due largely to the framework provided by the CCP campaign. However, data sources used and methods of measurement vary greatly among local inventories, which limit the ability to compare results. This highlights the need for a standard reporting protocol for community inventories. This baseline emissions inventory document provides the technical information necessary for the city to set reduction goals and facilitates the development of the climate action plan outlining policies and programs that when implemented would reach those goals.

Stormwater runoff from existing impervious surfaces needs to be managed to protect downstream waterbodies from hydrologic and water quality impacts associated with development. As urban expansion continues at a rapid pace, increasing impervious cover, and climate change yields more frequent extreme precipitation events, increasing the need for improved stormwater management. Although green infrastructure such as bioretention has been implemented in urban areas for stormwater quality improvements and volume reductions, these systems are seldom monitored to validate their performance. Herein, we evaluate flow attenuation, stormwater quality performance, and nutrient cycling from eight roadside bioretention cells in their third and fourth years of implementation in Burlington, Vermont. Bioretention cells received varying treatments: (1) vegetation with high-diversity (7 species) and low-diversity plant mixes (2 species); (2) proprietary SorbtiveMediaTM (SM) containing iron and aluminum oxide granules to enhance sorption capacity for phosphorus; and (3) enhanced rainfall and runoff (RR) to certain cells (including one with SM treatment) at three levels (15%, 20%, 60% more than their control counterparts), mimicking anticipated precipitation increases from climate change. Bioretention water quality parameters monitored include total suspended solids (TSS), nitrate/nitrite-nitrogen (NOx), ortho-phosphorus (Ortho-P), total nitrogen (TN) and total phosphorus (TP), which were compared among bioretention cells’ inflows and outflows across 121 storms. Simultaneous measurements of flow rates and volumes allowed for evaluation of the cells’ hydraulic performances and estimation of pollutant load and event mean concentration (EMC) removal. We also monitored soil CO2 and N2O fluxes, as they represent a potential nutrient loss pathway from the bioretention cells. We determined C and N stocks in the soil media and vegetation, which are critical design elements of any bioretention, to determine the overall C and N balances in these systems. Significant average reductions in effluent stormwater volumes and peak flows were reported, with 31% of the storms events completely captured. Influent TSS loads and EMCs were well retained by all cells irrespective of treatments, storm characteristics, or seasonality. Nutrient removal was treatment-dependent, where the SM treatments consistently removed P loads and EMCs, and sometimes N as well. The vegetation and RR treatments mostly exported nutrients to the effluent. We attribute observed nutrient exports to the presence of excess compost in the soil filter media. Rainfall depth and peak inflow rate undermined bioretention performance, likely by increasing pollutant mobilization through the filter media. While the bioretention cells were a source of CO2, they varied between being a sink and source of N2O. CO2 fluxes were orders of magnitude higher than N2O fluxes. However, soil C and N, and plant C and N in biomass was seen to largely offset respiratory CO2-C and biochemical N2O-N losses from bioretention soil. The use of compost in bioretention soil media should be reduced or eliminated. If necessary, compost with low P content and high C: N ratio should be considered to minimize nutrients losses via leaching or gas fluxes. In order to understand trade-offs stemming from compost amendments, we conducted a laboratory pot study utilizing switchgrass and various organic soil amendments (e.g., different compost types and coir fiber) to a sandy loam soil contaminated with heavy metals and studied potential nutrient leaching and pollutant uptake. Addition of organic amendments significantly reduced metal bioavailability, and improved switchgrass growth and metal uptake potential. While no differences in soil or plant metal uptake were observed among the amendments, significant differences in nutrient leaching were observed.

Exposure to air pollution is a leading cause of premature death worldwide. An increasing part of air pollution results from industrial activity and the production of energy. When unregulated, emissions of air pollutants constitute a market failure as polluters do not bear the costs imposed on society at large. My dissertation develops empirical methods to test the effectiveness and distributional effects of environmental policies designed to address this externality. To do so, I apply econometrics and data science techniques on large datasets from cutting-edge research in environmental science and engineering that I match with microeconomic data. The dissertation makes use of new datasets on air pollution derived from satellite imagery, as well as micro-level data on power plant operations and housing transactions across the United States. Chapter 1 assembles unit-level data to disentangle the factors that led US power plants to achieve the unprecedented reductions in emissions of the past fifteen years. I calculate the costs incurred by the electricity generation sector and compare these costs to the correspond- ing health benefits. In hedonic regressions, I use these shocks to emissions to estimate the demand for clean air with micro-level data on housing transactions. Chapter 2 studies the causal impacts and evaluates the distributional effects of stringent emissions markets that were put in place to target power plants emissions of air pollutants in the Eastern US. Chapter 3 uses new satellite imagery to document the inequalities in the exposure to air pollution in American cities and their recent evolutions.

Water and energy are two of the most important resources for societal prosperity and economic development. It is clear that water and energy are intrinsically linked together and depend on one another in modern society. To date, however, efforts on water-energy nexus concentrate on quantifying the energy use in water cycle or the water use in energy production. From management perspective, water and energy are still managed separately. Little work has been done to investigate the impacts of the management options associated with one resource on the other and examine the integrated water and energy management options. Accordingly, the overall goal of this study is to examine the integrated management options for long-term regional water and energy resources management with consideration of their interactions through a system dynamics approach. System dynamics is based on systems thinking, which focuses on the system structure and offers a deeper insight into problems. It can link ecological, human, and social elements of water and energy systems in one modeling platform to investigate their interactions A four-step system dynamics modeling process was used in this study, which includes problem articulation, model formulation, model testing, and scenario design and simulation. Tampa Bay region was chosen as the study area, which is located on the west central coast of Florida and estuary along the Gulf of Mexico. This study considered a 100-year time scale with monthly interval, the first 30 years of which are used for model validation and the rest of which are for simulation. In order to investigate the interrelationship between water and energy systems, two sub-models (i.e., water sub-model and energy sub-model) were developed first. The water sub-model is composed of sectoral water demand (agriculture, industry, municipality, and energy sector), water supply (surface water, groundwater, reclaimed water, and water imports), and water quality and energy consumption associated with water supply. The result shows that surface water level increases by 1.32~1.39% when considering water quality and 1.10~1.30% considering both water quality and energy consumption. There is a slight decrease in groundwater storage (0.02~0.08%) compared with the reference behavior. The result also reveals that water conservation education is the most effective option to reduce the freshwater withdrawals (~17.3%), followed by rebates on indoor water-efficient appliances (~15.4%). Water loss control has a high potential to reduce freshwater withdrawals but it is not effective currently due to limited budget. The implementation of minimum surface water level reduces the surface water withdrawal by 26 MGD (million gallons per day) and requires alternative water supply sources to meet the water demands. The energy sub-model consists of sectoral energy demand (agriculture, industry, municipality, and water sector), energy supply (coal, natural gas, oil, and electricity), and greenhouse gas (GHG) emissions and water pollution associated with energy supply. The result finds that cost of fuels is the primary concern of determining the energy mix for power generation. The current electricity mix in the study area consists of 35.4% fuels from coal, 44.6% from natural gas, and 20% from oil. When considering the environmental impacts associated with energy supply, this percentage of coal reduces to 10.6%, and GHG emissions and water pollution can be reduced by 22% and 43% accordingly. The result also shows that energy price is most effect of reducing the demand (~16.3%), followed by energy conservation education (~10.6%). Rebates on household appliances are the least effective option (~3.6%) due to consumers' low willingness to pay. Combining the supply decision incorporating environmental impacts and the demand option of energy price increase, the reductions of GHG emissions and water pollution can reach 37% and 55%, respectively. The integrated model is developed by linking the water and energy models through the interactions between water and energy systems identified by the system archetypes. The result shows that water demand is reinforced by energy demand, and vice versa. This growth, however, is limited by water and energy availability. The result also reveals that some decisions to solve the problems of one resource result in the problems of the other resource. The increase of water price is one of these, which decreases the water demand by 24.3% but leads to increase of the energy demand by 1.53% due to the use of reclaimed water. Rebates on indoor water-efficient appliances are effective to reduce both water and energy demands largely due to the household energy use in water heating. In addition, this study demonstrates that integrated management options can improve the uses of water and energy, but decisions without considering each other may lead to more issues. For example, reclaimed water, a supply management option considering the energy, can increase the water balance index by 27.3% and the energy balance index by 0.14%; it can also reduce the water pollution by 11.76% and the GHG emissions by 13.16%. Seawater desalination, a supply management option without integrated consideration, intends to decrease the water shortage but eventually increases the water balance index by 29.7%. It also causes the increases in water pollution and GHG emissions by 89.79% and 14.53%, respectively. Similarly, solar energy presents the advantage in increasing the balance indices and reducing the environmental impacts. This study is an initial attempt to link water and energy systems to explore integrated management options. It is limited by the data availability, assumptions for model simplification, and lack of consideration of climate change. The recommendations for future study include (a) employing a more accurate projection or representation of precipitation, (b) testing the energy model with local data, (c) considering water and energy allocation between different users under shortages, (d) examining the environmental impacts associated with bay water withdrawal for power generation, (e) investigating the water and energy use under climate change, and (f) involving stakeholders early in model development and continuous participation in policy analysis.

The energy consumption and greenhouse gas (GHG) emissions associated with urban water systems have come under scrutiny in recent times, as a result of increasing interest in climate change, to which urban water systems are particularly vulnerable. The approach most commonly taken previously to modelling these results has been to consider various urban water system components in great detail, but in isolation from the rest of the system. This piecewise approach is suboptimal, since it systematically fails to reveal the relative importance of the energy consumption and GHG emissions associated with each system component in the context of the entire urban water system. Hence, it was determined that a new approach to modelling the energy consumption and GHG emissions associated with urban water systems was necessary. It was further determined that the value derived from such a model would be greatly enhanced if it could also model the water consumption and wastewater generation associated with each system component, such that integrated policies could be developed, aimed at minimising water consumption, wastewater generation, energy consumption and GHG emissions concurrently. Hence, the following research question was posed: How should the relationships between the water consumption, wastewater generation, energy consumption and GHG emissions associated with the operation of urban water systems be modelled such that the impact of various changes to the system configuration made at different spatial scales can be determined within the context of the entire system? In this research project, life cycle assessment ideas were employed to develop such a new modelling methodology. Initially, the approach was developed at the building-scale, such that the end uses of water present in a selected building and any associated appliances could be modelled, along with the fraction of the citywide water supply and wastewater systems directly associated with providing services to that building. This vast breadth of scope was delivered by considering only the operational life cycle stage of each urban water system component, excluding both the pre- and post-operational life cycle stages of the associated infrastructure. The value of this pilot model was illustrated by several case studies, focused on residential buildings connected to the centralised water supply and wastewater systems in Melbourne, Australia. Later, the approach was extended to the city-scale by using probabilistic distributions of each input parameter, such that all of the end uses of water present in a city, and all of the associated building-scale appliances could be modelled, along with the associated complete water supply and wastewater systems. The value of this city-scale model was illustrated by applying it to model a hypothetical case study city, resembling Melbourne, Australia in many ways. Due to a lack of data, this application was limited to the residential sector of the case study city, along with the fraction of the citywide water supply and wastewater systems directly associated with providing services to that sector. The results generated by the pilot and city-scale models showed that the new modelling methodology could be employed at a wide range of scales to assess the relative importance of each modelled urban water system component in terms of the specified results. Importantly, the high resolution of those results enabled the identification of the underlying causes of the relative importance of each urban water system component, such that efficient and effective approaches to reducing each result for each system component could be developed. Interestingly, for the specific case studies investigated, it was revealed that some commonly neglected system components were actually extremely important, such as domestic hot water services, a trend found to be largely driven by hot water consumption in showers.

<p>The Earth's atmosphere is expected to warm in response to increasing atmospheric concentrations of greenhouse gases (GHG). The response of the Earth's complex and chaotic climate system to the GHG emissions is, however, difficult to assess. In this thesis, two issues of importance for the assessment of this response are studied. The first concerns the magnitude of the natural and anthropogenic emissions of CO₂. An atmospheric transport model is used, combined with inventories of anthropogenic CO₂ emissions and estimates of natural emissions, to compare modelled and observed variations in the concentration of CO₂ at an Arctic monitoring site. The anthropogenic and natural emissions are shown to exert approximately equal influence on Arctic CO₂variations during winter.</p><p>The primary focus of this thesis is the response of the climate system to the enhanced GHG forcing. It has been proposed that this response may project onto the leading modes of variability. In the present thesis, this hypothesis is tested against the alternative that the spatial patterns of variability change in response to the enhanced forcing. The response of the atmospheric circulation to the enhanced GHG forcing as simulated by a specific coupled global climate model (CGCM) is studied. The response projects strongly onto the leading modes of present-day variability. The spatial patterns of the leading modes are however changed in response to the enhanced GHG forcing. These changes in the spatial patterns are associated with a strengthening of the waveguide for barotropic Rossby waves in the Southern Hemisphere. The Northern Hemisphere waveguide is however unchanged.</p><p>The magnitude of the global mean responses to an enhanced GHG forcing as simulated by CGCMs vary. Moreover, the regional responses vary considerably among CGCMs. In this thesis, it is hypothesised that the inter-CGCM differences in the spatial patterns of the response to the enhanced GHG forcing are partially explained by inter-CGCM differences in zonal-mean properties of the atmospheric flow. In order to isolate the effect of these differences in the zonal-mean background state from the effects of other sensitivities, a simplified model with idealised forcing is employed. The model used is a global three-level quasi-geostrophic model. The sensitivity of the stationary wave pattern (SWP) to changes in the zonal-mean wind and tropopause height of similar magnitude as those found in response to the enhanced GHG forcing in CGCMs is investigated. The SWP in the simplified model shows a sensitivity of comparable magnitude to the analogous response in CGCMs. These results indicate that the CGCM-simulated response is sensitive to relatively small differences in the zonal-mean background state. To assess the uncertainties in the regional response to the enhanced forcing associated with this sensitivity, ensemble simulations of climate change are of great importance.</p>