Managing energy demand is essential to energy security and climate change mitigation. The industrial sector accounts for over a fifth of UK primary energy demand and greenhouse gas emissions. Energy intensive industry is uniquely restricted in the way it uses energy and emits greenhouse gasses. In this thesis, the potential of radical measures to achieve significant energy demand reduction and emissions abatement in UK energy intensive industry is assessed. Adopted is a multidisciplinary approach combining thermodynamic and techno-economic analysis techniques. Bottom-up assessments are applied to key energy intensive sectors of industry to capture the diverse and interactive array of technological characteristics invisible from a top-down perspective. Detailed projection models are built to design and analyse technology roadmaps for the sectors out to 2050. In an illustrative roadmap assessment, the technological pathways of radical process transition and carbon sequestration were each shown to achieve about 80% abatement in 2050 from 1990 emissions levels. Radical process transition achieved greater abatement before 2030 and this was reflected in lower cumulative emissions over the full period. Higher risk is associated with carbon sequestration from its reliance on timely access to CO2 transport and storage technology to compensate for lower short-medium term abatement. Although, combining carbon sequestration with high levels of biomass combustion indicated the largest potential abatement to 2050. Abatement economics in the iron and steel sector are notably sensitive to resource costs and the carbon trading price. The carbon trading price influences relative production costs in favour of higher abating pathways, but increases absolute costs. This signals the need for supportive policy measures that accelerate technology development and deployment while mitigating the risk of the carbon trading price to competitiveness. Some carbon capture technologies reduce relative production cost even in the absence of a carbon price, but this excludes the cost of CO2 transport and storage. Meanwhile, radical process transition pathways have a higher dependence on the future prices of natural gas, electricity, and scrap. Future work should focus on expanding the economic appraisal to other sectors and to indirect costs, as well as incorporating wider material efficiency strategies and running different future scenarios.

Environmental concerns about the effect of greenhouse gases have led governments to regulate industrial CO2 emissions, including through emissions caps, trading and penalties, thus creating economic incentives to reduce CO2 emissions. This research focuses on strategies to reduce CO2 emissions from energy systems in the context of the process industries. In the process industries, energy systems consume fuel to generate steam and power for site process units. Improving energy efficiency can reduce costs of energy generation and use, as well as CO2 emissions. This research develops an integrated design and optimisation methodology for energy systems, allowing effective capture and control of carbon dioxide emissions. The first focus of this study is to develop a systematic approach to evaluate combinatorial strategies for reducing CO2 emissions, based on a techno-economic analysis. A conceptual design procedure with hierarchical decision-making is introduced to combine CO2 emissions reduction strategies, accounting for interactions between site components, including the heat exchanger network and utility system. CO2 emissions reduction options considered in development of this procedure include process integration techniques for improving the energy efficiency of the site and fuel switching. The proposed approach considers trade-offs between the economy of energy retrofit and CO2 emissions penalties. Opportunity for reducing the CO2 penalty is included in the economic evaluation of the combined emissions reduction strategies. A mathematical model for simultaneous optimization of emissions reduction strategies is developed. In addition to emissions reduction strategies, options for trading CO2 allowances are considered in the model. The proposed mathematical method applies Mixed Integer Non Linear Programming (MINLP) optimization, which employs a superstructure of the strategies for CO2 reduction. The proposed mathematical model relates the selected options to their operating and capital costs and to their associated CO2 emissions, allowing the optimizer to search for the optimal combination of emissions reduction strategies. While the reduction in CO2 emissions through process integration techniques is based on the existing configuration of a site and the associated structural limitations, integration of Carbon Capture and Storage (CCS) technologies can provide greater mitigation of CO2 emissions from a site. However, important challenges of implementing CCS in the process industries are the energetic and economic impact of the CCS plant on the integrated site. In the second part of this study, these energy-economic issues are explored. The CCS technologies addressed in this thesis include post- and pre-combustion CO2 capture techniques. Simulation of each capture technique is carried out in process simulation software to characterize the energy performance of the CO2 capture plant. Sensitivity analyses are carried out for key parameters of the CO2 capture plant. The relationship between these key parameters and the energy balance of the capture plant is represented using a simple energy performance model for the CO2 capture plant. This model allows the integration of the CO2 capture plant with the site utility system to be explored. Interactions between the utility system and CO2 capture plant are considered. The site utility system, together with the CO2 capture plant, is optimized for minimum operating cost. The proposed procedures are illustrated by application to a case study of a medium-scale oil refinery. The results illustrate that to reduce CO2 emissions, heat integration, utility system optimization and fuel switching provide more cost-effective solutions than integrating CCS technologies. The mathematical model allows more cost-effective solutions to be identified than using sequential, conceptual methods, but the value of the conceptual method for developing insights is also illustrated. The results demonstrate that, depending on the potential of the site for increasing heat recovery and the type of fuel used on site, solutions that combine energy efficiency and fuel switching can provide up to 40% reduction in site CO2 emissions. Integrating a post-combustion CO2 capture plant with the site utility system can provide up to 90 mol% pure CO2 for sequestration; however, the high capital cost of the capture plant reduces the economic performance of the integrated site. The high heat demand of post-combustion CO2 capture for solvent regeneration increases the fuel consumption of the site and its utility system, which in turn reduces the recovery of CO2. The results reveal that pre-combustion CO2 capture can provide opportunities for heat and power generation to improve the techno-economic performance of the overall integrated site.

Given the energy intensive nature of the South African economy and the country’s dependence on fossil fuels, the reduction of greenhouse gas (GHG) emissions poses a serious problem to poverty alleviation, economic growth and employment. This study assesses the inter-industry and macro-economic impacts of carbon dioxide emissions reduction in South Africa. A monetary energy input-output table was developed using data from supply and use tables and a physical energy-emissions input-output table was developed from the national energy balance and the country’s GHG inventory. Both tables were used to develop the energy-emissions input-output model. Carbon dioxide taxes and energy subsidy reform were selected as potential economic policy instruments for analysis in South Africa. The energy-emissions input-output model was used to analyse the implications of the selected policy scenarios in terms of their effect on gross domestic product (GDP), employment, household consumption, energy consumption and energy emissions reduction. According to the energy-emissions input-output model developed in this study, financial and community services, construction and accommodation and machinery and equipment have the largest final demand and value added while nuclear energy, natural gas and biomass have the smallest final demand and value added. Renewable energy is labour intensive but not energy intensive as this energy sector has the highest labour to value added and the lowest energy to labour and energy to value added ratios. The petroleum products sector is the least labour intensive and the most energy intensive as it has a low labour to value added ratio and high energy to labour and energy to value added ratios. For every one unit increase in biomass, renewable energy and nuclear energy results in the largest increase in output, income and employment while machinery and equipment, natural gas and gold and other mining sectors have the lowest increase in simple and total output, income and employment multipliers. There is not much movement between natural gas, nuclear energy, renewable energy and biomass and the rest of the economy. Coal and crude oil have a relatively moderate impact and are moderately impacted on by other industries in the economy. Although almost all other industries in the economy depend heavily on electricity and petroleum products, these two industries are not as heavily dependent on other industries. Coal is responsible for the largest direct primary energy emissions followed by crude oil while natural gas; nuclear energy, renewable energy and biomass have a low direct impact. The electricity sector accounts for the highest indirect impact on coal emissions and petroleum products have the highest indirect impact on crude oil emissions. The petroleum products sector has the highest indirect impact on natural gas emissions. The electricity sector is largely responsible for the direct impact on coal emissions in terms of total economic output and the petroleum products sector accounts for all crude oil emissions from output. Natural gas, renewable energy, nuclear energy and biomass have no effect on direct emission output ratio. The iron and metals sector has the largest direct impact on electricity emissions per output and transport and communication has the highest direct impact on petroleum products emission per output. The largest indirect coal pollution per output impact is in the electricity sector, followed by petroleum products and iron and metals, while machinery and equipment has the smallest indirect impact on coal emissions per output. Petroleum products have the largest indirect crude oil pollution per output and the petroleum products sector is the only sector with an indirect impact on natural gas emissions per output. The iron and metals sector has the largest indirect electricity emission per output followed by household consumption and financial and community services while natural gas has the smallest indirect electricity emissions per output followed by machinery and equipment. Nuclear energy, renewable energy and biomass have no indirect petroleum products emissions per output. Machinery and equipment and crude oil have the lowest indirect petroleum products emissions per output. Inter-industry analysis indicates that the tax on coal results in the largest decrease in total output in the electricity and petroleum products sectors while output in the petroleum products and gold and other mining sectors decreases the most with the tax on oil. The tax on electricity has the largest negative impact on the iron and metals and financial and community services sectors and the tax on petroleum products results in the largest decrease in the transport and communication and financial and community services sectors. The electricity and coal mining sectors suffer the largest decrease in output as a result of energy subsidy reform. Macro-economic impacts were analysed according to real and marginal decreases. Real changes were used to assess the impact of each policy in terms of direct changes to each specific variable. Marginal decreases were calculated as a ratio of decreasing GDP for each variable hence marginal employment equals change in employment as a ratio of change in GDP and marginal household consumption equals change in household consumption as change a ratio of change in GDP. Marginal excess burden of taxes was calculated as changes in tax revenue, as a ratio of decrease in GDP. In terms of decreasing GDP, employment and household consumption, the lower the marginal burden the better the policy. Although the tax on coal offers the highest reduction in real energy emissions, this scenario also results in the highest reduction in GDP, employment and household consumption. Therefore the coal tax is not considered as the best option for carbon dioxide emissions reduction in South Africa. The electricity tax offers a moderate reduction in real energy emissions, GDP, employment and household consumption. It is concluded that the electricity tax could be an option for carbon dioxide emissions reduction in South Africa. However energy subsidy reform offers higher energy emissions reduction and a moderate reduction in GDP, employment and household consumption. This scenario is recognised as the most efficient option for carbon dioxide reduction in South Africa in terms of real changes. The tax on coal indicates high marginal decreases in employment and household consumption, moderate marginal tax revenue and moderate marginal decrease in energy consumption and energy emissions reduction. The tax on crude oil indicates low marginal decreases in employment and household consumption, low marginal excess burden on taxes, low marginal decrease in energy consumption and a moderate marginal decrease in energy emissions. The tax on petroleum products indicates low marginal decreases in employment and household consumption, low marginal excess burden on taxes and a high marginal decrease in energy consumption and energy emissions. Energy subsidy reform offers moderate marginal decreases in employment and household consumption, low marginal excess burden on taxes and a low marginal decrease in energy consumption and energy emissions. The comparison of marginal burdens of energy emissions reduction policies indicates that energy subsidy reform offers the best option as this scenario has moderate marginal decreases in employment and household consumption, low marginal excess burden on taxes and a low marginal decrease in energy consumption and energy emissions. The tax on crude oil is selected as the second best alternative as this scenario has low marginal decreases in employment and household consumption, low marginal excess burden on taxes, low marginal decrease in energy consumption and a moderate marginal decrease in energy emissions. Therefore in terms of real and marginal reduction in energy emissions, energy consumption, GDP, employment and household consumption, energy subsidy reform proves to be the best policy instrument in terms of energy emissions reduction, energy consumption, poverty alleviation, economic growth and employment. / Thesis (PhD)--University of Pretoria, 2008. / Agricultural Economics, Extension and Rural Development / unrestricted

This research proposes the use of electric energy storage (EES) in conjunction with a power generation unit organic Rankine cycle system (PGU-ORC). The EES is used when available so that continuous operation of the PGU is not required. The potential of the PGU-ORC-EES system’s performance is evaluated in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE) from simulations of a restaurant building in twelve U.S. locations with different climate conditions. The performance of the proposed system is compared to a conventional system. Results indicate that the EES addition to the PGU-ORC system is beneficial for most locations. Ratios between electricity and fuel cost, CDE conversion factors, and PEC conversion factors are used to estimate potential performance benefits. The effect of the EES size and the capital cost available are also analyzed.

Yes / The production of blue ammonia is considered an alternative fuel to reduce CO2 emissions in the ecosystem. Qatar aims to construct the world's largest blue ammonia plant, with an annual capacity of 1.2 million tons (MT), in the first quarter of 2026. Blue ammonia is produced by combining nitrogen with "blue" hydrogen from natural gas feedstocks, with carbon dioxide captured and stored safely. Blue Ammonia can be transported by conventional ships and utilized in power stations to produce low-carbon electricity and potential future applications in decarbonized industries. The new plant will be located in Mesaieed Industrial City (MIC) and operated by QAFCO as part of its integrated facilities. QAFCO is already a significant ammonia and urea producer worldwide, with an annual production capacity of 3.8 million MT of ammonia and 5.6 million MT of urea per annum. Furthermore, QAFCO is the largest producer of urea and ammonia at a single facility worldwide. Qatar Energy Renewable Solutions (QERS) will develop and manage integrated carbon capture and storage facilities to capture and sequester 1.5 MT of CO2 per year for the blue ammonia plant. QERS will also provide more than 35 MW of renewable electricity to the Ammonia-7 facility from its upcoming PV Solar Power Plant in MIC. This project is a step towards reducing the carbon intensity of energy products and is a crucial pillar of Qatar’s sustainability and energy transition strategy to align with Qatar’s 2030 National Vision.

The UK is required to reduce its greenhouse gas emissions by 80 per cent from 1990 levels, by 2050. Greenhouse gas emissions attributed to the UK higher education sector have increased by 34.5 per cent from 1990 to 2005. Higher education institutions have a unique role in the UK greenhouse gas emissions inventory, beyond management of their own estates and compliance with policy and legislation, higher education institutions have responsibilities as innovators and educators, inspiring students and employees through example and best practice. This study sought to understand acceptability of greenhouse gas emissions reduction policies among employees of a higher education institution. The value-belief-norm theory was used in a questionnaire to understand individual attitudinal factors thought to influence policy acceptability (N=405). Recognising that an employee's attitudinal factors may be influenced by their work colleagues, this study used social network analysis to understand the social context within which individual attitudinal factors sit. Support was found for higher education institutions to reduce their greenhouse gas emissions. Employees found policies that encouraged desired behaviours, such as assistance with train travel costs and working from home, to be more acceptable than policies that discouraged undesired behaviours, such as doubling the price of a car-parking permit. Support was found for the structure and content of the value-belief-norm theory, but logistic regression suggested that it provided a weak explanation of employee policy acceptability, indicating that other factors may have a greater role. Analysis of workplace social networks suggested that employees have small social groups (x̄=8) and do not select to be close to colleagues that reflect their own perspectives. Practitioners and policymakers should seek to address this void in environmental social norms through recruitment of more environmental champions to deliver strong and persuasive pro-environmental messages.

A pecuária de corte que gera emprego e renda para bilhões de pessoas em todo o mundo, vem ganhando destaque pelos impactos negativos causados ao meio ambiente. Isso decorre do sistema extensivo de produção adotado na maioria das regiões produtoras, que consome uma grande quantidade de recursos naturais como terra e água. Nas últimas décadas, a crescente preocupação com o aquecimento global estimulou as investigações sobre as fontes de emissões de Gases Efeito Estufa - GEE. Como resultado dessas investigações tem-se que a pecuária bovina comercial contribui com cerca de 11% das emissões globais causadas pela ação do homem (FAO, 2006). Os gases emitidos por esta atividade são principalmente o metano (CH4), gerado pela fermentação entérica e pelas fezes do animal, e o óxido nitroso (N2O), proveniente das fezes. No Brasil, o rebanho de 180 milhões de cabeças elevou esta atividade a ser a segunda principal emissora de GEE, perdendo apenas para o desmatamento. Os sistemas extensivos também predominam no cenário brasileiro. Uma das formas de mitigar os impactos ambientais é a intensificação da produção através da melhora da qualidade do alimento fornecido aos animais. No caso particular das emissões de GEE isto ocorre porque melhora o processo ruminal e diminui o tempo de vida do animal. Este trabalho teve como objetivo: i) avaliar do ponto de vista econômico o confinamento de animais em fase de terminação, a partir de propriedades modais do Centro-Oeste Brasileiro; e ii) apresentar as mudanças nas emissões de GEE desde a produção do alimento até o animal estar pronto para o abate decorrentes do confinamento, de acordo com a metodologia do Painel Intergovernamental de Mudanças Climáticas IPCC. Os resultados mostram que o confinamento dos animais na fase de terminação podem reduzir as emissões em 17%, de 41 kg de CO2 equivalente por quilo de carne produzida (kg CO2 eq./kg carne) para 33 kg CO2 eq./kg carne. Ficou claro também a redução promovida pela melhora no manejo do rebanho. Comparando o pior sistema, em termos das emissões (a pasto e com IEP de 21 meses) com o melhor (confinamento, com IEP de 15 meses) pôde-se perceber uma diferença de 33% na quantidade de CO2 eq/kg carne. Quanto à análise econômica, a intensificação da propriedade, através do confinamento dos animais em fase de terminação, se mostrou inviável para a maioria das propriedades modais apresentadas quando comparado com o sistema a pasto. / The beef cattle industry that generates jobs and income for billions of people around the world has been drawing attention over negative impacts caused to the environment. This is due to the extensive production system adopted in most producing areas, which consumes a large amount of natural resources such as land and water. In recent decades, the growing concern about global warming has stimulated investigations into sources of Greenhouse Gases Emissions GHG. Results show that cattle production accounts about 11% of global emissions caused by human action (FAO, 2006). Gases emitted by this activity are mainly methane (CH4), generated from enteric fermentation and feces, and nitrous oxide (N2O) from feces. In Brazil, the cattle herd comprises 180 million heads and this industry is the second largest in greenhouse gases emissions, only surpassed by deforestation. Extensive systems are also prevalent in the Brazilian scenario. One way to mitigate environmental impacts is to increase production by improving food quality supplied to animals. In the case of GHGs, particularly, this benefit occurs because there is improvement to the ruminal process and reduction of the life span of the animal. This study aimed to: i) assess the economic aspect of confining animals at slaughter phase, originally from modal properties of the Brazilian Center-West, and ii) to show changes in GHG emissions of feedlot system from food production to animal slaughter phase according to the methodology of the Intergovernmental Panel on Climate Change IPCC. Results show that confinement of animals at slaughter phase can reduce emissions by 17% from 41 kg of CO2 equivalent per kg of meat produced (kg CO2 eq. / kg meat) to 33 kg CO2 eq. / kg meat. Gas reduction deriving from management improvements of the heard was also observed. Comparing the worst system in terms of emissions (pasture and IEP 21 months) with the most effective (confinement, with IEP 15 months) we reported a 33% difference in the amount of CO2 eq / kg meat. Regarding the economic analysis, intensifying production through the confinement of animals at slaughter phase, proved to be unfeasible for most modal properties studied when compared with pasture system.

<div>Strict emissions regulations are mandated by the environmental protection agency (EPA) to reduce emission of greenhouse gases and criteria air pollutants from diesel engines, which are widely used in commercial vehicles. A ten-fold reduction in allowable heavy-duty on-road oxides of nitrogen (NOx) emissions are projected to be enforced by 2024. The need to meet these emission regulations, along with consumer demand for better fuel efficiency, has resulted in greater effort towards cleaner and more efficient diesel engines.</div><div><br></div><div><div>Diesel engine aftertreatment systems are effective in reducing engine-out emissions, but only at catalyst bed temperatures above 200°C. The aftertreatment system needs to be quickly warmed up to its efficient operating temperatures, and maintain elevated temperatures in a fuel-efficient manner, which is a challenge using conventional engine strategies. This study details the use of advanced gas-exchange management, via variable valve actuation, to improve both `warm-up' and `stay-warm' aftertreatment thermal management.</div></div><div><br></div><div><div>Fast initial warm-up of the aftertreatment system, following a cold engine start, is enabled by strategies such as early exhaust valve opening (EEVO), internal exhaust gas recirculation (iEGR) and late intake valve closure (LIVC). Steady state and drive cycle results of a combination of EEVO and iEGR at idle operation, and a combination of EEVO and LIVC at off-idle conditions below 7.6 bar BMEP, are presented. It is demonstrated that ~ 150°C higher steady state temperatures are achieved at idle, and up to 10.1% reduction in predicted tailpipe-out NOx is achieved at 3.1% fuel penalty over the heavy-duty federal test procedure (HD-FTP) drive cycle.</div></div><div><br></div><div><div>Fuel-efficient `stay-warm' aftertreatment thermal management is demonstrated to be effectively achieved via cylinder deactivation (CDA), to reduce fuel consumption, elevate engine-outlet temperatures and reduce exhaust flow rates at idle and low load engine operation. Implementation of CDA at idle and low loads below 3 bar BMEP is demonstrated to achieve fuel savings of 4% over the HD-FTP drive cycle, while maintaining similar levels of tailpipe-out NOx emissions. It is demonstrated that lower air flow during CDA at, and near, idle operation does not compromise the transient torque/power capabilities of the engine- a key nding in enabling the practical implementation of CDA in diesel engines.</div></div><div><br></div><div><div>Some of the practical challenges expected with CDA are studied in detail, and alternate strategies addressing the challenges are introduced. Dynamic cylinder activation (DCA) is introduced as a means to enable greater control over the torsional vibration characteristics of the engine, via selection of appropriate ring patterns, while maintaining similar performance and emissions as xed CDA. A generic strategy to use CDA and an appropriate DCA strategy to operate away from driveline resonant frequencies at different engine speeds is described. Ventilated cylinder cutout (VCC) is introduced as a means to potentially mitigate oil accumulation concerns during CDA, by ventilating the non-ring cylinders to the intake/exhaust manifold(s) by opening the intake/exhaust valves during all the four strokes of the engine cycle. The fuel efficiency and thermal management performance of VCC is assessed for different ventilation congurations and compared with CDA and baseline engine operation.</div></div>

A pecuária de corte que gera emprego e renda para bilhões de pessoas em todo o mundo, vem ganhando destaque pelos impactos negativos causados ao meio ambiente. Isso decorre do sistema extensivo de produção adotado na maioria das regiões produtoras, que consome uma grande quantidade de recursos naturais como terra e água. Nas últimas décadas, a crescente preocupação com o aquecimento global estimulou as investigações sobre as fontes de emissões de Gases Efeito Estufa - GEE. Como resultado dessas investigações tem-se que a pecuária bovina comercial contribui com cerca de 11% das emissões globais causadas pela ação do homem (FAO, 2006). Os gases emitidos por esta atividade são principalmente o metano (CH4), gerado pela fermentação entérica e pelas fezes do animal, e o óxido nitroso (N2O), proveniente das fezes. No Brasil, o rebanho de 180 milhões de cabeças elevou esta atividade a ser a segunda principal emissora de GEE, perdendo apenas para o desmatamento. Os sistemas extensivos também predominam no cenário brasileiro. Uma das formas de mitigar os impactos ambientais é a intensificação da produção através da melhora da qualidade do alimento fornecido aos animais. No caso particular das emissões de GEE isto ocorre porque melhora o processo ruminal e diminui o tempo de vida do animal. Este trabalho teve como objetivo: i) avaliar do ponto de vista econômico o confinamento de animais em fase de terminação, a partir de propriedades modais do Centro-Oeste Brasileiro; e ii) apresentar as mudanças nas emissões de GEE desde a produção do alimento até o animal estar pronto para o abate decorrentes do confinamento, de acordo com a metodologia do Painel Intergovernamental de Mudanças Climáticas IPCC. Os resultados mostram que o confinamento dos animais na fase de terminação podem reduzir as emissões em 17%, de 41 kg de CO2 equivalente por quilo de carne produzida (kg CO2 eq./kg carne) para 33 kg CO2 eq./kg carne. Ficou claro também a redução promovida pela melhora no manejo do rebanho. Comparando o pior sistema, em termos das emissões (a pasto e com IEP de 21 meses) com o melhor (confinamento, com IEP de 15 meses) pôde-se perceber uma diferença de 33% na quantidade de CO2 eq/kg carne. Quanto à análise econômica, a intensificação da propriedade, através do confinamento dos animais em fase de terminação, se mostrou inviável para a maioria das propriedades modais apresentadas quando comparado com o sistema a pasto. / The beef cattle industry that generates jobs and income for billions of people around the world has been drawing attention over negative impacts caused to the environment. This is due to the extensive production system adopted in most producing areas, which consumes a large amount of natural resources such as land and water. In recent decades, the growing concern about global warming has stimulated investigations into sources of Greenhouse Gases Emissions GHG. Results show that cattle production accounts about 11% of global emissions caused by human action (FAO, 2006). Gases emitted by this activity are mainly methane (CH4), generated from enteric fermentation and feces, and nitrous oxide (N2O) from feces. In Brazil, the cattle herd comprises 180 million heads and this industry is the second largest in greenhouse gases emissions, only surpassed by deforestation. Extensive systems are also prevalent in the Brazilian scenario. One way to mitigate environmental impacts is to increase production by improving food quality supplied to animals. In the case of GHGs, particularly, this benefit occurs because there is improvement to the ruminal process and reduction of the life span of the animal. This study aimed to: i) assess the economic aspect of confining animals at slaughter phase, originally from modal properties of the Brazilian Center-West, and ii) to show changes in GHG emissions of feedlot system from food production to animal slaughter phase according to the methodology of the Intergovernmental Panel on Climate Change IPCC. Results show that confinement of animals at slaughter phase can reduce emissions by 17% from 41 kg of CO2 equivalent per kg of meat produced (kg CO2 eq. / kg meat) to 33 kg CO2 eq. / kg meat. Gas reduction deriving from management improvements of the heard was also observed. Comparing the worst system in terms of emissions (pasture and IEP 21 months) with the most effective (confinement, with IEP 15 months) we reported a 33% difference in the amount of CO2 eq / kg meat. Regarding the economic analysis, intensifying production through the confinement of animals at slaughter phase, proved to be unfeasible for most modal properties studied when compared with pasture system.

Integrating energy across different sectors is an efficient solution for improving energy systems to meet energy demands with low CO2 emissions. Such integration includes combining the supply and demand of heating, cooling, and electricity by implementing appropriate equipment, as well as combining the energy systems of civic and industrial sectors. This thesis develops various optimization approaches to identify the optimal design and operation of distributed energy systems and the integration of energy systems across commercial, industrial, and transportation sectors, which minimize CO2 emissions and costs of the systems. Available equipment of the energy systems includes combined cooling, heating, and power system, absorption chiller, solar thermal collector, photovoltaic, boiler, electric chiller, battery, ground source heat pump, and air source heat pump. This thesis provides the following contributions to this area. (1) Identify optimal structures of distributed energy systems under different electric grid CO2 footprints. The work implements representative periods when formulating the energy system, which reduces computation time. (2) Differentiate heating demands of entities in the integrated system at different temperature levels to ensure feasible heat transfer. It removes the simplified assumptions in existing studies on the integrated energy system that assume all heating demands are at a uniform temperature. (3) Optimize production rates of plants instead of assuming steady industrial production rates. The switchable production rates lead to a further reduction in CO2 emissions of the integrated system. (4) Identify the environmental and economic benefits of the integrated operation under different electric grid CO2 footprints. It presents that integrated operation reduces more CO2 emissions when the electric grid has higher CO2 footprints. (5) Identify the optimal relative sizes of entities in the integrated system that maximize the CO2 emissions reduction benefits brought by the integrated system. (6) Prove the integrated system has lower CO2 emissions than individual energy systems both under deterministic and stochastic scenarios. Overall, the work in this thesis contributes to developing energy systems and integrated energy systems with the lowest possible CO2 emissions under various scenarios. / Thesis / Doctor of Philosophy (PhD) / As the total population continues to increase worldwide, it is necessary to improve community energy systems to reduce CO2 emissions when meeting energy demands. An efficient solution is integrating energy systems across different sectors. This work explores novel structures of energy systems – integrated energy systems that combine the supply and demand of heating, cooling, and electricity in residential, commercial, industrial, and transportation sectors. The optimal energy system configurations, sizes of subsystems, production rates of plants, heat transfer and electricity transfer, as well as capacity and operation of the equipment, have been identified by developing optimization approaches that minimize CO2 emissions and costs of the integrated system. The optimal design and operation are found under both deterministic and stochastic scenarios and different grid electricity generation scenarios, which provide references for developing community energy systems with the lowest possible CO2 emissions under various scenarios.