Adjoint sensitivity analysis of the intercontinental impacts of aviation emissions on air quality and health

Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 75-79).Over 10,000 premature mortalities per year globally are attributed to the exposure to particulate matter caused by aircraft emissions. Unlike previous studies that focus on the regional impacts from the aircraft emissions below 3,000 feet, this thesis studies the impact from emissions at all altitudes and across continents on increasing particulates in a receptor region, thereby increasing exposure. In addition to these intercontinental impacts, the thesis analyzes the temporal variations of sensitivities of the air quality and health, the proportion of the impacts attributable to different emission species, and the background emissions' influence on the impact of aircraft emissions. To quantify the impacts of aircraft emissions at various locations and times, this study uses the adjoint model of GEOS-Chem, a chemical transport model. The adjoint method efficiently computes sensitivities of a few objective functions, such as aggregated PM concentration and human exposure to PM concentration, with respect to many input parameters, i.e. emissions at different locations and times. Whereas emissions below 3,000 feet have mostly local impacts, cruise emissions from North America impair the air quality in Europe and Asia, and European cruise emissions affect Asia. Due to emissions entering Asia, the premature mortalities in Asia were approximately two to three times larger than the global mortalities caused by the Asian emissions. In contrast, North America observed only about one-ninth of the global premature mortalities caused by North American emissions because emissions get carried out of the region. This thesis calculates that most of the premature mortalities occured in Europe and Asia in 2006. Sensitivities to emissions also have seasonal and diurnal cycles. For example, ground level NOx emissions in the evening contribute to 50% more surface PM formation than the same emissions in the morning, and cruise level NOx emissions in early winter cause six times more PM concentration increase than the same emissions in spring. Aircraft NOx emissions cause 78% of PM from aviation emissions, and given the population exposure to PM concentration increase, NOx contributes 90% of the total impact. By showing the second-order sensitivities, this study finds that increases in background emissions of ammonia increase the impact of aircraft emissions on the air quality and increases in background NOx emissions decrease the impact. These results show the effectiveness of the adjoint model for analyzing the longterm sensitivities. Some of the analyses presented are practically only possible with the adjoint method. By regulating emissions at high sensitivities in time and region, calculated by the adjoint model, governments can design effective pollutant reduction policies.by Jamin Koo.S.M

Image multi-level-thresholding with Mayfly optimization

Image thresholding is a well approved pre-processing methodology and enhancing the image information based on a chosen threshold is always preferred. This research implements the mayfly optimization algorithm (MOA) based image multi-level-thresholding on a class of benchmark images of dimension 512x512x1. The MOA is a novel methodology with the algorithm phases, such as; i) Initialization, ii) Exploration with male-mayfly (MM), iii) Exploration with female-mayfly (FM), iv) Offspring generation and, v) Termination. This algorithm implements a strict two-step search procedure, in which every Mayfly is forced to attain the global best solution. The proposed research considers the threshold value from 2 to 5 and the superiority of the result is confirmed by computing the essential Image quality measures (IQM). The performance of MOA is also compared and validated against the other procedures, such as particle-swarm-optimization (PSO), bacterial foraging optimization(BFO), firefly-algorithm(FA), bat algorithm (BA), cuckoo search(CS) and moth-flame optimization (MFO) and the attained p-value of Wilcoxon rank test confirmed the superiority of the MOA compared with other algorithms considered in this wor

Optimization of an Organic Rankine Cycle System for an LNG-Powered Ship

Recovering energy from waste energy sources is an important issue as environmental pollution and the energy crisis become serious. In the same context, recovering liquefied natural gas (LNG) cold energy from an LNG-powered ship is also important in terms of energy savings. To this end, this study investigated a novel solution for a LNG-powered ship to recover LNG cold energy. Six different organic Rankine cycle (ORC) systems (three for high-pressure dual-fuel engines and three for medium-pressure dual-fuel engines) were proposed and optimized; nine different working fluids were investigated; annualized costs for installing proposed ORC systems were estimated based on the optimization results. In addition, a sensitivity analysis was performed to identify the effect of uncertainties on the performance of the ORC systems. As a result, the ORC system for the medium-pressure engines with direct expansion, multi-condensation levels, and a high evaporation temperature exhibited the best performance in terms of exergy efficiency, net power output and actual annualized cost. These results demonstrate the possibility of replacing a typical LNG supply system with an ORC system

PDF to PDF/A: Evaluation of Converter Software for Implementation in Digital Repository Workflow: Poster - iPRES 2012 - Digital Curation Institute, iSchool, Toronto

PDF/A is a version of Portable Document Format backed by ISO standard that is designed for archiving and preservation of electronic documents. Many electronic documents exist in PDF format. Due to its popularity, the ability to convert an existing PDF into a conforming PDF/A file is as important, if not more, as being able to produce documents in PDF/A format in digital preservation. In recognition of this fact and encouraged by growing interest from its affiliates, the Florida Digital Archive (FDA) conducted an evaluation of several of the PDF to PDF/A converter applications, the result of which is reported in this paper. There is room for interpretation in the ISO standards concerning PDF/A, which can be manifest in the development of software. In selecting a PDF to PDF/A converter product, reliability of the outcome in terms of PDF/A compliance must be established along with functionality. The goal of this paper is not to rank or promote the software evaluated, but rather to document the FDA’s evaluation process and present the results in such a way that they provide insight into challenges and potential drawbacks during similar evaluation or implementation

Integration of CCS, emissions trading and volatilities of fuel prices into sustainable energy planning, and its robust optimization

In this paper, a new approach has been proposed that allows a robust optimization of sustainable energy planning over a period of years. It is based on the modified energy flow optimization model (EFOM) and minimizes total costs in planning capacities of power plants and CCS to be added, stripped or retrofitted. In the process, it reduces risks due to a high volatility in fuel prices; it also provides robustness against infeasibility with respect to meeting the required emission level by adopting a penalty constant that corresponds to the price level of emission allowances. In this manner, the proposed methodology enables decision makers to determine the optimal capacities of power plants and/or CCS, as well as volumes of emissions trading in the future that will meet the required emission level and satisfy energy demand from various user-sections with minimum costs and maximum robustness. They can also gain valuable insights on the effects that the price of emission allowances has on the competitiveness of RES and CCS technologies; it may be used in, for example, setting appropriate subsidies and tax policies for promoting greater use of these technologies. The proposed methodology is applied to a case based on directions and volumes of energy flows in South Korea during the year 2008.Energy planning Renewable energy Carbon capture and storage Robust optimization Uncertain environment

Economic evaluation of renewable energy systems under varying scenarios and its implications to Korea's renewable energy plan

This paper studies economics of renewable energy systems with consideration of future prospects on costs and uncertain external conditions that may affect competitiveness in the power plant market. The concept of learning curve is adopted to compute estimates on the costs of installing and operating renewable energy systems in the future; fuel costs and carbon price are modeled as scenario-dependent variables to analyze their impact on total costs under different scenarios. The proposed approach allows evaluation and comparison of total costs necessary in implementing renewable energy plans under varying technological, and/or economical conditions that face uncertainty at present. Moreover, analyzing the evaluation results further with techniques like sensitivity analysis can identify factors central to reducing the total costs. As an illustrative case-study, the Korean government's renewable energy plan has been evaluated accordingly, under three different scenarios defined by International Energy Agency (IEA). The evaluation results indicate minor changes in total costs of achieving the plan among three scenarios, mainly due to counterbalancing between the price of fossil fuels and carbon price. Further analyses revealed factors central to lowering the total costs necessary in implementing the plan--hybridization between renewable energy systems, reduction of biomass production costs via technological innovation, increasing learning rates by focusing on R&D and international cooperation.Economic evaluation Energy policy Learning effect Renewable energy South Korea

Optimization of an Organic Rankine Cycle System for an LNG-Powered Ship

Recovering energy from waste energy sources is an important issue as environmental pollution and the energy crisis become serious. In the same context, recovering liquefied natural gas (LNG) cold energy from an LNG-powered ship is also important in terms of energy savings. To this end, this study investigated a novel solution for a LNG-powered ship to recover LNG cold energy. Six different organic Rankine cycle (ORC) systems (three for high-pressure dual-fuel engines and three for medium-pressure dual-fuel engines) were proposed and optimized; nine different working fluids were investigated; annualized costs for installing proposed ORC systems were estimated based on the optimization results. In addition, a sensitivity analysis was performed to identify the effect of uncertainties on the performance of the ORC systems. As a result, the ORC system for the medium-pressure engines with direct expansion, multi-condensation levels, and a high evaporation temperature exhibited the best performance in terms of exergy efficiency, net power output and actual annualized cost. These results demonstrate the possibility of replacing a typical LNG supply system with an ORC system

Sensitivity of total tropospheric O₃ to aviation NO_<em>x</em> emissions (black); ozone production efficiency (blue) weighted by aviation NO_<em>x</em> emissions; aviation-attributable ozone production rate (green); aviation-attributable ozone lifetime (red); all with one month averages (thick line) and normalized by annual mean, which is 3.2 kg O₃ / kg NO_<em>x</em> (black), 17.5 (blue), 1375 molecules cm⁻³ s⁻¹ (green), 26.9 days (red)

<p><strong>Figure 1.</strong> Sensitivity of total tropospheric O₃ to aviation NO_<em>x</em> emissions (black); ozone production efficiency (blue) weighted by aviation NO_<em>x</em> emissions; aviation-attributable ozone production rate (green); aviation-attributable ozone lifetime (red); all with one month averages (thick line) and normalized by annual mean, which is 3.2 kg O₃ / kg NO_<em>x</em> (black), 17.5 (blue), 1375 molecules cm⁻³ s⁻¹ (green), 26.9 days (red).</p> <p><strong>Abstract</strong></p> <p>Aviation NO_<em>x</em> emissions promote tropospheric ozone formation, which is linked to climate warming and adverse health effects. Modeling studies have quantified the relative impact of aviation NO_<em>x</em> on O₃ in large geographic regions. As these studies have applied forward modeling techniques, it has not been possible to attribute O₃ formation to individual flights. Here we apply the adjoint of the global chemistry–transport model GEOS-Chem to assess the temporal and spatial variability in O₃ production due to aviation NO_<em>x</em> emissions, which is the first application of an adjoint to this problem. We find that total aviation NO_<em>x</em> emitted in October causes 40% more O₃ than in April and that Pacific aviation emissions could cause 4–5 times more tropospheric O₃ per unit NO_<em>x</em> than European or North American emissions. Using this sensitivity approach, the O₃ burden attributable to 83 000 unique scheduled civil flights is computed individually. We find that the ten highest total O₃-producing flights have origins or destinations in New Zealand or Australia. The top ranked O₃-producing flights normalized by fuel burn cause 157 times more normalized O₃ formation than the bottom ranked ones. These results show significant spatial and temporal heterogeneity in environmental impacts of aviation NO_<em>x</em> emissions.</p

Change in aviation-only O₃ production and loss pathways for (a) aviation emissions in October relative to April and (b) cruise altitude NO_<em>x</em> emissions near the Solomon Islands relative to Europe

<p><strong>Figure 3.</strong> Change in aviation-only O₃ production and loss pathways for (a) aviation emissions in October relative to April and (b) cruise altitude NO_<em>x</em> emissions near the Solomon Islands relative to Europe.</p> <p><strong>Abstract</strong></p> <p>Aviation NO_<em>x</em> emissions promote tropospheric ozone formation, which is linked to climate warming and adverse health effects. Modeling studies have quantified the relative impact of aviation NO_<em>x</em> on O₃ in large geographic regions. As these studies have applied forward modeling techniques, it has not been possible to attribute O₃ formation to individual flights. Here we apply the adjoint of the global chemistry–transport model GEOS-Chem to assess the temporal and spatial variability in O₃ production due to aviation NO_<em>x</em> emissions, which is the first application of an adjoint to this problem. We find that total aviation NO_<em>x</em> emitted in October causes 40% more O₃ than in April and that Pacific aviation emissions could cause 4–5 times more tropospheric O₃ per unit NO_<em>x</em> than European or North American emissions. Using this sensitivity approach, the O₃ burden attributable to 83 000 unique scheduled civil flights is computed individually. We find that the ten highest total O₃-producing flights have origins or destinations in New Zealand or Australia. The top ranked O₃-producing flights normalized by fuel burn cause 157 times more normalized O₃ formation than the bottom ranked ones. These results show significant spatial and temporal heterogeneity in environmental impacts of aviation NO_<em>x</em> emissions.</p