Hydrocarbon quantification using neural networks and deep learning based hyperspectral unmixing

Hydrocarbon (HC) spills are a global issue, which can seriously impact human life and the environment, therefore early identification and remedial measures taken at an early stage are important. Thus, current research efforts aim at remotely quantifying incipient quantities of HC mixed with soils. The increased spectral and spatial resolution of hyperspectral sensors has opened ground-breaking perspectives in many industries including remote inspection of large areas and the environment. The use of subpixel detection algorithms, and in particular the use of the mixture models, has been identified as a future advance that needs to be incorporated in remote sensing. However, there are some challenging tasks since the spectral signatures of the targets of interest may not be immediately available. Moreover, real time processing and analysis is required to support fast decision-making. Progressing in this direction, this thesis pioneers and researches novel methodologies for HC quantification capable of exceeding the limitations of existing systems in terms of reduced cost and processing time with improved accuracy. Therefore the goal of this research is to develop, implement and test different methods for improving HC detection and quantification using spectral unmixing and machine learning. An efficient hybrid switch method employing neural networks and hyperspectral is proposed and investigated. This robust method switches between state of the art hyperspectral unmixing linear and nonlinear models, respectively. This procedure is well suited for the quantification of small quantities of substances within a pixel with high accuracy as the most appropriate model is employed. Central to the proposed approach is a novel method for extracting parameters to characterise the non-linearity of the data. These parameters are fed into a feedforward neural network which decides in a pixel by pixel fashion which model is more suitable. The quantification process is fully automated by applying further classification techniques to the acquired hyperspectral images. A deep learning neural network model is designed for the quantification of HC quantities mixed with soils. A three-term backpropagation algorithm with dropout is proposed to avoid overfitting and reduce the computational complexity of the model. The above methods have been evaluated using classical repository datasets from the literature and a laboratory controlled dataset. For that, an experimental procedure has been designed to produce a labelled dataset. The data was obtained by mixing and homogenizing different soil types with HC substances, respectively and measuring the reflectance with a hyperspectral sensor. Findings from the research study reveal that the two proposed models have high performance, they are suitable for the detection and quantification of HC mixed with soils, and surpass existing methods. Improvements in sensitivity, accuracy, computational time are achieved. Thus, the proposed approaches can be used to detect HC spills at an early stage in order to mitigate significant pollution from the spill areas

DEVELOPMENT OF A SUNKEN OIL TRANSPORT TOOL USING MESOSCALE EXPERIMENTS

Oil spilled into fresh or saline water can float, become submerged in the water column (i.e., submerged oil), or sink to the bottom (i.e., sunken oil). Once introduced to the environment, oil can negatively impact ecological and public health, and the economy. Non-floating oil spills pose unique challenges to responders including the complexity of trajectory modeling; the inability to detect, track and recover oil due to limited visibility; the lack of readily deployable response technology; and limited understanding of how bottom substrate dynamics influence its fate and behavior. This dissertation research determined that the driving factors used to predict sunken oil transport are the oil’s kinematic viscosity (v_o) and the median sediment size (d_50). The stages of oil transport were characterized based on v_o, and empirical relationships using v_o and d_50 were derived to predict the oil’s critical shear stress (CSS). For v_o\u3c 2x104 cSt, thresholds of movement were defined as: (1) gravity dispersion, (2) rope formation, (3) ripple formation, and (4) break-apart/resuspension. For v_o \u3e 6x104 cSt, the stages include: (1) type II erosions, and (2) bedload transport. Using the experimentally derived oil transport equations, a prototype sunken oil transport tool (SOTT) was developed to predict sunken oil transport in a current driven environment. In the event of a non-floating oil spill, responders can input the spilled oil’s characteristics (i.e., density, viscosity) and in-situ environmental conditions (e.g., water velocity, temperature, sediment type) to evaluate if oil will transport along the bottom, resuspend into the water column, or be buried by sediments

Shipping and sustainability liquefied natural gas as an alternative fuel : evidence from Portugal

O transporte marítimo é um elo vital do comércio mundial graças à sua capacidade, confiabilidade e relação custo-eficácia no transporte de grande quantidade de bens; nenhum outro modo de transporte consegue alcançar tais economias de escala. Mas este argumento subestima os custos reais. A frota marítima internacional, excluindo barcos de pesca e navios militares, produziu em 2012 cerca de 796 milhões de toneladas (Mt) de dióxido de carbono (CO2) e 816 Mt de dióxido de carbono equivalente (CO2e) de gases de efeito de estufa (GEE) combinando dióxido de carbono (CO2), metano (CH4) e óxido nitroso (N2O) correspondendo a cerca de 3,1% das emissões globais (IMO-International Maritime Organization, 2015; Rahman e Mashud, 2015) e é um dos setores de mais rápido crescimento em termos de emissões de GEE (Gilbert, Bows e Starkey, 2010; Bows-Larkin, 2014) previstas aumentar entre 102% a 193% em relação aos níveis de 2000 até 2050 (Bows-Larkin, 2014), crescendo a uma taxa mais elevada do que a taxa média de todos os outros sectores, com excepção da aviação. Como as emissões marítimas são produzidas, em grande parte, em mar aberto e por navios registados em países de bandeira de conveniência, foram excluídas dos compromissos nacionais no âmbito do Protocolo de Quioto de 1997, que cedeu o controlo à IMO o organismo da ONU responsável pelo sector1. De acordo com o Maritime Knowledge Centre da IMO, a frota mercante mundial de navios com pelo menos 100 gross tonnage (tonelagem bruta) era composta por 93.161 navios no final do ano de 2016. Espera-se que um número crescente de navios mercantes entre em operação nas próximas décadas, nomeadamente navios porta-contentores de grande capacidade, navios metaneiros e outros adstritos a actividades diversificadas como produção, armazenamento e descarga de gás natural e de petróleo (em inglês Floating Production Storage and Offloading - FPSOs). Os combustíveis marítimos tradicionais também produzem emissões de óxido de enxofre (SOx), óxidos de azoto (NOx) e micropartículas e o impacto sobre o ambiente dos poluentes primários e secundários resultantes da combustão do fuelóleo pesado (HFO) tem contribui para a acidificação, eutrofização e formação de ozono (O3) fotoquímico (Bengtsson, 2011). Um efeito particularmente pernicioso na saúde das populações expostas é a mortalidade prematura relacionada com micropartículas inaláveis associadas com o aumento do cancro de pulmão e problemas cardiorrespiratórios (Corbett et al., 2007) e, embora os efeitos nocivos mais graves sejam particularmente sentidos nas zonas costeiras e em áreas próximas das atividades portuárias, estes efeitos também ocorrem no interior dos países devido às condições predominantes dos ventos (Corbett, Fischbeck and Pandis, 1999) incluindo efeitos transfronteiriços (Nore, 2011). Em Portugal e de acordo com o World Resources Institute, as emissões de CO2 com origem nos combustíveis marítimos cresceram 24,5%, entre 2003 e 2012, em linha com o crescimento mundial (de 26,8%) no mesmo período de dez anos (World Resources Institute, 2015). Nesta tese, para efeitos de monetarização das emissões produzidas pela frota mercante nacional serão utilizados os dados do Inventário Nacional de Emissões, dados de 2014, os quais revelam que, embora o contributo do sector para o registo nacional seja mínimo – devido nomeadamente à exiguidade da frota – o potencial de danos causados não é de todo despiciente. Técnicas para aumentar a eficiência energética e tecnologias de mitigação dos efeitos nocivos - scrubbers, (depuradores) e dispositivos catalíticos - têm sido desenvolvidas e implementadas -, no entanto, embora o seu contributo para a descarbonização do sector deva ser levado em conta, estas tecnologias não correspondem à alteração pretendida do paradigma energético e podem constituir um incentivo ao business-as-usual. Por outro lado, o recurso a combustíveis com menor conteúdo de enxofre como o diesel marítimo é contraproducente uma vez que as emissões dos motores a diesel foram recentemente classificadas como cancerígenas pelo Centro Internacional de Investigação do Cancro (Oeder et al, 2015). O que isto significa é que embora o diesel corresponda ao exigido futuramente pelo Regulamento Tier III emitido pela IMO, na realidade não respeita suficientemente as preocupações com a saúde humana. De qualquer modo as refinarias não teriam provavelmente capacidade suficiente de fornecer todo o diesel necessário para abastecer a frota mundial. Por outro lado, as medidas de redução de poluentes emitidas pela IMO poderão ver seus efeitos reduzidos pelo crescimento esperado da atividade marítima nas próximas décadas e são destinadas a ser adoptadas lentamente ao longo de um largo período de tempo e mostram um progresso muito lento no contexto de evitar um aumento de temperatura superior a 2ºC acima dos níveis pré-industriais (Gilbert, 2013; Bows-Larkin, 2014), daí a necessidade urgente de investir em novas tecnologias e em novos tipos de combustíveis.The objective of this Ph.D. thesis is to provide important inputs for the decarbonisation of marine transport and climate change mitigation policies concerning liquefied natural gas (LNG) as a substitute fuel. Real-world results show efficiency gains from LNG compared with traditional fossil fuels burned on-board vessel’s engines even when equipped with mitigation technologies. Yet, this is a necessary but not a sufficient condition to LNG be elected as a substitute fuel. For a fuel switch of such order of magnitude to occur within a major end-use sector, other requirements are to be fulfilled: the government intervention in the public interest, and, to justify such policy intervention, the degree of social acceptability. This is accomplished by developing a social cost-benefit analysis (SCBA) performed at a regional basis after the assessment of the trade-off between the provision level of the good and Portuguese nationals’ disposable income had been examined. SCBA attaches money prices - a metric of everything that everyone can recognise - to as many costs and benefits as possible in order to uniformly weigh the policy objectives. As a result, these prices reflect the value a society ascribe to the paradigm change enabling the decision maker to form an opinion about the net social welfare effects. Empirically, emissions from the Portuguese merchant fleet weighted by their contribution for the National Inventory were used to quantify and monetise externalities compared with benefits from LNG as a substitute marine fuel. Benefits from the policy implementation are those related with the reduction of negative externalities. Costs are those determined from the price nationals are hypothetically willing-to-pay for. Conclusions show that benefits are largely superior to the costs, so action must be taken instead of a doing nothing scenario. Apart from the social ex-ante evaluation, this thesis also imprints the first step for developing furthermore complete studies in this aspect and it can help fill policy makers’ knowledge gap to what concerns to strategic energy options vis-à-vis sustainability stakeholders engagement. Although it addresses Portuguese particularities, this methodology should be applied elsewhere

Environmental, health and safety assessment of phase-change solvents for post combustion CO2 capture

A novel class of solvents exhibiting liquid-liquid phase separation upon reaction with CO2 and/or change in temperature, promises significant reduction of energy requirement of the post combustion capture by chemical absorption. However, proceeding to a large-scale application of novel materials requires holistic evaluation of the aspects related to human health, safety, and environmental impacts currently missing for phase-change solvent alternatives. The current work addresses the gap by performing such an evaluation by help of combined life cycle (LCA) and environmental, health and safety hazard (EHS) assessment. The evaluation is done at the substance level, during the process of design and selection of the solvent alternatives by computer-aided molecular design (CAMD), and the process level, estimating the impact of the capture system deploying phase-change solvents. The integration of the LCA and EHS impact criteria into the solvent design procedure leads to identification of a much wider set of optimal solvent structures compared to having only thermodynamic properties as objective functions in CAMD. The search enriched the Pareto fronts with the -OH group containing structures beneficial in terms of their lower impact. On one hand, such molecules are highly soluble in water, thus they might not be the best option from the phase-change perspective. On the other hand, there are OH-containing amines proven to exhibit liquid-liquid separation, which have so far received considerably less attention and might require further investigation.The process level assessment showed that phase-change solvent systems have a potential to be a better alternative to the conventional amine solvent systems due to the reduced reboiler duty and possible lower impact on the environment. Less mobile solvents might be preferable with respect to human safety. With respect to long-term impacts, the process design of the capture systems with the phase-change solvents might promote accumulation of carcinogenic nitrosamines, thus their concentration should be monitored. The life cycle impact was mostly defined by the steam requirement for solvent regeneration and electricity demand for cooling media delivery. The use of renewable electricity and industrial waste heat can decrease the LCA impact of the phase-change capture plant by 70-90%. Then, the remaining impact will be dominated by the degradation behaviour of the solvent molecules, which emphasizes the benefit of the solvents displaying low degradation rates and highlights the importance of experimental studies addressing the degradation behaviour of the solvents

Electrokinetic Enhanced Bioremediation of Soils Contaminated with Petroleum Hydrocarbons

Desorption of phenanthrene resulting from hydraulic flow is compared to desorption driven by electroosmotic flow with a similar flow rate. The power required for the hydraulic flow test was compared with the consumed power in the electrokinetics test. A novel approach, anode-cathode-compartment (ACC), was proposed to stabilize pH and distribute nutrients in soil in order to enhance electrokinetic bioremediation of soil contaminated with biodegradable compounds. The ACC technique was applied to investigate electrokinetic bioremediation of soil contaminated with phenanthrene. Mycobacterium pallens sp. was used to degrade phenanthrene. Solar energy was used to generate power for the hybrid technique. Three distinct bacterial strains designated as AC16, SM155, and SB53, were subjected to investigation, including ability to grow in liquid medium at different diesel fuel concentrations, identifying functional genes, and the ability to grow at different temperatures and pH. Electrokinetic bioremediation with ACC technique was conducted to mitigate soil contaminated with diesel fuel. The tests were conducted using the novel bacterial strains AC16, SM155 and SB53. The results showed that, the phenanthrene concentration in effluent samples after desorption by electroosmotic flow was found to be three to four times the concentration after desorption by hydraulic flow. The new ACC technique overcomes the shortcomings of other pH stabilization techniques by stabilizing the pH without the need for pumping or amendments. The use of solar panels as a sole source of power can reduce electricity transmission expenses and eliminate power loss in transmission lines. Diesel degradation in tests conducted with electrokinetic bioremediation was between 20 and 30%

Remote Sensing of the Oceans

This book covers different topics in the framework of remote sensing of the oceans. Latest research advancements and brand-new studies are presented that address the exploitation of remote sensing instruments and simulation tools to improve the understanding of ocean processes and enable cutting-edge applications with the aim of preserving the ocean environment and supporting the blue economy. Hence, this book provides a reference framework for state-of-the-art remote sensing methods that deal with the generation of added-value products and the geophysical information retrieval in related fields, including: Oil spill detection and discrimination; Analysis of tropical cyclones and sea echoes; Shoreline and aquaculture area extraction; Monitoring coastal marine litter and moving vessels; Processing of SAR, HF radar and UAV measurements