O aumento da prevalência de lesões erosivas tem levado a um crescente interesse por medidas preventivas e para controle de tais lesões. Este estudo avaliou in vitro e in situ o efeito da associação de fluoretos à irradiação com laser de CO2 na permeabilidade do esmalte dental erodido. Para o experimento in vitro, foram selecionados oitenta fragmentos (n=10) de esmalte bovino (3x2x2 mm). Para formação de lesão de erosão, os espécimes foram submetidos a desafios ácidos iniciais duas vezes ao dia, durante dois dias, através de um regime alternado de erosão e remineralização. Para isso, os espécimes foram imersos individualmente em 20 ml de suco de laranja (pH 3,84) por 5 min sob agitação, enxaguados com água deionizada e armazenados em saliva artificial por 4 h. Os espécimes com as lesões de erosão pré-formadas foram divididos em 4 grupos para serem submetidos aos diferentes tratamentos: amina fluoretada (AmF), tetrafluoreto de titânio (TiF4), fluoreto de sódio (NaF) e placebo. Metade dos espécimes foi irradiada no modo contínuo com laser de CO2 ( λ= 10.6 µm; 2.0 W). Após a realização dos tratamentos, foram simulados novos desafios erosivos durante 2 dias, utilizando o mesmo protocolo descrito anteriormente. Terminadas as ciclagens, os espécimes foram preparados para a avaliação da permeabilidade, sendo submetidos ao método de coloração histoquímica. Uma vez obtidos os resultados do estudo in vitro, foi conduzido um experimento in situ constituído por um delineamento crossover, com duas fases de 5 dias cada. No estudo in situ, os fatores em estudo foram os tratamentos (TiF4 e placebo) e a aplicação do laser de CO2 (presente ou ausente.) Os fragmentos de esmalte bovino foram montados em dispositivo palatino para serem instalados nos participantes para a realização dos desafios erosivos, através da ingestão de 10 alíquotas de 25 ml cada, (9, 11, 13 e 15h). A avaliação da permeabilidade foi realizada conforme descrita para o estudo in vitro. Os dados foram analisados através da ANOVA e Tukey. No estudo in vitro, houve interação significativa entre fluoreto e laser (p=0,0152). Quando os géis fluoretados foram aplicados sozinhos, TiF4 promoveu menor permeabilidade do esmalte do que aquela observada após a aplicação do placebo, enquanto resultados intermediários foram encontrados para os géis de NaF e AmF. Redução na permeabilidade do esmalte foi observada quando a aplicação dos fluoretos foi associada à irradiação com laser de CO2 . No estudo in situ, houve efeito significativo da interação entre os fatores fluoreto e laser de CO2 (p = 0,0002). Em relação ao placebo, a aplicação do TiF4 reduziu significativamente a permeabilidade do esmalte, para substratos irradiados ou não. Mediante a aplicação do placebo, o laser foi capaz de reduzir significativamente a permeabilidade do esmalte, porém, quando se utilizou o TiF4, a aplicação do laser não implicou em redução da permeabilidade. Combinada à aplicação de gel fluoretado, a irradiação com laser de CO2 pode representar uma medida adjuvante no controle da permeabilidade do esmalte erodido. / The increased prevalence of erosive lesion has led to a growing interest of preventive means and to control such lesions. This study evaluated in vitro and in situ the effect of fluoride compounds combined with a CO2 laser on permeability of eroded dental enamel. To in vitro experiment, 80 bovine enamel slabs (n=10) were selected. To create erosion-like lesions, specimens were submitted to inicial erosive challenges, twice a day, during two days, through an alternating erosive and remineralizing regimen. For that, specimens were immersed in 20 ml of orange juice (pH 3.84) for 5 min under agitation, rinsed with deionized water and stored in artificial saliva for 4 h. Specimens with pre-formed lesions were divided into four groups to be treated with different fluoride gels: amine fluoride (AmF), titanium tetrafluoride (TiF4 ), sodium fluoride (NaF) and placebo. Half of the specimens were irradiated with CO2 laser ( λ= 10.6 µm; 2.0 W).Then, specimens were further cycled twice through the previously described erosive-remineralizing regimen. After cycled, specimens were subjected to permeability assessment. Once the results of in vitro study were obtained, an in situ experiment, consisting of a crossover design, with 2 phases of 5 days each, was performed. To in situ study, factors involved were treatments (TiF4 and placebo) and CO2 laser irradiation (present or absent). Bovine enamel slabs (n=10) were placed in palatal device to perform erosive challenges. Volunteers ingested orange juice as 250 mL volumes 4 times per day (9,11,13,15h). Permeability assessment was performed as described to in vitro study. Data were analyzed by ANOVA and Tukey. In vitro study demonstrated significant interaction between fluoride and laser (p = 0,0152). When fluoride gels were applied alone, TiF4 provided to enamel lower permeability than that observed following placebo application, while intermediate results were found to NaF and AmF gels. Reduction of enamel permeability was observed when fluorides were combined to CO2 laser irradiation. To in situ study, there was significant interaction between fluoride and laser (p=0,0002). When compared to placebo, TiF4 application reduced significantly enamel permeability, regardless of irradiation. Through application of placebo, laser was able to reduce significantly enamel permeability; however, when TiF4 was applied, laser irradiation did not decreased permeability. Combined to fluoride gel application, CO2 laser irradiation can represent an adjunctive way in controlling eroded enamel permeability.

En raison de leurs propriétés : légèreté, isolation thermique et acoustique, résistance aux chocs. . . , les mousses de polymères sont omniprésentes dans notre société. Ce travail, portant sur les mousses de polyuréthane, a deux objectifs : remplacer les agents d’expansion physiques (CFC, HFC) par le dioxyde de carbone issu de la réaction isocyanate-eau & fixer le catalyseur au sein du réseau polyuréthane. Pour cela, les cinétiques des réactions de formation du réseau de polyuréthane et de libération du dioxyde de carbone sont étudiées séparément. La cinétique de polymérisation est étudiée par spectroscopie IRFT et par rhéométrie. Nous considérons les polyuréthanes linéaires et réticulés. L’effet de la nature du catalyseur et de sa concentration ainsi que celui de la température sur la cinétique de polymérisation a été étudié. L’intérêt du butanediol pour le contrôle de la structure du polyuréthane formé a été démontré. La triéthanolamine possédant des fonctions amines jouant le rôle de catalyseur et des fonctions hydroxyles permettant la réticulation est testée. Nous montrons que les paramètres suivants : température, masses du diisocyanate, nature et concentration en catalyseur, n’ont qu’une influence relativement limitée sur la cinétique de libération du dioxyde de carbone. Enfin, des mousses sont réalisées à partir d’une formulation industrielle et différents agents d’expansion physiques et chimique. Nous montrons qu’il est possible de remplacer ces agents par de l’eau. / Because of their properties (low density, insulation, impact resistance. . . ), polymer foams are widely used. This work focused on polyurethane foams aims at : replacing physical blowing agents (CFCs, HFCs) by the carbon dioxide formed by the reaction of isocyanate and water & trapping a catalyst in the polyurethane network. The formation of water-blown polyurethane foams involves two reactions. The polymerization (or gelling) reaction which creates the polyurethane network. And the blowing reaction which generates carbon dioxide. A proper balance is required between the two reaction rates to obtain a foam with atisfactory properties. The kinetics of each reaction considered separately was studied. Thus, on one hand IRFT and rheology were used to study the kinetic of the polyurethane formation. Both linear and crosslinked polyurethane were studied. We showed the interest of using utanediol to control the structure of the linear polyurethane. The effect of temperature and nature and concentration of catalyst on the kinetics of polymersation was showed. Moreover, triethanolamine which contains amine groups ( catalyst) and hydroxyl groups (crosslinkingagent) was tested. One the other hand, an appartus was made to study the kinetic of the blowing reaction. We show that the following parameters : temperature, weight of the diisocyanate, nature and concentration of catalyst, have a relatively limited influence on the kinetics of release of carbon dioxide. A study of polyurethane foams based on a commercial fomulation showed that it is possible to replace the physical blowing agents by water.

O presente estudo, composto por 2 experimentos in situ, buscou avaliar o efeito da irradiação com laser de CO2 no controle da progressão de lesões de erosão e, posteriormente, analisar a influência da abrasão em superfícies irradiadas e erodidas. No primeiro experimento, 56 fragmentos de incisivos bovinos (5x3x2.5mm) tiveram suas superfícies de esmalte divididas em 4 áreas: 1. Hígida (área de referência); 2. Erosão inicial; 3. Tratamento (irradiado ou não com laser de CO2); 4. Após fase in situ. O desafio erosivo inicial foi realizado com ácido cítrico 1% (pH=2,3) por 5 minutos, 2x/dia, por 2 dias. Os espécimes foram divididos em 2 grupos de acordo com o tratamento da superfície: irradiados com laser de CO2 ( λ= 10,6 m; 0,5 W) e não irradiados. Após um período de lead-in de 2 dias, 14 voluntários usaram um dispositivo intraoral palatino contendo 2 espécimes (irradiado e não irradiado), em 2 fases intraorais de 5 dias cada. Seguindo um desenho cross-over, durante a primeira fase, metade dos voluntários imergiu seu dispositivo em 100mL de ácido cítrico por 5 minutos, 3x/dia, enquanto a outra metade usou água deionizada (controle). Os voluntários foram cruzados quanto aos desafios na segunda fase. O desgaste do esmalte foi determinado quantitativamente por um perfilômetro óptico e a morfologia da superfície do esmalte foi avaliada qualitativamente por microscopia eletrônica de varredura. ANOVA a três critérios para medidas repetidas mostrou que não houve interação significativa entre desafio erosivo e irradiação com laser de CO2 (p=0,419). O desafio erosivo aumentou significativamente o desgaste do esmalte (p=0,001), independente de ter sido realizada ou não a irradiação com laser de CO2. Não houve diferença no desgaste do esmalte entre os espécimes irradiados e não irradiados (p=0,513). No segundo experimento, o preparo e seleção dos espécimes de esmalte bovino, a indução das lesões de erosão iniciais e os tratamentos foram realizados como no primeiro experimento. Após um período de 2 dias de lead-in, 12 voluntários usaram um dispositivo palatino contendo dois espécimes irradiados e dois não irradiados, em duas fases intraorais de 5 dias cada. Seguindo um protocolo split-mouth, os voluntários imergiram extraoralmente, durante 5 minutos, os dispositivos em ácido cítrico 3x/dia por 5 dias. Uma hora após cada desafio erosivo, um espécime irradiado e um não irradiado foram escovados usando uma escova elétrica e slurry de dentifrício. As variáveis de resposta foram as mesmas empregadas no primeiro experimento. ANOVA a dois critérios revelou que não houve interação significativa entre desafio erosivo-abrasivo e irradiação com laser de CO2 (p=0,614). A irradiação laser não influenciou no desgaste do esmalte (p=0,742). O desgaste do esmalte dos espécimes submetidos a erosão + abrasão não foi diferente daquele verificado quando a erosão foi realizada sozinha (p=0,626), independente do laser de CO2 ter sido aplicado ou não. Pode-se concluir que, em condições intraorais, a irradiação com laser de CO2 não controlou a progressão de lesões de erosão nem de lesões de erosivo-abrasivas no esmalte. / This study, composed of 2 in situ experiments, aimed to evaluate the effect of CO2 laser irradiation to control the progression of erosive lesions and, after, analyze the influence of abrasion on irradiated and eroded surfaces. At the first experiment, 56 slabs of bovine incisors (5x3x2.5mm) had its enamel surface divided in 4 areas: 1. Sound (reference area); 2. Initial erosion; 3. Treatment (irradiated or not with CO2 laser); 4. After in situ phase. The erosive challenge was performed with 1% citric acid (pH 2.3), during 5 minutes, 2x/day, for 2 days. The specimens were divided in 2 groups according to the surface treatment: CO2 laser irradiated (λ = 10.6 m; 0.5 W) and non-irradiated. After a 2-day-lead-in period, 14 volunteers wore an intraoral palatal device containing 2 specimens (irradiated and non-irradiated), in 2 intraoral phases of 5 days each. Following a crossover design, during the first phase, half of the volunteers immersed its device on 100mL of citric acid during 5 minutes, 3x/day, while the other half immersed on deionized water (control). Volunteers were crossed on the challenges on the second phase. The enamel wear was quantitatively determined by an optical profilometer and the morphology of enamel surface was qualitatively evaluated by scanning electron microscopy. Three-way ANOVA for repeated measures showed that there was no significant interaction between erosive challenge and CO2 laser irradiation (p=0.419). The erosive challenge significantly increased the enamel wear (p=0.001), regardless of irradiated or not with CO2 laser. There was no difference on the enamel wear of irradiated and non-irradiated specimens (p=0.513). At the second experiment, preparation and selection of bovine enamel specimens, induction of initial erosive lesion and treatments were performed as already described for the first experiment. After a 2-day-lead-in period, 12 volunteers wore and intraoral palatal device containing 2 irradiated and 2 non-irradiated specimens, at two intraoral phases of 5 days each. Following a split-mouth protocol, volunteers immersed the devices extra orally, during 5 minutes, in 1% citric acid, 3x/day for 5 days. One hour after each erosive challenge, one irradiated and one non-irradiated specimen were brushed with an electrical toothbrush and dentifrice slurry. The response variables were the same studied at the first experiment. Two-way ANOVA revealed that there was no significant interaction between erosive-abrasive challenge and CO2 laser irradiation (p=0.614). The laser irradiation did not influence on the enamel wear (p=0.742). The enamel wear presented by the specimens subjected to erosion + abrasion did not differ from that verified when the erosion was performed alone. It can be concluded that, in intraoral conditions, the CO2 laser irradiation did not controlled the progression of erosive lesions or erosive-abrasive lesions on enamel

Pour l’industrie pharmaceutique, la conception de cocristaux permet de moduler les propriétés physico-chimiques de composés d’intérêt sans en altérer l’activité thérapeutique.Ces solides monophasés sont définis comme étant des structures comportant plusieurs espèces reliées entre elles par des liaisons faibles et neutres. Alors que la majorité des études de cocristallisation sont centrées sur la génération et la caractérisation de nouvelles phases, ce travail a eu pour objectif d’explorer une nouvelle méthode de fabrication de cocristaux, en utilisant des procédés assistés au CO2 supercritique. La possibilité de formerdes interactions entre composés de différentes natures par recristallisation au CO2antisolvant a été étudiée avec les versions discontinue GAS (Gaseous Anti-Solvent) et semicontinue SAS (Supercritical Anti-Solvent) sur deux systèmes: naproxène-nicotinamide et acétazolamide-théophylline. Le naproxène étant chiral, la cocristallisation à partir du mélange naproxène racémique-nicotinamide a également été abordée. Un cocristal connu etdeux phases cocristallines jamais observées, dont une racémique, ont pu être synthétisés.L’étude de l’influence de divers paramètres opératoires des procédés GAS et SAS, tels que la concentration de la solution initiale, le ratio des espèces ou le débit d’ajout de l’antisolvant,a permis une meilleure compréhension de la cocristallisation induite par CO2 supercritique.Les résultats ont montré que la pureté en cocristaux des poudres obtenues était influencée à la fois par la proportion de CO2 dans le mélange solution/CO2 et les concentrations des espèces en solution (contribution des équilibres thermodynamiques) mais également par l’homogénéité du réacteur de précipitation. / For the pharmaceutical industry, cocrystal design allows tuning physicochemical propertiesof an active compound without altering its therapeutic activity. These monophasic solidscontain two or more different species interacting by weak and neutral bonds. Whereas themajority of cocrystallization studies pertain to generation and characterization of newcocrystalline phases, this work was aiming at exploring a new way of cocrystal fabrication,using supercritical CO2-assisted processes. The possibility of interaction formation betweendifferent types of compounds when these are precipitated by antisolvent CO2 has beenstudied by the batch GAS (Gaseous Anti-Solvent) and the semi-continuous SAS(Supercritical Anti-Solvent) versions of the antisolvent method on two different molecularsystems: naproxen-nicotinamide and acetazolamide-theophylline. Naproxen being a chiralcompound, its cocrystallization with nicotinamide from a racemic mixture has also beenaddressed. A known naproxen-based cocrystal and a new racemic cocrystalline phase havebeen obtained thanks to the antisolvent precipitation. A new acetazolamide-theophyllinecocrystal has also been produced for the first time with the GAS process. The influence ofGAS and SAS operational parameters such as CO2 feed rate, species molar ratio andconcentrations in the initial solution, has been investigated to allow a better understanding ofthe mechanisms involved in supercritical CO2-induced cocrystallization. Results have shownthat purity in cocrystal of the produced powders is influenced by the CO2 composition of thesolution/antisolvent mixture and by the ratio and concentrations of the solutes(thermodynamic equilibria), but also by the homogeneity of the mixture in the precipitationchamber of the process.

Les levures non-Saccharomyces, naturellement présentes dans les moûts, peuvent impacter positivement ou négativement la qualité des vins. Depuis quelques années, l’utilisation de cultures mixtes comme starters, associant une souche de Saccharomyces cerevisiae et une souche d’une autre espèce est proposée aux œnologues. C’est le cas du couple S. cerevisiae/Torulaspora delbrueckii. L’étude des interactions entre la souche T. delbrueckii Zymaflore Alpha et S. cerevisiae Zymaflore X5, de la société Laffort, a été réalisée. Les fermentations alcooliques ont été effectuées dans un réacteur à double compartiment permettant la séparation physique des levures tout en conservant l’homogénéité du milieu de culture. Les résultats ont mis en évidence que la séparation impacte la croissance des deux souches suggérant l’existence d’interactions de type cell-cell contact entre ces deux souches. Si une grande majorité de praticiens utilise désormais les levures sélectionnées, certains ont fait le choix de favoriser les populations autochtones de levures S .cerevisiae et de levures non-Saccharomyces. L’incidence de deux facteurs de l’environnement a été étudié sur un mélange de cinq espèces de non-Saccharomyces (T. delbrueckii, Metschnikowia spp., Candida zemplinina, Hanseniaspora uvarum, Pichia kluyveri) et de deux souches de S. cerevisiae (une à phase de latence courte, une à phase de latence longue) en cultures pures et en mélange. L’inoculation de la souche de S. cerevisiae à phase de latence longue dans un moût saturé en CO2 permet de stimuler les levures non-Saccharomyces d’intérêt (T. delbrueckii/P. kluyveri) tout en inhibant les espèces indésirables (H. uvarum, C. zemplinina). / Non-Saccharomyces yeasts, naturally found in grape must, can impact wine quality positively or negatively. In recent years, the use of mixed cultures as starters (association of S. cerevisiae species and other species) such as the couple Saccharomyces cerevisiae/Torulaspora delbrueckii is proposed to winemakers. Interactions between these two species have been studied with two commercial strains, T. delbrueckii Zymaflore Alpha and S. cerevisiae Zymaflore X5 (Laffort). Alcoholic fermentations were carried out in a fermentor with double compartment allowing a physical separation of yeasts and preserving the homogeneity culture medium. The results highlighted that the physical separation impacts the growth of both strains, suggesting interactions of type cell-cell contact between these two strains. If a large majority of winemakers use selected yeasts strains, some of them chose to favor native yeasts, S. cerevisiae species and non- Saccharomyces species. The impact of two environmental factors was investigated on five non-Saccharomyces species (T. delbrueckii, Metschnikowia spp., Candida zemplinina, Hanseniaspora uvarum, Pichia kluyveri) and two strains of S. cerevisiae (one with short fermentation lag phase, one with long fermentation lag phase), in pure and mixed cultures. The inoculation with S. cerevisiae with a long fermentation lag phase in a must saturated with CO2 allowed to stimulate some of non-Saccharomyces which present an interest in winemaking (T. delbrueckii/P. kluyveri) and inhibit the undesirable ones (H. uvarum, C. zemplinina).

Em virtude da necessidade de se quantificar os carbamatos provenientes de processos de absorção química do gás CO2 por monoetanolamina (MEA) e dietanolamina (DEA), curvas analíticas por espectroscopia no infravermelho (IV) foram construídas visando à determinação do teor de carbamatos de MEA e DEA, além da quantificação de MEA, DEA e metildietanolamina (MDEA) em soluções puras e em misturas. O procedimento analítico compreendeu o preparo das amostras-padrão constituintes das curvas de calibração e suas quantificações com o emprego de técnicas instrumentais de referência titulação potenciométrica, pesagem e GC-FID. As amostras-padrão de aminas puras foram quantificadas por titulação potenciométrica, sendo possível a detecção exata do ponto de equivalência. As composições dos padrões analíticos de misturas foram estabelecidas segundo um diagrama triangular para misturas e o teor de cada componente foi determinado por gravimetria e GC-FID. Tanto a hidrólise quanto a degradação térmica dos carbamatos foram fatores que restringiram o emprego da titulação potenciométrica, HPLC-MS/MS e GC-FID como técnicas de referência em suas quantificações. Essas restrições, somadas ao fato de não haver disponibilidade comercial desses carbamatos, levaram ao uso da espectroscopia de RMN de 1H na determinação quantitativa. As curvas de calibração apresentaram ótimo ajuste dos valores preditos com relação aos de referência e erro máximo de predição de 0,594 %. Dois processos de absorção química do gás CO2 foram realizados em escala semipiloto e os resultados obtidos foram de 1,02 % e 0,98 % de CO2 absorvido por solução de MEA e DEA, respectivamente. Os mesmos processos foram simulados no software Aspen Plus, obtendo-se 1,18 % de CO2 absorvido por solução de MEA e 1,00 % por solução de DEA. / Due to the need to quantify carbamates from the CO2 gas chemical absorption process by monoethanolamine (MEA) and diethanolamine (DEA), analytical curves by IR spectroscopy were obtained with the aim of quantifying MEA and DEA carbamates and MEA, DEA and methyldiethanolamine (MDEA) in pure solutions and mixtures. The analytical procedure considered the preparation of standard samples constituents of the calibration curves and their quantification using reference instrumental techniques potentiometric titration, gravimetry and GC-FID. The standard samples of pure amines were quantified by potentiometric titration, getting the accurate detection of the equivalence point. The compositions of the analytical standards of the mixtures were established according to a triangular diagram for mixtures and the content of each component was determined by gravimetry and GC-FID. The carbamate hidrolysis and its thermal degradation were factors that limited the use of potentiometric titration, HPLCMS/ MS and GC-FID as reference techniques in their quantitation. These restrictions, added to the fact of not having commercial availability of these carbamates, led the use of 1H NMR spectroscopy for the quantitative determination. The calibration curves resulted in an excellent adjustment of the expected values related to the reference values and maximum error of prediction of 0.594 %. Two chemical absorption processes of CO2 gas were performed in semi-pilot scale and the obtained results were of 1.02 % and 0.98 % of absorbed CO2 by MEA and DEA solutions, respectively. Both processes were simulated using Aspen Plus software, presenting 1.18 % of CO2 absorbed by MEA solution and 1.00 % by DEA solution.

This work considers the value of flexible power provision from natural gas-fired combined cycle (NGCC) power plants operating post-combustion carbon dioxide (CO2) capture in low carbon electricity markets. Specifically, the work assesses the value of the flexibility gained by varying CO2 capture levels, thus the specific energy penalty of capture and the resultant power plant net electricity export. The potential value of this flexible operation is quantified under different electricity market scenarios, given the corresponding variations in electricity export and CO2 emissions. A quantified assessment of natural gas-fired power plant integrated with amine-based post-combustion capture and compression is attempted through the development of an Aspen Plus simulation. To enable evaluation of flexible operation, the simulation was developed with the facility to model off-design behaviour in the steam cycle, amine capture unit and CO2 compression train. The simulation is ultimately used to determine relationships between CO2 capture level and the total specific electricity output penalty (EOP) of capture for different plant configurations. Based on this relationship, a novel methodology for maximising net plant income by optimising the operating capture level is proposed and evaluated. This methodology provides an optimisation approach for power plant operators given electricity market stimuli, namely electricity prices, fuel prices, and carbon reduction incentives. The techno-economic implications of capture level optimisation are considered in three different low carbon electricity market case studies; 1) a CO2 price operating in parallel to wholesale electricity selling prices, 2) a proportional subsidy for low carbon electricity considered to be the fraction of plant electrical output equal to the capture level, and 3) a subsidy for low carbon electricity based upon a counterfactual for net plant CO2 emissions (similar to typical approaches for implementing an Emissions Performance Standard). The incentives for variable capture levels are assessed in each market study, with the value of optimum capture level operation quantified for both plant operators and to the wider electricity market. All market case studies indicate that variable capture is likely to increase plant revenue throughout the range of market prices considered. Different market approaches, however, lead to different valuation of flexible power provision and therefore different operating outcomes.

Estágio realizado na Empesa Grupo Soares da Costa SGPS, SA e orientado pela Engª Eloísa Isabel Fernandes Cepinha / Tese de mestrado integrado. Engenharia do Ambiente. Faculdade de Engenharia. Universidade do Porto. 2010

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Energia). Faculdade de Engenharia. Universidade do Porto. 2010

Die Energieerzeugung aus fossilen Brennstoffen trägt weltweit erheblich zum Treibhauseffekt bei. So entfielen 2005 24 % der gesamten CO2-Emissionen in der Europäischen Union auf die Stromerzeugung aus Kohle [1]. Recherchen im Rahmen eines Forschungsvorhabens an der Professur für Betriebliche Umweltökonomie der TU Dresden ergaben, dass öffentliche Gebietskörperschaften einen Anteil von ca. 7,8 % am Stromverbrauch in Deutschland haben. Bisher berücksichtigen jedoch nur wenige Kommunen die CO2-Emissionen als Entscheidungskriterium bei der Ausschreibung von Strom. Damit wird deutlich, welches Potenzial in der Ausschreibung von Strom liegen kann. Hierbei stellt sich allerdings nicht nur die Frage, welche Herausforderungen öffentliche Ausschreibungen mit sich bringen, sondern auch wie diese Möglichkeiten den Markt aus der Sicht des Nachfragers eingrenzen, d. h. ob überhaupt ein entsprechendes Angebot am Markt verfügbar ist. / Energy supplies on the basis of fossil fuels contribute significantly to the global greenhouse effect. In 2005, for example, 24 % of the total CO2 emissions in the EU were attributable to coal-fired power generation. The work of a research project at TU Dresden revealed that public administrative bodies account for approx. 7.8 % of electricity consumption in Germany. To date, however, only few communities have made CO2 emissions a decision criterion in their electricity procurement. It is thus clear, just how much potential lies in the procurement process for electricity. At the same time, however, consideration must be given not only to the challenges arising from the appraisal of public procurement, but also to how these options limit the market scope from the point of view of the community, i.e. whether corresponding offers are actually available on the market.