Gestion des matières résiduelles dans les écoquartiers

Dans un monde où plus de la moitié de la population demeure désormais en milieu urbain, et où les villes exercent une pression toujours plus importante sur les ressources naturelles et les écosystèmes, il est plus que jamais essentiel de remplacer les modes traditionnels d’urbanisation par de nouvelles pratiques axées sur le développement durable. C’est dans ce contexte qu’ont émergé les premiers écoquartiers en Europe, puis en Amérique du Nord, au cours des dernières décennies. Le Québec accuse un certain retard en ce qui concerne le développement de ce type de quartiers durables, notamment axés sur une gestion plus efficiente et environnementalement responsable des matières résiduelles. Avec l’aide des outils législatifs et politiques en vigueur, la mise en place de nouveaux écoquartiers constitue une occasion d’optimiser la gestion des matières résiduelles dans la province, tout en assurant un développement urbain respectueux des principes du développement durable. La mise en oeuvre de pratiques de gestion des matières résiduelles inspirées d’exemples européens et nord-américains faciliterait aussi le développement de nouveaux projets d’écoquartiers au Québec. C’est dans ce contexte que s’inscrit l’objectif principal du présent essai, soit de proposer des modèles européens et nord-américains de gestion des matières résiduelles, afin de les intégrer aux projets d’écoquartiers actuels et futurs au Québec. Les cinq écoquartiers retenus en guise de modèles parmi les douze analysés ont, à l’instar des autres, obtenu une performance environnementale élevée; cependant, c’est leur application fructueuse des sphères économique et sociale du développement durable qui leur ont permis de se démarquer, notamment en ce qui concerne le niveau d’implication citoyenne dans ces quartiers. La transférabilité des pratiques de gestion des matières résiduelles de ces modèles, soit Augustenborg, BedZED, EVA-Lanxmeer, Hammarby Sjöstad et Kronsberg, dans le contexte québécois a été évaluée. Les pratiques retenues, au nombre de trois par écoquartier, semblent généralement transférables au Québec sans que des modifications majeures ne soient nécessaires. Néanmoins, certaines de ces pratiques, dont la tenue de réunions citoyennes de planification environnementale analogues à celles d’EVA-Lanxmeer, nécessitent un changement de mentalité important de la part de la population et des décideurs politiques, ce qui risque d’en compliquer ou retarder l’application. D’autres pratiques nécessiteraient certains investissements en matière d’infrastructures ou de formation. En fin de compte, ces pratiques et les recommandations formulées en conclusion de l’essai constituent autant d’opportunités de développer une gestion des matières résiduelles plus efficace et durable au Québec, en autant que la volonté politique et la participation citoyenne soient au rendez-vous.

Conditions d’articulation urbanisme-transports : le cas de l’agglomération d’Alger

L’articulation de l’urbanisme et des transports s’est imposée comme une question centrale dans la sphère des planifications à incidences spatiales. Le développement durable comme concept cadre a mis en relief cette problématique dont les enjeux décident de la qualité de vie urbaine au quotidien. Les objectifs de cette articulation coïncident avec la maitrise de l’étalement urbain et le report modale de la voiture vers le transport collectif. Pour atteindre ces objectifs, la cohérence des planifications respectives et de leur mise en œuvre doit être assurée. Ce qui appelle à remplir des conditions technico-politiques et organisationnelles. L’agglomération d’Alger présente dans ce cadre, un cas d’étude idéal pour l’évaluation du degré d’articulation urbanisme-transports de par les caractéristiques de son développement urbanistique et infrastructurel de transport collectif.

Le Village Olympique de Vancouver. Un modèle de développement durable?

Affiche de projet terminal, baccalauréat en Urbanisme. Institut d'urbanisme, Université de Montréal.

Gestion de l'eau potable. Un service urbain durable? Le cas de Montréal

Affiche de projet terminal, baccalauréat en Urbanisme. Institut d'urbanisme, Université de Montréal.

The ghost in the city industrial complex: Le Corbusier and the fascist theory of Urbanisme

Le Corbusier participated in an urban dialogue with the first group in France to call itself fascist: the journalist Georges Valois’s militant Faisceau des Combattants et Producteurs (1925-1927), the “Blue Shirts,” inspired by the Italian “Fasci” of Mussolini. Le Corbusier’s portrait photograph materialised on the front cover of the January 1927 issue of the Faisceau League’s newspaper Le Nouveau Siècle edited by the former anarcho-syndicalist journalist Georges Valois, its leader, who fashioned himself as the French Mussolini. Le Corbusier was described in the Revue as one of les animateurs (the “organisers”) of the Party1 – meaning a member of the technical elite who would drive the Faisceau’s plans. On 1 May 1927, the Nouveau Siècle printed a full-page feature “Le Plan Voisin” on Le Corbusier’s 1922 redesign of Paris : the architect’s single-point perspective sketch appeared below an extract lifted from the architect’s original polemic Le Centre de Paris on the pages of Le Corbusier’s second book Urbanisme published two years earlier, a treatise on urbanism.2 Three weeks later, Le Corbusier presented a slide show of his urban plans at a fascist rally for the inauguration of the Faisceau’s new headquarters on the rue du faubourg Poissonniere, thereby crystalising the architect’s hallowed status in the league...

A Durable PEFC with Carbon-Supported Pt-TiO2 Cathode: A Cause and Effect Study

Durability is central to the commercialization of polymer electrolyte fuel cells (PEFCs). The incorporation of TiO2 with platinum (Pt) ameliorates both the stability and catalytic activity of cathodes in relation to pristine Pt cathodes currently being used in PEFCs. PEFC cathodes comprising carbon-supported Pt-TiO2 (Pt-TiO2/C) exhibit higher durability in relation to Pt/C cathodes as evidenced by cell polarization, impedance, and cyclic voltammetry data. The degradation in performance of the Pt-TiO2/C cathodes is 10% after 5000 test cycles as against 28% for Pt/C cathodes. These data are in conformity with the electrochemical surface area and impedance values. Pt-TiO2/C cathodes can withstand even 10,000 test cycles with nominal effect on their performance. X-ray diffraction, transmission electron microscope, and cross-sectional field-emission-scanning electron microscope studies on the catalytic electrodes reflect that incorporating TiO2 with Pt helps in mitigating the aggregation of Pt particles and protects the Nafion membrane against peroxide radicals formed during the cathodic reduction of oxygen. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3421970] All rights reserved.

Graphitic Carbon as Durable Cathode-Catalyst Support for PEFCs

Long-term deterioration in the performance of PEFCs is attributed largely to reduction in active area of the platinum catalyst at cathode, usually caused by carbon-support corrosion. It is found that the use of graphitic carbon as cathode-catalyst support enhances its long-term stability in relation to non-graphitic carbon. This is because graphitic-carbon-supported- Pt (Pt/GrC) cathodes exhibit higher resistance to carbon corrosion in-relation to non-graphitic-carbon-supported- Pt (Pt/Non-GrC) cathodes in PEFCs during accelerated stress test (AST) as evidenced by chronoamperometry and carbon dioxide studies. The corresponding change in electrochemical surface area (ESA), cell performance and charge-transfer resistance are monitored through cyclic voltammetry (CV), cell polarisation and impedance measurements, respectively. The degradation in performance of PEFC with Pt/GrC cathode is found to be around 10% after 70 h of AST as against 77% for Pt/Non-GrC cathode. It is noteworthy that Pt/GrC cathodes can withstand even up to 100 h of AST with nominal effect on their performance. Xray diffraction (XRD), Raman spectroscopy, transmission electron microscopy and cross-sectional field-emission scanning electron microscopy (FE-SEM) studies before and after AST suggest lesser deformation in catalyst layer and catalyst particles for Pt/GrC cathodes in relation to Pt/Non-GrC cathodes, reflecting that graphitic carbon-support resists carbon corrosion and helps mitigating aggregation of Pt-particles.

Durable electrocatalytic-activity of Pt-Au/C cathode in PEMFCs

Longevity remains as one of the central issues in the successful commercialization of polymer electrolyte membrane fuel cells (PEMFCs) and primarily hinges on the durability of the cathode. Incorporation of gold (Au) to platinum (Pt) is known to ameliorate both the electrocatalytic activity and stability of cathode in relation to pristine Pt-cathodes that are currently being used in PEMFCs. In this study, an accelerated stress test (AST) is conducted to simulate prolonged fuel-cell operating conditions by potential cycling the carbon-supported Pt-Au (Pt-Au/C) cathode. The loss in performance of PEMFC with Pt-Au/C cathode is found to be similar to 10% after 7000 accelerated potential-cycles as against similar to 60% for Pt/C cathode under similar conditions. These data are in conformity with the electrochemical surface-area values. PEMFC with Pt-Au/C cathode can withstand > 10 000 potential cycles with very little effect on its performance. X-ray diffraction and transmission electron microscopy studies on the catalyst before and after AST suggest that incorporating Au with Pt helps mitigate aggregation of Pt particles during prolonged fuel-cell operations while X-ray photoelectron spectroscopy reflects that the metallic nature of Pt is retained in the Pt-Au catalyst during AST in comparison to Pt/C that shows a major portion of Pt to be present as oxidic platinum. Field-emission scanning electron microscopy conducted on the membrane electrode assembly before and after AST suggests that incorporating Au with Pt helps mitigating deformations in the catalyst layer.

Durable Transition-Metal-Carbide-Supported Pt-Ru Anodes for Direct Methanol Fuel Cells

Molybdenum carbide (MoC) and tungsten carbide (WC) are synthesized by direct carbonization method. PtRu catalysts supported on MoC, WC, and Vulcan XC-72R are prepared, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy in conjunction with electrochemistry. Electrochemical activities for the catalysts towards methanol electro-oxidation are studied by cyclic voltammetry. All the electro-catalysts are subjected to accelerated durability test (ADT). The electrochemical activity of carbide-supported electro-catalysts towards methanol electro-oxidation is found to be higher than carbon-supported catalysts before and after ADT. The study suggests that PtRu/MoC and PtRu/WC catalysts are more durable than PtRu/C. Direct methanol fuel cells (DMFCs) with PtRu/MoC and PtRu/WC anodes also exhibit higher performance than the DMFC with PtRu/C anode.

Realization of thermally durable close-packed 2D gold nanoparticle arrays using self-assembly and plasma etching

Realization of thermally and chemically durable, ordered gold nanostructures using bottom-up self-assembly techniques are essential for applications in a wide range of areas including catalysis, energy generation, and sensing. Herein, we describe a modular process for realizing uniform arrays of gold nanoparticles, with interparticle spacings of 2 nm and above, by using RF plasma etching to remove ligands from self-assembled arrays of ligand-coated gold nanoparticles. Both nanoscale imaging and macroscale spectroscopic characterization techniques were used to determine the optimal conditions for plasma etching, namely RF power, operating pressure, duration of treatment, and type of gas. We then studied the effect of nanoparticle size, interparticle spacing, and type of substrate on the thermal durability of plasma-treated and untreated nanoparticle arrays. Plasma-treated arrays showed enhanced chemical and thermal durability, on account of the removal of ligands. To illustrate the application potential of the developed process, robust SERS (surface-enhanced Raman scattering) substrates were formed using plasma-treated arrays of silver-coated gold nanoparticles that had a silicon wafer or photopaper as the underlying support. The measured value of the average SERS enhancement factor (2 x 10(5)) was quantitatively reproducible on both silicon and paper substrates. The silicon substrates gave quantitatively reproducible results even after thermal annealing. The paper-based SERS substrate was also used to swab and detect probe molecules deposited on a solid surface.

A Durable RuO2-Carbon-Supported Pt Catalyst for PEFCs: A Cause and Effect Study

As Polymer Electrolyte Fuel Cells (PEFCs) are nearing the acceptable performance level for automotive and stationary applications, the focus on the research is shifting more and more toward enhancing their durability that still remains a major concern in their commercial acceptability. Hydrous ruthenium oxide (RuO2) is a promising material for pseudocapacitors due to its high stability, high specific-capacitance and rapid faradaic-reaction. Incorporation of carbon-supported RuO2 (RuO2/C) to platinum (Pt) is found to ameliorate both stability and catalytic activity of fuel cell cathodes that exhibit higher performance and durability in relation to Pt/C cathodes as evidenced by cell polarization, impedance and cyclic voltammetry data. The degradation in performance of Pt-RuO2/C cathodes is found to be only similar to 8% after 10000 accelerated stress test (AST) cycles as against similar to 60% for Pt/C cathodes after 7000 AST cycles under similar conditions. These data are in conformity with the Electrochemical Surface Area and impedance results. Interestingly, Pt-RuO2/C cathodes can withstand more than 10000 AST cycles with only a nominal loss in their performance. Studies on catalytic electrodes with X-ray diffraction, transmission electron microscopy and cross-sectional field-emission scanning electron microscopy reflect that incorporation of RuO2 to Pt helps mitigating aggregation of Pt particles and improves its stability during long-term operation of PEFCs. (C) 2012 The Electrochemical Society. DOI: 10.1149/2.jes113440] All rights reserved.