Anàlisi global de la petjada ecològica i la forma urbana

Cada cop són més els estudiosos que consideren aquest nou segle com el segle de les ciutats. L’any 2008 més de la meitat de la població mundial viurà en ambients urbans, i això es veu amb temor pel gran impacte que tenen les ciutats sobre el medi, i per la qualitat de vida dins aquestes urbs. Aquest document estudia com els factors urbans determinen la Petjada Ecològica global de les activitats humanes, utilitzant variables com : densitat mitjana de les ciutats, percentatge de població urbana, renda per càpita, latitud, preus de la gasolina i mida de la població.

(No)competition in the Spanish retailing gasoline market: a variance filter approach

Various methodologies in economic literature have been used to analyse the international hydrocarbon retail sector. Nevertheless at a Spanish level these studies are much more recent and most conclude that generally there is no effective competition present in this market, regardless of the approach used. In this paper, in order to analyse the price levels in the Spanish petrol market, our starting hypothesis is that in uncompetitive markets the prices are higher and the standard deviation is lower. We use weekly retail petrol price data from the ten biggest Spanish cities, and apply Markov chains to fill the missing values for petrol 95 and diesel, and we also employ a variance filter. We conclude that this market demonstrates reduced price dispersion, regardless of brand or city.

La Demanda de gasolinas en México: efectos y alternativas ante el cambio climático

El autotransporte es de los sectores más contaminantes en México, generando el 17% del total de emisiones de CO2. El consumo de gasolina y diesel son la principal fuente de estas emisiones. Este artículo analiza empíricamente la demanda de gasolinas del sector automotor en México durante el período 1960-2007. Las estimaciones de las elasticidades de corto y largo plazos del precio e ingreso fueron: -0.07, -0.17, 0.46 y 1.06. Lo que implica que la demanda de gasolinas es sensible a la trayectoria del ingreso e inelástica a los precios. Por tanto, un crecimiento económico continúo sin una adecuada política de precios generará un aumento en el consumo de gasolinas. Esta situación puede ser más grave al considerar los efectos del cambio climático atendiendo a una demanda relativamente onstante. Bajo estas circunstancias es necesario implementar diversas políticas públicas imultáneamente para frenar las consecuencias del consumo de gasolinas sobre el cambio climático.

Driving competition in local gasoline markets

Relevant market definition is still a key element of economic analysis of competition in the gasoline market. It is particularly difficult to handle when competition is local and market power is geographically constrained like is the case in the gasoline market. We analyse how the application of the hypothetical monopolist or Small but Significant Non-Transitory Increase in Prices (SSNIP) test performs for defining isochrones using only information on prices and distance among competitors. We conclude that geographic information systems can be very successfully used to define more precisely relevant geographic market in the gasoline retailing. The application to the Spanish gasoline market concludes that geographic relevant market is composed by 5-6 minutes of travel time. Localised market power should be taken into account when analysing the adverse effects of mergers and entry regulations in gasoline retailing. Only drawing small enough isochrones will drive competition in local markets because it is just close rivals that compete effectively with each other.

Prototip culata del vehicle de baix consum (equip EPS-UdG Shell Eco)

Aquest projecte s’ha portat a terme per tal de millorar en diferentsaspectes el motor Honda Gx35 , del vehicle de baix consum de la Universitat deGirona (Udg). Aquest és un motor de combustió interna de gasolina (cicle Otto).L’objectiu és el disseny d’una culata per poder minimitzar el consum de gasolina, la qual s’ha de poder acoblar amb el motor Honda Gx35. Aquest motor,prèviament s’haurà de modificar per poder-hi instal•lari la nova culata

Industrialització i fabricació d'una carrosseria d'un vehicle de baix consum

El projecte es desenvolupa amb la intenció de millorar ell cotxe queparticipa, en nom de la Universitat de Girona, a la shell eco-marathon en lacategoria de prototips i amb gasolina com a combustible.El motiu principal que ha donat peu a aquest projecte és la realització d’unestudi aerodinàmic que ha desembocat en un disseny totalment nou de lageometria de la carrosseria. Aquest estudi i el disseny aerodinàmic de lacarrosseria obtingut es pot consultar al projecte titulat “Disseny i estudi del’aerodinàmica del vehicle àliga” de l’autor Albert Marron

Equilibrium of the simultaneous etherification ofisobutene and isoamylenes with ethanol inliquid-phase

The simultaneous etherification of isobutene and isoamylenes with ethanol has been studied using macroreticu-lar acid ion-exchange resins as catalyst. Most of the experiments were carried out over Amberlyst-35. In addition,Amberlyst-15 and Purolite CT-275 were also tested. Chemical equilibrium of four chemical reactions was studied:ethyl tert-butyl ether formation, tert-amyl ethyl ether formation from isoamylenes (2-methyl-1-butene and 2-methyl-2-butene) and isomerization reaction between both isoamylenes. Equilibrium data were obtained in a batchwisestirred tank reactor operated at 2.0 MPa and within the temperature range from 323 to 353 K. Experimental molarstandard enthalpy and entropy changes of reaction were determined for each reaction. From these data, the molarenthalpy change of formation of ethyl tert-butyl ether and tert-amyl ethyl ether were estimated. Besides, the chemical equilibrium between both diisobutene dimers, 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, wasevaluated. A good agreement between thermodynamic results for the simultaneous etherification carried out in thiswork and those obtained for the isolated ethyl tert-butyl ether and tert-amyl ethyl ether systems was obtained.

Viabilitat energètica de la sobrealimentació tèrmica de motors de combustió interna alternatius

Avaluació de la la viabilitat energètica de la millora de prestacions d’un motor de combustió interna alternatiu de tipus MEP (Motor d’Encesa Provocada o gasolina), mitjançant una sobrealimentació tèrmica. En aquest projecte, s’ha defugit de les tecnologies més esteses i s’ha estudiat una nova via no tant explorada, l’augment de la densitat de l’aire mitjançant la disminució de la seva temperatura a l’admissió, tecnologia que es coneix amb el nom de “sobrealimentació tèrmica”. Així doncs, respecte a les tecnologies de sobrealimentació més clàssiques, en aquest cas no es disposarà de cap sistema de compressió mecànica que augmenti la densitat de l’aire comprimint-lo, sinó que s’utilitzarà un sistema totalment diferent, el qual consistirà en un circuit de refrigeració per compressió mecànica de refrigerant, molt semblant a l’utilitzat pel sistema de climatització del vehicle i que en aquest cas refrigerarà l’aire d’admissió fent-lo passar per un intercanviador de calor (evaporador). Aquest fet repercutirà en un augment de potència i de les prestacions del motor tèrmic, que per contra haurà d’alimentar el cicle de compressió de vapor que produeix el fred. L’elecció d’aquest sistema, ha estat motivada sobretot per demostrar que altres sistemes de sobrealimentació són possibles a partir d’elements en part ja presents en el vehicle i que siguin fàcilment implementables, sense haver de modificar elements mecànics importants del motor

Equilibrium of the simultaneous etherification ofisobutene and isoamylenes with ethanol inliquid-phase

The simultaneous etherification of isobutene and isoamylenes with ethanol has been studied using macroreticu-lar acid ion-exchange resins as catalyst. Most of the experiments were carried out over Amberlyst-35. In addition,Amberlyst-15 and Purolite CT-275 were also tested. Chemical equilibrium of four chemical reactions was studied:ethyl tert-butyl ether formation, tert-amyl ethyl ether formation from isoamylenes (2-methyl-1-butene and 2-methyl-2-butene) and isomerization reaction between both isoamylenes. Equilibrium data were obtained in a batchwisestirred tank reactor operated at 2.0 MPa and within the temperature range from 323 to 353 K. Experimental molarstandard enthalpy and entropy changes of reaction were determined for each reaction. From these data, the molarenthalpy change of formation of ethyl tert-butyl ether and tert-amyl ethyl ether were estimated. Besides, the chemical equilibrium between both diisobutene dimers, 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, wasevaluated. A good agreement between thermodynamic results for the simultaneous etherification carried out in thiswork and those obtained for the isolated ethyl tert-butyl ether and tert-amyl ethyl ether systems was obtained.

Entry Regulation Asymmetries and Gasoline Competition in a Mixed Motorway Network

Regulatory and funding asymmetries in the Spanish motorway network produce huge differences in the structure of gasoline markets by motorway type: free or toll. While competition is encouraged among gas stations on free motorways, the regulations for toll motorways allow private concessionaires to auction all gas stations to the same provider, thereby limiting competition and consolidating market power. This paper reports how this regulatory asymmetry results in higher prices and fewer gas stations. Specifically, we show that competition is constrained on toll motorways by the granting of geographical monopolies, resulting in a small number of rivals operating in close proximity to each other, and allowing gas stations to operate as local monopolies. The lack of competition would seem to account for the price differential between toll and free motorways. According to available evidence, deregulation measures affecting toll motorway concessions could help to mitigate price inefficiencies and increase consumer welfare.

Does Rigidity of Prices Hide Collusion?

Cartel detection is one of the most basic and most complicated tasks of competition authorities. In recent years, however, variance filters have provided a fairly simple tool for rejecting the existence of price-fixing, with the added advantage that the methodology requires only a low volume of data. In this paper we analyze two aspects of variance filters: 1- the relationship established between market structure and price rigidity, and 2- the use of different benchmarks for implementing the filters. This paper addresses these two issues by applying a variance filter to a gasoline retail market characterized by a set of unique features. Our results confirm the positive relationship between monopolies and price rigidity, and the variance filter's ability to detect non-competitive behavior when an appropriate benchmark is used. Our findings should serve to promote the implementation of this methodology among competition authorities, albeit in the awareness that a more exhaustive complementary analysis is required.

Symmetric or asymmetric gasoline prices? A meta-analysis approach

The analysis of price asymmetries in the gasoline market is one of the most studied in the energy economics literature. Nevertheless, the great variability of results makes it very difficult to extract conclusive results on the existence or not of asymmetries. This paper shows through a meta-analysis approach how the industry segment analysed, the quality and quantity of data, the estimator and the model used may explain this heterogeneity of results.