Economics and the Refinery's CO

The establishment of a market for CO2 emission rights in Europe leads oil-refining companies to add a cost associated with carbon emissions to the objective function of linear programming models used to manage refineries. These models may be used to compute the marginal contribution of each finished product to the CO2 emissions of the refinery. Babusiaux (Oil. Gas Sci. Technol., 58, 2003, 685-692) has shown that, under some conditions, this marginal contribution is a relevant means of allocating the carbon emissions of the refinery. Thus, it can be used in a well-to-wheel Life Cycle Assessment. In fact, this result holds if the demand equations are the only binding constraints with a non-zero right-hand side coefficient. This is not the case for short-run models with fixed capacity. Then, allocating CO2 emissions on a marginal basis tends to overvalue (or undervalue) the total volume of emissions. In order to extend the existing methodology, we discuss two distinct solutions to this problem, inspired by economic theory: adapting either the Aumann-Shapley cost sharing method (Values of non-atomic games, 1974, Princeton University Press) or the Ramsey pricing formula (Econ. J., 37, 1927, 47-61; J. Econ. Theory, 3, 1971, 219-240). We compare these two solutions, with a strong argument in favour of Ramsey prices, based on the determination of the optimal environmental tax rate to which imported finished products should be subject

Etude de l'influence de stimuli chimiques sur la sélection du site de ponte par olfaction chez Ceratitis (Pterandrus) rosa Karsh (Diptera : Tephritidae)

La mouche du Natal, Ceratitis rosa Karsch (Diptera : Tephritidae), est un ravageur du fruit très important à la Réunion. L'influence de quatre substances chimiques (limonène, linalol, fluorène et naringine) sur la sélection du site de ponte par olfaction est étudiée. Ces essais sont réalisés dans des cages. Dans chacune d'entre elles, deux pondoirs artificiels en cire sont disposés : le premier est un dôme témoin et le second recouvre la solution testée. Les mouches utilisées sont issues d'asticots recoltés dans la nature et élevés en laboratoir

Adjustment of the Standard WACC Method to Subsidized Loans: a clarification

In this article, we show how to value projects fi nanced by subsidized loans using the standard WACC method, with three distinct assumptions concerning the debt ratio targeted by the fi rm. In fact, the subsidized loan amount used to calculate this debt ratio can be determined according to book value, economic value or market value. This three defi nitions are equivalent when considering a non-subsidized loan. In each case, the value of a subsidized loan is determined with the help of a general dynamic non-linear model for the selection of projects with the option of subsidized fi nancing. As a result, when considering economic value, we fi nd the adjustment advocated by Myers (1974) in his Adjusted Present Value approach.Este articulo describe la manera de valorar proyectos fi nanciados con préstamos subsidiados usando el método estandar del costo medio ponderado del capital, bajo tres supuestos concernientes al nivel de endeudamiento fi jado por la empresa. El valor de los préstamos subsidiados usado para calcular el nivel de deuda puede ser determinado segun el valor contable, valor economico o valor de mercado. Estas tres defi niciones son equivalentes cuando se consideran los prestamos sin subsidios. En cada caso, el valor de un prestamo subsidiado es determinado con la ayuda de un modelo general dinamico no-linear para la seleccion de proyectos con la opcion de fi nanciacion subsidiada. Como resultado, cuando se considera un valor economico, se consigue la modifi cacion sugerida por Myers (1974) en su metodo del valor presente ajustado