Anomalies in net present value calculations. A solution

The so-called anomalies that arise in the computation and interpretation of the Net Present Value (NPV) and the Internal Rate of Return (IRR) can be easily overcome if the properties of the NPV function are taken into account and it is clearly defined what is an investment and what is a credit. All the roots of the NPV function have economic meaning and, when there is at least one IRR, the NPV and the IRR criteria agree.Net Present Value; Internal Rate of Return; Investment Analysis; Project Evaluation.

Environmental costs of residuals: a characterization of efficient tax policies.

Durable goods leave residuals after being retired from use. If the environmental costs of the residuals are external to consumers and producers of the good, then overproduction and excess residuals will result. Ad valorem taxes are show to be ineffective in eliminating this externality. The efficient regulatory policy is shown to be based on a pigouvian tax.Externalities; Pollution control; Optimal taxation; Durable goods; Residuals;

Nuevos y viejos criterios de rentabilidad que concuerdan con el criterio del valor actual neto

El análisis de criterios clásicos de rentabilidad, como la Tasa Interna de Rendimiento o el Cociente Beneficio/Coste, revela que, contra lo que se suponía, concuerdan con el criterio Valor Actual Neto si se aplican correctamente. Lo mismo ocurre con los viejos criterios Valor Final Neto y Anualidad Equivalente y los nuevos Demora Máxima de Beneficios y Plazo de Recuperación de Costes. Se demuestra, además, que para elegir entre dos proyectos mutuamente excluyentes, la aplicación de los criterios citados al proyecto diferencia o incremental es una condición suficiente para que exista concordancia con el criterio Valor Actual Neto

Individual and Social optimality of Intergenerational Investments

Conventional evaluation methods, as the net present value, consider any future consumption applying the time preference of present individuals. A more coherent analysis requires distinguishing between time preferences and the preferences about the consumption to be enjoyed by the individuals of future generations. In this paper we use an overlapping generations model with intergenerational altruism for studying optimality conditions of intergenerational investments. This tool allows us to consider the problem of intergenerational allocation without obviating the individuals’ intertemporal allocation of consumption.Cost-benefit analysis, Future generations, Intergenerational altruism, Net present value, Project appraisal, Time discounting

Realization of a 10 kW MES power to methane plant based on unified AC/DC converter

This paper presents a galvanic isolated multi output AC/DC topology that is suitable for Microbial electrosynthesis (MES) based Power to Methane energy storage systems. The presented scheme utilizes a three phase back to back converters, a single-input and multiple-output three phase transformer, single diode rectifiers and buck converters that employ a proper interconnection between MES cells and the mains. The proposed topology merges all the required single phase AC/DC converters as a unified converter which reduces the overall system size and provides system integrity and overall controllability. The proposed control scheme allows to achieve the following desired goals:1) Simultaneous control of all cells; 2) Absorbing power from the grid and covert to methane when the electricity price goes down; 3) the power factor and the quality of grid current is under control; 4) Supplying MES cells at the optimal operating point. For verification of system performance, Real time simulation results that are obtained from a 10-kW MES energy storage are presented.Postprint (author's final draft

Costes y beneficios de unos JJOO : La excepción de Barcelona?

Con posterioridad a los Juegos Olímpicos de Barcelona de 1992, han aparecido numerosos estudios que cuestionan la existencia de beneficios sociales netos una vez descontados los costes derivados de los grandes acontecimientos deportivos. En este trabajo se ofrece por primera vez, veinte años después de su celebración, un análisis de los juegos de Barcelona a la luz de estos estudios más recientes, y se ponen las bases conceptuales para un completo análisis coste-beneficio ex post de dicho proyecto. Se concluye que los juegos de Barcelona fueron en efecto excepcionales comparados con la mayoría de grandes eventos deportivos, pero que existen motivos para pensar que, al igual que en otros eventos de este tipo, se han infravalorado los costes y se han exagerado los beneficios. Otros proyectos que se plantean animados por este precedente exitoso, pero único, deberían tener esta reflexión en cuenta

Diode-clamped multilevel converters with integrable gate-driver power-supply circuits

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.This paper presents a novel modulation for a two-stage dc-ac power converter with high-frequency isolation installed in a photovoltaic stand-alone system. The presented modulation, which is designed for the converter discontinuous conduction mode of operation, solves the problem of connection to a grid, and permits a bidirectional power flow. In this document is described the modulation strategy and some simulation and experimental results are presented.Peer ReviewedPostprint (published version