Coût marginal

Le coût marginal est le coût induit par une variation de l'activité. Pour les économistes, cette variation peut être infinitésimale, et le coût marginal est alors la dérivée de la fonction de coût. Pour les comptables, le coût marginal est défini comme la variation du coût engendrée par la production ou la vente d'une unité supplémentaire (ce qui est plus concret qu'un calcul de dérivée). Dans la réalité du monde de l'entreprise, la variation d'activité correspond généralement à une commande supplémentaire (qui peut donc porter sur un lot de plusieurs produits). Enjeux et rôle du coût marginal vignette|une courbe coût/revenu classique : le coût marginal (MC) augmente du fait des rendements décroissants, tandis que le revenu marginal (MR) reste constant L'analyse microéconomique classique est marginaliste : elle considère que les chefs d'entreprise rationnels ne doivent produire que tant que le prix de vente est supérieur au coût marginal. Le profit total est maximum lorsque

Design of solar driven supercritical water desalination plant

Grzegorz Adam Koblanski

The objective of this master project is to develop model for the solar driven supercritical desalination plant. Furthermore we propose a possible system integration and examination of its performance in terms of energy and cost effectiveness. The model simulations and calculations are performed using Belsim Vali and in-house LENI developed program OSMOSE. Supercritical salt separation model was created based on the solubility models proposed by Leusbrock and research conducted by Khan and Rogak on salt mixture solubility. This allowed the creation of a salt separation model as a function of pressure and temperature in supercritical conditions. The proposed model is validated in certain range of pure water density and is characterized by 86% water recovery ratio for salts inlet concentration of 4%. During the simulation, a reactor was operated in fixed temperature of 660 K and 221 bar in order to fulfill potable water requirements in terms of TDS value. The simulations results show that through integration of recompression and steam network, a significant improvement in terms of energy usage and cost incurred can be obtain. Steam network integration with double steam step allows to eliminate electricity requirements and increase the exergy efficiency to 3.16%. The majority cost of the system is caused by the investment in the solar system due to linear behavior of costing function for solar installations. It is shown that 75% of overall investment cost is intended for hot utility. However, it was found that profitability can be obtain when secondary products income are taken into account. By possibility of selling industry salts that are separated in the reactor, it is possible to obtain cost of 0.96 CHF per cubic meter of generated potable water. Moreover, to achieve higher economic performance and fresh water recovery ratio hybrid, the “Reverse Osmosis – Supercritical Desalination Plant” system was investigated. It was found that joining two technologies led to significant economic savings together with drastic increase in water recovery ratio up to 91%. This shows that proposed integration not only increased profitability of the installation, but also increased water recovery ratio. Thus showing promising perspectives for possible future desalination systems.

2013

Electricity market operations under increasing uncertainty

Farzaneh Abbaspourtorbati

Decision making in electricity markets under uncertainty has worldwide gained attention due to an increasing number of uncertain parameters associated to technology developments and market evolution. Hence, the market operator faces new challenges pertaining to technical and economic aspects of electricity markets. To tackle these challenges, appropriate models are necessary. This dissertation aims to analyze some of the challenges pertaining to the management in electricity markets under uncertainty and to provide the market operator with the models that enable it to make informed decisions in such uncertain market environments. In the context above, we categorize market operation problems into the following four groups. With the aim of obtaining informed day-ahead decisions in the presence of a number of intra-day markets and high renewable production, we propose a multi-stage stochastic clearing model, where the first stage represents the day-ahead market, n stages model n intra-day markets, and a final stage represents real-time operation. The proposed multi-stage clearing model considers not only different realizations of renewable power output, but also how these realizations evolve from day-ahead forecasts into real-time values, and allows flexibility for the contribution of renewable production in both the day-ahead and intra-day markets in form of scheduled productions and their adjustments. This improves the market outcomes and integration of renewable generation. With the purpose of obtaining marginal prices with cost-recovery features, we develop novel pricing methodologies in the presence of non-convexities and uncertainty in the market. These models minimize the duality gap of a stochastic non-convex clearing model and the dual problem of a relaxed version of this original model subject to primal constraints, dual constraints, cost-recovery constraints, and integrity constraints. The prices obtained deviate in the least possible manner from conventional marginal prices. This implies that a minimum deviation from the optimal value of social welfare is also guaranteed. Moreover, the new prices preserve the short-term economic efficiency and long-term cost recovery properties of marginal prices, while eliminating a need for uplifts. We provide insightful analyses on the impact of demand flexibility on the operational and economic aspects of the power system operation. We investigate how market prices are affected by flexible demands and what economic consequences are observed. For this purpose, we consider a system with high renewable production and a number of comparatively expensive fast-ramping units, which are flexible to react to the uncertainty pertaining to renewable power production. We investigate the role of flexible demands froman economic viewpoint, particularly the impact of flexible demands on demand revenues. Lastly, we develop a risk-neutral two-stage stochastic clearing model and a risk-averse one for reserve markets. We particularly focus on the Swiss reserve market, which consists of a weekly market with a gate closure one week ahead of real-time operation and a daily market with a gate closure two days ahead of real time. The decision-making problem consists of determining which amount of reserves to procure in the weekly market and which one in the daily market. If a risk-averse instance of this two-stage model is also proposed.

EPFL2017

Design of solar driven supercritical water desalination plant

Grzegorz Adam Koblanski

2013

Electricity market operations under increasing uncertainty

Farzaneh Abbaspourtorbati

EPFL2017

Marginal cost analysis and pricing of water and electric power

Design of solar driven supercritical water desalination plant

Electricity market operations under increasing uncertainty

Design of solar driven supercritical water desalination plant

Electricity market operations under increasing uncertainty

Marginal cost analysis and pricing of water and electric power