Lucia Parisio

Market Power and the Power Market: Multi-Unit Bidding and (In)Efficiency in Electricity Auctions

In this paper we apply auction theory to the modelling of competition in a multi-unit wholesale electricity market. Bidding strategies of multi-plant producers are derived and examined assuming various degrees of market concentration. Unlike previous literature, which mainly focuses on demand uncertainty, we assume both demand and cost uncertainty as well as cost differentials among the two types of generating units considered in the model, namely baseload units and peak units. Results indicate that the System Marginal Price (competitive pricing) rule provides incentives for bid shading on the part of all those generators-units who have a non-null probability of setting the market price. We also show that the extent of the bid shading is positively affected by the differential in the endowments of the baseload generation capacity of multi-plant firms. The inefficiency of the resulting allocation is also examined and some policy implications are briefly discussed.

A Robust Multivariate Long Run Analysis of European Electricity Prices

This paper analyses the interdependencies existing in wholesale European electricity prices. The results of a multivariate long run dynamic analysis of weekly median prices reveal the presence of a strong although not perfect integration among some neighboring markets considered in the sample and the existence of common long-term dynamics of electricity prices and gas prices but not oil prices. The existence of long-term dynamics among gas prices and electricity prices may prove to be important for long-term hedging operations to be conducted even in markets where there are no electricity derivatives.

Deregulated Wholesale Electricity Prices in Italy

In this paper we analyze the time series of daily average prices generated in the Italian electricity market, which started to operate as a Pool in April 2004. The objective is to characterize the high degree of autocorrelation and multiple seasonalities in the electricity prices. We use periodic time series models with GARCH disturbances and leptokurtic distributions and compare their performance with more classical ARMA-GARCH processes. The within-year seasonal variation is modelled using the low frequencies components of physical quantities, which are very regular throughout the sample. Results reveal that much of the variability of the price series is explained by deterministic multiple seasonalities which interact with each other. Periodic AR-GARCH models seem to perform quite well in mimicking the features of the stochastic part of the price process.

Market coupling between electricity markets: Theory and empirical evidence for the Italian-Slovenian interconnection

Since January 1st, 2011 the electricity exchanges of Italy and Slovenia are working under a mechanism of market coupling for their respective day-ahead markets. Similar mechanisms are being implemented in many European countries to foster the integration of electricity markets that eventually will merge into one large European power market. This short paper is one of the first works in which, by analysing market results, we try to assess the degree of integration of the Italian and Slovenian electricity markets due to the market coupling policy.

Estimating marginal costs and market power in the Italian electricity auctions

In this paper we examine the bidding behaviour of firm competing in the Italian wholesale electricity market where generators submit hourly supply schedule to sell power. We describe the institutional characteristics of the Italian market and derive generators equilibrium bidding functions. We also discuss the main empirical strategies followed by the recent econometrical literature to obtain estimates of (unobservable) optimal bids. Then, we use individual bid data, quantity volumes and other control variables to compare actual bidding behaviour to theoretical benchmarks of profit maximization. We obtain estimates of generators costs to be used in conjunction with hourly market equilibrium prices to derive some measures of the extent of market power in the Italian electricity sector and of its exploitation by firms.

A cobweb model for electricity markets

In this paper we study some dynamical features of electricity markets modelling demand and supply by means of a nonlinear cobweb model. We consider a demand function periodically perturbed to take into account the real world seasonalities (daily, weekly and yearly) while supply function can include a stochastic term that is able to encompass possible shocks like outages and plants unavailability. Using adaptive expectations we investigate the effects on equilibrium prices in a perturbed and in an unperturbed model considering peak and off-peak market configurations. The model we propose is based on a well known partial equilibrium model which is used to describe price dynamics of non-storable goods. The novelty we introduce is a sigmoid supply function and a periodically perturbed demand function. Our simulative investigations confirm that the model is able to reproduce several effects observed in real price dynamics. We also focus on how the dynamics can be influenced by altering some market rules set by regulators, like price caps and floors. In particular, we show that taking into account periodical perturbations in the demand function can lead to the anticipation, with respect to the classical model, of chaotic dynamics. Moreover, we study how the dynamic is influenced if negative prices are allowed.

RES effects in Italian wholesale electricity market

We empirically analyze the relationship between wholesale electricity day-ahead and regulation prices in the presence of high share of RES generation. Our results only partly confirm those obtained by Skytte (1999) for the Oslo area. In the Italian case, regulating power prices follow spot prices and, in some cases, they are two or three times larger than the latter ones. We generally observe that the amount of regulation does not affect regulating power prices, even if they actually behave differently to up- and down-regulation. In addition, we find empirical evidence of very high premia for readiness with different behaviors according to Italian zones.

Italian wholesale electricity market: RES effects across day-ahead and balancing markets

The relationship between wholesale electricity day-ahead and balancing prices is empirically investigated in Italy during years 2012-2014 characterized by high RES generation. We assess the situations of excess demand and excess supply with respect to the differences in quantities promised on the day-ahead market and actually delivered/demanded on real time; hence, we provide empirical evidence on Italian regulation power and corresponding prices. Our results partly confirm those obtained by Skytte (1999). We observe that regulating power prices are not influenced by the amount of regulation in both scenarios; even if they actually behave differently to up- and down-regulation. In addition, we quantify the premia of readiness according to specific selected hours and across Italian zones.

Optimal pricing behavior of vertically integrated utilities: Theory and evidence from the Italian electricity wholesale market

In this paper we present a model of supply prices coordination in electricity markets in which a group of firms is vertically integrated. We show that vertical integration, i.e. the presence of a supplier and a buyer belonging to the same coordinated group, represents an obstacle to the full exploitation of market power on the part of generators. This empirical evidence is still in search of a theoretical explanation and this paper contributes to the existing literature by offering both a theoretical discussion and an empirical investigation. The latter is conducted using Italian electricity auction data and shows that bid prices of generators are significantly affected (i.e. moderated) by variables incorporating vertical integration into the econometric model. This is what we call the counterspeculation effect of vertical integration. Italian empirical estimations confirm the presence of this effect and give information about its magnitude and significance.

Price capping in partially monopolistic electricity markets

In this paper we consider an oligopolistic market in which one firm can be monopolist on her residual demand function and derive implications on the shape of her profit function, which we show may not be concave in price. We propose a simple price-capping rule that induce the pivotal operator to compete for quantity instead of taking advantage of her monopoly. Then, we analyze the bidding behaviour of the dominant electricity producer operating in the Italian wholesale power market (IPEX). This firm is vertically integrated and in many instances she acts as a monopolist on the residual demand. We find that, contrary to expectations, this pivotal firm refrains to exploit totally her unilateral market power and, therefore, bids at levels well below the cap. We discuss such a behaviour and derive implications for the setting of the price cap.