Supply function competition in a mixed electric power market

In this paper, we present a mixed oligopoly model where electric power generators compete in supply functions in a liberalized market. A former monopolist, the state-owned generator, is assumed to be (partially) privatized. First, we obtain that there is a relationship between privatization and the number of electric power generators concerning the level of consumer surplus and total welfare. Indeed, a fully state-owned generator is socially optimal, lowering private generators' profits and enhancing consumer surplus; that is, if the degree of privatization decreases, consumer surplus increases compensating the damage imposed on generators' profits. Second, as the number of generators increases, full privatization may provide similar levels of consumer surplus and social welfare than those observed in a mixed oligopoly. Moreover, it is also obtained that price-cost margins increase as marginal cost increases. Overall, our results suggest that the state-owned generator should be privatized when entry barriers are low enough, and competitiveness is enhanced. Otherwise, a state-owned generator may protect consumers, enhancing consumer surplus.