Measuring market performance in restructured electricity markets: An empirical analysis of the PJM energy market

Today the electric industry in the U.S. is transitioning to competitive markets for wholesale electricity. Independent system operators (ISOs) now manage broad regional markets for electrical energy in several areas of the U.S. A recent rulemaking by the Federal Energy Regulatory Commission (FERC) encourages the development of regional transmission organizations (RTOs) and restructured competitive wholesale electricity markets nationwide.; To date, the transition to competitive wholesale markets has not been easy. The increased reliance on market forces coupled with unusually high electricity demand for some periods have created conditions amenable to market power abuse in many regions throughout the U.S. In the summer of 1999, hot and humid summer conditions in Pennsylvania, New Jersey, Maryland, Delaware, and the District of Columbia pushed peak demand in the PJM Interconnection to record levels. These demand conditions coincided with the introduction of market-based pricing in the wholesale electricity market. Prices for electricity increased on average by 55 percent, and reached the {dollar}1,000/MWh range.; This study examines the extent to which generator market power raised prices above competitive levels in the PJM Interconnection during the summer of 1999. It simulates hourly market-clearing prices assuming competitive market behavior and compares these prices with observed market prices in computing price markups over the April 1–August 31, 1999 period. The results of the simulation analysis are supported with an examination of actual generator bid data of incumbent generators.; Price markups averaged 14.7 percent above expected marginal cost over the 5-month period for all non-transmission-constrained hours. The evidence presented suggests that the June and July monthly markups were strongly influenced by generator market power as price inelastic peak demand approached the electricity generation capacity constraint of the market. While this analysis of the performance of the PJM market finds evidence of market power, the measured markups are markedly less than estimates from prior analysis of the PJM market.