Generators supplying electricity markets are subject to volatile input and output prices and uncertain fuel availability. Price-risk may be hedged to a considerable extent but fuel-risk — water flows in the case of hydro and gas availability in the case of thermal plants — may not be. We show that a price-taking generator will only generate when the output price exceeds its marginal cost by an amount that reflects the value of the option to delay the use of stored fuel. The corresponding offer price is different from the theorized offer prices of static uniform auctions and more akin to pay-as-bid auction prices. We argue that the option value of delaying fuel use, which is an increasing function of spot price volatility and the uncertainty about fuel availability, must be considered when evaluating whether market power is present in electricity markets. The engineering approach to simulating an electricity supply curve, which has been used in market power evaluations to date, may lead to supply curves that are quite different from those that recognize possible fuel availability limitations, even in the complete absence of market power.
This paper examines a number of issues associated with alternative analytical approaches for evaluating investments in electricity transmission infrastructure and alternative institutional arrangements to govern network operation, maintenance and investment. The economic and physical attributes of different types of transmission investments are identified and discussed. Alternative organizational and regulatory structures and their attributes are presented. The relationships between transmission investments driven by opportunities to reduce congestion and loss costs and transmission investment driven by traditional engineering reliability criteria are discussed. Reliability rules play a much more important role in transmission investment decisions today than do economic investment criteria as depicted in standard economic models of transmission networks. These models fail to capture key aspects of transmission operating and investment behavior that are heavily influenced by uncertainty, contingency criteria and associated engineering reliability rules. I illustrate how the wholesale market and transmission investment frameworks have addressed these issues in England and Wales (E&W) since 1990 and in the PJM Regional Transmission Organization (RTO) in the U.S. since 2000. I argue that economic and reliability-based criteria for transmission investment are fundamentally interdependent. Ignoring these interdependencies will have adverse effects on the efficiency of investment in transmission infrastructure and undermine the success of electricity market liberalization.