Optimal congestion treatment for bilateral electricity trading

Abstract

How to treat transmission constraints in electricity markets that are not based on a pool but on bilateral trading? Three approaches are currently discussed: First, the system operator resolves constraints and socialises costs; second, physical transmission contracts; third, locational charging with the option of financial hedging. Socialisation of costs for constraint resolution results in inefficient dispatch and incorrect incentives for investment in generation. Physical contracts and locational charging designs have identical properties in a very simplified model world, but differ if transaction costs, illiquid markets and uncertainty about demand are considered. Physical transmission contracts are best designed as zonal access rights, but have to be centrally administered to be efficient. Only locational charging can cope with uncertainty and volatility of electricity demand efficiently and non-discriminatory.