Assessing wholesale competition in the Australian National Electricity Market

Understanding competition in electricity markets is fundamental to developing good regulatory, market design and associated policy frameworks for the electricity sector. Where and when competition is effective, appropriate market designs can be largely left to run; where it is not, interventions may be needed. Despite the need to monitor competition in electricity markets, there appears to be a gap in the current literature around the competitiveness of the Australian National Electricity Market (NEM). This means that policymakers and researchers may not have enough information to adequately address the policy needs of Australia's electricity sector. This research applies a number of key measures of competition used by regulators and researchers to the NEM's historical market dataset. Using ten years of bidding and dispatch data, a more complete picture of competition in the NEM has been constructed. This research has identified that common measures of competition may either vastly over or under-estimate levels of competitiveness because they do not account for constrained electricity trading between various regional nodes, as in the NEM. This paper implements a simple solution to this problem, termed the network-extended residual supply index (NERSI), which may present a more accurate predictor of market power for regulators and policymakers. •Market power in the Australian energy market is measured with concentration indices.•There may be concentration issues when regional interconnectors are constrained.•Existing measures either under-estimate or over-estimate levels of competition.•A novel approach accounts for energy via constrained interconnectors.•Most regions are competitive at most times, with short periods of constraint.