The WEM in Western Australia experienced a moderate price spike to $276/MWh during the 09:35 trading interval on 29 July 2026, representing a sharp 102% increase from the preceding five intervals which had settled around $131–137/MWh. The spike was isolated to a single interval before prices normalised, indicating a temporary constraint-driven event rather than sustained market tightness.
The price spike was driven by binding constraints with marginal values up to $4.99/MWh, indicating transmission or operational limitations activated during the interval. The generation mix at the time included substantial coal (936.63 MW), wind (1,160.86 MW combined) and gas-fired generation (896.09 MW combined), along with 450 MW of battery output, suggesting available capacity was present but constrained dispatch availability. The absence of hydro generation and the dominance of inflexible coal and wind resources, combined with multiple binding constraint equations, point to localised network congestion or minimum load requirements rather than overall system capacity shortage as the primary driver of the elevated price.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.