Commodity Demand — SA1: Thursday 17 September 2026
South Australia demand sits at 1,447 MW at 20:30 AEST, with spot price at $99.74/MWh — right at the region's administered floor-ish cluster given VWA smoothing through the evening peak. Demand has been oscillating in a 1,330-1,750 MW band since midday, and price is tracking that curve tightly: the 09:00-11:00 AEST period saw demand peak near 1,762 MW with prices holding $110-135/MWh as wind output faded and gas (CCGT/OCGT) picked up the residual load. As demand eased through early afternoon toward 1,420-1,470 MW, prices softened correspondingly into the $82-100/MWh range, confirming SA's price-demand elasticity is currently steep — each ~50 MW swing in demand is moving price by roughly $10-20/MWh at these levels.
The evening peak has already passed its demand high (1,751 MW at 08:30 UTC / mid-morning AEST) and is now in the down-ramp, but a secondary evening peak is visible in the 19:00-20:30 AEST window where demand climbed back to 1,410-1,483 MW alongside a price spike to $117.44/MWh at 20:25 before easing to $99.74. Wind generation at 902 MW is currently supplying the bulk of the mix (62% of the 1,156 MW generation total), with battery contributing 129 MW and gas (OCGT+CCGT) around 124 MW combined — this wind strength is capping price upside despite the evening demand ramp.
Looking at AEMO's forecast trajectory, prices are set to fall sharply overnight: the 21:00-21:30 AEST window is forecast at $78-138/MWh (volatile, reflecting the tail of tonight's peak), then collapsing to near-zero and deeply negative territory from 22:00 AEST through to at least 05:00 AEST tomorrow (forecast range -$64 to -$8/MWh), consistent with the demand collapse pattern seen last night where SA demand fell to sub-100 MW by 03:00-04:00 AEST. Traders should note the active AEMO market intervention notice for foreseeable voltage-related dispatch from 23:00 AEST tonight, plus a standing Minimum System Load (MSL1) advisory flagging forecast negative demand (as low as -178 MW) for 19 September — a reminder that SA's low-demand overnight troughs are increasingly testing system security limits, not just price floors. Carbon intensity is currently 0.0585 tCO2/MWh with renewable penetration at 89.24%, both set to improve further as gas backs off overnight.